Cyclam Derivatives with a Bis(phosphinate) or a Phosphinato-Phosphonate Pendant Arm: Ligands for Fast and Efficient Copper(II) Complexation for Nuclear Medical Applications.

PubMed

David, Tomáš; Kubíček, Vojtěch; Gutten, Ondrej; Lubal, Přemysl; Kotek, Jan; Pietzsch, Hans-Jürgen; Rulíšek, Lubomír; Hermann, Petr

2015-12-21

Cyclam derivatives bearing one geminal bis(phosphinic acid), -CH2PO2HCH2PO2H2 (H2L(1)), or phosphinic-phosphonic acid, -CH2PO2HCH2PO3H2 (H3L(2)), pendant arm were synthesized and studied as potential copper(II) chelators for nuclear medical applications. The ligands showed good selectivity for copper(II) over zinc(II) and nickel(II) ions (log KCuL = 25.8 and 27.7 for H2L(1) and H3L(2), respectively). Kinetic study revealed an unusual three-step complex formation mechanism. The initial equilibrium step leads to out-of-cage complexes with Cu(2+) bound by the phosphorus-containing pendant arm. These species quickly rearrange to an in-cage complex with cyclam conformation II, which isomerizes to another in-cage complex with cyclam conformation I. The first in-cage complex is quantitatively formed in seconds (pH ≈5, 25 °C, Cu:L = 1:1, cM ≈ 1 mM). At pH >12, I isomers undergo nitrogen atom inversion, leading to III isomers; the structure of the III-[Cu(HL(2))] complex in the solid state was confirmed by X-ray diffraction analysis. In an alkaline solution, interconversion of the I and III isomers is mutual, leading to the same equilibrium isomeric mixture; such behavior has been observed here for the first time for copper(II) complexes of cyclam derivatives. Quantum-chemical calculations showed small energetic differences between the isomeric complexes of H3L(2) compared with analogous data for isomeric complexes of cyclam derivatives with one or two methylphosphonic acid pendant arm(s). Acid-assisted dissociation proved the kinetic inertness of the complexes. Preliminary radiolabeling of H2L(1) and H3L(2) with (64)Cu was fast and efficient, even at room temperature, giving specific activities of around 70 GBq of (64)Cu per 1 μmol of the ligand (pH 6.2, 10 min, ca. 90 equiv of the ligand). These specific activities were much higher than those of H3nota and H4dota complexes prepared under identical conditions. The rare combination of simple ligand synthesis, very

Design, Synthesis, and Biological Evaluation of Benzimidazole-Derived Biocompatible Copper(II) and Zinc(II) Complexes as Anticancer Chemotherapeutics

PubMed Central

AlAjmi, Mohamed F.; Hussain, Afzal; Khan, Azmat Ali; Shaikh, Perwez Alam; Khan, Rais Ahmad

2018-01-01

Herein, we have synthesized and characterized a new benzimidazole-derived “BnI” ligand and its copper(II) complex, [Cu(BnI)2], 1, and zinc(II) complex, [Zn(BnI)2], 2, using elemental analysis and various spectroscopic techniques. Interaction of complexes 1 and 2 with the biomolecules viz. HSA (human serum albumin) and DNA were studied using absorption titration, fluorescence techniques, and in silico molecular docking studies. The results exhibited the significant binding propensity of both complexes 1 and 2, but complex 1 showed more avid binding to HSA and DNA. Also, the nuclease activity of 1 and 2 was analyzed for pBR322 DNA, and the results obtained confirmed the potential of the complexes to cleave DNA. Moreover, the mechanistic pathway was studied in the presence of various radical scavengers, which revealed that ROS (reactive oxygen species) are responsible for the nuclease activity in complex 1, whereas in complex 2, the possibility of hydrolytic cleavage also exists. Furthermore, the cytotoxicity of the ligand and complexes 1 and 2 were studied on a panel of five different human cancer cells, namely: HepG2, SK-MEL-1, HT018, HeLa, and MDA-MB 231, and compared with the standard drug, cisplatin. The results are quite promising against MDA-MB 231 (breast cancer cell line of 1), with an IC50 value that is nearly the same as the standard drug. Apoptosis was induced by complex 1 on MDA-MB 231 cells predominantly as studied by flow cytometry (FACS). The adhesion and migration of cancer cells were also examined upon treatment of complexes 1 and 2. Furthermore, the in vivo chronic toxicity profile of complexes 1 and 2 was also studied on all of the major organs of the mice, and found them to be less toxic. Thus, the results warrant further investigations of complex 1. PMID:29772746

Design, Synthesis, and Biological Evaluation of Benzimidazole-Derived Biocompatible Copper(II) and Zinc(II) Complexes as Anticancer Chemotherapeutics.

PubMed

AlAjmi, Mohamed F; Hussain, Afzal; Rehman, Md Tabish; Khan, Azmat Ali; Shaikh, Perwez Alam; Khan, Rais Ahmad

2018-05-16

Herein, we have synthesized and characterized a new benzimidazole-derived "BnI" ligand and its copper(II) complex, [Cu(BnI)₂], 1 , and zinc(II) complex, [Zn(BnI)₂], 2 , using elemental analysis and various spectroscopic techniques. Interaction of complexes 1 and 2 with the biomolecules viz. HSA (human serum albumin) and DNA were studied using absorption titration, fluorescence techniques, and in silico molecular docking studies. The results exhibited the significant binding propensity of both complexes 1 and 2 , but complex 1 showed more avid binding to HSA and DNA. Also, the nuclease activity of 1 and 2 was analyzed for pBR322 DNA, and the results obtained confirmed the potential of the complexes to cleave DNA. Moreover, the mechanistic pathway was studied in the presence of various radical scavengers, which revealed that ROS (reactive oxygen species) are responsible for the nuclease activity in complex 1 , whereas in complex 2 , the possibility of hydrolytic cleavage also exists. Furthermore, the cytotoxicity of the ligand and complexes 1 and 2 were studied on a panel of five different human cancer cells, namely: HepG2, SK-MEL-1, HT018, HeLa, and MDA-MB 231, and compared with the standard drug, cisplatin. The results are quite promising against MDA-MB 231 (breast cancer cell line of 1 ), with an IC 50 value that is nearly the same as the standard drug. Apoptosis was induced by complex 1 on MDA-MB 231 cells predominantly as studied by flow cytometry (FACS). The adhesion and migration of cancer cells were also examined upon treatment of complexes 1 and 2 . Furthermore, the in vivo chronic toxicity profile of complexes 1 and 2 was also studied on all of the major organs of the mice, and found them to be less toxic. Thus, the results warrant further investigations of complex 1 .

Mechano-switchable, luminescent gels derived from salts of a long-chained, fatty-acid gelator.

PubMed

Zhang, Mohan; Weiss, Richard G

2016-07-27

Stimulus-responsive molecular gel systems, based on metal salts of a luminescent gelator, 9,10-dioxooctadecanoic acid (DODA), are reported. These salts are structurally the simplest metallo-gelators of which we are aware that exhibit controllable mechano-responsive and luminescent properties. Aggregation is more favored by the metal salts than for DODA itself. However, gelation ability differs dramatically depending on the metal ion: whereas the salts with zinc(ii) and calcium(ii) are inefficient gelators, those with nickel(ii) and copper(ii) can gelate various aromatic liquids, alkanes, and long-chained alcohols. Unlike the DODA gels, no aggregation-induced shift in the positions of the emission spectra of the metal salts could be observed as the sols were transformed to their gel phases. Gels of both nickel(ii) and copper(ii) salts in benzonitrile are among the few known examples with crystalline networks and exhibiting thixotropic behavior. However, there are significant differences in their abilities to recover the initial viscoelastic properties. Structural data for the solid and gel states lead us to conclude that differences among the gelating abilities can be attributed principally to the specific nature of interactions of the salts at their head groups. They appear to control the mechanical and emissive properties of the gels as well as whether the initial aggregation of the salts in the sol phases will support the growth of 1D objects that are capable of maintaining strong contacts, leading to 3D networks and gel formation. Overall, the results provide a facile strategy for the design of luminescent materials with controllable mechano-responsiveness by modifying the metal ions within fibrillar assemblies.

Theoretical investigation, biological evaluation and VEGFR2 kinase studies of metal(II) complexes derived from hydrotris(methimazolyl)borate.

PubMed

Jayakumar, S; Mahendiran, D; Srinivasan, T; Mohanraj, G; Kalilur Rahiman, A

2016-02-01

The reaction of soft tripodal scorpionate ligand, sodium hydrotris(methimazolyl)borate with M(ClO4)2·6H2O [MMn(II), Ni(II), Cu(II) or Zn(II)] in methanol leads to the cleavage of B-N bond followed by the formation of complexes of the type [M(MeimzH)4](ClO4)2·H2O (1-4), where MeimzH=methimazole. All the complexes were fully characterized by spectro-analytical techniques. The molecular structure of the zinc(II) complex (4) was determined by X-ray crystallography, which supports the observed deboronation reaction in the scorpionate ligand with tetrahedral geometry around zinc(II) ion. The electronic spectra of complexes suggested tetrahedral geometry for manganese(II) and nickel(II) complexes, and square-planar geometry for copper(II) complex. Frontier molecular orbital analysis (HOMO-LUMO) was carried out by B3LYP/6-31G(d) to understand the charge transfer occurring in the molecules. All the complexes exhibit significant antimicrobial activity against Gram (-ve) and Gram (+ve) bacterial as well as fungal strains, which are quite comparable to standard drugs streptomycin and clotrimazole. The copper(II) complex (3) showed excellent free radical scavenging activity against DPPH in all concentration with IC50 value of 30μg/mL, when compared to the other complexes. In the molecular docking studies, all the complexes showed hydrophobic, π-π and hydrogen bonding interactions with BSA. The cytotoxic activity of the complexes against human hepatocellular liver carcinoma (HepG2) cells was assessed by MTT assay, which showed exponential responses toward increasing concentration of complexes. Copyright © 2015 Elsevier B.V. All rights reserved.

LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes.

PubMed

Economou, Anastasios; Voulgaropoulos, Anastasios

2003-01-01

The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV.

LabVIEW-based sequential-injection analysis system for the determination of trace metals by square-wave anodic and adsorptive stripping voltammetry on mercury-film electrodes

PubMed Central

Economou, Anastasios; Voulgaropoulos, Anastasios

2003-01-01

The development of a dedicated automated sequential-injection analysis apparatus for anodic stripping voltammetry (ASV) and adsorptive stripping voltammetry (AdSV) is reported. The instrument comprised a peristaltic pump, a multiposition selector valve and a home-made potentiostat and used a mercury-film electrode as the working electrodes in a thin-layer electrochemical detector. Programming of the experimental sequence was performed in LabVIEW 5.1. The sequence of operations included formation of the mercury film, electrolytic or adsorptive accumulation of the analyte on the electrode surface, recording of the voltammetric current-potential response, and cleaning of the electrode. The stripping step was carried out by applying a square-wave (SW) potential-time excitation signal to the working electrode. The instrument allowed unattended operation since multiple-step sequences could be readily implemented through the purpose-built software. The utility of the analyser was tested for the determination of copper(II), cadmium(II), lead(II) and zinc(II) by SWASV and of nickel(II), cobalt(II) and uranium(VI) by SWAdSV. PMID:18924623

Photochemical studies and nanomolar photodynamic activities of phthalocyanines functionalized with 1,4,7-trioxanonyl moieties at their non-peripheral positions.

PubMed

Sobotta, Lukasz; Wierzchowski, Marcin; Mierzwicki, Michal; Gdaniec, Zofia; Mielcarek, Jadwiga; Persoons, Leentje; Goslinski, Tomasz; Balzarini, Jan

2016-02-01

Manganese(III), cobalt(II), copper(II), magnesium(II), zinc(II) and metal-free phthalocyanines, possessing 1,4,7-trioxanonyl substituents, at their non-peripheral positions, were subjected to photochemical, photodynamic and biological activity studies. Demetallated phthalocyanine and its metallated d-block analogues, with copper(II), cobalt(II), manganese(III) chloride, were found to be less efficient singlet oxygen generators in comparison to the zinc(II) analogue and zinc(II) phthalocyanine reference. Irradiation of several phthalocyanines for short time periods resulted in a substantially increased cytostatic activity against both suspension (leukemic/lymphoma at 85nM) and solid (cervix carcinoma at 72nM and melanoma at 81nM) tumour cell lines (up to 200-fold). Noteworthy is that enveloped viruses, such as for herpesvirus and influenza A virus, but not, non-enveloped virus strains, such as Coxsackie B4 virus and reovirus-1, exposed to irradiation in the presence of the phthalocyanines, markedly lost their infectivity potential. Copyright © 2015 Elsevier Inc. All rights reserved.

Production of High-Purity Anhydrous Nickel(II) Perrhenate for Tungsten-Based Sintered Heavy Alloys

PubMed Central

Leszczyńska-Sejda, Katarzyna; Benke, Grzegorz; Kopyto, Dorota; Majewski, Tomasz; Drzazga, Michał

2017-01-01

This paper presents a method for the production of high-purity anhydrous nickel(II) perrhenate. The method comprises sorption of nickel(II) ions from aqueous nickel(II) nitrate solutions, using strongly acidic C160 cation exchange resin, and subsequent elution of sorbed nickel(II) ions using concentrated perrhenic acid solutions. After the neutralization of the resulting rhenium-nickel solutions, hydrated nickel(II) perrhenate is then separated and then dried at 160 °C to obtain the anhydrous form. The resulting compound is reduced in an atmosphere of dissociated ammonia in order to produce a Re-Ni alloy powder. This study provides information on the selected properties of the resulting Re-Ni powder. This powder was used as a starting material for the production of 77W-20Re-3Ni heavy alloys. Microstructure examination results and selected properties of the produced sintered heavy alloys were compared to sintered alloys produced using elemental W, Re, and Ni powders. This study showed that the application of anhydrous nickel(II) perrhenate in the production of 77W-20Re-3Ni results in better properties of the sintered alloys compared to those made from elemental powders. PMID:28772808

Monitoring of trace amounts of heavy metals in different food and water samples by flame atomic absorption spectrophotometer after preconcentration by amine-functionalized graphene nanosheet.

PubMed

Behbahani, Mohammad; Tapeh, Nasim Akbari Ghareh; Mahyari, Mojtaba; Pourali, Ali Reza; Amin, Bahareh Golrokh; Shaabani, Ahmad

2014-11-01

We are introducing graphene oxide modified with amine groups as a new solid phase for extraction of heavy metal ions including cadmium(II), copper(II), nickel(II), zinc(II), and lead(II). Effects of pH value, flow rates, type, concentration, and volume of the eluent, breakthrough volume, and the effect of potentially interfering ions were studied. Under optimized conditions, the extraction efficiency is >97 %, the limit of detections are 0.03, 0.05, 0.2, 0.1, and 1 μg L(-1) for the ions of cadmium, copper, nickel, zinc, and lead, respectively, and the adsorption capacities for these ions are 178, 142, 110, 125, and 210 mg g(-1). The amino-functionalized graphene oxide was characterized by thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectrometry. The proposed method was successfully applied in the analysis of environmental water and food samples. Good spiked recoveries over the range of 95.8-100.0 % were obtained. This work not only proposes a useful method for sample preconcentration but also reveals the great potential of modified graphene as an excellent sorbent material in analytical processes.

Preparation and adsorption characteristics for heavy metals of active silicon adsorbent from leaching residue of lead-zinc tailings.

PubMed

Lei, Chang; Yan, Bo; Chen, Tao; Xiao, Xian-Ming

2018-05-19

To comprehensively reuse the leaching residue obtained from lead-zinc tailings, an active silicon adsorbent (ASA) was prepared from leaching residue and studied as an adsorbent for copper(II), lead(II), zinc(II), and cadmium(II) in this paper. The ASA was prepared by roasting the leaching residue with either a Na 2 CO 3 /residue ratio of 0.6:1 at 700 °C for 1 h or a CaCO 3 /residue ratio of 0.8:1 at 800 °C for 1 h. Under these conditions, the available SiO 2 content of the ASA was more than 20%. The adsorption behaviors of the metal ions onto the ASA were investigated and the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were used to analyze the adsorption isotherm. The result showed that the maximum adsorption capacities of copper(II), lead(II), cadmium(II), and zinc(II) calculated by the Langmuir model were 3.40, 2.83, 0.66, and 0.62 mmol g -1 , respectively. The FT-IR spectra of the ASA and the mean free adsorption energies indicated that ion exchange was the mechanism of copper(II), lead(II), and cadmium(II) adsorption and that chemical reaction was the mechanism of zinc(II) adsorption. These results provide a method for reusing the leaching residue obtained from lead-zinc tailings and show that the ASA is an effective adsorbent for heavy metal pollution remediation.

Elementary sulfur in effluent from denitrifying sulfide removal process as adsorbent for zinc(II).

PubMed

Chen, Chuan; Zhou, Xu; Wang, Aijie; Wu, Dong-hai; Liu, Li-hong; Ren, Nanqi; Lee, Duu-Jong

2012-10-01

The denitrifying sulfide removal (DSR) process can simultaneously convert sulfide, nitrate and organic compounds into elementary sulfur (S(0)), di-nitrogen gas and carbon dioxide, respectively. However, the S(0) formed in the DSR process are micro-sized colloids with negatively charged surface, making isolation of S(0) colloids from other biological cells and metabolites difficult. This study proposed the use of S(0) in DSR effluent as a novel adsorbent for zinc removal from wastewaters. Batch and continuous tests were conducted for efficient zinc removal with S(0)-containing DSR effluent. At pH<7.5, removal rates of zinc(II) were increased with increasing pH. The formed S(0) colloids carried negative charge onto which zinc(II) ions could be adsorbed via electrostatic interactions. The zinc(II) adsorbed S(0) colloids further enhanced coagulation-sedimentation efficiency of suspended solids in DSR effluents. The DSR effluent presents a promising coagulant for zinc(II) containing wastewaters. Copyright © 2012 Elsevier Ltd. All rights reserved.

An in vitro study of interactions between insulin-mimetic zinc(II) complexes and selected plasma components.

PubMed

Enyedy, Eva Anna; Horváth, László; Gajda-Schrantz, Krisztina; Galbács, Gábor; Kiss, Tamás

2006-12-01

The speciations of some potent insulin-mimetic zinc(II) complexes of bidentate ligands: maltol and 1,2-dimethyl-3-hydroxypyridinone with (O,O) and picolinic acid with (N,O) coordination modes, were studied via solution equilibrium investigations of the ternary complex formation in the presence of small relevant bioligands of the blood serum such as cysteine, histidine and citric acid. Results show that formation of the ternary complexes, especially with cysteine, is favoured at physiological pH range in almost all systems studied. Besides these low molecular mass binders, serum proteins among others albumin and transferrin can bind zinc(II) or its complexes. Accordingly, the distribution of zinc(II) between the small and high molecular mass fractions of the serum was also studied by ultrafiltration. Modelling calculations relating to the distribution of zinc(II), using the stability constants of the ternary complexes studied and those of the serum proteins reported in the literature, confirmed the ultrafiltration results, namely, the primary role of albumin in zinc(II) binding among the low and high molecular mass components of the serum.

Flotation-separation and ICP-AES determination of ultra trace amounts of copper, cadmium, nickel and cobalt using 2-aminocyclopentene-1-dithiocarboxylic acid.

PubMed

Shamsipur, Mojtaba; Hashemi, Omid Reza; Safavi, Afsaneh

2005-09-01

A rapid flotation method for separation and enrichment of ultra trace amounts of copper(II), cadmium(II), nickel(II) and cobalt(II) ions from water samples is established. At pH 6.5 and with sodium dodecylsulfate used as a foaming reagent, Cu2+, Cd2+, Ni2+ and Co2+ were separated simultaneously with 2-aminocyclopentene-1-dithiocarboxylic acid (ACDA) added to 1 l of aqueous solution. The proposed procedure of preconcentration is applied prior to the determination of these four analytes using inductivity coupled plasma-atomic emission spectrometry (ICP-AES). The effects of pH, concentration of ACDA, applicability of different surfactants and foreign ions on the separation efficiency were investigated. The preconcentration factor of the method is 1000 and the detection limits of copper(II), cadmium(II), nickel(II) and cobalt(II) ions are 0.078, 0.075, 0.072 and 0.080 ng ml(-1), respectively.

Synthesis, spectral and magnetic studies of mono- and bi-nuclear metal complexes of a new bis(tridentate NO2) Schiff base ligand derived from 4,6-diacetylresorcinol and ethanolamine.

PubMed

Shebl, Magdy

2009-07-15

A new bis(tridentate NO2) Schiff base ligand, H(4)L, was prepared by the reaction of the bifunctional carbonyl compound; 4,6-diacetylresorcinol (DAR) with ethanolamine. The ligand reacted with iron(III), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), cerium(III) and uranyl(VI) ions, in absence and in presence of LiOH, to yield mono- and bi-nuclear complexes with different coordinating sites. The ligand and its metal complexes were characterized by elemental analyses, IR, (1)H NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. In absence of LiOH, mononuclear complexes (2, 3 and 5-9) as well as binuclear complexes (1 and 4) were obtained. In mononuclear complexes, the ligand acted as a neutral, mono- and di-basic/bi- and tetra-dentate ligand while in binuclear complexes (1 and 4), the ligand acted as a bis(mono- or di-basic/tridentate) ligand. On the other hand, in presence of LiOH, only binuclear complexes (10-15) were obtained in which the ligand acted as a bis(dibasic tridentate) ligand. The metal complexes exhibited different geometrical arrangements such as octahedral, tetrahedral, square planar, square pyramidal and pentagonal bipyramidal arrangements.

Template engineered biopotent macrocyclic complexes involving furan moiety: Molecular modeling and molecular docking

NASA Astrophysics Data System (ADS)

Rathi, Parveen; Singh, D. P.

2015-08-01

Bioactive cobalt(II), nickel(II), copper(II) and zinc(II) complexes of octaazamacrocycle, 19, 20-dioxa-2,3,5,6,11,12,14,15-octaazatricyclo[14.2.1.1]icosa-1,6,8,10,15,17-hexaene-4,13-dithione, derived from furan-2,5-dione and thiocarbonohydrazide in the mole ratio 2:2:1 have been engineered via template methodology. The synthesized metal complexes have also been structurally characterized in the light of various physicochemical techniques and evaluated for antimicrobial and antioxidant activities. All these studies point toward the formation of divalent macrocyclic complexes possessing distorted octahedral geometry and having significant antimicrobial and antioxidant properties as compared to the starting precursors. Virtual screening of a representative complex was done through docking to the binding site of COX-2 to evaluate the anti-inflammatory activity of the series. Non-electrolytic nature of the complexes has been predicted on the basis of low value of molar conductivity in DMSO. All the complexes were having notable activities against pathogenic microbes as compared to precursors-thiocarbonohydrazide and furan-2,5-dione however, the complex 5, [Ni (C10H8N8O2S2) (NO3)2], shows the best antimicrobial activity.

Indirect electroreductive cyclization and electrohydrocyclization using catalytic reduced nickel(II) salen.

PubMed

Miranda, James A; Wade, Carolyn J; Little, R Daniel

2005-09-30

[Chemical reaction: See text] We describe efforts to achieve the electroreductive cyclization (ERC) and the electrohydrocyclization (EHC) reactions using catalytic nickel(II) salen as a mediator. While nickel(II) salen proved effective, the analogous cobalt complex as well as nickel(II) cyclam were not. The transformations were achieved in yields ranging from 60 to 94% using either a mercury pool or an environmentally preferable reticulated vitreous carbon (RVC) cathode. These examples represent the first instances wherein a nickel salen complex has been used in this manner. Clear differences between the voltammetric behavior of the ERC and EHC substrates were observed. The bisenoate 14, for example, displays a substantially larger catalytic current. When the structurally modified mediator 31 was used, the electron-transfer pathway shuts down. Instead, the reduced form of 31 behaves as an electrogenerated base, leading to the formation of the intramolecular Michael adduct 23. Presumably, the methyl groups of the modified ligand diminish the ability of the reduced form of the complex to serve as a nucleophile but not as a base. Aldehyde 23 was also characterized as a side product of the nickel(II) salen mediated electroreductive cyclization of 11. Given that it is absent from nonmediated processes, its formation is linked to the presence of the mediator. To account for the results, we favor the existence of a mechanistic continuum involving an equilibrium between nickel(II) salen (15) and two reduced forms, one being the metal-centered species 16, the other being a ligand-centered species 17. We postulate that one form may be more prominently involved with the chemistry than another, depending upon the electronic properties/requirements of the substrate, and suggest that the equilibrium will shift to accommodate the need. Thus, for a hard electrophile like an alkyl halide, the properties of 16 ought to dominate, whereas 17 ought to predominate as the reactive

Synthesis and Characterization of Dimethylbis(2-pyridyl)borate Nickel(II) Complexes: Unimolecular Square-Planar to Square-Planar Rotation around Nickel(II)

PubMed Central

2015-01-01

The syntheses of novel dimethylbis(2-pyridyl)borate nickel(II) complexes 4 and 6 are reported. These complexes were unambiguously characterized by X-ray analysis. In dichloromethane solvent, complex 4 undergoes a unique square-planar to square-planar rotation around the nickel(II) center, for which activation parameters of ΔH⧧ = 12.2(1) kcal mol–1 and ΔS⧧ = 0.8(5) eu were measured via NMR inversion recovery experiments. Complex 4 was also observed to isomerize via a relatively slow ring flip: ΔH⧧ = 15.0(2) kcal mol–1; and ΔS⧧ = −4.2(7) eu. DFT studies support the experimentally measured rotation activation energy (cf. calculated ΔH⧧ = 11.1 kcal mol–1) as well as the presence of a high-energy triplet intermediate (ΔH = 8.8 kcal mol–1). PMID:24882919

Homoleptic nickel(II) complexes of redox-tunable pincer-type ligands.

PubMed

Hewage, Jeewantha S; Wanniarachchi, Sarath; Morin, Tyler J; Liddle, Brendan J; Banaszynski, Megan; Lindeman, Sergey V; Bennett, Brian; Gardinier, James R

2014-10-06

Different synthetic methods have been developed to prepare eight new redox-active pincer-type ligands, H(X,Y), that have pyrazol-1-yl flanking donors attached to an ortho-position of each ring of a diarylamine anchor and that have different groups, X and Y, at the para-aryl positions. Together with four previously known H(X,Y) ligands, a series of 12 Ni(X,Y)2 complexes were prepared in high yields by a simple one-pot reaction. Six of the 12 derivatives were characterized by single-crystal X-ray diffraction, which showed tetragonally distorted hexacoordinate nickel(II) centers. The nickel(II) complexes exhibit two quasi-reversible one-electron oxidation waves in their cyclic voltammograms, with half-wave potentials that varied over a remarkable 700 mV range with the average of the Hammett σ(p) parameters of the para-aryl X, Y groups. The one- and two-electron oxidized derivatives [Ni(Me,Me)2](BF4)n (n = 1, 2) were prepared synthetically, were characterized by X-band EPR, electronic spectroscopy, and single-crystal X-ray diffraction (for n = 2), and were studied computationally by DFT methods. The dioxidized complex, [Ni(Me,Me)2](BF4)2, is an S = 2 species, with nickel(II) bound to two ligand radicals. The mono-oxidized complex [Ni(Me,Me)2](BF4), prepared by comproportionation, is best described as nickel(II) with one ligand centered radical. Neither the mono- nor the dioxidized derivative shows any substantial electronic coupling between the metal and their bound ligand radicals because of the orthogonal nature of their magnetic orbitals. On the other hand, weak electronic communication occurs between ligands in the mono-oxidized complex as evident from the intervalence charge transfer (IVCT) transition found in the near-IR absorption spectrum. Band shape analysis of the IVCT transition allowed comparisons of the strength of the electronic interaction with that in the related, previously known, Robin-Day class II mixed valence complex, [Ga(Me,Me)2](2+).

Nickel(ii) inhibits the oxidation of DNA 5-methylcytosine in mammalian somatic cells and embryonic stem cells.

PubMed

Yin, Ruichuan; Mo, Jiezhen; Dai, Jiayin; Wang, Hailin

2018-03-01

Nickel is found widely in the environment. It is an essential microelement but also toxic. However, nickel displays only weak genotoxicity and mutagenicity. Exploration of the epigenetic toxicity of nickel is extremely interesting. Iron(ii)- and 2-oxoglutarate-dependent Tet dioxygenases are a class of epigenetic enzymes that catalyze the oxidation of DNA 5-methylcytosine (5mC). Thus, they are critical for DNA demethylation and, importantly, are involved with nuclear reprogramming, embryonic development, and regulation of gene expression. Here, we demonstrated that nickel(ii) dramatically inhibits Tet proteins-mediated oxidation of DNA 5mC in cells ranging from somatic cell lines to embryonic stem cells, as manifested by the consistent observation of a significant decrease in 5-hydroxymethylcytosine, a critical intermediate resulting from the oxidation of 5mC. The inhibitory effects of nickel(ii) were concentration- and time-dependent. Using HEK293T cells overexpressing Tet proteins and ascorbic acid-stimulated Tet-proficient ES cells, we observed that nickel(ii) significantly reduced DNA demethylation at the global level. Interestingly, we also showed that nickel(ii) might affect the naïve or ground state of pluripotent embryonic stem cells. Here we show, for the first time, that nickel(ii) represses the oxidation of DNA 5mC and potentially alters the Tet proteins-regulated DNA methylation landscape in human cells. These findings provide new insights into the epigenetic toxicology of nickel.

Reversible double oxidation and protonation of the non-innocent bridge in a nickel(II) salophen complex.

PubMed

de Bellefeuille, David; Askari, Mohammad S; Lassalle-Kaiser, Benedikt; Journaux, Yves; Aukauloo, Ally; Orio, Maylis; Thomas, Fabrice; Ottenwaelder, Xavier

2012-12-03

Substitution on the aromatic bridge of a nickel(II) salophen complex with electron-donating dimethylamino substituents creates a ligand with three stable, easily and reversibly accessible oxidation states. The one-electron-oxidized product is characterized as a nickel(II) radical complex with the radical bore by the central substituted aromatic ring, in contrast to other nickel(II) salen or salophen complexes that oxidize on the phenolate moieties. The doubly oxidized product, a singlet species, is best described as having an iminobenzoquinone bridge with a vinylogous distribution of bond lengths between the dimethylamino substituents. Protonation of the dimethylamino substituents inhibits these redox processes on the time scale of cyclovoltammetry, but electrolysis and chemical oxidation are consistent with deprotonation occurring concomitantly with electron transfer to yield the mono- and dioxidized species described above.

Synthetic bioactive novel ether based Schiff bases and their copper(II) complexes

NASA Astrophysics Data System (ADS)

Shabbir, Muhammad; Akhter, Zareen; Ismail, Hammad; Mirza, Bushra

2017-10-01

Novel ether based Schiff bases (HL1- HL4) were synthesized from 5-chloro-2-hydroxy benzaldehyde and primary amines (1-amino-4-phenoxybenzene, 4-(4-aminophenyloxy) biphenyl, 1-(4-aminophenoxy) naphthalene and 2-(4-aminophenoxy) naphthalene). From these Schiff bases copper(II) complexes (Cu(L1)2-Cu(L4)2)) were synthesized and characterized by elemental analysis and spectroscopic (FTIR, NMR) techniques. The synthesized Schiff bases and copper(II) complexes were further assessed for various biological studies. In brine shrimp assay the copper(II) complexes revealed 4-fold higher activity (LD50 3.8 μg/ml) as compared with simple ligands (LD50 12.4 μg/ml). Similar findings were observed in potato disc antitumor assay with higher activities for copper(II) complexes (IC50 range 20.4-24.1 μg/ml) than ligands (IC50 range 40.5-48.3 μg/ml). DPPH assay was performed to determine the antioxidant potential of the compounds. Significant antioxidant activity was shown by the copper(II) complexes whereas simple ligands have shown no activity. In DNA protection assay significant protection behavior was exhibited by simple ligand molecules while copper(II) complexes showed neutral behavior (neither protective nor damaging).

Determining the Amount of Copper(II) Ions in a Solution Using a Smartphone

ERIC Educational Resources Information Center

Montangero, Marc

2015-01-01

When dissolving copper in nitric acid, copper(II) ions produce a blue-colored solution. It is possible to determine the concentration of copper(II) ions, focusing on the hue of the color, using a smartphone camera. A free app can be used to measure the hue of the solution, and with the help of standard copper(II) solutions, one can graph a…

Synthesis of asymmetric zinc(II) phthalocyanines with two different functional groups & spectroscopic properties and photodynamic activity for photodynamic therapy.

PubMed

Göksel, Meltem

2016-09-15

Zinc(II) phthalocyanine containing [2-(tert-butoxycarbonyl)amino]ethoxy and iodine groups (A and B), as well as their deprotected mono-amino and tri-iodine zinc(II) phthalocyanine (2) were obtained. This structure surrounds by substituents with functional groups. From this perspective it can be used a starting material for many reactions and applications, such as sonogashira coupling, carbodiimide coupling. An example of a first diversification reaction of this compound was obtained with conjugation of a biotin. Asymmetrically biotin conjugated and heavy atom bearing zinc(II) phthalocyanine (3) were synthesized characterized for the first time and photophysical, photochemical and photobiological properties of these phthalocyanines were compared in this study. Copyright © 2016 Elsevier Ltd. All rights reserved.

Investigation of the interaction of copper(II) oxide and electron beam irradiation crosslinkable polyethylene

NASA Astrophysics Data System (ADS)

Bee, Soo-Tueen; Sin, Lee Tin; Ratnam, C. T.; Haraveen, K. J. S.; Tee, Tiam-Ting; Rahmat, A. R.

2015-10-01

In this study, the effects of electron beam irradiation on the properties of copper(II) oxide when added to low-density polyethylene (LDPE) blends were investigated. It was found that the addition of low loading level of copper(II) oxide (⩽2 phr) to LDPE results in significantly poorer gel content and hot set results. However, the incorporation of higher loading level of copper(II) oxide (⩾3 phr) could slightly increase the degree of crosslinking in all irradiated LDPE composites. This is due to the fact that higher amounts of copper(II) oxide could slightly induce the formation of free radicals in LDPE matrix. Besides, increasing irradiation doses was also found to gradually increase the gel content of LDPE composites by generating higher amounts of free radicals. As a consequence, these higher amounts of free radicals released in the LDPE matrix could significantly increase the degree of crosslinking. The addition of copper(II) oxide could reduce the tensile strength and fracture strain (elongation at break) of LDPE composites because of poorer interfacial adhesion effect between copper(II) oxide particles and LDPE matrix. Meanwhile, increasing irradiation doses on all copper(II) oxide added LDPE composites could marginally increase the tensile strength. In addition, increasing irradiation dose could enhance the thermal stability of LDPE composites by increasing the decomposition temperature. The oxidation induction time (OIT) analysis showed that, because of the crosslinking network in the copper(II) oxide added LDPE composites, oxidation reaction is much delayed.

Polymers containing nickel(II) complexes of Goedken's macrocycle: optimized synthesis and electrochemical characterization.

PubMed

Paquette, Joseph A; Sauvé, Ethan R; Gilroy, Joe B

2015-04-01

The synthesis and characterization of a new class of nickel-containing polymers is described. The optimized copolymerization of alkyne-bearing nickel(II) complexes of Goedken's macrocycle (4,11-dihydro-5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine) and brominated 9,9-dihexylfluorene produced polymers with potential application as functional redox-active materials. The title polymers exhibit electrochemically reversible, ligand-centered oxidation events at 0.24 and 0.73 V versus the ferrocene/ferrocenium redox couple. They also display exceptional thermal stability and interesting absorption properties due to the presence of the macrocyclic nickel(II) complexes and π-conjugated units incorporated in their backbones. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural basis for bifunctional zinc(II) macrocyclic complex recognition of thymine bulges in DNA.

PubMed

del Mundo, Imee Marie A; Siters, Kevin E; Fountain, Matthew A; Morrow, Janet R

2012-05-07

The zinc(II) complex of 1-(4-quinoylyl)methyl-1,4,7,10-tetraazacyclododecane (cy4q) binds selectively to thymine bulges in DNA and to a uracil bulge in RNA. Binding constants are in the low-micromolar range for thymine bulges in the stems of hairpins, for a thymine bulge in a DNA duplex, and for a uracil bulge in an RNA hairpin. Binding studies of Zn(cy4q) to a series of hairpins containing thymine bulges with different flanking bases showed that the complex had a moderate selectivity for thymine bulges with neighboring purines. The dissociation constants of the most strongly bound Zn(cy4q)-DNA thymine bulge adducts were 100-fold tighter than similar sequences with fully complementary stems or than bulges containing cytosine, guanine, or adenine. In order to probe the role of the pendent group, three additional zinc(II) complexes containing 1,4,7,10-tetraazacyclododecane (cyclen) with aromatic pendent groups were studied for binding to DNA including 1-(2-quinolyl)methyl-1,4,7,10-tetraazacyclododecane (cy2q), 1-(4-biphenyl)methyl-1,4,7,10-tetraazacyclododecane (cybp), and 5-(1,4,7,10-tetraazacyclododecan-1-ylsulfonyl)-N,N-dimethylnaphthalen-1-amine (dsc). The Zn(cybp) complex binds with moderate affinity but little selectivity to DNA hairpins with thymine bulges and to DNA lacking bulges. Similarly, Zn(dsc) binds weakly both to thymine bulges and hairpins with fully complementary stems. The zinc(II) complex of cy2q has the 2-quinolyl moiety bound to the Zn(II) center, as shown by (1)H NMR spectroscopy and pH-potentiometric titrations. As a consequence, only weak (500 μM) binding is observed to DNA with no appreciable selectivity. An NMR structure of a thymine-bulge-containing hairpin shows that the thymine is extrahelical but rotated toward the major groove. NMR data for Zn(cy4q) bound to DNA containing a thymine bulge is consistent with binding of the zinc(II) complex to the thymine N3(-) and stacking of the quinoline on top of the thymine. The thymine-bulge bound

Phosphate effects on copper(II) and lead(II) sorption to ferrihydrite

NASA Astrophysics Data System (ADS)

Tiberg, Charlotta; Sjöstedt, Carin; Persson, Ingmar; Gustafsson, Jon Petter

2013-11-01

Transport of lead(II) and copper(II) ions in soil is affected by the soil phosphorus status. Part of the explanation may be that phosphate increases the adsorption of copper(II) and lead(II) to iron (hydr)oxides in soil, but the details of these interactions are poorly known. Knowledge about such mechanisms is important, for example, in risk assessments of contaminated sites and development of remediation methods. We used a combination of batch experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy and surface complexation modeling with the three-plane CD-MUSIC model to study the effect of phosphate on sorption of copper(II) and lead(II) to ferrihydrite. The aim was to identify the surface complexes formed and to derive constants for the surface complexation reactions. In the batch experiments phosphate greatly enhanced the adsorption of copper(II) and lead(II) to ferrihydrite at pH < 6. The largest effects were seen for lead(II).

Synthesis and characterization of two new zinc(II) coordination polymers with bidentate flexible ligands: Formation of a 2D structure with (44.62)-sql topology

NASA Astrophysics Data System (ADS)

Lalegani, Arash; Khaledi Sardashti, Mohammad; Gajda, Roman; Woźniak, Krzysztof

2017-12-01

Zinc(II) coordination polymers [Zn(bip)2(NCS)2]n (1) and [Zn(μ-bbd)(N3)2]n (2) were synthesized by using the neutral flexible bidentate N-donor ligands 1,4-bis(3,5-dimethylpyrazolyl)butane (bbd) and 1,3-bis(imidazolyl)propane (bip), mono-anionic NCS- or N3-ligand and zinc(II) chloride salts. The results of the X-ray analyses demonstrate that in the structure of 1, the zinc(II) ion is located on an inversion center and exhibits an ZnN6 octahedral arrangement while, in the structure of 2, the zinc(II) ion adopts an ZnN4 tetrahedral geometry. In the polymer 1, the NCS groups are terminally N-bonded to the metal center and the each bip with anti-gauche conformation acts as bridging connecting four zinc(II) ions to form a two-dimensional network with a sql [point symbol (44.62)] topology while, in the polymer 1, the N3 groups are terminally bonded to the metal center and each bbd with anti-anti-anti conformation acts as bridging ligand connecting two zinc(II) ions to form a one-dimensional zig-zag chain. Coordination compounds 1 and 2 have been characterized by infrared spectroscopy, elemental analyses and single-crystal X-ray diffraction. Thermal analyses of polymers were also presented.

Isolation of metallothionein from cells derived from aggressive form of high-grade prostate carcinoma using paramagnetic antibody-modified microbeads off-line coupled with electrochemical and electrophoretic analysis.

PubMed

Masarik, Michal; Gumulec, Jaromir; Sztalmachova, Marketa; Hlavna, Marian; Babula, Petr; Krizkova, Sona; Ryvolova, Marketa; Jurajda, Michal; Sochor, Jiri; Adam, Vojtech; Kizek, Rene

2011-12-01

Prostate cancer with altered zinc(II) cell metabolism is the second most frequently diagnosed cancer in developed countries. The alterations of zinc(II) metabolism can influence metabolism of other metal ions and can also be associated with the expression and translation of metal-binding proteins including metallothioneins. The aim of this article was to optimize immunoseparation protocol based on paramagnetic beads conjugated with protein G for the isolation of metallothionein. Isolated metallothionein was determined by differential pulse voltammetry Brdicka reaction and SDS-PAGE. Optimal conditions: antigen-binding time - 60 min, temperature - 70°C, and buffer composition and pH - acetate buffer, pH 4.3, were determined. Under the optimized conditions, lysates from 22Rv1 prostate cancer cells treated with various concentrations of cadmium(II) and copper(II) ions were analyzed. We observed strong correlation in all experimental groups and all lysate types (r>0.83 at p<0.041) between metallothionein concentration related to viability and concentration of copper(II) ions and cadmium(II) ions in medium. Moreover, the results were compared with standard sample preparation as heat treatment and SDS-PAGE analysis. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and antimalarial activity of metal complexes of cross-bridged tetraazamacrocyclic ligands.

PubMed

Hubin, Timothy J; Amoyaw, Prince N-A; Roewe, Kimberly D; Simpson, Natalie C; Maples, Randall D; Carder Freeman, TaRynn N; Cain, Amy N; Le, Justin G; Archibald, Stephen J; Khan, Shabana I; Tekwani, Babu L; Khan, M O Faruk

2014-07-01

Using transition metals such as manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II), several new metal complexes of cross-bridged tetraazamacrocyclic chelators namely, cyclen- and cyclam-analogs with benzyl groups, were synthesized and screened for in vitro antimalarial activity against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum. The metal-free chelators tested showed little or no antimalarial activity. All the metal complexes of the dibenzyl cross-bridged cyclam ligand exhibited potent antimalarial activity. The Mn(2+) complex of this ligand was the most potent with IC50s of 0.127 and 0.157μM against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) P. falciparum strains, respectively. In general, the dibenzyl hydrophobic ligands showed better anti-malarial activity compared to the activity of monobenzyl ligands, potentially because of their higher lipophilicity and thus better cell penetration ability. The higher antimalarial activity displayed by the manganese complex for the cyclam ligand in comparison to that of the cyclen, correlates with the larger pocket of cyclam compared to that of cyclen which produces a more stable complex with the Mn(2+). Few of the Cu(2+) and Fe(2+) complexes also showed improvement in activity but Ni(2+), Co(2+) and Zn(2+) complexes did not show any improvement in activity upon the metal-free ligands for anti-malarial development. Published by Elsevier Ltd.

Ferrate(VI)-Prompted Removal of Metals in Aqueous Media: Mechanistic Delineation of Enhanced Efficiency via Metal Entrenchment in Magnetic Oxides

EPA Science Inventory

The removal efficiency of heavy metal ions (cadmium(II) – Cd(II), cobalt(II) – Co(II), nickel(II) – Ni(II), and copper(II) – Cu(II)) by potassium ferrate(VI) (K2FeO4, Fe(VI)), was studied as a function of added amount of Fe(VI) (or Fe) and varying pH. At pH = 6.6, the effective r...

Mononuclear thiocyanate containing nickel(II) and binuclear azido bridged nickel(II) complexes of N4-coordinate pyrazole based ligand: Syntheses, structures and magnetic properties

NASA Astrophysics Data System (ADS)

Solanki, Ankita; Monfort, Montserrat; Kumar, Sujit Baran

2013-10-01

Two mononuclear nickel(II) complexes [NiL1(NCS)2] (1) and [NiL2(NCS)2] (2) and two azido bridged binuclear nickel(II) complexes [Ni(()2()2] (3) and [Ni(()2()2] (4), where L1, L2, L1‧ and L2‧ are N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1), N,N-bis((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2), N,N-diethyl-N‧-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1‧) and N-((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2‧) have been synthesized and characterized by microanalyses and physico-chemical methods. Single crystal X-ray diffraction analyses revealed that complexes 1 and 2 are mononuclear NCS- containing Ni(II) complex with octahedral geometry and complexes 3 and 4 are end-on (μ-1,1) azido bridged binuclear Ni(II) complexes with distorted octahedral geometry. Variable temperature magnetic studies of the complexes 3 and 4 display ferromagnetic interaction with J values 19 and 32 cm-1, respectively.

Investigation of the photophysical and photochemical properties of peripherally tetra-substituted water-soluble zwitterionic and cationic zinc(ii) phthalocyanines.

PubMed

Çolak, Senem; Durmuş, Mahmut; Yıldız, Salih Zeki

2016-06-21

In this study, 4-{4-[N-((3-dimethylamino)propyl)amide]phenoxy}phthalonitrile () and its zinc(ii) phthalocyanine derivative () were synthesized for the first time. 4-(N-((3-Dimethylamino)propyl)amide)phenoxy substituted zinc(ii) phthalocyanine () was converted to its water-soluble sulfobetaine (), betaine () and N-oxide () containing zwitterionic and quaternized cationic () derivatives. All newly synthesized compounds () were characterized by the combination of UV-vis, FT-IR, (1)H NMR, mass spectroscopy techniques and elemental analysis. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen quantum yields) properties were investigated in DMSO for all the synthesized zinc(ii) phthalocyanines () and in both DMSO and aqueous solutions for zwitterionic and cationic phthalocyanines () for the specification of their capability as photosensitizers in photodynamic therapy (PDT). The binding behavior of water soluble phthalocyanines () to the bovine serum albumin protein was also examined for the determination of their transportation ability in the blood stream.

Nickel(II) affects poly(ADP-ribose) polymerase-mediated DNA repair in normal and cancer cells.

PubMed

Wozniak, Katarzyna; Czechowska, Agnieszka; Blasiak, Janusz

2006-01-01

Nickel(II) can be genotoxic, but the mechanism of its genotoxicity is not fully understood and the process of DNA repair may be considered as its potential target. We studied the effect of nickel chloride on the poly(ADP-ribose) polymerase (PARP)-mediated repair of DNA damaged by gamma-radiation and idarubicin with the alkaline comet assay in normal and cancer cells. Our results indicate that nickel chloride at very low, non-cytotoxic concentration of 1 microM can affect PARP-mediated DNA repair of lesions evoked by idarubicin and gamma-radiation. We also suggest that in the quiescent lymphocytes treated with gamma-radiation, nickel(II) could interfere with DNA repair process independent of PARP.

Effect of Dioxygen on Copper(II) Binding to α-Synuclein

PubMed Central

Lucas, Heather R.; Lee, Jennifer C.

2010-01-01

Using the fluorescent amino acid tryptophan (Trp), we have characterized the copper(II) binding of F4W α-synuclein in the presence and absence of dioxygen at neutral pH. Variations in Trp fluorescence indicate that copper(II) binding is enhanced by the presence of dioxygen, with the apparent dissociation constant (Kd(app)) changing from 100 nM (anaerobic) to 10 nM (aerobic). To investigate the possible role of methionine oxidation, complementary work focused on synthetic peptide models of the N-terminal Cu(II)-α-syn site, MDV(F/W) and M*DV(F/W), where M*= methionine sulfoxide. Furthermore, we employed circular dichroism (CD) spectroscopy to demonstrate that the phenyl-to-indole (F→W) substitution does not alter copper(II) binding properties and to confirm the 1:1 metal-peptide binding stoichiometry. CD comparisons also revealed that Met1 oxidation does not affect the copper-peptide conformation and further suggested the possible existence of a CuII-Trp/Phe (cation-π) interaction. PMID:20064662

Packed-bed column biosorption of chromium(VI) and nickel(II) onto Fenton modified Hydrilla verticillata dried biomass.

PubMed

Mishra, Ashutosh; Tripathi, Brahma Dutt; Rai, Ashwani Kumar

2016-10-01

The present study represents the first attempt to investigate the biosorption potential of Fenton modified Hydrilla verticillata dried biomass (FMB) in removing chromium(VI) and nickel(II) ions from wastewater using up-flow packed-bed column reactor. Effects of different packed-bed column parameters such as bed height, flow rate, influent metal ion concentration and particle size were examined. The outcome of the column experiments illustrated that highest bed height (25cm); lowest flow rate (10mLmin(-1)), lowest influent metal concentration (5mgL(-1)) and smallest particle size range (0.25-0.50mm) are favourable for biosorption. The maximum biosorption capacity of FMB for chromium(VI) and nickel(II) removal were estimated to be 89.32 and 87.18mgg(-1) respectively. The breakthrough curves were analyzed using Bed Depth Service Time (BDST) and Thomas models. The experimental results obtained agree to both the models. Column regeneration experiments were also carried out using 0.1M HNO3. Results revealed good reusability of FMB during ten cycles of sorption and desorption. Performance of FMB-packed column in treating secondary effluent was also tested under identical experimental conditions. Results demonstrated significant reduction in chromium(VI) and nickel(II) ions concentration after the biosorption process. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis and structural characterization of two half-sandwich nickel(II) complexes with the scorpionate ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, G.-F., E-mail: wgf1979@126.com, E-mail: s-shuwen@163.com; Zhang, X., E-mail: zhangx@hit.edu.cn; Sun, S.-W.

The synthesis and characterization of two new halfsandwich mononuclear nickel(II) complexes with the scorpionate ligands, [k{sup 3}-N, N',N''-Tp{sup t-Bu}, {sup Me}NiI] (1) and [k{sup 3}-N,N',N''-Tp{sup t-Bu}, {sup Me}NiNO{sub 3}] (2), are reported. These complexes have been fully characterized by elemental analyses and infrared spectra. Their molecular structures were determined by single crystal X-ray diffraction. The nickel(II) ion of complex 1 is in a four-coordinate environment, in which the donor atoms are provided by three nitrogen atoms of a hydrotris(pyrazolyl) borate ligand and one iodide atom, while that of complex 2 is in a five-coordinate environment with three nitrogen atoms frommore » a hydrotris(pyrazolyl)borate ligand and two oxygen atoms from a nitrate ion.« less

Biosorption characteristic of Alcaligenes sp. BAPb.1 for removal of lead(II) from aqueous solution.

PubMed

Jin, Yu; Yu, Sumei; Teng, Chunying; Song, Tao; Dong, Liying; Liang, Jinsong; Bai, Xin; Xu, Xiuhong; Qu, Juanjuan

2017-06-01

In this study, strain BAPb.1 was isolated from lead mining area and used as an adsorbent to remove lead(II) ions from aqueous solution. The physicochemical characteristics, heavy metal resistance and antibiotic sensitivity of strain BAPb.1 were investigated. Biosorption capacity was evaluated by batch biosorption experiments, and isothermal characteristics were discussed. Atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectrometry (FTIR) were conducted to explore the mechanism for lead(II) adsorption. Based on morphological and physiological characteristics as well as the phylogenetic analysis of 16S rDNA sequences, strain BAPb.1 was identified as a member of the genus Alcaligenes. It exhibited high resistances to multiple heavy metals such as lead(II), copper(II), zinc(II), nickel(II) and chromium(VI), and to antibiotics such as kanamycin, ampicillin, streptomycin, chloramphenicol, and tetracycline. The optimum conditions for maximum biosorption rate of 85.2% and maximum capacity of 56.8 mg g -1 were found at pH of 5, adsorbent dosage of 1.5 g L -1 (dry weight), initial lead(II) concentration of 100 mg L -1 , and contact time of 30 min at 30 °C. Biosorption isotherms were well fitted with Langmuir isotherm model. Mechanism analysis reveals that the lead(II) ions may exchange with sodium and potassium ions, and the hydroxyl, carbonyl and phosphate groups on the cell surface can chelate the lead(II) ions, therefore, surface adsorption play significant role in the biosorption process.

Pyrrolidine dithiocarbamate-zinc(II) and -copper(II) complexes induce apoptosis in tumor cells by inhibiting the proteasomal activity☆

PubMed Central

Milacic, Vesna; Chen, Di; Giovagnini, Lorena; Diez, Alejandro; Fregona, Dolores; Dou, Q. Ping

2013-01-01

Zinc and copper are trace elements essential for proper folding, stabilization and catalytic activity of many metalloenzymes in living organisms. However, disturbed zinc and copper homeostasis is reported in many types of cancer. We have previously demonstrated that copper complexes induced proteasome inhibition and apoptosis in cultured human cancer cells. In the current study we hypothesized that zinc complexes could also inhibit the proteasomal chymotrypsin-like activity responsible for subsequent apoptosis induction. We first showed that zinc(II) chloride was able to inhibit the chymotrypsin-like activity of a purified 20S proteasome with an IC50 value of 13.8 μM, which was less potent than copper(II) chloride (IC50 5.3 μM). We then compared the potencies of a pyrrolidine dithiocarbamate (PyDT)-zinc(II) complex and a PyDT-copper(II) complex to inhibit cellular proteasomal activity, suppress proliferation and induce apoptosis in various human breast and prostate cancer cell lines. Consistently, zinc complex was less potent than copper complex in inhibiting the proteasome and inducing apoptosis. Additionally, zinc and copper complexes appear to use somewhat different mechanisms to kill tumor cells. Zinc complexes were able to activate calpain-, but not caspase-3-dependent pathway, while copper complexes were able to induce activation of both proteases. Furthermore, the potencies of these PyDT-metal complexes depend on the nature of metals and also on the ratio of PyDT to the metal ion within the complex, which probably affects their stability and availability for interacting with and inhibiting the proteasome in tumor cells. PMID:18501397

Synthesis, spectral, thermal and antimicrobial studies on cobalt(II), nickel(II), copper(II), zinc(II) and palladium(II) complexes containing thiosemicarbazone ligand

NASA Astrophysics Data System (ADS)

El-Sawaf, Ayman K.; El-Essawy, Farag; Nassar, Amal A.; El-Samanody, El-Sayed A.

2018-04-01

The coordination characteristic of new N4-morpholinyl isatin-3-thiosemicarbazone (HL) towards Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) has been studies. The structures of the complexes were described by elemental analyses, molar conductivity, magnetic, thermal and spectral (IR, UV-Vis, 1H and 13C NMR and ESR) studies. On the basis of analytical and spectral studies the ligand behaves as monobasic tridentate ONS donor forming two five membered rings towards cobalt, copper and palladium and afforded complexes of the kind [M(L)X], (Mdbnd Co, Cu or Pd; Xdbnd Cl, Br or OAc). Whereas the ligand bound to NiCl2 as neutral tridentate ONS donor and with ZnCl2 as neutral bidentate NS donor. The newly synthesized thiosemicarbazone ligand and some of its complexes were examined for antimicrobial activity against 2 gram negative bacterial strains (Escherichia coli Pseudomonas and aeruginosa), 2 gram positive bacterial strains (Streptococcus pneumoniae and Staphylococcus aureus)} and two Pathogenic fungi (Aspergillus fumigatus and Candida albicans). All metal complexes possess higher antimicrobial activity comparing with the free thiosemicarbazone ligand. The high potent activities of the complexes may arise from the coordination and chelation, which tends to make metal complexes act as more controlling and potent antimicrobial agents, thus hindering the growing of the microorganisms. The antimicrobial results also show that copper bromide complex is better antimicrobial agent as compared to the Schiff base and its metal complexes.

The Synthesis of Copper(II) Carboxylates Revisited

ERIC Educational Resources Information Center

Kushner, Kevin; Spangler, Robert E.; Salazar, Ralph A., Jr.; Lagowski, J. J.

2006-01-01

An electrochemical synthesis of copper(II) carboxylates has been developed and used in the general chemistry laboratory course for chemistry majors. This synthesis, using nonaqueous solutions, supplements the strategy of providing experiences in synthetic chemistry described by Yoder et al. ("J. Chem. Educ." 1995, 72, 267). (Contains 1 table.)

Stability of nickel(II) glycylglycinate complexes in aqueous solutions of dimethylsulfoxide at 298.15 K

NASA Astrophysics Data System (ADS)

Naumov, V. V.; Isaeva, V. A.; Kovaleva, Yu. A.; Sharnin, V. A.

2013-07-01

Stability constants of nickel(II) glycylglycinate complexes in aqueous solutions of dimethylsulfoxide of variable composition (from 0.00 to 0.60 mole fractions DMSO) are determined according to potentiometry at 298.15 K and an ionic strength of 0.1 M (NaClO4). It is determined that with a rise in the concentration of an organic cosolvent in solution, the stability of nickel(II) complexes with glycylglycinate ion on the whole increases, but the log K stability = f( X DMSO) dependences are of a critical character with a maximum of 0.3 mole fractions DMSO. It is demonstrated that the rise in the stability of complexes is related to the destabilization of ligands in the low concentration range of the organic component, while the presence of a maximum is due to the different dynamics of the solvation contributions from reagents during changes in the Gibbs energy of reaction.

Interactions between copper(II) and DOM in the urban stormwater runoff: modeling and characterizations.

PubMed

Zhao, Chen; Wang, Chong-Chen; Li, Jun-Qi; Wang, Peng; Ou, Jia-Qi; Cui, Jing-Rui

2018-01-01

Dissolved organic matter (DOM) can strongly interact with both organic and inorganic contaminants to influence their transportation, transformation, bioavailability, toxicity and even their ultimate fate. Within this work, DOM was extracted from urban stormwater runoff samples collected from a regular sampling site of a typical residential area in Beijing, China. Copper(II) ions were selected as model to investigate the interactions between DOM and typical heavy metals. Both ultraviolet (UV) absorbance and fluorescence titration methods were introduced to determine the complex capacities (C L ) and conditional stability constants (log K M ) of bonding between DOM and copper (II) ions, which revealed that the values of C L were 85.62 and 87.23 μmol mg -1 and the log K M values were 5.37 and 5.48, respectively. The results suggested the successful complexation between DOM and copper(II) ions. Furthermore, morphology of the DOM binding to copper(II) ions was confirmed by both energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS), which can facilitate to clarify the corresponding mechanism. The Cu 2p 3/2 peak at 933.7 eV and the characteristic shake-up peaks of Cu-O were found in the XPS spectra, implying that copper(II) ions might coordinate with hydroxyl (aliphatic or phenolic) or carboxyl groups. With these profitable results, it can be concluded that DOM in urban stormwater runoff has a strong binding affinity with copper(II) ions, which may further lead to potentially significant influence on their migration and transformation.

Photochemistry of copper(II) complexes with macrocyclic amine ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muralidharan, S.; Ferraudi, G.

1981-07-01

The photochemical properties of Cu(dl-Me/sub 6/(14)aneN/sub 4/)/sup 2 +/ and Cu(rac-Me/sub 6/(14)aneN/sub 4/)/sup 2 +/ in the presence and absence of axially coordinated ligands have been investigated by continuous and flash irradiations. Flash photolysis of the complexes in deaerated aqueous solutions revealed the presence of copper-ligand radical complexes with closed- and open-cycle ligands. Flash photolysis of methanolic solutions of the complexes, in the presence of halides and pseudohalides, shows Cu(III) macrocyclic intermediates. The experimental observations can be explained in terms of two primary photoprocesses with origins in distinctive charge transfer to metal states. These states have been assigned as aminomore » to copper(II) charge-transfer state and acido to copper(II) charge-transfer state.« less

Surface Structures Formed by a Copper(II) Complex of Alkyl-Derivatized Indigo

PubMed Central

Honda, Akinori; Noda, Keisuke; Tamaki, Yoshinori; Miyamura, Kazuo

2016-01-01

Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II) ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM) analysis revealed that the copper(II) complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed. PMID:28773957

Synthesis, spectroscopic and thermal studies of the copper(II) aspartame chloride complex

NASA Astrophysics Data System (ADS)

Çakır, S.; Coşkun, E.; Naumov, P.; Biçer, E.; Bulut, İ.; İçbudak, H.; Çakır, O.

2002-08-01

Aspartame adduct of copper(II) chloride Cu(Asp) 2Cl 2·2H 2O (Asp=aspartame) is synthesized and characterized by elemental analysis, FT IR, UV/vis, ESR spectroscopies, TG, DTG, DTA measurements and molecular mechanics calculations. Aqueous solution of the green solid absorbs strongly at 774 and 367 nm. According to the FT IR spectra, the aspartame moiety coordinates to the copper(II) ion via its carboxylate ends, whereas the ammonium terminal groups give rise to hydrogen bonding network with the water, the chloride ions or neighboring carboxylate groups. The results suggest tetragonally distorted octahedral environment of the copper ions.

A Noble-Metal-Free Nickel(II) Polypyridyl Catalyst for Visible-Light-Driven Hydrogen Production from Water.

PubMed

Yuan, Yong-Jun; Lu, Hong-Wei; Tu, Ji-Ren; Fang, Yong; Yu, Zhen-Tao; Fan, Xiao-Xing; Zou, Zhi-Gang

2015-10-05

The complex [Ni(bpy)3](2+) (bpy=2,2'-bipyridine) is an active catalyst for visible-light-driven H2 production from water when employed with [Ir(dfppy)2 (Hdcbpy)] [dfppy=2-(3,4-difluorophenyl)pyridine, Hdcbpy=4-carboxy-2,2'-bipyridine-4'-carboxylate] as the photosensitizer and triethanolamine as the sacrificial electron donor. The highest turnover number of 520 with respect to the nickel(II) catalyst is obtained in a 8:2 acetonitrile/water solution at pH 9. The H2 -evolution system is more stable after the addition of an extra free bpy ligand, owing to faster catalyst regeneration. The photocatalytic results demonstrate that the nickel(II) polypyridyl catalyst can act as a more effective catalyst than the commonly utilized [Co(bpy)3 ](2+). This study may offer a new paradigm for constructing simple and noble-metal-free catalysts for photocatalytic hydrogen production. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectroscopic and electrochemical behavior of the novel tetra-2-methyl-pyrazinoporphyrazines

NASA Astrophysics Data System (ADS)

Pişkin, Mehmet; Öztürk, Naciye; Durmuş, Mahmut

2017-12-01

This study presents the synthesis and characterization of novel metal-free (H2Pc) and metallo porphyrazines (magnesium(II) (MgPz), copper(II) (CuPz), iron(II) (FePz), manganese(II) (MnPz) and nickel(II) (NiPz)) substituted with four 2-methylpyrazine groups on the peripheral positions. The spectroscopic properties of newly synthesized porphyrazines were investigated. The electrochemical behaviors of these porphyrazines were also determined in DMSO solution by cyclic voltammetry (CV) and square wave voltammetry (SWV) methods on edge plane pyrolytic graphite electrode (EPPG) electrode.

Preparation of Enteromorpha prolifera-based cetyl trimethyl ammonium bromide-doped activated carbon and its application for nickel(II) removal.

PubMed

Wang, Man; Hao, Fang; Li, Gang; Huang, Ji; Bao, Nan; Huang, Lihui

2014-06-01

Activated carbon was prepared from Enteromorpha prolifera (EP) by H3PO4 activation in the presence of doped cetyl trimethyl ammonium bromide (CTAB), producing EPAC-CTAB. The thermal decomposition process of the activated carbon substrate was identified by thermo-gravimetric analysis. Scanning electron microscope (SEM), N2 adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), Boehm titration, and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the physicochemical properties of native EPAC and EPAC-CTAB. EPAC-CTAB exhibited smaller surface area (689.0m(2)/g) and lower total pore volume (0.361cm(3)/g) than those of EPAC (1045.8m(2)/g and 1.048cm(3)/g), while the number of acidic groups, oxygen and nitrogen groups on the surface of EPAC-CTAB increased through CTAB doping. The batch kinetics and isotherm adsorption studies of nickel(II) onto the adsorbents were examined and agreed well with the pseudo-second-order model and the Langmuir model. The maximum adsorption capacity determined from the Langmuir model was 16.9mg/g for EPAC and 49.8mg/g for EPAC-CTAB. Under acidic condition, the adsorption of nickel(II) onto EPAC and EPAC-CTAB was hindered due to ion competition and electrostatic repulsion. The results indicated that using CTAB as a dopant for EPAC modification could markedly enhance the nickel(II) removal. Copyright © 2014. Published by Elsevier Inc.

CFD simulation of copper(II) extraction with TFA in non-dispersive hollow fiber membrane contactors.

PubMed

Muhammad, Amir; Younas, Mohammad; Rezakazemi, Mashallah

2018-04-01

This study presents computational fluid dynamics (CFD) simulation of dispersion-free liquid-liquid extraction of copper(II) with trifluoroacetylacetone (TFA) in hollow fiber membrane contactor (HFMC). Mass and momentum balance Navier-Stokes equations were coupled to address the transport of copper(II) solute across membrane contactor. Model equations were simulated using COMSOL Multiphysics™. The simulation was run to study the detailed concentration distribution of copper(II) and to investigate the effects of various parameters like membrane characteristics, partition coefficient, and flow configuration on extraction efficiency. Once-through extraction was found to be increased from 10 to 100% when partition coefficient was raised from 1 to 10. Similarly, the extraction efficiency was almost doubled when porosity to tortuosity ratio of membrane was increased from 0.05 to 0.81. Furthermore, the study revealed that CFD can be used as an effective optimization tool for the development of economical membrane-based dispersion-free extraction processes.

Copper(II) carboxylate promoted intramolecular diamination of terminal alkenes: improved reaction conditions and expanded substrate scope.

PubMed

Zabawa, Thomas P; Chemler, Sherry R

2007-05-10

The copper(II) carboxylate promoted diamination reaction has been improved by the use of the organic soluble copper(II) neodecanoate [Cu(ND)2]. Cu(ND)2 allowed the less-polar solvent dichloroethane (DCE) to be used, and as a consequence, decomposition of less-reactive substrates could be avoided. High diastereoselectivity was observed in the synthesis of 2,5-disubstituted pyrrolidines. Ureas, bis(anilines), and alpha-amido pyrroles derived from 2-allylaniline could also participate in the diamination reaction.

Synthesis, characterization and investigation of the photophysical and photochemical properties of highly soluble novel metal-free, zinc(II), and indium(III) phthalocyanines substituted with 2,3,6-trimethylphenoxy moieties.

PubMed

Gürel, Ekrem; Pişkin, Mehmet; Altun, Selçuk; Odabaş, Zafer; Durmuş, Mahmut

2015-04-07

This work presents the synthesis and characterization of metal-free, zinc(II), and indium(III)acetate phthalocyanines substituted with 2,3,6-trimethylphenoxy groups at the peripheral and non-peripheral positions. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties of these novel phthalocyanines and unsubstituted zinc(II) and indium(III)acetate phthalocyanines were investigated in dimethylformamide solution. The effects of the types of substituents and their positions and the variety of central metal ions on the phthalocyanine core on their spectroscopic, photophysical and photochemical properties were also determined. The studied 2,3,6-trimethylphenoxy substituted metal-free, zinc(II) and indium(III)acetate phthalocyanines especially indium(III)acetate derivatives exhibited appropriate photophysical and photochemical properties such as high singlet oxygen generation and these phthalocyanines can be potential Type II photosensitizers for photodynamic therapy in cancer applications.

Dependence of the enthalpies of formation of glycylglycinate complexes of nickel(II) on the composition of a mixed water-dimethylsulfoxide solvent

NASA Astrophysics Data System (ADS)

Naumov, V. V.; Kovaleva, Yu. A.; Isaeva, V. A.; Usacheva, T. R.; Sharnin, V. A.

2014-06-01

The heat effects of the complexation reactions of nickel(II) with a glycylglycinate ion in a water-dimethylsulfoxide solvent in a range of compositions of 0.00-0.60 molar parts of dimethylsulfoxide (DMSO) (an ionic strength of 0.1 was maintained using sodium perchlorate) were determined by means of calorimetry at 298.15 K. It is established that the exothermicity of complexation reactions rises by the first two steps and falls upon the addition of a third glycylglycinate anion with an increase in the concentration of DMSO. It is shown that the formation of mono- and bis-glycylglycinate complexes of nickel(II) in a water-DMSO solvent is determined mostly by the enthalpic contribution. It is concluded that the formation of tris-ligand complexes is more associated with the entropic contribution.

Mononuclear zinc(II) complexes of 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols: Synthesis, structural characterization, DNA binding and cheminuclease activities

NASA Astrophysics Data System (ADS)

Ravichandran, J.; Gurumoorthy, P.; Karthick, C.; Kalilur Rahiman, A.

2014-03-01

Four new zinc(II) complexes [Zn(HL1-4)Cl2] (1-4), where HL1-4 = 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols, have been isolated and fully characterized using various spectro-analytical techniques. The X-ray crystal structure of complex 4 shows the distorted trigonal-bipyramidal coordination geometry around zinc(II) ion. The crystal packing is stabilized by intermolecular NH⋯O hydrogen bonding interaction. The complexes display no d-d electronic band in the visible region due to d10 electronic configuration of zinc(II) ion. The electrochemical properties of the synthesized ligands and their complexes exhibit similar voltammogram at reduction potential due to electrochemically innocent Zn(II) ion, which evidenced that the electron transfer is due to the nature of the ligand. Binding interaction of complexes with calf thymus DNA was studied by UV-Vis absorption titration, viscometric titration and cyclic voltammetry. All complexes bind with CT DNA by intercalation, giving the binding affinity in the order of 2 > 1 ≫ 3 > 4. The prominent cheminuclease activity of complexes on plasmid DNA (pBR322 DNA) was observed in the absence and presence of H2O2. Oxidative pathway reveals that the underlying mechanism involves hydroxyl radical.

Structural and magnetic characterization of a tetranuclear copper(II) cubane stabilized by intramolecular metal cation-π interactions.

PubMed

Papadakis, Raffaello; Rivière, Eric; Giorgi, Michel; Jamet, Hélène; Rousselot-Pailley, Pierre; Réglier, Marius; Simaan, A Jalila; Tron, Thierry

2013-05-20

A novel tetranuclear copper(II) complex (1) was synthesized from the self-assembly of copper(II) perchlorate and the ligand N-benzyl-1-(2-pyridyl)methaneimine (L(1)). Single-crystal X-ray diffraction studies revealed that complex 1 consists of a Cu4(OH)4 cubane core, where the four copper(II) centers are linked by μ3-hydroxo bridges. Each copper(II) ion is in a distorted square-pyramidal geometry. X-ray analysis also evidenced an unusual metal cation-π interaction between the copper ions and phenyl substituents of the ligand. Calculations based on the density functional theory method were used to quantify the strength of this metal-π interaction, which appears as an important stabilizing parameter of the cubane core, possibly acting as a driving parameter in the self-aggregation process. In contrast, using the ligand N-phenethyl-1-(2-pyridyl)methaneimine (L(2)), which only differs from L(1) by one methylene group, the same synthetic procedure led to a binuclear bis(μ-hydroxo)copper(II) complex (2) displaying intermolecular π-π interactions or, by a slight variation of the experimental conditions, to a mononuclear complex (3). These complexes were studied by X-ray diffraction techniques. The magnetic properties of complexes 1 and 2 are reported and discussed.

Copper(II) Carboxylate Promoted Intramolecular Diamination of Terminal Alkenes: Improved Reaction Conditions and Expanded Substrate Scope

PubMed Central

Zabawa, Thomas P.

2008-01-01

The copper(II) carboxylate promoted diamination reaction has been improved by the use of the organic soluble copper(II) neodecanoate [Cu(ND)2]. Cu(ND)2 allowed the less polar solvent, dichloroethane (DCE) to be used, and as a consequence, decomposition of less reactive substrates could be avoided. High diastereoselectivity was observed in the synthesis of 2,5-disubstituted pyrrolidines. Ureas, bis(anilines) and α-amido pyrroles derived from 2-allylaniline could also participate in the diamination reaction. PMID:17447781

Magnetic separation of heavy metal ions and evaluation based on surface-enhanced Raman spectroscopy: copper(II) ions as a case study.

PubMed

Yan, Xue; Zhang, Xue-Jiao; Yuan, Ya-Xian; Han, San-Yang; Xu, Min-Min; Gu, Ren'ao; Yao, Jian-Lin

2013-11-01

A new approach was developed for the magnetic separation of copper(II) ions with easy operation and high efficiency. p-Mercaptobenzoic acid served as the modified tag of Fe2O3@Au nanoparticles both for the chelation ligand and Raman reporter. Through the chelation between the copper(II) ions and carboxyl groups on the gold shell, the Fe2O3@Au nanoparticles aggregated to form networks that were enriched and separated from the solution by a magnet. A significant decrease in the concentration of copper(II) ions in the supernatant solution was observed. An extremely sensitive method based on surface-enhanced Raman spectroscopy was employed to detect free copper(II) ions that remained after the magnetic separation, and thus to evaluate the separation efficiency. The results indicated the intensities of the surface-enhanced Raman spectroscopy bands from p-mercaptobenzoic acid were dependent on the concentration of copper(II) ions, and the concentration was decreased by several orders of magnitude after the magnetic separation. The present protocol effectively decreased the total amount of heavy metal ions in the solution. This approach opens a potential application in the magnetic separation and highly sensitive detection of heavy metal ions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, spectroscopic, molecular orbital calculation, cytotoxic, molecular docking of DNA binding and DNA cleavage studies of transition metal complexes with N-benzylidene-N'-salicylidene-1,1-diaminopropane

NASA Astrophysics Data System (ADS)

Al-Mogren, Muneerah M.; Alaghaz, Abdel-Nasser M. A.; Elbohy, Salwa A. H.

2013-10-01

Eight mononuclear chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes of Schiff's base ligand were synthesized and determined by different physical techniques. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMSO indicate that the complexes are non-electrolytic in nature. All the eight metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The analytical data helped to elucidate the structure of the metal complexes. The Schiff base is found to act as tridentate ligand using N2O donor set of atoms leading to an octahedral geometry for the complexes around all the metal ions. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. Additionally in silico, the docking studies and the calculated pharmacokinetic parameters show promising futures for application of the ligand and complexes as high potency agents for DNA binding activity. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by UV absorption method, and the mode of CT-DNA binding to the complexes has been explored. Furthermore, the DNA cleavage activity by the complexes was performed. The Schiff base and their complexes have been screened for their antibacterial activity against bacterial strains [Staphylococcus aureus (RCMB010027), Staphylococcus epidermidis (RCMB010024), Bacillis subtilis (RCMB010063), Proteous vulgaris (RCMB 010085), Klebsiella pneumonia (RCMB 010093) and Shigella flexneri (RCMB 0100542)] and fungi [(Aspergillus fumigates (RCMB 02564), Aspergillus clavatus (RCMB 02593) and Candida albicans (RCMB05035)] by disk diffusion method. All the metal complexes have potent biocidal activity than the free ligand.

Synthesis, characterization and extraction studies of some metal (II) complexes containing (hydrazoneoxime and bis-acylhydrazone) moieties

NASA Astrophysics Data System (ADS)

Al-Ne'aimi, Mohammed Mahmmod; Al-Khuder, Mohammed Moudar

2013-03-01

In this study, diacetylmonoximebenzoylhydrazone (L1H2) and 1,4-diacetylbenzene bis(benzoyl hydrazone) (L2H2) were synthesized by the condensation of benzohydrazide with diacetyl monoxime and 1,4-diacetylbenzene, respectively. Complexes of these ligands with Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) inos were prepared with a metal:ligand ratio of 1:2 for L1H2 ligand, and 1:1 for L2H2 ligand. The ligands and their complexes were elucidated on the basis of elemental analyses CHN, AAS, FT-IR, 1H- and 13C NMR spectra, UV-vis spectra and magnetic susceptibility measurements. Results show the L1H2 ligand act as monoanionic O,N,N-tridentate and coordination takes place in the enol form through the oxime nitrogen, the imine nitrogen and the enolate oxygen atoms with a N4O2 donor environment, while the L2H2 ligand act as a dianionic O,N,N,O-tetradentate and coordination takes place in the enol form through the enolate oxygen and the azomethine nitrogen atoms with a N2O2 donor environment. These results are consistent with the formation of mononuclear metal (II) complexes [M(L1H)2], and binuclear polymeric metal (II) complexes [{M2(L2)}n]. The extraction ability of both ligands were examined in chloroform by the liquid-liquid extraction of selected transition metal [Co2+, Ni2+, Cu2+, Zn2+ and Pb2+] cations. The effects of pH and contact time on the percentage extraction of metal (II) ions were studied under the optimum extraction conditions. The (L1H2) ligand shows strong binding ability toward copper(II) and lead(II) ions, while the (L2H2) ligand shows strong binding ability toward nickel(II) and zinc(II) ions.

Mechanisms and efficiency of the simultaneous removal of metals and cyanides by using ferrate(VI): crucial roles of nanocrystalline iron(III) oxyhydroxides and metal carbonates.

PubMed

Filip, Jan; Yngard, Ria A; Siskova, Karolina; Marusak, Zdenek; Ettler, Vojtech; Sajdl, Petr; Sharma, Virender K; Zboril, Radek

2011-08-29

The reaction of potassium ferrate(VI), K(2)FeO(4), with weak-acid dissociable cyanides--namely, K(2)[Zn(CN)(4)], K(2)[Cd(CN)(4)], K(2)[Ni(CN)(4)], and K(3)[Cu(CN)(4)]--results in the formation of iron(III) oxyhydroxide nanoparticles that differ in size, crystal structure, and surface area. During cyanide oxidation and the simultaneous reduction of iron(VI), zinc(II), copper(II), and cadmium(II), metallic ions are almost completely removed from solution due to their coprecipitation with the iron(III) oxyhydroxides including 2-line ferrihydrite, 7-line ferrihydrite, and/or goethite. Based on the results of XRD, Mössbauer and IR spectroscopies, as well as TEM, X-ray photoelectron emission spectroscopy, and Brunauer-Emmett-Teller measurements, we suggest three scavenging mechanisms for the removal of metals including their incorporation into the ferrihydrite crystal structure, the formation of a separate phase, and their adsorption onto the precipitate surface. Zn and Cu are preferentially and almost completely incorporated into the crystal structure of the iron(III) oxyhydroxides; the formation of the Cd-bearing, X-ray amorphous phase, together with Cd carbonate is the principal mechanism of Cd removal. Interestingly, Ni remains predominantly in solution due to the key role of nickel(II) carbonate, which exhibits a solubility product constant several orders of magnitude higher than the carbonates of the other metals. Traces of Ni, identified in the iron(III) precipitate, are exclusively adsorbed onto the large surface area of nanoparticles. We discuss the relationship between the crystal structure of iron(III) oxyhydroxides and the mechanism of metal removal, as well as the linear relationship observed between the rate constant and the surface area of precipitates. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The speciation of aqueous zinc(II) bromide solutions to 500 °C and 900 MPa determined using Raman spectroscopy

USGS Publications Warehouse

Mibe, Kenji; Chou, I-Ming; Anderson, Alan J.; Mayanovic, Robert A.; Bassett, William A.

2009-01-01

A Raman spectral study was carried out on 3 solutions of varying concentration and bromide/zinc ratios. Spectra were collected at 11 different temperature-pressure conditions ranging from ambient to 500????C-0.9??GPa. Raman band assignments for zinc(II) bromide species reported in previous studies were used to determine the relative concentrations of ZnBr42-, ZnBr3-, ZnBr2, and ZnBr+ species at various temperatures and pressures. Our results are in close agreement with X-ray absorption spectroscopic (XAS) data, and confirm that the tetrabromo zinc(II) complex, ZnBr42-, is the predominant species up to 500????C in solutions having high Zn concentrations (1??m) and high bromide/zinc molar ratios ([Br]/[Zn] = 8). In agreement with previous solubility and Raman spectroscopic experiments, our measurements indicate that species with a lower number of halide ligands and charge are favored with increasing temperature in dilute solutions, and solutions with low bromide/zinc ratios ([Br]/[Zn] < 2.5). The Raman technique provides an independent experimental means of evaluating the quality of XAS analyses of data obtained from high temperature disordered systems. The combination of these two techniques provides complementary data on speciation and the structure of zinc(II) bromide complexes. The preponderance of the ZnBr42- species in highly saline brines at high temperature is consistent with the predominance of ZnCl42- in chloride-rich brines reported in previous XAS studies. Knowledge of Zn complexing in metal-rich highly saline brines is important for numerical models of ore deposition in high temperature systems such as skarns and porphyry-type deposits. ?? 2008 Elsevier B.V.

Copper(II) complexes of methimazole, an anti Grave's disease drug. Synthesis, characterization and its potential biological behavior as alkaline phosphatase inhibitor.

PubMed

Urquiza, Nora M; Manca, Silvia G; Moyano, María A; Dellmans, Raquel Arrieta; Lezama, Luis; Rojo, Teófilo; Naso, Luciana G; Williams, Patricia A M; Ferrer, Evelina G

2010-04-01

Methimazole (MeimzH) is an anti-thyroid drug and the first choice for patients with Grave's disease. Two new copper(II) complexes of this drug: [Cu(MeimzH)(2)(NO(3))(2)]*0.5H(2)O and [Cu(MeimzH)(2)(H(2)O)(2)](NO(3))(2)*H(2)O were synthesized and characterized by elemental analysis, dissolution behavior, thermogravimetric analysis and UV-vis, diffuse reflectance, FTIR and EPR spectroscopies. As it is known that copper(II) cation can act as an inhibitor of alkaline phosphatase (ALP), the inhibitory effect of methimazole and its copper(II) complexes on ALP activity has also been investigated.

[CNN]-pincer nickel(II) complexes of N-heterocyclic carbene (NHC): synthesis and catalysis of the Kumada reaction of unactivated C-Cl bonds.

PubMed

Sun, Yunqiang; Li, Xiaoyan; Sun, Hongjian

2014-07-07

Three novel [CNN]-pincer nickel(ii) complexes with NHC-amine arms were synthesized in three steps. Complex was proven to be an efficient catalyst for the Kumada coupling of aryl chlorides or aryl dichlorides under mild conditions.

Spectroscopic and molecular docking studies on the interaction of human serum albumin with copper(II) complexes

NASA Astrophysics Data System (ADS)

Guhathakurta, Bhargab; Pradhan, Ankur Bikash; Das, Suman; Bandyopadhyay, Nirmalya; Lu, Liping; Zhu, Miaoli; Naskar, Jnan Prakash

2017-02-01

Two osazone based ligands, butane-2,3-dione bis(2‧-pyridylhydrazone) (BDBPH) and hexane-3,4-dione bis(2‧-pyridylhydrazone) (HDBPH), were synthesized out of the 2:1 M Schiff base condensation of 2-hydrazino pyridine respectively with 2,3-butanedione and 3,4-hexanedione. The X-ray crystal structures of both the ligands have been determined. The copper(II) complex of HDBPH has also been synthesized and structurally characterized. HDBPH and its copper(II) complex have thoroughly been characterized through various spectroscopic and analytical techniques. The X-ray crystal structure of the copper complex of HDBPH shows that it is a monomeric Cu(II) complex having 'N4O2' co-ordination chromophore. Interaction of human serum albumin (HSA) with these ligands and their monomeric copper(II) complexes have been studied by various spectroscopic means. The experimental findings show that the ligands as well as their copper complexes are good HSA binders. Molecular docking investigations have also been done to unravel the mode of binding of the species with HSA.

Thermodynamic Analysis of Nickel(II) and Zinc(II) Adsorption to Biochar.

PubMed

Alam, Md Samrat; Gorman-Lewis, Drew; Chen, Ning; Flynn, Shannon L; Ok, Yong Sik; Konhauser, Kurt O; Alessi, Daniel S

2018-05-21

While numerous studies have investigated metal uptake from solution by biochar, few of these have developed a mechanistic understanding of the adsorption reactions that occur at the biochar surface. In this study, we explore a combined modeling and spectroscopic approach for the first time to describe the molecular level adsorption of Ni(II) and Zn(II) to five types of biochar. Following thorough characterization, potentiometric titrations were carried out to measure the proton (H + ) reactivity of each biochar, and the data was used to develop protonation models. Surface complexation modeling (SCM) supported by synchrotron-based extended X-ray absorption fine structure (EXAFS) was then used to gain insights into the molecular scale metal-biochar surface reactions. The SCM approach was combined with isothermal titration calorimetry (ITC) data to determine the thermodynamic driving forces of metal adsorption. Our results show that the reactivity of biochar toward Ni(II) and Zn(II) directly relates to the site densities of biochar. EXAFS along with FT-IR analyses, suggest that Ni(II) and Zn(II) adsorption occurred primarily through proton-active carboxyl (-COOH) and hydroxyl (-OH) functional groups on the biochar surface. SCM-ITC analyses revealed that the enthalpies of protonation are exothermic and Ni(II) and Zn(II) complexes with biochar surface are slightly exothermic to slightly endothermic. The results obtained from these combined approaches contribute to the better understanding of molecular scale metal adsorption onto the biochar surface, and will facilitate the further development of thermodynamics-based, predictive approaches to biochar removal of metals from contaminated water.

trans-Bis(azido-kappaN)bis(pyridine-2-carboxamide-kappa2N1,O2)nickel(II).

PubMed

Daković, Marijana; Popović, Zora

2007-11-01

In the title compound, [Ni(N(3))(2)(C(6)H(6)N(2)O)(2)], the Ni(II) atom lies on an inversion centre. The distorted octahedral nickel(II) coordination environment contains two planar trans-related N,O-chelating picolinamide ligands in one plane and two monodentate azide ligands perpendicular to this plane. Molecules are linked into a three-dimensional framework by N-H...N hydrogen bonds.

Synthesis of 6-alkyluridines from 6-cyanouridine via zinc(II) chloride-catalyzed nucleophilic substitution with alkyl Grignard reagents.

PubMed

Shih, Yu-Chiao; Yang, Ya-Ying; Lin, Chun-Chi; Chien, Tun-Cheng

2013-04-19

6-Cyanouracil derivatives underwent a direct nucleophilic substitution reaction with alkyl Grignard reagents in the presence of zinc(II) chloride as a catalyst to form the corresponding 6-alkyluracils. This methodology is applicable to sugar-protected 6-cyanouridine and 6-cyano-2'-deoxyuridine without the protection at the N(3)-imide and provides a facile and general access to versatile 6-alkyluracil and 6-alkyluridine derivatives.

The effect of copper(II), iron(II) sulphate, and vitamin C combinations on the weak antimicrobial activity of (+)-catechin against Staphylococcus aureus and other microbes.

PubMed

Holloway, Andrew C; Mueller-Harvey, Irene; Gould, Simon W J; Fielder, Mark D; Naughton, Declan P; Kelly, Alison F

2012-12-01

Few attempts have been made to improve the activity of plant compounds with low antimicrobial efficacy. (+)-Catechin, a weak antimicrobial tea flavanol, was combined with putative adjuncts and tested against different species of bacteria. Copper(II) sulphate enhanced (+)-catechin activity against Pseudomonas aeruginosa but not Staphylococcus aureus, Proteus mirabilis or Escherichia coli. Attempts to raise the activity of (+)-catechin against two unresponsive species, S. aureus and E. coli, with iron(II) sulphate, iron(III) chloride, and vitamin C, showed that iron(II) enhanced (+)-catechin against S. aureus, but not E. coli; neither iron(III) nor combined iron(II) and copper(II), enhanced (+)-catechin activity against either species. Vitamin C enhanced copper(II) containing combinations against both species in the absence of iron(II). Catalase or EDTA added to active samples removed viability effects suggesting that active mixtures had produced H(2)O(2)via the action of added metal(II) ions. H(2)O(2) generation by (+)-catechin plus copper(II) mixtures and copper(II) alone could account for the principal effect of bacterial growth inhibition following 30 minute exposures as well as the antimicrobial effect of (+)-catechin-iron(II) against S. aureus. These novel findings about a weak antimicrobial flavanol contrast with previous knowledge of more active flavanols with transition metal combinations. Weak antimicrobial compounds like (+)-catechin within enhancement mixtures may therefore be used as efficacious agents. (+)-Catechin may provide a means of lowering copper(II) or iron(II) contents in certain crop protection and other products.

Syntheses, structures, and properties of two new zinc(II) metal-organic frameworks based on flexible 1,6-bis(2-methyl-imidazole-1-yl)hexane ligand

NASA Astrophysics Data System (ADS)

Jin, Jun-Cheng; Fu, Ai-Yun; Li, Dian; Chang, Wen-Gui; Wu, Ju; Yang, Mei; Xie, Cheng-Gen; Xu, Guang-Nian; Cai, An-Xing; Wu, Ai-Hua

2014-11-01

Two new zinc(II) metal-organic compounds of [Zn(ADC)(bimh)]n (1) and [Zn(ADA)(bimh)]n (2) (H2ADC = 1,3-adamantanedicarboxylic acid, H2ADA = 1,3-adamantanediacetic acid, bimh = 1,6-bis(2-methyl-imidazole-1-yl)-hexane, have been structurally characterized by X-ray diffraction analysis. In compound 1, the zinc(II) ions are bridged by ADC and bimh ligands to form a 1D looped chain. In compound 2, the ADA molecules alternately bridge Zn(II) atoms to form infinite chains, and then the 1D chain is connected through the bimh ligand resulting in an undulating infinite two-dimensional (2D) polymeric network. Additionally, TG analysis, XRPD and fluorescent properties for compounds 1 and 2 are also measured and discussed.

Hierarchical flower-like nickel(II) oxide microspheres with high adsorption capacity of Congo red in water.

PubMed

Zheng, Yingqiu; Zhu, Bicheng; Chen, Hua; You, Wei; Jiang, Chuanjia; Yu, Jiaguo

2017-10-15

Monodispersed hierarchical flower-like nickel(II) oxide (NiO) microspheres were fabricated by a facile solvothermal reaction with the assistance of ethanolamine and a subsequent calcination process. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms, zeta potential measurement and Fourier transform infrared spectroscopy. Flower-like nickel(II) hydroxide microspheres with uniform diameters of approximate 6.3μm were obtained after the solvothermal reaction. After heat treatment at 350°C, the crystal phase transformed to NiO, but the hierarchical porous structure was maintained. The as-prepared microspheres exhibited outstanding performance for the adsorption of Congo red (CR), an anionic organic dye, from aqueous solution at circumneutral pH. The pseudo-second-order model can make a good description of the adsorption kinetics, while Langmuir model could well express the adsorption isotherms, with calculated maximum CR adsorption capacity of 534.8 and 384.6mgg -1 , respectively, for NiO and Ni(OH) 2 . The adsorption mechanism of CR onto the as-synthesized samples can be mainly attributed to electrostatic interaction between the positively charged sample surface and the anionic CR molecules. The as-prepared NiO microspheres are a promising adsorbent for CR removal in water treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis and characterization of a new zinc(II) complex with tetradentate azo-thioether ligand: X-ray structure, DNA binding study and DFT calculation

NASA Astrophysics Data System (ADS)

Mondal, Apurba Sau; Pramanik, Ajoy Kumar; Patra, Lakshman; Manna, Chandan Kumar; Mondal, Tapan Kumar

2017-10-01

A new zinc(II) complex, [Zn(L)(H2O)](ClO4) (1) with azo-thioether containing NSNO donor ligand, 3-(2-(2-((pyridin-2-ylmethyl)thio)phenyl)hydrazono)pentane-2,4-dione (HL) is synthesized and characterized by several spectroscopic techniques. The distorted square based pyramidal (DSBP) geometry is confirmed by single crystal X-ray structure. The ability of the complex to bind with CT DNA is investigated by UV-vis method and the binding constant is found to be 4.16 × 104 M-1. Competitive binding study with ethidium bromide (EB) by fluorescence method suggests that the zinc(II) complex efficiently displaces EB from EB-DNA. The Stern-Volmer dynamic quenching constant, Ksv is found to be 1.2 × 104 M-1. Theoretical calculations by DFT and TDDFT/CPCM methods are used to interpret the electronic structure and UV-vis spectrum of the complex.

Determination of formal redox potentials in aqueous solution of copper(II) complexes with ligands having nitrogen and oxygen donor atoms and comparison with their EPR and UV-Vis spectral features.

PubMed

Tabbì, Giovanni; Giuffrida, Alessandro; Bonomo, Raffaele P

2013-11-01

Formal redox potentials in aqueous solution were determined for copper(II) complexes with ligands having oxygen and nitrogen as donor atoms. All the chosen copper(II) complexes have well-known stereochemistries (pseudo-octahedral, square planar, square-based pyramidal, trigonal bipyramidal or tetrahedral) as witnessed by their reported spectroscopic, EPR and UV-visible (UV-Vis) features, so that a rough correlation between the measured redox potential and the typical geometrical arrangement of the copper(II) complex could be established. Negative values have been obtained for copper(II) complexes in tetragonally elongated pseudo-octahedral geometries, when measured against Ag/AgCl reference electrode. Copper(II) complexes in tetrahedral environments (or flattened tetrahedral geometries) show positive redox potential values. There is a region, always in the field of negative redox potentials which groups the copper(II) complexes exhibiting square-based pyramidal arrangements. Therefore, it is suggested that a measurement of the formal redox potential could be of great help, when some ambiguities might appear in the interpretation of spectroscopic (EPR and UV-Vis) data. Unfortunately, when the comparison is made between copper(II) complexes in square-based pyramidal geometries and those in square planar environments (or a pseudo-octahedral) a little perturbed by an equatorial tetrahedral distortion, their redox potentials could fall in the same intermediate region. In this case spectroscopic data have to be handled with great care in order to have an answer about a copper complex geometrical characteristics. © 2013.

Increased sensitivity of anodic stripping voltammetry at the hanging mercury drop electrode by ultracathodic deposition.

PubMed

Rodrigues, José A; Rodrigues, Carlos M; Almeida, Paulo J; Valente, Inês M; Gonçalves, Luís M; Compton, Richard G; Barros, Aquiles A

2011-09-09

An improved approach to the anodic stripping voltammetric (ASV) determination of heavy metals, using the hanging mercury drop electrode (HMDE), is reported. It was discovered that using very cathodic accumulation potentials, at which the solvent reduction occurs (overpotential deposition), the voltammetric signals of zinc(II), cadmium(II), lead(II) and copper(II) increase. When compared with the classical methodology a 5 to 10-fold signal increase is obtained. This effect is likely due to both mercury drop oscillation at such cathodic potentials and added local convection at the mercury drop surface caused by the evolution of hydrogen bubbles. Copyright © 2011 Elsevier B.V. All rights reserved.

Application of Colorimetric Solid Phase Extraction (C-SPE) to Monitoring Nickel(II) and Lead(II) in Spacecraft Water Supplies

NASA Technical Reports Server (NTRS)

Diaz, Neil C.; Gazda, Daniel B.; Fritz, James S.; Porter, Marc D.; Rutz, Jeff; Mudgett, Paul; Schultz, John

2004-01-01

Archived water samples collected on the International Space Station (ISS) and returned to Earth for analysis have, in a few instances, contained trace levels of heavy metals. Building on our previous advances using Colorimetric Solid Phase Extraction (C-SPE) as a biocide monitoring technique, we are devising methods for the low level monitoring of nickel(II), lead(II) and other heavy metals. C-SPE is a sorption-spectrophotometric platform based on the extraction of analytes onto a membrane impregnated with a colorimetric reagent that are then quantified on the surface of the membrane using a diffuse reflectance spectrophotometer. Along these lines, we have determined nickel(II) via complexation with dimethylglyoxime (DMG) and begun to examine the analysis of lead(II) by its reaction with 2,5- dimercapto-1,3,4-thiadiazole (DMTD) and 4-(2- pyridylazo)-resorcinol (PAR). These developments are also extending a new variant of C-SPE in which immobilized reagents are being incorporated into this methodology in order to optimize sample reaction conditions and to introduce the colorimetric reagent. This paper describes the status of our development of these two new methods.

Polymeric networks of copper(II) phenylmalonate with heteroaromatic n-donor ligands: synthesis, crystal structure, and magnetic properties.

PubMed

Pasán, Jorge; Sanchiz, Joaquín; Ruiz-Pérez, Catalina; Lloret, Francesc; Julve, Miguel

2005-10-31

Two new phenylmalonate-bridged copper(II) complexes with the formulas [Cu(4,4'-bpy)(Phmal)](n).2nH(2)O (1) and [Cu(2,4'-bpy)(Phmal)(H(2)O)](n)() (2) (Phmal = phenylmalonate dianion, 4,4'-bpy = 4,4'-bipyridine, 2,4'-bpy = 2,4'-bipyridine) have been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in monoclinic space group P2(1), Z = 4, with unit cell parameters of a = 9.0837(6) Angstroms, b = 9.3514(4) Angstroms, c = 11.0831(8) Angstroms, and beta = 107.807(6) degrees , whereas complex 2 crystallizes in orthorhombic space group C2cb, Z = 8, with unit cell parameters of a = 10.1579(7) Angstroms, b = 10.3640(8) Angstroms, and c = 33.313(4) Angstroms. The structures of 1 and 2 consist of layers of copper(II) ions with bridging bis-monodentate phenylmalonate (1 and 2) and 4,4'-bpy (1) ligands and terminal monodentate 2,4'-bpy (2) groups. Each layer in 1 contains rectangles with dimensions of 11.08 x 4.99 Angstroms(2), the edges being defined by the Phmal and 4,4'-bpy ligands. The intralayer copper-copper separations in 1 through the anti-syn equatorial-apical carboxylate-bridge and the 4,4'-bpy molecule are 4.9922(4) and 11.083(1) Angstroms, respectively. The anti-syn equatorial-equatorial carboxylate bridge links the copper(II) atoms in complex 2 within each layer with a mean copper-copper separation of 5.3709(8) Angstroms. The presence of 2,4'-bpy as a terminal ligand accounts for the large interlayer separation of 15.22 Angstroms. The copper(II) environment presents a static pseudo-Jahn-Teller disorder which has been studied by EPR and low-temperature X-ray diffraction. Magnetic susceptibility measurements of both compounds in the temperature range 2-290 K show the occurrence of weak antiferromagnetic [J = -0.59(1) cm(-1) (1)] and ferromagnetic [J = +0.77(1) cm(-1) (2)] interactions between the copper(II) ions. The conformation of the phenylmalonate-carboxylate bridge and other structural factors, such as the planarity of the exchange

Strong copper(II) species in estuarine and sea waters investigated by a method with high detection window.

PubMed

Alberti, Giancarla; Biesuz, Raffaela; D'Agostino, Girolamo; Scarponi, Giuseppe; Pesavento, Maria

2007-02-15

The distribution of copper(II) in species of different stability in some estuarine and sea water samples (Adriatic Sea) was investigated by a method based on the sorption of the metal ion on a strongly sorbing resin, Chelex 100, whose sorbing properties have been previously characterized. From them, it is possible to predict very high values of detection windows at the considered conditions, for example side reaction coefficient as high as 10(10) at pH 7.5. Strong copper(II) species in equilibrium with Chelex 100 were detected, at concentration 2-20nM, with a reaction coefficient approximately 10(10.6) at pH 7.45 in sea water, strictly depending on the acidity. They represent 50-70% of the total metal ion and are the strongest copper(II) complexes found in sea water. Weak complexes too were detected in all the samples, with reaction coefficient lower than ca. 10(9) at the same pH. The method applied, named resin titration (RT), was described in a previous investigation, and is here modified in order to be carried out on oceanographic boat during a cruise in the Adriatic Sea.

Unusual Coexistence of Nickel(II) and Nickel(IV) in the Quadruple Perovskite Ba 4Ni 2Ir 2O 12 Containing Ir 2NiO 12 Mixed-Metal-Cation Trimers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferreira, Timothy; Heald, Steve M.; Smith, Mark. D.

In this paper, the crystal chemistry and magnetic properties of two hexagonal nickel(IV)-containing perovskites, Ba 4Ni 1.94Ir 2.06O 12 and BaNiO 3, are reported. The 12R perovskite, Ba 4Ni 1.94Ir 2.06O 12, possesses an unexpected coexistence of nickel(II) and nickel(IV). This quadruple perovskite structure contains Ir 2NiO 12 mixed-metal-cation units in which direct metal–metal bonding between nickel(IV) and iridium(V) is inferred. Finally, X-ray absorption near-edge spectroscopy and X-ray photoelectron spectroscopy measurements were conducted to confirm the simultaneous presence of nickel(II) and nickel(IV).

Unusual Coexistence of Nickel(II) and Nickel(IV) in the Quadruple Perovskite Ba 4Ni 2Ir 2O 12 Containing Ir 2NiO 12 Mixed-Metal-Cation Trimers

DOE PAGES

Ferreira, Timothy; Heald, Steve M.; Smith, Mark. D.; ...

2018-03-02

In this paper, the crystal chemistry and magnetic properties of two hexagonal nickel(IV)-containing perovskites, Ba 4Ni 1.94Ir 2.06O 12 and BaNiO 3, are reported. The 12R perovskite, Ba 4Ni 1.94Ir 2.06O 12, possesses an unexpected coexistence of nickel(II) and nickel(IV). This quadruple perovskite structure contains Ir 2NiO 12 mixed-metal-cation units in which direct metal–metal bonding between nickel(IV) and iridium(V) is inferred. Finally, X-ray absorption near-edge spectroscopy and X-ray photoelectron spectroscopy measurements were conducted to confirm the simultaneous presence of nickel(II) and nickel(IV).

Structural characterization of two solvates of a luminescent copper(II) bis­(pyridine)-substituted benzimidazole complex

PubMed Central

DeStefano, Matthew R.; Lewis, Robert A.

2017-01-01

Copper(II) complexes of benzimidazole are known to exhibit biological activity that makes them of inter­est for chemotherapeutic and other pharmaceutical uses. The complex bis­(acetato-κO){5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)meth­yl]-1H-benzimidazole-κ2 N 2,N 3}copper(II), has been prepared. The absorption spectrum has features attributed to intra­ligand and ligand-field transitions and the complex exhibits ligand-centered room-temperature luminescence in solution. The aceto­nitrile monosolvate, [Cu(C2H3O2)2(C20H18N4)]·C2H3N (1), and the ethanol hemisolvate, [Cu(C2H3O2)2(C20H18N4)]·0.5C2H6O (2), have been structurally characterized. Compound 2 has two copper(II) complexes in the asymmetric unit. In both 1 and 2, distorted square-planar N2O2 coordination geometries are observed and the Cu—N(Im) bond distance is slightly shorter than the Cu—N(py) bond distance. Inter­molecular π–π inter­actions are found in 1 and 2. A weak C—H⋯π inter­action is observed in 1. PMID:29152336

Exploitation of knowledge databases in the synthesis of zinc(II) malonates with photo-sensitive and photo-insensitive N,N'-containing linkers.

PubMed

Zorina-Tikhonova, Ekaterina N; Chistyakov, Aleksandr S; Kiskin, Mikhail A; Sidorov, Aleksei A; Dorovatovskii, Pavel V; Zubavichus, Yan V; Voronova, Eugenia D; Godovikov, Ivan A; Korlyukov, Alexander A; Eremenko, Igor L; Vologzhanina, Anna V

2018-05-01

Photoinitiated solid-state reactions are known to affect the physical properties of coordination polymers, such as fluorescence and sorption behaviour, and also afford extraordinary architectures ( e.g. three-periodic structures with polyorganic ligands). However, the construction of novel photo-sensitive coordination polymers requires an understanding of the factors which govern the mutual disposition of reactive fragments. A series of zinc(II) malonate complexes with 1,2-bis(pyridin-4-yl)ethylene and its photo-insensitive analogues has been synthesized for the purpose of systematic analysis of their underlying nets and mutual disposition of N -donor ligands. The application of a big data-set analysis for the prediction of a variety of possible complex compositions, coordination environments and networks for a four-component system has been demonstrated for the first time. Seven of the nine compounds possess one of the highly probable topologies for their underlying nets; in addition, two novel closely related four-coordinated networks were obtained. Complexes containing 1,2-bis(pyridin-4-yl)ethylene and 1,2-bis(pyridin-4-yl)ethane form isoreticular compounds more readily than those with 4,4'-bipyridine and 1,2-bis(pyridin-4-yl)ethylene. The effects of the precursor, either zinc(II) nitrate or zinc(II) acetate, on the composition and dimensionality of the resulting architecture are discussed. For three of the four novel complexes containing 1,2-bis(pyridin-4-yl)ethylene, the single-crystal-to-single-crystal [2 + 2] cycloaddition reactions were carried out. UV irradiation of these crystals afforded either the 0D→1D or the 3D→3D transformations, with and without network changes. One of the two 3D→3D transformations was accompanied by solvent (H 2 O) cleavage.

Spontaneous resolution of binary copper(II) complexes with racemic dipeptides: crystal structures of glycyl-L-alpha-amino-n-butyrato copper(II) monohydrate, glycyl-D-valinato copper(II) hemihydrate, and glycyl-L-valinato copper(II) hemihydrate.

PubMed

Inomata, Yoshie; Yamaguchi, Takeshi; Tomita, Airi; Yamada, Dai; Howell, F Scott

2005-08-01

Copper(II) complexes with glycyl-DL-alpha-amino-n-butyric acid (H2gly-DL-but), glycyl-DL-valine (H2gly-DL-val), glycyl-DL-norleucine (H2gly-DL-norleu), glycyl-DL-threonine (H2gly-DL-thr), glycyl-DL-serine (H2gly-DL-ser), glycyl-DL-phenylalanine (H2gly-DL-phe), and glycyl-L-valine (H2gly-L-val), have been prepared and characterized by IR, powder diffuse reflection, CD and ORD spectra, and magnetic susceptibility measurements, and by single-crystal X-ray diffraction. The crystal structures of the copper complex with H2gly-DL-but, the copper complex with H2gly-DL-val, and [Cu(gly-L-val)]n.0.5nH2O have been determined by a single-crystal X-ray diffraction method. As for the structure of the copper complex with H2gly-DL-but, the configuration around the asymmetric carbon atom is similar to that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-DL-but is [Cu(gly-L-but)]n.nH2O. On the contrary, as for the structure of the copper complex with H2gly-DL-val, the configuration around the asymmetric carbon atom is different from that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-dl-val is [Cu(gly-D-val)]n.0.5nH2O. So during the crystallization of the copper(II) complexes with H2gly-DL-but and H2gly-DL-val, spontaneous resolution has been observed; the four complexes have separated as [Cu(gly-D-but)]n.nH2O, [Cu(gly-L-but)]n.nH2O, [Cu(gly-D-val)]n.0.5nH2O, and [Cu(gly-L-val)]n.0.5nH2O, respectively. [Cu(gly-L-but)]n.nH2O is orthorhombic with the space group P2(1)2(1)2(1). [Cu(gly-D-val)]n.0.5nH2O and [Cu(gly-L-val)]n.0.5nH2O are monoclinic with the space group C2. In these complexes, the copper atom is in a square-pyramidal geometry, ligated by a peptide nitrogen atom, an amino nitrogen atom, a carboxyl oxygen atom, and a carboxyl oxygen atom and a peptide oxygen atom from neighboring molecules. So these complexes consist of a two-dimensional polymer chain bridged by a carboxyl oxygen atom and a

Spectrophotometr1c determination of cadmium with 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol.

PubMed

Villarreal, M; Porta, L; Marchevsky, E; Olsina, R

1986-05-01

The reaction between cadmium and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol (5-Cl DMPAP) in aqueous alcohol media at pH 8.8-10.7 results in an intense violet colour which is stable for at least 8 hr. The composition is 2:1 reagent:metal and the formation constant (5.29 +/- 0.01) x 10(18). Beer's law is obeyed up to 1.34 ppm of cadmium at 550 nm. The optimal concentration range (Ringbom) is between 0.16 and 0.72 ppm. The apparent molar absorptivity at 550 nm is (1.20 +/- 0.01) x 10(5) l.mole(-1). cm(-1), making the sensitivity one of the highest known. The interference due to copper(III), iron(III), cobalt(II), nickel(II), gold(III), zinc(II) and manganese(II) can be suppressed.

Theoretical, biological and in silico studies of pendant-armed heteroleptic copper(II) phenolate complexes

NASA Astrophysics Data System (ADS)

Arthi, P.; Mahendiran, D.; Shobana, S.; Srinivasan, P.; Rahiman, A. Kalilur

2018-06-01

A new series of pendant-armed heteroleptic copper(II) phenolate complexes of the type [CuL1-3(diimine)] (1-6) have been synthesized by the reaction of pendant-armed ligands 2,2'-(benzoyliminodiethylene)bissalicylidene (H2L1), 2,2'-(4-nitrobenzoyliminodiethylene)bissalicylidene (H2L2) or 2,2'-(3,5-dinitrobenzoyliminodiethylene)bissalicylidene (H2L3) with coligands (diimine; 2,2‧-bipyridyl (bpy) or 1,10-phenanthroline (phen)) in the presence of copper(II) chloride, and characterized by spectroscopic techniques. The seven coordinated pentagonal-bipyramidal geometry around the copper(II) center was inferred from the electronic spectra of the complexes. The bond length, bond angle and HOMO-LUMO energy gap calculations were carried out by DFT studies, using Gaussian 03 program. Electrochemical studies of the mononuclear complexes evidenced one-electron irreversible reduction wave in the cathodic region (Epc = -0.61 to -0.65 V). Experimental and in silico molecular docking studies support groove mode of binding with DNA. Further, the molecular docking studies of complexes with B-DNA indicate the binding of the guanine-cytosine residues in the minor groove of the DNA. Molecular docking studies also revealed the interaction of complexes with protein ERK2 kinase and significant topoisomerase (Topo-I) inhibitory activity. All the complexes display pronounced cleavage activity against supercoiled pBR322 DNA in the presence of H2O2. In vitro cytotoxicity of the complexes was tested against liver cancer cell line (HepG2) by MTT reduction assay.

Pyrrolidine and Piperidine Formation Via Copper(II) Carboxylate Promoted Intramolecular Carboamination of Unactivated Olefins: Diastereoselectivity and Mechanism

PubMed Central

Sherman, Eric S.; Fuller, Peter H.; Kasi, Dhanalakshmi; Chemler, Sherry R.

2008-01-01

An expanded substrate scope and in depth analysis of the reaction mechanism of the copper(II) carboxylate promoted intramolecular carboamination of unactivated alkenes is described. This method provides access to N-functionalized pyrrolidines and piperidines. Both aromatic and aliphatic γ- and δ-alkenyl N-arylsulfonamides undergo the oxidative cyclization reaction efficiently. N-Benzoyl-2-allylaniline also underwent the oxidative cyclization. The terminal olefin substrates examined were more reactive than those with internal olefins, and the latter terminated in elimination rather than carbon-carbon bond formation. The efficiency of the reaction was enhanced by the use of more organic soluble copper(II) carboxylate salts, copper(II) neodecanoate in particular. The reaction times were reduced by the use of microwave heating. High levels of diastereoselectivity were observed in the synthesis of 2,5-disubstituted pyrrolidines, wherein the cis substitution pattern predominates. The mechanism of the reaction is discussed in the context of the observed reactivity and in comparison to analogous reactions promoted by other reagents and conditions. Our evidence supports a mechanism wherein the N-C bond is formed via intramolecular syn aminocupration and the C-C bond is formed via intramolecular addition of a primary carbon radical to an aromatic ring. PMID:17428100

Synthesis, characterization, electrical conductivity and luminescence properties of two copper(II) complexes with tridentate N2O chelating ligands containing imine bond

NASA Astrophysics Data System (ADS)

Gönül, İlyas; Ay, Burak; Karaca, Serkan; Şahin, Onur; Serin, Selahattin

2018-03-01

In the present study, we describe the synthesis and characterization of two tridentate N2O donor ligands, namely, (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-methoxyphenol (HL1) and (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-ethoxyphenol (HL2), and their copper(II) complexes, [Cu(L1)(CH3COO)] (1), [Cu(L2)(CH3COO)] (2). They have been synthesized under conventional methods and characterized by elemental analysis, FTIR, 1H and 13C NMR, ICP-OES, TGA and GC/MS analysis. For the morphological analysis field emission scanning electron microscopy (FESEM) was used. The geometry of the copper(II) complexes was determined by single crystal X-ray diffraction analysis. The copper(II) ions are in distorted square-pyramidal coordination environments. Complexes crystallize in monoclinic space group, P21/c. The electrical conductivity and luminescence properties of 1-2 have been investigated.

Rapid assessment of human amylin aggregation and its inhibition by copper(II) ions by laser ablation electrospray ionization mass spectrometry with ion mobility separation

DOE PAGES

Li, Hang; Ha, Emmeline; Donaldson, Robert P.; ...

2015-09-09

Native electrospray ionization (ESI) mass spectrometry (MS) is often used to monitor noncovalent complex formation between peptides and ligands. The relatively low throughput of this technique, however, is not compatible with extensive screening. Laser ablation electrospray ionization (LAESI) MS combined with ion mobility separation (IMS) can analyze complex formation and provide conformation information within a matter of seconds. Islet amyloid polypeptide (IAPP) or amylin, a 37-amino acid residue peptide, is produced in pancreatic beta-cells through proteolytic cleavage of its prohormone. Both amylin and its precursor can aggregate and produce toxic oligomers and fibrils leading to cell death in the pancreasmore » that can eventually contribute to the development of type 2 diabetes mellitus. The inhibitory effect of the copper(II) ion on amylin aggregation has been recently discovered, but details of the interaction remain unknown. Finding other more physiologically tolerated approaches requires large scale screening of potential inhibitors. In this paper, we demonstrate that LAESI-IMS-MS can reveal the binding stoichiometry, copper oxidation state, and the dissociation constant of human amylin–copper(II) complex. The conformations of hIAPP in the presence of copper(II) ions were also analyzed by IMS, and preferential association between the β-hairpin amylin monomer and the metal ion was found. The copper(II) ion exhibited strong association with the —HSSNN– residues of the amylin. In the absence of copper(II), amylin dimers were detected with collision cross sections consistent with monomers of β-hairpin conformation. When copper(II) was present in the solution, no dimers were detected. Thus, the copper(II) ions disrupt the association pathway to the formation of β-sheet rich amylin fibrils. Using LAESI-IMS-MS for the assessment of amylin–copper(II) interactions demonstrates the utility of this technique for the high-throughput screening of

Distinctive EPR signals provide an understanding of the affinity of bis-(3-hydroxy-4-pyridinonato) copper(II) complexes for hydrophobic environments.

PubMed

Rangel, Maria; Leite, Andreia; Silva, André M N; Moniz, Tânia; Nunes, Ana; Amorim, M João; Queirós, Carla; Cunha-Silva, Luís; Gameiro, Paula; Burgess, John

2014-07-07

In this work we report the synthesis and characterization of a set of 3-hydroxy-4-pyridinone copper(ii) complexes with variable lipophilicity. EPR spectroscopy was used to characterize the structure of copper(ii) complexes in solution, and as a tool to gain insight into solvent interactions. EPR spectra of solutions of the [CuL2] complexes recorded in different solvents reveal the presence of two copper species whose ratio depends on the nature of the solvent. Investigation of EPR spectra in the pure solvents methanol, dimethylsulfoxide, dichloromethane and their 50% (v/v) mixtures with toluene allowed the characterization of two types of copper signals (gzz = 2.30 and gzz = 2.26) whose spin-Hamiltonian parameters are consistent with solvated and non-solvated square-planar copper(ii) complexes. Regarding the potential biological application of ligands and complexes and to get insight into the partition properties in water-membrane interfaces, EPR spectra were also obtained in water-saturated octanol, an aqueous solution buffered at pH = 7.4 and liposome suspensions, for three compounds representative of different hydro-lipophilic balances. Analysis of the EPR spectra obtained in liposomes allowed establishment of the location of the complexes in the water and lipid phases. In view of the results of this work we put forward the use of EPR spectroscopy to assess the affinity of copper(ii) complexes for a hydrophobic environment and also to obtain indirect information about the lipophilicity of the ligands and similar EPR silent complexes.

Ternary copper(II) complexes with amino acid chains and heterocyclic bases: DNA binding, cytotoxic and cell apoptosis induction properties.

PubMed

Ma, Tieliang; Xu, Jun; Wang, Yuan; Yu, Hao; Yang, Yong; Liu, Yang; Ding, Weiliang; Zhu, Wenjiao; Chen, Ruhua; Ge, Zhijun; Tan, Yongfei; Jia, Lei; Zhu, Taofeng

2015-03-01

Nowadays, chemotherapy is a common means of oncology. However, it is difficult to find excellent chemotherapy drugs. Here we reported three new ternary copper(II) complexes which have potential chemotherapy characteristics with reduced Schiff base ligand and heterocyclic bases (TBHP), [Cu(phen)(TBHP)]H2O (1), [Cu(dpz)(TBHP)]H2O (2) and [Cu(dppz)(TBHP)]H2O (3) (phen=1,10-phenanthroline, dpz=dipyrido [3,2:2',3'-f]quinoxaline, dppz=dipyrido [3,2-a:2',3'-c]phenazine, H2TBHP=2-(3,5-di-tert-butyl-2-hydroxybenzylamino)-2-benzyl-acetic acid). The DNA-binding properties of the complexes were investigated by spectrometric titrations, ethidium bromide displacement experiments and viscosity measurements. The results indicated that the three complexes, especially the complex 13, can strongly bind to calf-thymus DNA (CT-DNA). The intrinsic binding constants Kb of the ternary copper(II) complexes with CT-DNA were 1.37×10(5), 1.81×10(5) and 3.21×10(5) for 1, 2 and 3 respectively. Comparative cytotoxic activities of the copper(II) complexes were also determined by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed that the ternary copper(II) complexes had significant cytotoxic activity against the human lung cancer (A549), human esophageal cancer (Eca109) and human gastric cancer (SGC7901) cell lines. Cell apoptosis were detected by AnnexinV/PI flow cytometry and by Western blotting with the protein expression of p53, Bax and Bcl-2. All the three copper complexes can effectively induce apoptosis of the three human tumor cells. Copyright © 2014 Elsevier Inc. All rights reserved.

A Fluorescent Indicator for Imaging Lysosomal Zinc(II) with Förster Resonance Energy Transfer (FRET)-Enhanced Photostability and a Narrow Band of Emission

PubMed Central

Sreenath, Kesavapillai; Yuan, Zhao; Allen, John R.

2015-01-01

We demonstrate a strategy to transfer the zinc(II) sensitivity of a fluoroionophore with low photostability and a broad emission band to a bright and photostable fluorophore with a narrow emission band. The two fluorophores are covalently connected to afford an intramolecular Förster resonance energy transfer (FRET) conjugate. The FRET donor in the conjugate is a zinc(II)-sensitive arylvinylbipyridyl fluoroionophore, the absorption and emission of which undergo bathochromic shifts upon zinc(II) coordination. When the FRET donor is excited, efficient intramolecular energy transfer occurs to result in the emission of the acceptor boron dipyrromethene (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene or BODIPY) as a function of zinc(II) concentration. The broad emission band of the donor/zinc(II) complex is transformed into the strong, narrow emission band of the BODIPY acceptor in the FRET conjugates, which can be captured within the narrow emission window that is preferred for multicolor imaging experiments. In addition to competing with other nonradiative decay processes of the FRET donor, the rapid intramolecular FRET of the excited FRET-conjugate molecule protects the donor fluorophore from photobleaching, thus enhancing the photostability of the indicator. FRET conjugates 3 and 4 contain aliphatic amino groups, which selectively target lysosomes in mammalian cells. This subcellular localization preference was verified by using confocal fluorescence microscopy, which also shows the zinc(II)-enhanced emission of 3 and 4 in lysosomes. It was further shown using two-color structured illumination microscopy (SIM), which is capable of extending the lateral resolution over the Abbe diffraction limit by a factor of two, that the morpholino-functionalized compound 4 localizes in the interior of lysosomes, rather than anchoring on the lysosomal membranes, of live HeLa cells. PMID:25382395

Two zinc(II) coordination complexes based on an asymmetric multidentate ligand: syntheses, structures, selective fluorescence sensing of iron(III) ions and thermal analyses.

PubMed

Liu, Yaru; Liu, Lan; Zhang, Xiao; Liang, Guorui; Gong, Xuebing

2018-01-01

The rational selection of ligands is vitally important in the construction of coordination complexes. Two novel Zn II complexes, namely bis(acetato-κO)bis[1-(1H-benzotriazol-1-ylmethyl)-2-propyl-1H-imidazole-κN 3 ]zinc(II) monohydrate, [Zn(C 13 H 15 N 5 ) 2 (C 2 H 3 O 2 ) 2 ]·H 2 O, (1), and bis(azido-κN 1 )bis[1-(1H-benzotriazol-1-ylmethyl)-2-propyl-1H-imidazole-κN 3 ]zinc(II), [Zn(C 13 H 15 N 5 ) 2 (N 3 ) 2 ], (2), constructed from the asymmetric multidentate imidazole ligand, have been synthesized under mild conditions and characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffraction analysis. Both complexes exhibit a three-dimensional supramolecular network directed by different intermolecular interactions between discrete mononuclear units. The complexes were also investigated by fluorescence and thermal analyses. The experimental results show that (1) is a promising fluorescence sensor for detecting Fe 3+ ions and (2) is effective as an accelerator of the thermal decomposition of ammonium perchlorate.

An efficient, cost effective, sensing behaviour liquid-liquid extraction and spectrophotometric determination of copper(II) incorporated with 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole: Analysis of food samples, leafy vegetables, fertilizers and environmental samples.

PubMed

Barache, Umesh B; Shaikh, Abdul B; Lokhande, Tukaram N; Kamble, Ganesh S; Anuse, Mansing A; Gaikwad, Shashikant H

2018-01-15

The aim of the present work is to develop an efficient, simple and selective moreover cost-effective method for the extractive spectrophotometric determination of copper(II) by using the Schiff base 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole [CBIMMT]. This chromogenic reagent forms a yellow coloured complex with copper(II) in acetate buffer at pH4.2. The copper(II) complex with ligand is instantly extracted into chloroform and shows a maximum absorbance at 414nm which remains stable for >48h. The composition of extracted complex is found to be 1:2 [copper(II): reagent] which was ascertained using Job's method of continuous variation, mole ratio method and slope ratio method. Under optimal conditions, the copper(II) complex in chloroform adheres to Beer's law up to 17.5μgmL -1 of copper(II). The optimum concentration range obtained from Ringbom's plot is from 5μgmL -1 to 17.5μgmL -1 . The molar absorptivity, Sandell's sensitivity and enrichment factor of the extracted copper(II) chelate are 0.33813×10 4 Lmol -1 cm -1 , 0.01996μgcm -2 and 2.49 respectively. In the extraction of copper(II), several affecting factors including the solution pH, ligand concentration, equilibrium time, effect of foreign ions are optimized. The interfering effects of various cations and anions were also studied and use of masking agents enhances the selectivity of the method. The chromogenic sulphur containing reagent, 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole has been synthesized in a single step with high purity and yield. The synthesized reagent has been successfully applied first time for determination of copper(II). The reagent forms stable chelate with copper(II) in buffer medium instantly and quantitatively extracted in chloroform within a minute. The method is successfully applied for the determination of copper(II) in various synthetic mixtures, complexes, fertilizers, environmental samples such as food samples, leafy

Synthesis, structure and catalytic activities of nickel(II) complexes bearing N4 tetradentate Schiff base ligand

NASA Astrophysics Data System (ADS)

Sarkar, Saikat; Nag, Sanat Kumar; Chattopadhyay, Asoke Prasun; Dey, Kamalendu; Islam, Sk. Manirul; Sarkar, Avijit; Sarkar, Sougata

2018-05-01

Two new nickel(II) complexes [Ni(L)Cl2] (1) and [Ni(L)(NCS)2] (2) of a neutral tetradentate mono-condensed Schiff base ligand, 3-(2-(2-aminoethylamino)ethylimino)butan-2-one oxime (L) have been synthesized and characterized using different physicochemical techniques e.g. elemental analyses, spectroscopic (IR, Electronic, NMR) methods, conductivity and molecular measurements. The crystal structure of complex (2) has been determined by using single crystal X-ray diffraction method and it suggests a distorted octahedral geometry around nickel(II) having a NiN6 coordinating atmosphere. The non-coordinated Osbnd H group on the ligand L remain engaged in H-bonding interactions with the S end of the coordinated thiocyanate moiety. These H-bonding interactions lead to Osbnd S separations of 3.132 Å and play prominent role in crystal packing. It is observed that the mononuclear units are glued together with such Osbnd H…S interactions and finally results in an 1D supramolecular sheet-like arrangement. DFT/TDDFT based theoretical calculations were also performed on the ligand and the complexes aiming at the accomplishment of idea regarding their optimized geometry, electronic transitions and the molecular energy levels. Finally the catalytic behavior of the complexes for oxidation of styrene has also been carried out. A variety of reaction conditions like the effect of solvent, effect of temperature and time as well as the effect of ratio of substrate to oxidant were thoroughly studied to judge the catalytic efficiency of the Ni(II) coordination entity.

Antimicrobial Activity and Urease Inhibition of Schiff Bases Derived from Isoniazid and Fluorinated Benzaldehydes and of Their Copper(II) Complexes.

PubMed

Habala, Ladislav; Varényi, Samuel; Bilková, Andrea; Herich, Peter; Valentová, Jindra; Kožíšek, Jozef; Devínsky, Ferdinand

2016-12-17

In order to evaluate the influence of substitution on biological properties of Schiff bases and their metal complexes, a series of differently substituted fluorine-containing Schiff bases starting from the drug isoniazid (isonicotinylhydrazide) were prepared and their structures were established by single-crystal X-ray diffraction. Also, four copper(II) complexes of these Schiff bases were synthesized. The prepared compounds were evaluated for their antimicrobial activity and urease inhibition. Two of the Schiff bases exerted activity against C. albicans . All copper(II) complexes showed excellent inhibitory properties against jack bean urease, considerably better than that of the standard inhibitor acetohydroxamic acid.

5-Nitroimidazole-derived Schiff bases and their copper(II) complexes exhibit potent antimicrobial activity against pathogenic anaerobic bacteria.

PubMed

Oliveira, Alexandre A; Oliveira, Ana P A; Franco, Lucas L; Ferencs, Micael O; Ferreira, João F G; Bachi, Sofia M P S; Speziali, Nivaldo L; Farias, Luiz M; Magalhães, Paula P; Beraldo, Heloisa

2018-05-07

In the present work a family of novel secnidazole-derived Schiff base compounds and their copper(II) complexes were synthesized. The antimicrobial activities of the compounds were evaluated against clinically important anaerobic bacterial strains. The compounds exhibited in vitro antibacterial activity against Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bacteroides ovatus, Parabacteroides distasonis and Fusubacterium nucleatum pathogenic anaerobic bacteria. Upon coordination to copper(II) the antibacterial activity significantly increased in several cases. Some derivatives were even more active than the antimicrobial drugs secnidazole and metronidazole. Therefore, the compounds under study are suitable for in vivo evaluation and the microorganisms should be classified as susceptible to them. Electrochemical studies on the reduction of the nitro group revealed that the compounds show comparable reduction potentials, which are in the same range of the bio-reducible drugs secnidazole and benznidazole. The nitro group reduction potential is more favorable for the copper(II) complexes than for the starting ligands. Hence, the antimicrobial activities of the compounds under study might in part be related to intracellular bio-reduction activation. Considering the increasing resistance rates of anaerobic bacteria against a wide range of antimicrobial drugs, the present work constitutes an important contribution to the development of new antibacterial drug candidates.

C-H functionalization of 1,4-naphthoquinone by oxidative coupling with anilines in the presence of a catalytic quantity of copper(II) acetate.

PubMed

Lisboa, Cinthia da S; Santos, Vanessa G; Vaz, Boniek G; de Lucas, Nanci C; Eberlin, Marcos N; Garden, Simon J

2011-07-01

The oxidative addition of anilines (2) with 1,4-naphthoquinone (3) to give N-aryl-2-amino-1,4-naphthoquinones (1) was found to be catalyzed by copper(II) acetate. In the absence of the catalyst, the reactions are slower and give lower yields with the formation of many colateral products. In the presence of 10 mol % hydrated copper(II) acetate, the reactions are generally more efficient in that they are cleaner, higher yielding, and faster.

Flocculation of copper(II) and tetracycline from water using a novel pH- and temperature-responsive flocculants.

PubMed

Yang, Zhen; Jia, Shuying; Zhuo, Ning; Yang, Weiben; Wang, Yuping

2015-12-01

Insufficient research is available on flocculation of combined pollutants of heavy metals and antibiotics, which widely exist in livestock wastewaters. Aiming at solving difficulties in flocculation of this sort of combined pollution, a novel pH- and temperature-responsive biomass-based flocculant, carboxymethyl chitosan-graft-poly(N-isoproyl acrylamide-co-diallyl dimethyl ammonium chloride) (denoted as CND) with two responsive switches [lower critical solution temperature (LCST) and isoelectric point (IEP)], was designed and synthesized. Its flocculation performance at different temperatures and pHs was evaluated using copper(II) and tetracycline (TC) as model contaminants. CND exhibited high efficiency for coremoval of both contaminants, whereas two commercial flocculants (polyaluminum chloride and polyacrylamide) did not. Especially, flocculation performance of the dual-responsive flocculant under conditions of temperature>LCST and IEP(contaminants)copper(II) and TC were present in bridging flocculation, including charge attraction, coordination and hydrophobic effect. Based on these pairwise interactions, copper(II) and TC exerted "aid" roles to each other's removal with the existence of CND, and preferable flocculation performance was thus achieved. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation and sonodynamic activities of water-soluble tetra-α-(3-carboxyphenoxyl) zinc(II) phthalocyanine and its bovine serum albumin conjugate.

PubMed

Xu, He-Nan; Chen, Hai-Jun; Zheng, Bi-Yuan; Zheng, Yun-Quan; Ke, Mei-Rong; Huang, Jian-Dong

2015-01-01

Sonodynamic therapy (SDT) is a new approach for cancer treatment, involving the synergistic effect of ultrasound and certain chemical compounds termed as sonosensitizers. A water-soluble phthalocyanine, namely tetra-α-(3-carboxyphenoxyl) zinc(II) phthalocyanine (ZnPcC4), has been prepared and characterized. The interactions between ZnPcC4 and bovine serum albumin (BSA) were also investigated by absorption and fluorescence spectroscopy. It was found that there were strong interactions between ZnPcC4 and BSA with a binding constant of 6.83×10(7)M(-1). A non-covalent BSA conjugate of ZnPcC4 (ZnPcC4-BSA) was prepared. Both ZnPcC4 and ZnPcC4-BSA exhibited efficient sonodynamic activities against HepG2 human hepatocarcinoma cells. Compared with ZnPcC4, conjugate ZnPcC4-BSA showed a higher sonodynamic activity with an IC50 value of 7.5μM. Upon illumination with ultrasound, ZnPcC4-BSA can induce an increase of intracellular reactive oxygen species (ROS) level, resulting in cellular apoptosis. The results suggest that the albumin conjugates of zinc(II) phthalocyanines functionalized with carboxyls can serve as promising sonosensitizers for sonodynamic therapy. Copyright © 2014 Elsevier B.V. All rights reserved.

An efficient, cost effective, sensing behaviour liquid-liquid extraction and spectrophotometric determination of copper(II) incorporated with 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole: Analysis of food samples, leafy vegetables, fertilizers and environmental samples

NASA Astrophysics Data System (ADS)

Barache, Umesh B.; Shaikh, Abdul B.; Lokhande, Tukaram N.; Kamble, Ganesh S.; Anuse, Mansing A.; Gaikwad, Shashikant H.

2018-01-01

The aim of the present work is to develop an efficient, simple and selective moreover cost-effective method for the extractive spectrophotometric determination of copper(II) by using the Schiff base 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole [CBIMMT]. This chromogenic reagent forms a yellow coloured complex with copper(II) in acetate buffer at pH 4.2. The copper(II) complex with ligand is instantly extracted into chloroform and shows a maximum absorbance at 414 nm which remains stable for > 48 h. The composition of extracted complex is found to be 1:2 [copper(II): reagent] which was ascertained using Job's method of continuous variation, mole ratio method and slope ratio method. Under optimal conditions, the copper(II) complex in chloroform adheres to Beer's law up to 17.5 μg mL- 1 of copper(II). The optimum concentration range obtained from Ringbom's plot is from 5 μg mL- 1 to 17.5 μg mL- 1. The molar absorptivity, Sandell's sensitivity and enrichment factor of the extracted copper(II) chelate are 0.33813 × 104 L mol- 1 cm- 1, 0.01996 μg cm- 2 and 2.49 respectively. In the extraction of copper(II), several affecting factors including the solution pH, ligand concentration, equilibrium time, effect of foreign ions are optimized. The interfering effects of various cations and anions were also studied and use of masking agents enhances the selectivity of the method. The chromogenic sulphur containing reagent, 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole has been synthesized in a single step with high purity and yield. The synthesized reagent has been successfully applied first time for determination of copper(II). The reagent forms stable chelate with copper(II) in buffer medium instantly and quantitatively extracted in chloroform within a minute. The method is successfully applied for the determination of copper(II) in various synthetic mixtures, complexes, fertilizers, environmental samples such as food samples

Luminescent zinc(ii) and copper(i) complexes for high-performance solution-processed monochromic and white organic light-emitting devices.

PubMed

Cheng, Gang; So, Gary Kwok-Ming; To, Wai-Pong; Chen, Yong; Kwok, Chi-Chung; Ma, Chensheng; Guan, Xiangguo; Chang, Xiaoyong; Kwok, Wai-Ming; Che, Chi-Ming

2015-08-01

The synthesis and spectroscopic properties of luminescent tetranuclear zinc(ii) complexes of substituted 7-azaindoles and a series of luminescent copper(i) complexes containing 7,8-bis(diphenylphosphino)-7,8-dicarba- nido -undecaborate ligand are described. These complexes are stable towards air and moisture. Thin film samples of the luminescent copper(i) complexes in 2,6-dicarbazolo-1,5-pyridine and zinc(ii) complexes in poly(methyl methacrylate) showed emission quantum yields of up to 0.60 (for Cu-3 ) and 0.96 (for Zn-1 ), respectively. Their photophysical properties were examined by ultrafast time-resolved emission spectroscopy, temperature dependent emission lifetime measurements and density functional theory calculations. Monochromic blue and orange solution-processed OLEDs with these Zn(ii) and Cu(i) complexes as light-emitting dopants have been fabricated, respectively. Maximum external quantum efficiency (EQE) of 5.55% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.16, 0.19) were accomplished with the optimized Zn-1 -OLED while these values were, respectively 15.64% and (0.48, 0.51) for the optimized Cu-3 -OLED. Solution-processed white OLEDs having maximum EQE of 6.88%, CIE coordinates of (0.42, 0.44), and colour rendering index of 81 were fabricated by using these luminescent Zn(ii) and Cu(i) complexes as blue and orange light-emitting dopant materials, respectively.

Synthesis, characterization and extraction studies of some metal (II) complexes containing (hydrazoneoxime and bis-acylhydrazone) moieties.

PubMed

Al-Ne'aimi, Mohammed Mahmmod; Al-Khuder, Mohammed Moudar

2013-03-15

In this study, diacetylmonoximebenzoylhydrazone (L(1)H(2)) and 1,4-diacetylbenzene bis(benzoyl hydrazone) (L(2)H(2)) were synthesized by the condensation of benzohydrazide with diacetyl monoxime and 1,4-diacetylbenzene, respectively. Complexes of these ligands with Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) inos were prepared with a metal:ligand ratio of 1:2 for L(1)H(2) ligand, and 1:1 for L(2)H(2) ligand. The ligands and their complexes were elucidated on the basis of elemental analyses CHN, AAS, FT-IR, (1)H- and (13)C NMR spectra, UV-vis spectra and magnetic susceptibility measurements. Results show the L(1)H(2) ligand act as monoanionic O,N,N-tridentate and coordination takes place in the enol form through the oxime nitrogen, the imine nitrogen and the enolate oxygen atoms with a N(4)O(2) donor environment, while the L(2)H(2) ligand act as a dianionic O,N,N,O-tetradentate and coordination takes place in the enol form through the enolate oxygen and the azomethine nitrogen atoms with a N(2)O(2) donor environment. These results are consistent with the formation of mononuclear metal (II) complexes [M(L(1)H)(2)], and binuclear polymeric metal (II) complexes [{M(2)(L(2))}(n)]. The extraction ability of both ligands were examined in chloroform by the liquid-liquid extraction of selected transition metal [Co(2+), Ni(2+), Cu(2+), Zn(2+) and Pb(2+)] cations. The effects of pH and contact time on the percentage extraction of metal (II) ions were studied under the optimum extraction conditions. The (L(1)H(2)) ligand shows strong binding ability toward copper(II) and lead(II) ions, while the (L(2)H(2)) ligand shows strong binding ability toward nickel(II) and zinc(II) ions. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis, X-ray crystal structures, and phosphate ester cleavage properties of bis(2-pyridylmethyl)amine copper(II) complexes with guanidinium pendant groups.

PubMed

Belousoff, Matthew J; Tjioe, Linda; Graham, Bim; Spiccia, Leone

2008-10-06

Three new derivatives of bis(2-pyridylmethyl)amine (DPA) featuring ethylguanidinium (L (1)), propylguanidinium (L (2)), or butylguanidinium (L (3)) pendant groups have been prepared by the reaction of N, N- bis(2-pyridylmethyl)alkane-alpha,omega-diamines with 1 H-pyrazole-1-carboxamidine hydrochloride. The corresponding mononuclear copper(II) complexes were prepared by reacting the ligands with copper(II) nitrate and were isolated as [Cu(LH (+))(OH 2)](ClO 4) 3. xNaClO 4. yH 2O ( C1: L = L (1), x = 2, y = 3; C2: L = L (2), x = 2, y = 4; C3: L = L (3), x = 1, y = 0) following cation exchange purification. Recrystallization yielded crystals of composition [Cu(LH (+))(X)](ClO 4) 3.X ( C1': L = L (1), X = MeOH; C2': L = L (2), X = H 2O; C3': L = L (3), X = H 2O), which were suitable for X-ray crystallography. The crystal structures of C1', C2', and C3' indicate that the DPA moieties of the ligands coordinate to the copper(II) centers in a meridional fashion, with a water or methanol molecule occupying the fourth basal position. Weakly bound perchlorate anions located in the axial positions complete the distorted octahedral coordination spheres. The noncoordinating, monoprotonated guanidinium groups project away from the Cu(II)-DPA units and are involved in extensive charge-assisted hydrogen-bonding interactions with cocrystallized water/methanol molecules and perchlorate anions within the crystal lattices. The copper(II) complexes were tested for their ability to promote the cleavage of two model phosphodiesters, bis( p-nitrophenyl)phosphate (BNPP) and uridine-3'- p-nitrophenylphosphate (UpNP), as well as supercoiled plasmid DNA (pBR 322). While the presence of the guanidine pendants was found to be detrimental to BNPP cleavage efficiency, the functionalized complexes were found to cleave plasmid DNA and, in some cases, the model ribose phosphate diester, UpNP, at a faster rate than the parent copper(II) complex of DPA.

Synthesis, characterization, antibacterial activity, SOD mimic and interaction with DNA of drug based copper(II) complexes

NASA Astrophysics Data System (ADS)

Patel, Mohan N.; Dosi, Promise A.; Bhatt, Bhupesh S.; Thakkar, Vasudev R.

2011-02-01

Novel metal complexes of the second-generation quinolone antibacterial agent enrofloxacin with copper(II) and neutral bidentate ligands have been prepared and characterized with elemental analysis reflectance, IR and mass spectroscopy. Complexes have been screened for their in-vitro antibacterial activity against two Gram (+ve)Staphylococcus aureus, Bacillus subtilis, and three Gram (-ve)Serratia marcescens, Escherichia coli and Pseudomonas aeruginosa organisms using the double dilution technique. The binding of this complex with CT-DNA has been investigated by absorption titration, salt effect and viscosity measurements. Binding constant is ranging from 1.3 × 10 4-3.7 × 10 4. The cleavage ability of complexes has been assessed by gel electrophoresis using pUC19 DNA. The catalytic activity of the copper(II) complexes towards the superoxide anion (O 2rad -) dismutation was assayed by their ability to inhibit the reduction of nitroblue tetrazolium (NBT).

Extraction of heavy metals by mercaptans attached to silica gel by a corkscrew mechanism.

PubMed

Bowe, Craig A; Benson, Robert F; Martin, Dean F

2002-09-01

Saturated, straight chain mercaptans were attached to silica gel and used as coordinating agents for removal of cadmium(II), copper(II), lead(II), and nickel(II) ions from standard solutions. It is believed that the mercaptans become wedged in the silica pores, but are available for reaction. Four thiols were used, viz., 1-hexanethiol, 1-dodecanethiol, 1-hexadecanethiol, and 1-octadecanethiol. Standard solutions of metals (1.57 mM) were stirred with the supported mercaptans for two hours, and at 25 degrees C, and the sample supernatants were analyzed using atomic absorption spectrometry. At pH = 8, the percent removal was 99 (Cd), 91.5 (Cu), 80.8 (Pb), and 97 (Ni). It was possible to acidify the metal-containing solids, and regenerate the supported chelating agents.

The mononuclear nickel(II) complex bis(azido-κN)bis[2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ2 N2 ,N3 ]nickel(II) protects tomato from Verticillium dahliae by inhibiting fungal growth and activating plant defences.

PubMed

Zine, Hanane; Rifai, Lalla Aicha; Koussa, Tayeb; Bentiss, Fouad; Guesmi, Salaheddine; Laachir, Abdelhakim; Makroum, Kacem; Belfaiza, Malika; Faize, Mohamed

2017-01-01

The antifungal properties of the nickel(II) complex bis(azido-κN)bis[2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ 2 N 2 ,N 3 ]nickel(II) [NiL 2 (N 3 ) 2 ] and its parental ligand 2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole were examined to evaluate their ability to protect tomato plants against Verticillium dahliae. Our main objectives were to determine their effects on the in vitro growth of the pathogen, and their aptitude for controlling verticillium wilt and activating plant defence responses in the greenhouse. NiL 2 (N 3 ) 2 exhibited in vitro an elevated inhibition of radial growth of three strains of the pathogen. According to the strain, the EC 50 values ranged from 10 to 29 µg mL -1 for NiL 2 (N 3 ) 2 . In the greenhouse, it induced an elevated protection against V. dahliae when it was applied twice as foliar sprays at 50 µg mL -1 . It reduced the leaf alteration index by 85% and vessel browning by 96%. In addition, its protective ability was associated with the accumulation of H 2 O 2 and the activation of total phenolic content, as well as potentiation of the activity of peroxidase and polyphenol oxidase. These results demonstrated that the coordination of the ligand with Ni associated with the azide as a coligand resulted in an improvement in its biological activity by both inhibiting the growth of V. dahliae and activating plant defence responses. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

ATR-FTIR spectroscopic investigation of the cis- and trans-bis-(α-amino acids) copper(II) complexes

NASA Astrophysics Data System (ADS)

Berestova, Tatyana V.; Kuzina, Lyudmila G.; Amineva, Natalya A.; Faizrakhmanov, Ilshat S.; Massalimov, Ismail A.; Mustafin, Akhat G.

2017-06-01

The crystalline phases of the trans-(a) and cis-(b)-isomers of bis-(α-amino acids) copper(II) complexes [Cu(bL)2] 1-5 (bL - bidentate ligand: gly (1), S-ala (2), R,S-val (3), (±)-thr (4), R,S-phe (5)) were studied by ATR-FTIR spectroscopy in the mid region IR spectrum. It was established that asymmetric νas(COO) and symmetric νs(COO) stretching vibrations of carboxylic groups of 1-5 are sensitive to change of the geometric structure and have a different maxima for the trans(a)- and cis(b)-isomers. It found that νas(COO) and νs(COO) stretching vibrations of cis-isomers are broadened and shifted to longer wavelengths (b) as compared with trans-isomers (a). Shown that peculiarities of crystal packing molecules of geometric isomers may affect on carboxylate stretching vibration bis-α-amino acids complexes copper(II) 1-5 a,b.

Copper(II) complex of new non-innocent O-aminophenol-based ligand as biomimetic model for galactose oxidase enzyme in aerobic oxidation of alcohols

NASA Astrophysics Data System (ADS)

Safaei, Elham; Bahrami, Hadiseh; Pevec, Andrej; Kozlevčar, Bojan; Jagličić, Zvonko

2017-04-01

Mononuclear copper(II) complex of tetra-dentate o-aminophenol-based ligand (H2LBAPP) has been synthesized and characterized. The three dentate precursor (HLBAP) of the final ligand was synthesized first, while the title four-dentate copper bound ligand was synthesized in situ, isolated only in the final copper species [CuLBAPP]. This copper coordination complex reveals a distorted square-planar geometry around the copper(II) centre by one oxygen and three nitrogen atoms from the coordinating ligand. The ligand is thus twice deprotonated via hydroxy and amine groups. The complex is red, non-typical for copper(II), but the effective magnetic moment of 1.86 B M. and a single isotropic symmetry EPR signal with g 2.059 confirm a S = 1/2 diluted spin system, without copper-copper magnetic coupling. Electrochemical oxidation of this complex yields the corresponding Cu(II)-phenyl radical species. Finally, the title complex CuLBAPP has shown good and selective catalytic activity towards alcohol to aldehyde oxidation, at aerobic room temperature conditions, for a set of different alcohols.

Copper(II) imidazolate frameworks as highly efficient photocatalysts for reduction of CO{sub 2} into methanol under visible light irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jingtian; Luo, Deliang; Yang, Chengju

2013-07-15

Three copper(II) imidazolate frameworks were synthesized by a hydrothermal (or precipitation) reaction. The catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–vis), Fourier transform infrared spectra (FTIR), thermogravimetry (TG). Meanwhile, the photocatalytic activities of the samples for reduction of CO{sub 2} into methanol and degradation of methylene blue (MB) under visible light irradiation were also investigated. The results show that the as-prepared samples exhibit better photocatalytic activities for the reduction of carbon dioxide into methanol with water and degradation of MB under visible light irradiation. The orthorhombic copper(II) imidazolate frameworks with a bandmore » gap of 2.49 eV and green (G) color has the best photocatalytic activity for reduction of CO{sub 2} into methanol, 1712.7 μmol/g over 5 h, which is about three times as large as that of monoclinic copper(II) imidazolate frameworks with a band gap 2.70 eV and blue (J) color. The degradation kinetics of MB over three photocatalysts fitted well to the apparent first-order rate equation and the apparent rate constants for the degradation of MB over G, J and P (with pink color) are 0.0038, 0.0013 and 0.0016 min{sup −1}, respectively. The synergistic effects of smallest band gap and orthorhombic crystal phase structure are the critical factors for the better photocatalytic activities of G. Moreover, three frameworks can also be stable up to 250 °C. The investigation of Cu-based zeolitic imidazolate frameworks maybe provide a design strategy for a new class of photocatalysts applied in degradation of contaminations, reduction of CO{sub 2}, and even water splitting into hydrogen and oxygen under visible light. - Graphical abstract: Carbon dioxide was reduced into methanol with water over copper(II) imidazolate frameworks under visible light irradiation. - Highlights: • Three

The electronic spectra and the structures of the individual copper(II) chloride and bromide complexes in acetonitrile according to steady-state absorption spectroscopy and DFT/TD-DFT calculations

NASA Astrophysics Data System (ADS)

Olshin, Pavel K.; Myasnikova, Olesya S.; Kashina, Maria V.; Gorbunov, Artem O.; Bogachev, Nikita A.; Kompanets, Viktor O.; Chekalin, Sergey V.; Pulkin, Sergey A.; Kochemirovsky, Vladimir A.; Skripkin, Mikhail Yu.; Mereshchenko, Andrey S.

2018-03-01

The results of spectrophotometric study and quantum chemical calculations for copper(II) chloro- and bromocomplexes in acetonitrile are reported. Electronic spectra of the individual copper(II) halide complexes were obtained in a wide spectral range 200-2200 nm. Stability constants of the individual copper(II) halide complexes in acetonitrile were calculated: log β1 = 8.5, log β2 = 15.6, log β3 = 22.5, log β4 = 25.7 for [CuCln]2-n and log β1 = 17.0, log β2 = 24.6, log β3 = 28.1, log β4 = 30.4 for [CuBrn]2-n. Structures of the studied complexes were optimized and electronic spectra were simulated using DFT and TD-DFT methodologies, respectively. According to the calculations, the more is the number of halide ligands the less is coordination number of copper ion.

Synergistic extraction and spectrophotometric determination of copper(II) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol: Analysis of alloys, pharmaceuticals and biological samples

NASA Astrophysics Data System (ADS)

Kamble, Ganesh S.; Kolekar, Sanjay S.; Anuse, Mansing A.

2011-05-01

A simple and selective spectrophotometric method was developed for the determination of copper(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The procedure was based on the synergistic extraction of copper(II) with 2',4'-dinitro APTPT in the presence of 0.5 mol L -1 pyridine to give green colored ternary complex of a molar ratio 1:2:2 (M:L:Py) in the pH range 8.7-10.5. It exhibits a maximum absorption of colored complex at 445 nm and 645 nm in chloroform against the reagent blank. Beer's law was followed in the concentration range 10-80 μg mL -1 of copper(II) and optimum range of 20-70 μg mL -1 the metal as evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of copper(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 0.87 × 10 3 L mol -1 cm -1 and 0.072 μg cm -2, respectively. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The proposed method is rapid, reproducible and successfully applied for the determination of copper(II) in binary and synthetic mixtures, alloys, pharmaceutical formulations, environmental and fertilizer samples. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method.

Synthesis, supramolecular behavior, and in vitro photodynamic activities of novel zinc(II) phthalocyanines "side-strapped" with crown ether bridges.

PubMed

Chen, Xing-Wei; Ke, Mei-Rong; Li, Xing-Shu; Lan, Wen-Liang; Zhang, Miao-Fen; Huang, Jian-Dong

2013-12-01

Two new tetra- or di-α-substituted zinc(II) phthalocyanines 5 and 6 have been prepared through a "side-strapped" method. In the molecules, the adjacent benzene rings of the phthalocyanine core are linked at α-position through a triethylene glycol bridge to form a hybrid aza-/oxa-crown ether. The tetra-α-substituted phthalocyanine 5 shows an eclipsed self-assembly property in CH2Cl2 and the effect on the di-α-substituted analogue 6 is significantly weakened. Furthermore, the crown ethers of these compounds can selectively complex with Fe(3+) or Cu(2+) ion in DMF, leading to formation of J-aggregated nano-assemblies, which can be disaggregated in the presence of some organic or inorganic ligands, such as triethylamine, tetramethylethylenediamine, CH3COO(-), or OH(-). In addition, both compounds are efficient singlet oxygen generators with the singlet oxygen quantum yields (Φ(Δ)) of 0.54-0.74 in DMF relative to unsubstituted zinc(II) phthalocyanine (Φ(Δ)=0.56). They exhibit photodynamic activities toward HepG2 human hepatocarcinoma cells, but the compound 6, which has more than 40-fold lower IC50 value (0.08 μM) compared to the analogue 5 (IC50=3.31 μM), shows remarkablely higher in vitro photocytotoxicity due to its significantly higher cellular uptake and singlet oxygen generation efficiency. The results suggest that these compounds can serve as promising multifunctional materials both in (opto)electronic field and photodynamic therapy. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High stability and biological activity of the copper(II) complexes of alloferon 1 analogues containing tryptophan.

PubMed

Kadej, Agnieszka; Kuczer, Mariola; Czarniewska, Elżbieta; Urbański, Arkadiusz; Rosiński, Grzegorz; Kowalik-Jankowska, Teresa

2016-10-01

Copper(II) complex formation processes between the alloferon 1 (Allo1) (HGVSGHGQHGVHG) analogues where the tryptophan residue is introducing in the place His residue H1W, H6W, H9W and H12W have been studied by potentiometric, UV-visible, CD and EPR spectroscopic, and MS methods. For all analogues of alloferon 1 complex speciation have been obtained for a 1:1 metal-to-ligand molar ratio and 2:1 of H1W because of precipitation at higher (2:1, 3:1 and 4:1) ratios. At physiological pH7.4 and a 1:1 metal-to-ligand molar ratio the tryptophan analogues of alloferon 1 form the CuH -1 L and/or CuH -2 L complexes with the 4N binding mode. The introduction of tryptophan in place of histidine residues changes the distribution diagram of the complexes formed with the change of pH and their stability constants compared to the respective substituted alanine analogues of alloferon 1. The CuH -1 L, CuH -2 L and CuH -3 L complexes of the tryptophan analogues are more stable from 1 to 5 log units in comparison to those of the alanine analogues. This stabilization of the complexes may result from cation(Cu(II))-π and indole/imidazole ring interactions. The induction of apoptosis in vivo, in Tenebrio molitor cells by the ligands and their copper(II) complexes at pH7.4 was studied. The biological results show that copper(II) ions in vivo did not cause any apparent apoptotic features. The most active were the H12W peptide and Cu(II)-H12W complex formed at pH7.4. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis, characterization and catalytic oxidation properties of multi-wall carbon nanotubes with a covalently attached copper(II) salen complex

NASA Astrophysics Data System (ADS)

Salavati-Niasari, Masoud; Bazarganipour, Mehdi

2009-06-01

Hydroxyl functionalized copper(II) Schiff-base, N,N'-bis(4-hydroxysalicylidene)-ethylene-1,2-diaminecopper(II), [Cu((OH) 2-salen)], has been covalently anchored on modified MWCNTs. The new modified MWCNTs ([Cu((OH) 2-salen)]-MWCNTs) have been characterized by TEM, thermal analysis, XRD, XPS, UV-vis, DRS, FT-IR spectroscopy and elemental analysis. The modified copper(II) MWCNTs solid was used to affect the catalytic oxidation of ethylbenzene with tert-butylhydroperoxide as the oxidant at 333 K. The system is truly heterogeneous (no leaching observed) and reusable (no decrease in activity) in three consecutive runs. Acetophenone was the major product though small amounts of o- and p-hydroxyacetophenones were also formed revealing that C-H bond activation takes place both at benzylic and aromatic ring carbon atoms. Ring hydroxylation was more over the "neat" complexes than over the encapsulated complexes.

Effect of additives on the volatility of elements in a DC arc during the atomic emission analysis of nickel(II) oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zolotareva, N.I.; Kuzyakov, Yu.Ya.; Khlystova, A.D.

1986-10-20

The authors have studied the effect of traditional halogenating additives, AgCl, CdF/sub 2/, PTFE and that of an effective additive they have selected, ZnF/sub 2/, on the volatility of impurity elements, viz. tungsten, molybdenum, titanium, and zirconium from nickel (II) oxide, and determined the constants for the average relative volatility of the elements by the method of Kantor and Pungor. The results have been used to lower the limits of detection of the impurities cited in nickel(II) oxide.

Flotation of traces of silver and copper(II) ions with a methyl cellosolve solution of dithizone.

PubMed

Hiraide, M; Mizuike, A

1975-06-01

Microgram quantities of silver and copper(II) ions in aqueous solutions are collected on dithizone precipitates, which are then floated with the aid of small nitrogen bubbles. This separation technique has been successfully applied to the atomic-absorption spectrophotometric determination of down to a tenth ppm of silver and copper in high-purity lead and zinc metals.

Novel Cage-Like Hexanuclear Nickel(II) Silsesquioxane. Synthesis, Structure, and Catalytic Activity in Oxidations with Peroxides.

PubMed

Bilyachenko, Alexey N; Yalymov, Alexey I; Shul'pina, Lidia S; Mandelli, Dalmo; Korlyukov, Alexander A; Vologzhanina, Anna V; Es'kova, Marina A; Shubina, Elena S; Levitsky, Mikhail M; Shul'pin, Georgiy B

2016-05-19

New hexanuclear nickel(II) silsesquioxane [(PhSiO1.5)12(NiO)₆(NaCl)] (1) was synthesized as its dioxane-benzonitrile-water complex (PhSiO1,5)12(NiO)₆(NaCl)(C₄H₈O₂)13(PhCN)₂(H₂O)₂ and studied by X-ray and topological analysis. The compound exhibits cylinder-like type of molecular architecture and represents very rare case of polyhedral complexation of metallasilsesquioxane with benzonitrile. Complex 1 exhibited catalytic activity in activation of such small molecules as light alkanes and alcohols. Namely, oxidation of alcohols with tert-butylhydroperoxide and alkanes with meta-chloroperoxybenzoic acid. The oxidation of methylcyclohexane gave rise to the isomeric ketones and unusual distribution of alcohol isomers.

Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N4-methyl-3-thiosemicarbazone: Crystal structure of a novel sulfur bridged copper(II) box-dimer

NASA Astrophysics Data System (ADS)

Jayakumar, K.; Sithambaresan, M.; Aiswarya, N.; Kurup, M. R. Prathapachandra

2015-03-01

Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N4-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ = 0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)sbnd I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g|| > g⊥ > 2.0023 and the g values in frozen DMF are consistent with the dx2-y2 ground state. The thermal stabilities of some of the complexes were also determined.

Synthesis, characterization and crystal structure of a 1D thiocyanato bridged [Cu(en)2Zn(NCS)4]ṡH2O. Comparison of the three structures with the same [Cu(en)2Zn(NCS)4] unit - different in structural terms

NASA Astrophysics Data System (ADS)

Wrzeszcz, Grzegorz; Muzioł, Tadeusz M.; Tereba, Natalia

2015-03-01

In this paper we report the synthesis method and the structure of a one-dimensional thiocyanato bridged heterometallic compound, [Cu(en)2Zn(NCS)4]ṡH2O (1). Moreover, we compare the structure of (1) with the previously described structures of [Cu(en)2Zn(NCS)4]ṡ0.5H2O (2) and [Cu(en)2Zn(NCS)4]ṡCH3CN (3) Pryma et al. (2003) [7]. The compound (1) has been characterized by thermal decomposition, IR, Vis and EPR spectra, and magnetic studies. Structure has been determined by X-ray analysis. Described coordination polymer crystallizes in the orthorhombic Cmcm space group with a = 12.414(2), b = 10.3276(14), c = 14.967(2) Å, α = β = γ = 90°, V = 1918.8(5) Å3 and Z = 4. Each distorted tetrahedral zinc(II) centre (with N-bonded NCS-) links two tetragonally distorted octahedral copper(II) centres by two end-to-end thiocyanato bridges and vice versa forming a zigzag type of CuZn chain. The structures of (1), (2) and (3) differ in crystallographic system, space group and/or CuZn chain type as well as in details. Variable temperature magnetic susceptibility measurements show very weak antiferromagnetic interactions between the paramagnetic copper(II) ions for compound (1).

Highly preorganized pyrazolate-bridged palladium(II) and nickel(II) complexes in bimetallic norbornene polymerization.

PubMed

Sachse, Anna; Demeshko, Serhiy; Dechert, Sebastian; Daebel, Venita; Lange, Adam; Meyer, Franc

2010-04-28

New derivatives of pyrazolate-based binucleating ligands HL with appended imine functions have been synthesized to provide a versatile set of ligand systems with different backbone substituents both at the pyrazole-C(4) and the imine-C (H, Me, Ph). These scaffolds have two adjacent coordination compartments akin to the alpha-diimine type. A series of binuclear palladium(II) complexes [LPd(2)Cl(3)] (1-4) and tetranuclear nickel(II) complexes [L(2)Ni(4)Br(6)(solvent)(4)] (5, 6) of the various ligands have been prepared and characterized, including X-ray structural analyses for two representative Pd and the two Ni complexes. Complexes 5 and 6 were found to contain an unusual central mu(4)-bromide. Mononuclear nickel(II) complexes [L(2)Ni] were detected as intermediates in the formation of the tetranuclear complexes and have been characterized by X-ray analyses in two cases (7, 8). The interconversion between 5' and 7 has been investigated by UV/Vis spectroscopy and ESI mass spectrometry, and magnetic coupling in the [L(2)Ni(4)Br(6)(solvent)(4)] complexes has been studied (SQUID). Trans-coupling via the central mu(4)-bromide is suggested to mediate significant antiferromagnetic interaction. The reactivity of such types of Pd and Ni complexes has been tested for the vinyl/addition polymerization of norbornene. In the presence of an excess of cocatalyst methylaluminoxane (MAO) the palladium complexes show high activity up to 5.9 x 10(6) g(PNB) mol(Pd)(-1) h(-1) at 20 degrees C, while activities of the nickel systems are much lower, but strongly solvent dependent. Detailed studies on the dependence of activity on polymerization conditions such as molar ratios of catalyst and cocatalyst, temperature, reaction time and solvent were carried out. All obtained polynorbornenes (PNB) were noncrystalline and insoluble, but have high glass transition temperatures (T(g)). Microstructures were analyzed by IR spectroscopy and solid state (CP/MAS) (13)C NMR, revealing distinct

Electrocatalytic Hydrogen Production by a Nickel(II) Complex with a Phosphinopyridyl Ligand.

PubMed

Tatematsu, Ryo; Inomata, Tomohiko; Ozawa, Tomohiro; Masuda, Hideki

2016-04-18

A novel nickel(II) complex [Ni(L)2 Cl]Cl with a bidentate phosphinopyridyl ligand 6-((diphenylphosphino)methyl)pyridin-2-amine (L) was synthesized as a metal-complex catalyst for hydrogen production from protons. The ligand can stabilize a low Ni oxidation state and has an amine base as a proton transfer site. The X-ray structure analysis revealed a distorted square-pyramidal Ni(II)  complex with two bidentate L ligands in a trans arrangement in the equatorial plane and a chloride anion at the apex. Electrochemical measurements with the Ni(II) complex in MeCN indicate a higher rate of hydrogen production under weak acid conditions using acetic acid as the proton source. The catalytic current increases with the stepwise addition of protons, and the turnover frequency is 8400 s(-1) in 0.1 m [NBu4 ][ClO4 ]/MeCN in the presence of acetic acid (290 equiv) at an overpotential of circa 590 mV. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel tridentate coordination mode for the carbonatonickel system exhibited in an unusual hexanuclear nickel(II) mu3-carbonato-bridged complex.

PubMed

Anderson, James C; Blake, Alexander J; Moreno, Rafael Bou; Raynel, Guillaume; van Slageren, Joris

2009-11-14

The fixation of CO(2) at ambient temperature has been achieved by the reaction of Ni(cod)(2) and TMEDA in CO(2) saturated THF that yields a novel hexanuclear nickel(II) mu(3)-carbonato bridged complex [Ni(6)(mu(3)-CO(3))(4)(TMEDA)(6)(H(2)O)(12)](OH)(4) in 59% yield. The complex was characterised by MS analysis and the structure corroborated by single-crystal X-ray crystallography. The complex exhibits a rare carbonato binding mode for Ni(II) complexes and moderately strong antiferromagnetic interactions.

STUDIES ON BIOSORPTION OF ZINC(II) AND COPPER(II) ON DESULFOVIBRIO DESULFURICANS

EPA Science Inventory

The objectives of thes studies are to determine the equilibrium concentration and kinetics of metal sorption on sulfate-reducing bacteria (SRB) isolates. Adsorption establishes the net reversible cellular metal uptake and is related to SRB metal toxicity and the effects of enviro...

Determination of cadmium(II), cobalt(II), nickel(II), lead(II), zinc(II), and copper(II) in water samples using dual-cloud point extraction and inductively coupled plasma emission spectrometry.

PubMed

Zhao, Lingling; Zhong, Shuxian; Fang, Keming; Qian, Zhaosheng; Chen, Jianrong

2012-11-15

A dual-cloud point extraction (d-CPE) procedure has been developed for simultaneous pre-concentration and separation of heavy metal ions (Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion) in water samples by inductively coupled plasma optical emission spectrometry (ICP-OES). The procedure is based on forming complexes of metal ion with 8-hydroxyquinoline (8-HQ) into the as-formed Triton X-114 surfactant rich phase. Instead of direct injection or analysis, the surfactant rich phase containing the complexes was treated by nitric acid, and the detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by ICP-OES. Under the optimum conditions (pH=7.0, Triton X-114=0.05% (w/v), 8-HQ=2.0×10(-4) mol L(-1), HNO3=0.8 mol L(-1)), the detection limits for Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ions were 0.01, 0.04, 0.01, 0.34, 0.05, and 0.04 μg L(-1), respectively. Relative standard deviation (RSD) values for 10 replicates at 100 μg L(-1) were lower than 6.0%. The proposed method could be successfully applied to the determination of Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis, characterization, and antimicrobial activity of silver(I) and copper(II) complexes of phosphate derivatives of pyridine and benzimidazole.

PubMed

Kalinowska-Lis, Urszula; Szewczyk, Eligia M; Chęcińska, Lilianna; Wojciechowski, Jakub M; Wolf, Wojciech M; Ochocki, Justyn

2014-01-01

Two silver(I) complexes--[Ag(4-pmOpe)]NO₃}(n) and [Ag(2-bimOpe)₂]NO₃--and three copper(II) complexes--[Cu₄Cl₆O(2-bimOpe)₄], [CuCl₂(4-pmOpe)₂], and [CuCl₂(2-bis(pm)Ope]--were synthesized by reaction of silver(I) nitrate or copper(II) chloride with phosphate derivatives of pyridine and benzimidazole, namely diethyl (pyridin-4-ylmethyl)phosphate (4-pmOpe), 1H-benzimidazol-2-ylmethyl diethyl phosphate (2-bimOpe), and ethyl bis(pyridin-2-ylmethyl)phosphate (2-bis(pm)Ope). These compounds were characterized by ¹H, ¹³C, and ³¹P NMR as well as IR spectroscopy, elemental analysis, and ESIMS spectrometry. Additionally, molecular and crystal structures of {[Ag(4-pmOpe)]NO₃}n and [Cu₄Cl₆O(2-bimOpe)₄] were determined by single-crystal X-ray diffraction analysis. The antimicrobial profiles of synthesized complexes and free ligands against test organisms from the ATCC and clinical sources were determined. Silver(I) complexes showed good antimicrobial activities against Candida albicans strains (MIC values of ∼19 μM). [Ag(2-bimOpe)₂]NO₃ was particularly active against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus epidermidis, with MIC values of ∼5 and ∼10 μM, respectively. Neither copper(II) complexes nor the free ligands inhibited the growth of test organisms at concentrations below 500 μg mL⁻¹. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical speciation and bioavailability of Cu(II). Study of the ionic copper(II) and bis(glycinate)-copper(II) accumulation by Lemna species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benda, F.; Kouba, J.

1991-03-01

In this paper, the authors examined the accumulation of copper(II) in, and its toxic effect on, duckweed, a plant which exhibits extremely high concentration factors. The effect of copper(II) was investigated by adding it to the minimal medium in two forms: CuSO{sub 4} and (Cu(Gly){sub 2}). The neutral (2:1) tetracoordinated bis(glycinate)-copper(II) complex is constituted by two five-membered rings bonded to the central copper atom with the cis configuration. This complex was chosen to model the function of a neutral species (eliminating the charge effect) involving a nontoxic ligand, for which - in contrast to the hydrated Cu{sup 2+} species -more » direct permeation through the cell wall is conceivable.« less

Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N⁴-methyl-3-thiosemicarbazone: crystal structure of a novel sulfur bridged copper(II) box-dimer.

PubMed

Jayakumar, K; Sithambaresan, M; Aiswarya, N; Kurup, M R Prathapachandra

2015-03-15

Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N(4)-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ=0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g||>g⊥>2.0023 and the g values in frozen DMF are consistent with the d(x2-y2) ground state. The thermal stabilities of some of the complexes were also determined. Copyright © 2014 Elsevier B.V. All rights reserved.

Nickel(I) and nickel(III) complexes of substituted tetraaza macrocycles formed by pulse radiolysis and electrochemistry of nickel(II) precursors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernhardt, P.V.; Lawrance, G.A.; Sangster, D.F.

The square-planar nickel(II) complexes of the ligands 8-methyl-8-nitro-1,3,6,10,13,15-hexaazatricyclo(13.1.1.1/sup 13,15/)octadecane, 8-amino-8-methyl-1,3,6,10,13,15-hexaazatricyclo(13.1.1.1/sup 13,15/)octadecane, 3,7-bis(2-aminoethyl)-1,3,5,7-tetraazabicyclo(3.3.1)nonane, and 9-methyl-9-nitro-1,4,7,11-tetraazacyclotridecane (I-IV) react rapidly with hydroxyl radicals and aquated electrons (e/sub aq/). The initial transient products of these reactions decay via first-order kinetics within a few milliseconds in neutral aqueous solution at 22/degrees/C in all cases. Electronic spectra and decay rate constants, as well as formation rate constants, are reported for all transients. Reaction of the nitro-substituted complexes with e/sub aq/ led to electron addition to the nitro group rather than to the metal center; otherwise, a Ni/sup I/ transient is observed. Following reaction with OH, themore » product of the initial decay remains a Ni/sup III/ species. This is more long-lived, and stabilization of Ni/sup III/ by axial coordination of the pendant amine in II is indicated. No notable stabilization of Ni/sup I/ or Ni/sup III/ from the presence of the bicyclic azamethylene football in I-III occurs. Cyclic voltammetry in acetonitrile identified both one-electron oxidation and one-electron reduction processes for the nickel(II) complexes, as well as nitro group reduction, where this group was pendant to the macrocycle. 34 references, 3 figures, 3 tables.« less

Investigation of simultaneous biosorption of copper(II) and chromium(VI) on dried Chlorella vulgaris from binary metal mixtures: Application of multicomponent adsorption isotherms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aksu, Z.; Acikel, U.; Kutsal, T.

1999-02-01

Although the biosorption of single metal ions to various kinds of microorganisms has been extensively studied and the adsorption isotherms have been developed for only the single metal ion situation, very little attention has been given to the bioremoval and expression of adsorption isotherms of multimetal ions systems. In this study the simultaneous biosorption of copper(II) and chromium(VI) to Chlorella vulgaris from a binary metal mixture was studied and compared with the single metal ion situation in a batch stirred system. The effects of pH and single- and dual-metal ion concentrations on the equilibrium uptakes were investigated. In previous studiesmore » the optimum biosorption pH had been determined as 4.0 for copper(II) and as 2.0 for chromium(VI). Multimetal ion biosorption studies were performed at these two pH values. It was observed that the equilibrium uptakes of copper(II) or chromium(VI) ions were changed due to the biosorption pH and the presence of other metal ions. Adsorption isotherms were developed for both single- and dual-metal ions systems at these two pH values, and expressed by the mono- and multicomponent Langmuir and Freundlich adsorption models. Model parameters were estimated by nonlinear regression. It was seen that the adsorption equilibrium data fitted very well to the competitive Freundlich model in the concentration ranges studied.« less

Chiral Nickel(II) Complex Catalyzed Enantioselective Doyle-Kirmse Reaction of α-Diazo Pyrazoleamides.

PubMed

Lin, Xiaobin; Tang, Yu; Yang, Wei; Tan, Fei; Lin, Lili; Liu, Xiaohua; Feng, Xiaoming

2018-03-07

Although high enantioselectivity of [2,3]-sigmatropic rearrangement of sulfonium ylides (Doyle-Kirmse reaction) has proven surprisingly elusive using classic chiral Rh(II) and Cu(I) catalysts, in principle it is due to the difficulty in fine discrimination of the heterotopic lone pairs of sulfur and chirality inversion at sulfur of sulfonium ylides. Here, we show that the synergistic merger of new α-diazo pyrazoleamides and a chiral N, N'-dioxide-nickel(II) complex catalyst enables a highly enantioselective Doyle-Kirmse reaction. The pyrazoleamide substituent serves as both an activating and a directing group for the ready formation of a metal-carbene- and Lewis-acid-bonded ylide intermediate in the assistance of a dual-tasking nickel(II) complex. An alternative chiral Lewis-acid-bonded ylide pathway greatly improves the product enantiopurity even for the reaction of a symmetric diallylsulfane. The majority of transformations over a series of aryl- or vinyl-substituted α-diazo pyrazoleamindes and sulfides proceed rapidly (within 5-20 min in most cases) with excellent results (up to 99% yield and 96% ee), providing a breakthrough in enantioselective Doyle-Kirmse reaction.

Rapid determination of ions by combined solid-phase extraction--diffuse reflectance spectroscopy

NASA Technical Reports Server (NTRS)

Fritz, James S.; Arena, Matteo P.; Steiner, Steven A.; Porter, Marc D.

2003-01-01

We introduce colorimetric solid-phase extraction (C-SPE) for the rapid determination of selected ions. This new technique links the exhaustive concentration of an analyte by SPE onto a membrane disk surface for quantitative measurement with a hand-held diffuse reflectance spectrometer. The concentration/measurement procedure is complete in approximately 1 min and can be performed almost anywhere. This method has been used to monitor iodine and iodide in spacecraft water in the 0.1-5.0 ppm range and silver(I) in the range of 5.0-1000 microg/l. Applications to the trace analysis of copper(II), nickel(II), iron(III) and chromium(VI) are described. Studies on the mechanism of extraction showed that impregnation of the disk with a surfactant as well as a complexing reagent results in uptake of additional water, which markedly improves the extraction efficiency.

Synthesis, characterization and anti-microbial evaluation of Cu(II), Ni(II), Pt(II) and Pd(II) sulfonylhydrazone complexes; 2D-QSAR analysis of Ni(II) complexes of sulfonylhydrazone derivatives

NASA Astrophysics Data System (ADS)

Özbek, Neslihan; Alyar, Saliha; Alyar, Hamit; Şahin, Ertan; Karacan, Nurcan

2013-05-01

Copper(II), nickel(II), platinum(II) and palladium(II) complexes with 2-hydroxy-1-naphthaldehyde-N-methylpropanesulfonylhydrazone (nafpsmh) derived from propanesulfonic acid-1-methylhydrazide (psmh) were synthesized, their structure were identified, and antimicrobial activity of the compounds was screened against three Gram-positive and three Gram-negative bacteria. The results of antimicrobial studies indicate that Pt(II) and Pd(II) complexes showed the most activity against all bacteria. The crystal structure of 2-hydroxy-1-naphthaldehyde-N-methylpropanesulfonylhydrazone (nafpsmh) was also investigated by X-ray analysis. A series of Ni(II) sulfonyl hydrazone complexes (1-33) was synthesized and tested in vitro against Escherichia coli and Staphylococcus aureus. Their antimicrobial activities were used in the QSAR analysis. Four-parameter QSAR models revealed that nucleophilic reaction index for Ni and O atoms, and HOMO-LUMO energy gap play key roles in the antimicrobial activity.

Investigation on biomolecular interactions of nickel(II) complexes with monoanionic bidentate ligands

NASA Astrophysics Data System (ADS)

Jayamani, Arumugam; Sethupathi, Murugan; Ojwach, Stephen O.; Sengottuvelan, Nallathambi

2018-01-01

Reactions of monoanionic bidentate ligands 5-methylsalicylaldehyde (5-msal), 5-bromosalicylaldehyde (5-brsal), 5-nitrosalicylaldehyde (5-nsal) and 2-hydroxy-1-naphthaldehyde (2-hnap) with nickel perchlorate hexahydrate produced nickel(II) complexes 1-4, respectively. Single crystal X-ray analyses of complexes 1 and 2 confirmed bidentate mode of the ligands with O˄O coordination to give square planar geometry around nickel atoms. Complexes 1-4 showed one quasi-reversible redox peak at cathodic region (-0.67 to -0.80 V) and one redox peak at anodic region (+1.08 to +1.44 V) assignable to the Ni(II)/Ni(I) and Ni(II)/Ni(III) redox couples, respectively. The complexes exhibited good bovine serum albumin (BSA) binding abilities with a maximum binding constant of 1.96 × 105 M-1. The binding of complexes with calf thymus DNA (ctDNA) showed that the binding affinity is consistent with an increase in steric bulk of the ligands. The nuclease activity of the complexes showed efficient oxidative cleavage in the presence of hydrogen peroxide as an oxidizing agent. The complexes showed higher zone of inhibition when screened for antimicrobial activity against bacteria and human pathogenic fungi.

Syntheses and structural characterization of iron(II) and copper(II) coordination compounds with the neutral flexible bidentate N-donor ligands

NASA Astrophysics Data System (ADS)

Beheshti, Azizolla; Lalegani, Arash; Bruno, Giuseppe; Rudbari, Hadi Amiri

2014-08-01

Two new coordination compounds [Fe(bib)2(N3)2]n(1) and [Cu2(bpp)2(N3)4] (2) with azide and flexible ligands 1,4-bis(imidazolyl)butane (bib) and 1,3-bis(3,5-dimethylpyrazolyl)propane (bpp) were prepared and structurally characterized. In the 2D network structure of 1, the iron(II) ion lies on an inversion center and exhibits an FeN6 octahedral arrangement while in the dinuclear structure of 2, the copper(II) ion adopts an FeN5 distorted square pyramid geometry. In the complex 1, each μ2-bib acts as bridging ligand connecting two adjacent iron(II) ions while in the complex 2, the bpp ligand is coordinated to copper(II) ion in a cyclic-bidentate fashion forming an eight-membered metallocyclic ring. Coordination compounds 1 and 2 have been characterized by infrared spectroscopy, elemental analyses and single-crystal X-ray diffraction. Thermal analysis of polymer 1 was also studied.

Dynamics of the sorption of copper(II) and silver(I) by materials based on sulfoethylchitosan with various degrees of crosslinking

NASA Astrophysics Data System (ADS)

Petrova, Yu. S.; Pestov, A. V.; Alifkhanova, L. M. k.; Neudachina, L. K.

2017-04-01

Optimum conditions of the dynamic concentration of copper(II) and silver(I) ions simultaneously present in a solution with N-(2-sulfoethyl)chitosan with a degree of modification equal to 0.5 and different degrees of crosslinking by glutaraldehyde are determined. The values of coefficients of selectivity K Ag/Cu are determined under dynamic conditions. It is shown that the selectivity of the sorption of silver(I) increases (compared to copper(II)) as the degree of crosslinking of sorbents based on N-(2-sulfoethyl)chitosan is raised. Mathematical treatment of the obtained dynamic curves is performed according to the Thomas, Adams-Bohart, and Yoon and Nelson models. As a result, the values of dynamic capacity of sorbents, the rate constant of the reaction, and the release time of 50% of the sorbate are determined. The quantitative desorption of copper and silver from the surface of sorbents is achieved by using 1 mol/dm3 solution of nitric acid.

Iodometric determination of peroxydiphosphate in the presence of copper(II) or iron(II) as catalyst.

PubMed

Kapoor, S; Sharma, P D; Gupta, Y K

1975-09-01

Peroxydiphosphate can be determined iodometrically in the presence of a large excess of potassium iodide with copper(II) or iron(II) as catalyst through the operation of the Cu(II)/Cu(I) or Fe(II)/Fe(III) cycle. The method is applicable in HClO(4), H(2)SO(4), HCl and CH(3)COOH acid media in the range 0.1-1.0M studied. Nickel, manganese(II), cobalt(II), silver, chloride and phosphate are without effect.

Chemical and biosynthetic studies of chlorophylls

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huster, M.S.

1988-01-01

Chlorophyll occurrence, structure, biosynthesis, and degradation are discussed. Degradation and ring cleavage of heme is also discussed. The author examines the formation of dihydrobiliverdins by alkaline hydrolysis of zinc(II) meso-trifluoroacetoxypheophoribides, as a possible model for chlorophyll catabolism. {sup 18}O{sub 2}-labelling experiments show that the dihydrobiliverdin terminal lactam oxygens are derived from two different dioxygen molecules, also analogous to the Two Oxygen Molecular mechanism observed in heme degradation. The initially obtained dihydrobiliverdin readily undergoes an isomeric structural transformation, which is proposed as a model for the P{sub R}-P{sub FR} interconversion of the light sensor pigment phytochrome. The generality of the ring-openingmore » reaction is demonstrated with various chlorophyll-derived zinc(II) trifluoroacetoxychlorins, and side reactions of the isocyclic ring are discussed. The synthesis and properties of a chlorophyll-derived meso-oxochlorin are described. Facile one-electron oxidation, and its inhibition by protonation, is demonstrated by NMR, ESR, and cyclic voltammetry studies. Cyclic voltammetry is also used to measure redox potentials of a range of pheophorbide and meso-trifluoroacetoxypheophorbide metal complexes, including an oxochlorin nickel(II) complex. The results are presented of biosynthetic feeding studies of green sulfur bacteria with {sup 13}C- and {sup 14}C-labelled glutamate, glycine, and methionine. This study examines an unusual oxidation of a bacteriomethylpheophorbide 5-ethyl substituent, and describes attempts to elucidate the mechanism by {sup 18}O-labelling studies. Attempts to similarily derivatize a pyropheophorbide 5-methyl substituent are discussed.« less

Preparation and testing of a tetra-amine copper(II) chitosan bead system for enhanced phosphate remediation.

PubMed

Kumar, Ilango Aswin; Viswanathan, Natrayasamy

2018-03-01

A tetra-amine copper(II) chitosan bead system (TAC@CS composite beads) was developed by grafting tetra-amine copper(II) (TAC) with chitosan (CS) and utilized for phosphate removal. The prepared TAC@CS composite beads possess enhanced phosphate sorption capacity (SC) of 41.42 ± 0.071 mg/g than copper grafted chitosan (Cu@CS) composite, TAC and chitosan which were found to be 37.01 ± 0.803, 33.20 ± 0.650 and 7.24 ± 0.059 mg/g respectively. In batch mode, various adsorption influencing parameters like contact time, initial phosphate concentration, solution pH, co-anions and temperature were optimized for maximum phosphate sorption. The prepared adsorbents were characterized by FTIR, XRD, UV-Visible, SEM and EDAX analysis. The adsorption isotherms and thermodynamic parameters of the adsorbent were studied. The feasible phosphate uptake mechanism of TAC@CS biocomposite beads was reported. The reusability studies of TAC@CS composite beads were carried out using NaOH as elutant. The suitability of TAC@CS composite beads at field conditions was tested with phosphate contaminated field water samples collected from nearby areas of Dindigul district. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis, spectroscopy, magnetic and redox behaviors of copper(II) complexes with tert-butylated salen type ligands bearing bis(4-aminophenyl)ethane and bis(4-aminophenyl)amide backbones.

PubMed

Kasumov, Veli T; Yerli, Yusuf; Kutluay, Aysegul; Aslanoglu, Mehmet

2013-03-01

New salen type ligands, N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-ethylenedianiline [(X=H (1), 5-tert-butyl (2)] and N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-amidedianiline [X=H (3), 5-tert (4)] and their copper(II) complexes 5-8, have been synthesized. Their spectroscopic (IR, (1)H NMR, UV/vis, ESR) properties, as well as magnetic and redox-reactivity behavior are reported. IR spectra of 7 and 8 indicate the coordination of amide oxygen atoms of 3 and 4 ligands to Cu(II). The solid state ESR spectra of 5-8 exhibits less informative exchange narrowed isotropic or anisotropic signals with weak unresolved low field patterns. The magnetic moments of 5 (2.92 μ(B) per Cu(II)) and 6 (2.79 μ(B) per Cu(II)) are unusual for copper(II) complexes and considerably higher than those for complexes 7 and 8. Cryogenic measurements (300-10 K) show weak antiferromagnetic exchange interactions between the copper(II) centers in complexes 6 and 8. The results of electrochemical and chemical redox-reactivity studies are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Scalable room-temperature conversion of copper(II) hydroxide into HKUST-1 (Cu3 (btc)2).

PubMed

Majano, Gerardo; Pérez-Ramírez, Javier

2013-02-20

Copper(II) hydroxide is converted directly to HKUST-1 (Cu(3) (btc)(2) ) after only 5 min at room-temperature in aqueous ethanolic solution without the need of additional solvents. Scale up to the kilogram scale does not influence porous properties yielding pure-phase product with a remarkable total surface area exceeding 1700 m(2) g(-1) featuring aggregates of nanometer-sized crystals (<600 nm) and extremely high space-time yields. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ligand effects on the structure and magnetic properties of alternating copper(II) chains with 2,2'-bipyrimidine- and polymethyl-substituted pyrazolates as bridging ligands.

PubMed

Castro, Isabel; Calatayud, M Luisa; Barros, Wdeson P; Carranza, José; Julve, Miguel; Lloret, Francesc; Marino, Nadia; De Munno, Giovanni

2014-06-02

A novel series of heteroleptic copper(II) compounds of formulas {[Cu2(μ-H2O)(μ-pz)2(μ-bpm)(ClO4)(H2O)]ClO4·2H2O}n (1), {[Cu2(μ-H2O)(μ-3-Mepz)2(μ-bpm)](ClO4)2·2H2O}n (2), and {[Cu2(μ-OH)(μ-3,5-Me2pz)(μ-bpm)(H-3,5-Me2pz)2](ClO4)2}n (3) [bpm = 2,2'-bipyrimidine, Hpz = pyrazole, H-3-Mepz = 3-methylpyrazole, and H-3,5-Me2pz = 3,5-dimethylpyrazole] have been synthesized and structurally characterized by X-ray diffraction methods. The crystal structures of 1 and 2 consist of copper(II) chains with regular alternating bpm and bis(pyrazolate)(aqua) bridges, whereas that of 3 is made up of copper(II) chains with regular alternating bpm and (pyrazolate)(hydroxo) bridges. The copper centers are six- (1) or five-coordinate (2) in axially elongated, octahedral (1) or square-pyramidal (2) environments in 1 and 2, whereas they are five-coordinate in distorted trigonal-bipyramidal surroundings in 3. The values of the copper-copper separations across the bpm/pyrazolate bridges are 5.5442(7)/3.3131(6) (1), 5.538(1)/3.235(1) (2), and 5.7673(7)/3.3220(6) Å (3). The magnetic properties of 1-3 have been investigated in the temperature range of 25-300 K. The analysis of their magnetic susceptibility data through the isotropic Hamiltonian for an alternating antiferromagnetic copper(II) chain model [H = -J∑i=1-n/2 (S2i·S2i-1 + αS2i·S2i+1), with α = J'/J and Si = SCu = 1/2] reveals the presence of a strong to moderate antiferromagnetic coupling through the bis(pyrazolate)(aqua) [-J = 217 (1) and 215 cm(-1) (2)] and (pyrazolate)(hydroxo) bridges [-J = 153 cm(-1) (3)], respectively, whereas a strong to weak antiferromagnetic coupling occurs through the bis-bidentate bpm [-J' = 211 (1), 213 (2), and 44 cm(-1) (3)]. A simple orbital analysis of the magnetic exchange interaction within the bpm- and pyrazolate-bridged dicopper(II) fragments of 1-3 visualizes the σ-type pathways involving the (dx(2)-y(2)) (1 and 2) or d(z(2)) (3) magnetic orbitals on each metal ion, which account

Mixed-ligand complexes of zinc(II) with 1,1-dicyanoethylene-2,2-dithiolate and N-donor ligands: A combined experimental and theoretical study

NASA Astrophysics Data System (ADS)

Singh, Mahesh Kumar; Sutradhar, Sanjit; Paul, Bijaya; Adhikari, Suman; Laskar, Folguni; Acharya, Sandeep; Chakraborty, Debabrata; Biswas, Surajit; Das, Arijit; Roy, Subhadip; Frontera, Antonio

2018-07-01

The fascinating structural chemistry of zinc(II) with 1,1-dicyanoethylene- 2,2-dithiolate [i-MNT2- = {S2C:C(CN)2}2-] ligand is presented. To elaborate, the reactivity of zinc(II) salt towards potassium salt of 1,1-dicyanoethylene-2,2-dithiolate (K2i-MNT) and 1,3-diaminopropane (dap) was studied in the presence of two distinct N-donor ligands, α-picoline (2-Methylpyridine) and γ-picoline (4-Methylpyridine), respectively. As a result, two different Zn(II) coordination complexes of formule [Zn2(dap)2(i-MNT)2] (1) and {[Zn(dap)(i-MNT)(4-MePy)]·2H2O}n (2) were obtained. They were isolated as stable crystalline solids and fully characterized, including by single crystal X-ray diffraction. Complex 1 is a discrete 0D dimer, whereas 2 is a 1D coordination polymer. Although α-picoline was used during the synthesis of 1, it is not involved in the metal coordination. Aiming at rationalizing the influence of the different noncovalent interactions, such as H-bonding, unconventional Nsbnd H···π and anion-π, on the crystal packing of 1 and 2, DFT calculations (M06-2X/def2-TZVP) were performed. Moreover, luminescence property of the complex 2 was investigated. Finally, in vitro antifungal activity of complex 2 was also screened against five fungi viz. Synchitrium endobioticum, Pyricularia oryzae, Helminthosporium oryzae, Candida albicans (ATCC10231) and Trichophyton mentagrophytes by the disc diffusion method and found to be effective when compared to K2i-MNT.H2O.

Electrical conductivity of solutions of copper(II) nitrate crystalohydrate in dimethyl sulfoxide

NASA Astrophysics Data System (ADS)

Mamyrbekova, Aigul K.; Mamitova, A. D.; Mamyrbekova, Aizhan K.

2016-06-01

Conductometry is used to investigate the electric conductivity of Cu(NO3)2 ṡ 3H2O solutions in dimethyl sulfoxide in the 0.01-2.82 M range of concentrations and at temperatures of 288-318 K. The limiting molar conductivity of the electrolyte and the mobility of Cu2+ and NO 3 - ions, the effective coefficients of diffusion of copper(II) ions and nitrate ions, and the degree and constant of electrolytic dissociation are calculated for different temperatures from the experimental results. It is established that solutions containing 0.1-0.6 M copper nitrate trihydrate in DMSO having low viscosity and high electrical conductivity can be used in electrochemical deposition.

Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study.

PubMed

Hricovíni, Michal; Mazúr, Milan; Sîrbu, Angela; Palamarciuc, Oleg; Arion, Vladimir B; Brezová, Vlasta

2018-03-21

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.

Copper(II) sulfamate: an efficient catalyst for the one-pot synthesis of 3,4-dihydropyrimidine-2(1H)-ones and thiones.

PubMed

Liu, Chen-Jiang; Wang, Ji-De

2009-02-13

A simple, efficient procedure for the one-pot Biginelli condensation reaction of aldehydes, beta-ketoesters and urea or thiourea employing copper(II) sulfamate as a novel catalyst is described. Compared to the classical Biginelli reaction conditions, the present method has the advantages of good yields, short reaction times and experimental simplicity.

Thermodynamics of the complex formation of copper(II) with L-phenylalanine in aqueous ethanol solutions

NASA Astrophysics Data System (ADS)

Burov, D. M.; Ledenkov, S. F.; Vandyshev, V. N.

2013-05-01

Constants of the acid dissociation and complexation of L-phenylalanine (HPhe) with copper(II) ions are determined by potentiometry in aqueous ethanol solutions containing 0 to 0.7 molar fraction of alcohol. Changes in the Gibbs energy for the transfer from water to a binary solvent of L-phenylalanine, Phe- anion, and [CuPhe]+ complex are calculated. It is found that the weakening of solvation of the ligand donor groups in solvents with high ethanol contents is accompanied by an increase in the stability of [CuPhe]+ complex.

Electrochemical and spectroelectrochemical study on novel non-peripherally tetra 1,2,4-triazole substituted phthalocyanines

NASA Astrophysics Data System (ADS)

Demirbaş, Ümit; Akyüz, Duygu; Akçay, Hakkı Türker; Koca, Atıf; Bekircan, Olcay; Kantekin, Halit

2018-03-01

In the present study novel tetra 4-(4-fluorophenyl)-5-(4-methoxyphenyl)-4H-1,2,4-triazole-3-thio substituted non-peripherally metal free (4), zinc(II) (5), lead (II) (6) and copper(II) (7) phthalocyanines were synthesized. The obtained novel compounds were characterized by a combination of FT-IR, 1H NMR, UV-Vis and MALDI-TOF techniques. The redox properties of the complexes have been investigated via cyclic voltammetry, square wave voltammetry and in situ spectroelectrochemistry. The compounds displayed ring-based, reversible and/or quasi-reversible reduction and oxidation processes and aggregation of the complexes influenced the redox character of the processes. The color changes during the redox processes of metallo phthalocyanine were recorded by in-situ spectroelectrochemical measurements. In situ UV-vis spectroelectrochemical measurements, which was associated with color change of the complexes, showed their applicability in the fields of the electrochemical technologies.

Indirect spectrophotometric determination of trace cyanide with cationic porphyrins.

PubMed

Ishii, H; Kohata, K

1991-05-01

Three highly sensitive methods for the determination of cyanide have been developed, based on the fact that the complexation of silver ions with three cationic porphyrins, 5,10,15,20-tetrakis-(1-methyl-2-pyridinio)porphine [T(2-MPy)P], 5,10,15,20-tetrakis(1-methyl-3-pyridinio)porphine [T(3-MPy)P] and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphine [T(4-MPy)P], in alkaline media is inhibited by cyanide and the decrease in absorbance of the silver(II) complex is proportional to the cyanide concentration. Sensitivities of the procedures developed are 0.133, 0.126 and 0.234 ng/cm(2), respectively for an absorbance of 0.001. Cadmium(II), copper(II), mercury(II), zinc(II), iodide and sulfide interfere with the cyanide determination. One of the proposed methods was applied to the determination of cyanide in waste-water samples, with satisfactory results.

Syntheses, crystal structures, magnetic properties, and EPR spectra of tetranuclear copper(II) complexes featuring pairs of "roof-shaped" Cu2X2 dimers with hydroxide, methoxide, and azide bridges.

PubMed

Graham, B; Hearn, M T; Junk, P C; Kepert, C M; Mabbs, F E; Moubaraki, B; Murray, K S; Spiccia, L

2001-03-26

Hydroxo- and methoxo-bridged tetranuclear copper(II) complexes of the tetramacrocyclic ligand 1,2,4,5-tetrakis(1,4,7-triazacyclonon-1-ylmethyl)benzene (Ldur), have been prepared from [Cu4Ldur(H2O)8](ClO4)8.9H2O (1). Addition of base to an aqueous solution of 1 gave [Cu4Ldur(mu2-OH)4](ClO4)4 (2). Diffusion of MeOH into a DMF solution of 2 produces [Cu4Ldur(mu2-OMe)4](ClO4)4.HClO4.2/3MeOH (3), a complex which hydrolyzes on exposure to moisture regenerating 2. The structurally related azido-bridged complex, [Cu4Ldur(mu2-N3)4](PF6)4.4H2O.6CH3CN (4), was produced by reaction of Ldur with 4 molar equiv of Cu(OAc)2.H2O and NaN3 in the presence of excess KPF6. Compounds 2-4 crystallize in the triclinic space group P1 (No. 2) with a = 10.248(1) A, b = 12.130(2) A, c = 14.353(2) A, alpha = 82.23(1) degrees, beta = 80.79(1) degrees, gamma = 65.71(1) degrees, and Z = 1 for 2, a = 10.2985(4) A, b = 12.1182(4) A, c = 13.9705(3) A, alpha = 89.978(2) degrees, beta = 82.038(2) degrees, gamma = 65.095(2) degrees, and Z = 1 for 3, and a = 12.059(2) A, b = 12.554(2) A, c = 14.051(2) A, alpha = 91.85(1) degrees, beta = 98.22(1) degrees, gamma = 105.62(1) degrees, and Z = 1 for 4. The complexes feature pairs of isolated dibridged copper(II) dimers with "roof-shaped" Cu2(mu2-X)2 cores (X = OH-, OMe-, N3-), as indicated by the dihedral angle between the two CuX2 planes (159 degrees for 2, 161 degrees for 3, and 153 degrees for 4). This leads to Cu.Cu distances of 2.940(4) A for 2, 2.962(1) A for 3, and 3.006(5) A for 4. Variable-temperature magnetic susceptibility measurements indicate weak antiferromagnetic coupling (J = -27 cm(-1)) for the hydroxo-bridged copper(II) centers in 2 and very strong antiferromagnetic coupling (J = -269 cm(-1)) for the methoxo-bridged copper(II) centers in 3. Pairs of copper(II) centers in 4 display the strongest ferromagnetic interaction (J = 94 cm(-1)) reported thus far for bis(mu2-1,1-azido)-bridged dicopper units. Spectral measurements on a neat powdered

A copper(II) paddle-wheel structure of tranexamic acid: di-chloro-tetra-kis-[μ-4-(ammonio-meth-yl)cyclo-hexane-1-carboxyl-ato-O,O']dicopper(II) dichloride hexa-hydrate.

PubMed

Altaf, Muhammad; Stoeckli-Evans, Helen

2017-10-01

Tranexamic acid [systematic name: trans -4-(amino-meth-yl)cyclo-hexane-1-carb-oxy-lic acid], is an anti-fibrinolytic amino acid that exists as a zwitterion [ trans -4-(ammonio-meth-yl)cyclo-hexane-1-carboxyl-ate] in the solid state. Its reaction with copper chloride leads to the formation of a compound with a copper(II) paddle-wheel structure that crystallizes as a hexa-hydrate, [Cu 2 Cl 2 (C 8 H 15 NO 2 ) 4 ] 2+ ·2Cl - ·6H 2 O. The asymmetric unit is composed of a copper(II) cation, two zwitterionic tranexamic acid units, a coordinating Cl - anion and a free Cl - anion, together with three water mol-ecules of crystallization. The whole structure is generated by inversion symmetry, with the Cu⋯Cu axle of the paddle-wheel dication being located about a center of symmetry. The cyclo-hexane rings of the zwitterionic tranexamic acid units have chair conformations. The carboxyl-ate groups that bridge the two copper(II) cations are inclined to one another by 88.4 (8)°. The copper(II) cation is ligated by four carboxyl-ate O atoms in the equatorial plane and by a Cl - ion in the axial position. Hence, it has a fivefold O 4 Cl coordination sphere with a perfect square-pyramidal geometry and a τ 5 index of zero. In the crystal, the paddle-wheel dications are linked by a series of N-H⋯Cl hydrogen bonds, involving the coordinating and free Cl - ions, forming a three-dimensional network. This network is strengthened by a series of N-H⋯O water , O water -H⋯Cl and O water -H⋯O hydrogen bonds.

Bending nanofibers into nanospirals: coordination chemistry as a tool for shaping hydrophobic assemblies.

PubMed

Kossoy, Elizaveta; Weissman, Haim; Rybtchinski, Boris

2015-01-02

In the current work, we demonstrate how coordination chemistry can be employed to direct self-assembly based on strong hydrophobic interactions. To investigate the influence of coordination sphere geometry on aqueous self-assembly, we synthesized complexes of the amphiphilic perylene diimide terpyridine ligand with the first-row transition-metal centers (zinc, cobalt, and nickel). In aqueous medium, aggregation of these complexes is induced by hydrophobic interactions between the ligands. However, the final shapes of the resulting assemblies depend on the preferred geometry of the coordination spheres typical for the particular metal center. The self-assembly process was characterized by UV/Vis spectroscopy, zeta potential measurements, and cryogenic transmission electron microscopy (cryo-TEM). Coordination of zinc(II) and cobalt(II) leads to the formation of unique nanospiral assemblies, whereas complexation of nickel(II) leads to the formation of straight nanofibers. Notably, coordination bonds are utilized not as connectors between elementary building blocks, but as directing interactions, enabling control over supramolecular geometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and evaluation of copper(II) complexes with isoniazid-derived hydrazones as anticancer and antitubercular agents.

PubMed

Firmino, Gisele S S; de Souza, Marcus V N; Pessoa, Claudia; Lourenco, Maria C S; Resende, Jackson A L C; Lessa, Josane A

2016-12-01

In this study, the N,N,O metal chelator 2-pyridinecarboxaldehydeisonicotinoyl hydrazone (HPCIH, 1) and its derivatives 2-acetylpyridine-(HAPIH 2), 2-pyridineformamide-(HPAmIH, 3) and pyrazineformamide-(HPzAmIH, 4) were employed in the synthesis of four copper(II) complexes, [Cu(HPCIH)Cl 2 ]·0.4H 2 O (5), [Cu(HAPIH)Cl 2 ]·1.25H 2 O (6), [Cu(HPAmIH)Cl 2 ]·H 2 O (7) and [Cu(HPzAmIH)Cl 2 ]·1.25H 2 O (8). The compounds were assayed for their action toward Mycobacterium tuberculosis H37Rv ATCC 27294 strain and the human tumor cell lines OVCAR-8 (ovarian cancer), SF-295 (glioblastoma multiforme) and HCT-116 (colon adenocarcinoma). All copper(II) complexes were more effective in reducing growth of HCT-116 and SF-295 cells than the respective free hydrazones at 5 µg/mL, whereas only complex 7 was more cytotoxic toward OVCAR-8 lines than its ligand HPAmIH. 6 proved to be cytotoxic at submicromolar doses, whose IC 50 values (0.39-0.86 µM) are similar to those ones found for doxorubicin (0.23-0.43 µM). Complexes 5 and 6 displayed high activity against M. tuberculosis (MIC = 0.85 and 1.58 µM, respectively), as compared with isoniazid (MIC = 2.27 µM), which suggests the compounds are attractive candidates as antitubercular drugs.

Isolation of a new two-dimensional honeycomb carbonato-bridged copper(II) complex exhibiting long-range ferromagnetic ordering.

PubMed

Majumder, Arpi; Choudhury, Chirantan Roy; Mitra, Samiran; Rosair, Georgina M; El Fallah, M Salah; Ribas, Joan

2005-04-28

Atmospheric CO2 fixation by an aqueous solution containing Cu(ClO4)2.6H2O and 4-aminopyridine (4-apy) yields a novel example of a two-dimensional mu3-CO3 bridged copper(II) complex {[Cu(4-apy)2]3(mu3-CO3)2(ClO4)2.(1/2)CH3OH}n that has been characterized by IR, UV and X-ray crystallography; preliminary magnetic measurements show that complex exhibits long-range ordered ferromagnetic coupling.

Electrosynthesis of Metal-Organic Frameworks (MOFs)Based on Nickel(II) and Benzene 1,3,5-Tri Carboxylic Acid (H3BTC): An Optimization Reaction Condition

NASA Astrophysics Data System (ADS)

Lestari, W. W.; Winarni, I. D.; Rahmawati, F.

2017-02-01

Electrosynthesis of metal-organic frameworks based on nickel(II) and benzen 1,3,5-tricarboxylic acid (H3BTC) to form [Ni3(BTC)2] has been conducted. This study aims to determine the optimum electro-synthetic conditions of [Ni3(BTC)2] by varying the solvents, electrolytes, as well as the voltages. The optimum condition was determined based on the percent yield of the product which upon washing and drying at room temperature showed pale green precipitate. The materialhas high crystallinityaccording to XRD analysis with the main peak observed at 2θ 19° and 28° and appropriate with [Ni3(BTC)2] pattern (CCDC No. 1274034). The refinement results using Le Bail methods revealed the Rp and Rwp values are 3.29% and 3.47%, respectively. The coordination between nickel(II) and carboxylate moeties of the linker has been characterized using FTIR and showed significant shift from 1723 cm-1 to 1608 cm-1. The compound has thermal stability up to 400 °C according to TG/DTA analysis. The SEM analysis confirmed that compound has morphology nanoplates shape with a thickness of 75 ± 0.023 nm. Another interesting feature of the obtained material is the occupancy of the reversible frameworks, which proved after methanol absorption. The optimum condition of the electro-synthesis of [Ni3(BTC)2] achieved in the methanol with TBATFB (0.1 M) as electrolyte, and the voltage of 15 V at room temperature with a yield of 99.99%.

Copper(II) ions and the Alzheimer's amyloid-β peptide: Affinity and stoichiometry of binding

NASA Astrophysics Data System (ADS)

Tõugu, Vello; Friedemann, Merlin; Tiiman, Ann; Palumaa, Peep

2014-10-01

Deposition of amyloid beta (Aβ) peptides into amyloid plaques is the hallmark of Alzheimer's disease. According to the amyloid cascade hypothesis this deposition is an early event and primary cause of the disease, however, the mechanisms that cause this deposition remain elusive. An increasing amount of evidence shows that the interactions of biometals can contribute to the fibrillization and amyloid formation by amyloidogenic peptides. From different anions the copper ions deserve the most attention since it can contribute not only toamyloid formation but also to its toxicity due to the generation of ROS. In this thesis we focus on the affinity and stoichiometry of copper(II) binding to the Aβ molecule.

Comparisons of the spectroscopic and microbiological activities among coumarin-3-carboxylate, o-phenanthroline and zinc(II) complexes

NASA Astrophysics Data System (ADS)

Islas, María S.; Martínez Medina, Juan J.; Piro, Oscar E.; Echeverría, Gustavo A.; Ferrer, Evelina G.; Williams, Patricia A. M.

2018-06-01

Coumarins (2H-chromen-2-one) are oxygen-containing heterocyclic compounds that belong to the benzopyranones family. In this work we have synthesized different coordination complexes with coumarin-3-carboxylic acid (HCCA), o-phenanthroline (phen) and zinc(II). In the reported [Zn(CCA)2(H2O)2] complex, coumarin-3-carboxylate (CCA) is acting as a bidentate ligand while in the two prepared complexes, [Zn(phen)3]CCA(NO3) (obtained as a single crystal) and [Zn(CCA)2phen].4H2O, CCA is acting as a counterion of the complex cation [Zn(phen)3]+2 or coordinated to the metal center along with phen, respectively. These compounds were characterized on the basis of elemental analysis and thermogravimetry. NMR, FTIR and Raman spectroscopies of the compounds and the CCA potassium salt (KCCA) allow to determine several similarities and differences among them. Finally, their behavior against alkaline phosphatase enzyme and their antimicrobial activities were also measured.

Immobilized copper(II) macrocyclic complex on MWCNTs with antibacterial activity

NASA Astrophysics Data System (ADS)

Tarlani, Aliakbar; Narimani, Khashayar; Mohammadipanah, Fatemeh; Hamedi, Javad; Tahermansouri, Hasan; Amini, Mostafa M.

2015-06-01

In a new approach, a copper(II) tetraaza macrocyclic complex (CuTAM) was covalently bonded on modified multi-walled carbon nanotubes (MWCNTs). To achieve this purpose, MWCNTs were converted to MWCNT-COCl and then reacted to NH groups of TAM ligand. The prepared material was characterized by Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), and FESEM (field emission scanning electron microscopy). FT-IR and TGA demonstrated the presence of the organic moieties, and XRD proved that the structure of MWCNTs remained intact during the three modification steps. An increase in the ID/IG ratio in Raman spectra confirmed the surface modifications. Finally, the samples were subjected to an antibacterial assessment to compare their biological activity. The antibacterial test showed that the grafted complex on the surface of the nanotube (MWCNT-CO-CuTAM) has higher antibacterial activity against Bacillus subtilis ATCC 6633 than the MWCNT-COOH and CuTAM with 1000 and 2000 μg/mL.

Nanostructured lipid carriers for incorporation of copper(II) complexes to be used against Mycobacterium tuberculosis

PubMed Central

Sato, Mariana R; Oshiro Junior, João A; Machado, Rachel TA; de Souza, Paula C; Campos, Débora L; Pavan, Fernando R; da Silva, Patricia B; Chorilli, Marlus

2017-01-01

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis. Cessation of treatment before the recommended conclusion may lead to the emergence of multidrug-resistant strains. The aim of this study was to develop nanostructured lipid carriers (NLCs) for use in the treatment of M. tuberculosis. The NLCs comprised the following lipid phase: 2.07% polyoxyethylene 40 stearate, 2.05% caprylic/capric triglyceride, and 0.88% polyoxyl 40 hydrogenated castor oil; the following aqueous phase: 3.50% poloxamer 407 (F1–F6), and 0.50% cetyltrimethylammonium bromide (F7–F12); and incorporated the copper(II) complexes [CuCl2(INH)2]·H2O (1), [Cu(NCS)2(INH)2]·5H2O (2), and [Cu(NCO)2(INH)2]·4H2O (3) to form compounds F11.1, F11.2, and F11.3, respectively. The mean diameter of F11, F11.1, F11.2, and F11.3 ranged from 111.27±21.86 to 134.25±22.72 nm, 90.27±12.97 to 116.46±9.17 nm, 112.4±10.22 to 149.3±15.82 nm, and 78.65±6.00 to 122.00±8.70 nm, respectively. The polydispersity index values for the NLCs ranged from 0.13±0.01 to 0.30±0.09. The NLCs showed significant changes in zeta potential, except for F11.2, with F11, F11.1, F11.2, and F11.3 ranging from 18.87±4.04 to 23.25±1.13 mV, 17.03±1.77 to 21.42±1.87 mV, 20.51±1.88 to 22.60±3.44 mV, and 17.80±1.96 to 25.25±7.78 mV, respectively. Atomic force microscopy confirmed the formation of nanoscale spherical particle dispersions by the NLCs. Differential scanning calorimetry determined the melting points of the constituents of the NLCs. The in vitro activity of copper(II) complex-loaded NLCs against M. tuberculosis H37Rv showed an improvement in the anti-TB activity of 55.4, 27.1, and 41.1 times the activity for complexes 1, 2, and 3, respectively. An in vivo acute toxicity study of complex-loaded NLCs demonstrated their reduced toxicity. The results suggest that NLCs may be a powerful tool to optimize the activity of copper(II) complexes against M. tuberculosis. PMID:28356717

Synthesis and Ligand Non-Innocence of Thiolate-Ligated (N4S) Iron(II) and Nickel(II) Bis(imino)pyridine Complexes

PubMed Central

Widger, Leland R.; Jiang, Yunbo; Siegler, Maxime; Kumar, Devesh; Latifi, Reza; de Visser, Sam P.; Jameson, Guy N.L.; Goldberg, David P.

2013-01-01

The known iron(II) complex [FeII(LN3S)(OTf)] (1) was used as starting material to prepare the new biomimetic (N4S(thiolate)) iron(II) complexes [FeII(LN3S)(py)](OTf) (2) and [FeII(LN3S)(DMAP)](OTf) (3), where LN3S is a tetradentate bis(imino)pyridine (BIP) derivative with a covalently tethered phenylthiolate donor. These complexes were characterized by X-ray crystallography, UV-vis, 1H NMR, and Mössbauer spectroscopy, as well as electrochemistry. A nickel(II) analogue, [NiII(LN3S)](BF4) (5), was also synthesized and characterized by structural and spectroscopic methods. Cyclic voltammetric studies showed 1 – 3 and 5 undergo a single reduction process with E1/2 between −0.9 to −1.2 V versus Fc+/Fc. Treatment of 3 with 0.5% Na/Hg amalgam gave the mono-reduced complex [Fe(LN3S)(DMAP)]0 (4), which was characterized by X-ray crystallography, UV-vis, EPR (g = [2.155, 2.057, 2.038]) and Mössbauer (δ = 0.33 mm s−1; ΔEQ = 2.04 mm s−1) spectroscopies. Computational methods (DFT) were employed to model complexes 3 – 5. The combined experimental and computational studies show that 1 – 3 are 5-coordinate, high-spin (S = 2) FeII complexes, whereas 4 is best described as a 5-coordinate, intermediate-spin (S = 1) FeII complex antiferromagnetically coupled to a ligand radical. This unique electronic configuration leads to an overall doublet spin (Stotal = ½) ground state. Complexes 2 and 3 are shown to react with O2 to give S-oxygenated products, as previously reported for 1. In contrast, the mono-reduced 4 appears to react with O2 to give a mixture of S- and Fe-oxygenates. The nickel(II) complex 5 does not react with O2, and even when the mono-reduced nickel complex is produced, it appears to undergo only outer-sphere oxidation with O2. PMID:23992096

Non-covalent interactions in 2-methylimidazolium copper(II) complex (MeImH)2[Cu(pfbz)4]: Synthesis, characterization, single crystal X-ray structure and packing analysis

NASA Astrophysics Data System (ADS)

Sharma, Raj Pal; Saini, Anju; Kumar, Santosh; Kumar, Jitendra; Sathishkumar, Ranganathan; Venugopalan, Paloth

2017-01-01

A new anionic copper(II) complex, (MeImH)2 [Cu(pfbz)4] (1) where, MeImH = 2-methylimidazolium and pfbz = pentafluorobenzoate has been isolated by reacting copper(II) sulfate pentahydrate, pentafluorobenzoic acid and 2-methylimidazole in ethanol: water mixture in 1:2:2 molar ratio. This complex 1 has been characterized by elemental analysis, thermogravimetric analysis, spectroscopic techniques (UV-Vis, FT-IR) and conductance measurements. The complex salt crystallizes in monoclinic crystal system with space group C2/c. Single crystal X-ray structure determination revealed the presence of discrete ions: [Cu(pfbz)4]2- anion and two 2-methylimidazolium cation (C4H7N2)+. The crystal lattice is stabilized by strong hydrogen bonding and F⋯F interactions between cationic-anionic and the anionic-anionic moieties respectively, besides π-π interactions.

Coordination of different ligands to copper(II) and cobalt(III) metal centers enhances Zika virus and dengue virus loads in both arthropod cells and human keratinocytes.

PubMed

Dutta, Shovan; Celestine, Michael J; Khanal, Supreet; Huddleston, Alexis; Simms, Colin; Arca, Jessa Faye; Mitra, Amlan; Heller, Loree; Kraj, Piotr J; Ledizet, Michel; Anderson, John F; Neelakanta, Girish; Holder, Alvin A; Sultana, Hameeda

2018-01-01

Trace elements such as copper and cobalt have been associated with virus-host interactions. However, studies to show the effect of conjugation of copper(II) or cobalt(III) metal centers to thiosemicarbazone ligand(s) derived from either food additives or mosquito repellent such as 2-acetylethiazole or citral, respectively, on Zika virus (ZIKV) or dengue virus (serotype 2; DENV2) infections have not been explored. In this study, we show that four compounds comprising of thiosemicarbazone ligand derived from 2-acetylethiazole viz., (E)-N-ethyl-2-[1-(thiazol-2-yl)ethylidene]hydrazinecarbothioamide (acetylethTSC) (compound 1), a copper(II) complex with acetylethTSC as a ligand (compound 2), a thiosemicarbazone ligand-derived from citral (compound 3) and a cobalt(III) complex with a citral-thiosemicarbazone ligand (compound 4) increased DENV2 and ZIKV replication in both mosquito C6/36 cells and human keratinocytes (HaCaT cells). Treatment of both cell lines with compounds 2 or 4 showed increased dengue viral titers at all three tested doses. Enhanced dengue viral plaque formation was also noted at the tested dose of 100μM, suggesting higher production of infectious viral particles. Treatment with the compounds 2 or 4 enhanced ZIKV and DENV2 RNA levels in HeLa cell line and primary cultures of mouse bone marrow derived dendritic cells. Also, pre- or post treatments with conjugated compounds 2 or 4 showed higher loads of ZIKV or DENV2 envelope (E) protein in HaCaT cells. No changes in loads of E-protein were found in ZIKV-infected C6/36 cells, when compounds were treated after infection. In addition, we tested bis(1,10-phenanthroline)copper(II) chloride ([Cu(phen) 2 ]Cl 2 , (compound 5) and tris(1,10-phenanthroline)cobalt(III) chloride ([Co(phen) 3 ]Cl 3 , (compound 6) that also showed enhanced DENV2 loads. Also, we found that copper(II) chloride dehydrate (CuCl 2 ·2H 2 O) or cobalt(II) chloride hexahydrate (CoCl 2 ·6H 2 O) alone had no effects as "free" cations

Anticancer, antibacterial and antifungal activity of new ni (ii) and cu (ii) complexes of imidazole-phenanthroline derivatives.

PubMed

Moghadam, Mahboube Eslami; Divsalar, Adeleh; Zare, Marziye Shahraki; Gholizadeh, Roghayeh; Mahalleh, Doran; Saghatforosh, Lotfali; Sanati, Soheila

2017-11-02

Two new nickel(II) and copper(II) complexes of 2-(Furan-2-yl)-1H-Imidazo[4,5-f][1,10]Phenanthroline (FIP) and 2-(thiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (TIP), imidazophen derivatives were synthesized. The structures of the compounds were determined by UV-visible and FT-IR spectroscopic methods and elemental analysis. The biological activities of Ni and Cu complexes, as anticancer agents, were tested against chronic myelogenous leukemia cell line, K562, at micromolar concentration. The MTT studies showed Cc 50 values are 21 and 160 µM for Cu and Ni(II) complexes, respectively; suggesting that Ni (II) complex has Cc 50 almost seven times of that obtained for cisplatin. Biological activity of the Ni(II) and Cu(II) complexes were also assayed against selective microorganisms by disc diffusion method. These results showed that the Cu(II) complex is antifungal agent but Ni(II) complex has antibacterial activity.

Synthesis, crystal structures and antitumor activities of copper(II) complexes with a 2-acetylpyrazine isonicotinoyl hydrazone ligand

NASA Astrophysics Data System (ADS)

Xu, Jun; Zhou, Tao; Xu, Zhou-Qing; Gu, Xin-Nan; Wu, Wei-Na; Chen, Hong; Wang, Yuan; Jia, Lei; Zhu, Tao-Feng; Chen, Ru-Hua

2017-01-01

Five complexes, [Cu(L)2]·4.5H2O (1), [Cu(HL)2](NO3)2·CH3OH (2) {[Cu2(L)2(NO3)(H2O)2]·(NO3)}n (3), [Cu2(HL)2(SO4)2]·2CH3OH (4) and [Cu4(L)4Cl4]·5H2O (5) based on HL (where HL = 2-acetylpyrazine isonicotinoyl hydrazone) have been synthesized and characterized by X-ray diffraction analyses. The counter anion and organic base during the synthesis procedure influence the structures of the complexes efficiently, which generate five complexes as mono-, bi-, tetra-nuclear and one-dimensional structures. The antitumor activities of the complexes 1-5 (except for complex 3 with the poor solubility) against the Patu8988 human pancreatic cancer, ECA109 human esophagus cancer and SGC7901 human gastric cancer cell lines are screened by MTT assay. The results indicate that the chelation of Cu(II) with the ligand is responsible for the observed high cytotoxicity of the copper(II) complexes and the 1:2 copper species 1 and 2 demonstrate lower antitumor activities than that of the 1:1 copper species 4 and 5. In addition, the in vitro apoptosis inducing activity of the copper(II) complex 5 against SGC7901 cell line is determined. And the results show that the complex can bring about apoptosis of the cancerous cells in vitro.

Aqueous aerobic oxidation of alkyl arenes and alcohols catalyzed by copper(II) phthalocyanine supported on three-dimensional nitrogen-doped graphene at room temperature.

PubMed

Mahyari, Mojtaba; Laeini, Mohammad Sadegh; Shaabani, Ahmad

2014-07-25

Copper(ii) tetrasulfophthalocyanine supported on three-dimensional nitrogen-doped graphene-based frameworks was synthesized and introduced as a bifunctional catalyst for selective aerobic oxidation of alkyl arenes and alcohols to the corresponding carbonyl compounds. The ease of catalyst separation, high turnover, low catalyst loading and recyclability could potentially render it applicable in industrial setting.

Preparation and In Vitro Photodynamic Activity of Glucosylated Zinc(II) Phthalocyanines as Underlying Targeting Photosensitizers.

PubMed

Liu, Jian-Yong; Wang, Chen; Zhu, Chun-Hui; Zhang, Zhi-Hong; Xue, Jin-Ping

2017-05-19

Two novel glucosylated zinc(ІІ) phthalocyanines 7a-7b, as well as the acetyl-protected counterparts 6a-6b, have been synthesized by the Cu(I)-catalyzed 1,3-dipolar cycloaddition between the propargylated phthalocyanine and azide-substituted glucoses. All of these phthalocyanines were characterized with various spectroscopic methods and studied for their photo-physical, photo-chemical, and photo-biological properties. With glucose as the targeting unit, phthalocyanines 7a-7b exhibit a specific affinity to MCF-7 breast cancer cells over human embryonic lung fibroblast (HELF) cells, showing higher cellular uptake. Upon illumination, both photosensitizers show high cytotoxicity with IC 50 as low as 0.032 µM toward MCF-7 cells, which are attributed to their high cellular uptake and low aggregation tendency in the biological media, promoting the generation of intracellular reactive oxygen species (ROS). Confocal laser fluorescence microscopic studies have also revealed that they have high and selective affinities to the lysosomes, but not the mitochondria, of MCF-7 cells. The results show that these two glucosylated zinc(II) phthalocyanines are potential anticancer agents for targeting photodynamic therapy.

Crystal Structure and Magnetic Behavior of Two New Dinuclear Carbonato-Bridged Copper(II) Compounds. Superexchange Pathway for the Different Coordination Modes of the Carbonato Bridge in Polynuclear Copper(II) Compounds.

PubMed

Escuer, Albert; Mautner, Franz A.; Peñalba, Evaristo; Vicente, Ramon

1998-08-24

Four new &mgr;-CO(3)(2-) copper(II) complexes with different coordination modes for the carbonato bridge have been obtained by fixation of atmospheric CO(2): {(&mgr;(3)-CO(3))[Cu(3)(ClO(4))(3)(Et(3)dien)(3)]}(ClO(4)) (1), Et(3)dien = N,N',N"-triethylbis(2-aminoethane)amine; {(&mgr;-CO(3))[Cu(2)(H(2)O)(Et(4)dien)(2)]}(ClO(4))(2).H(2)O (2), Et(4)dien = N,N,N",N"-tetraethyl-bis(2-aminoethane)amine; {(&mgr;-CO(3))[Cu(2)(H(2)O)(2)(EtMe(4)dien)(2)]} (ClO(4))(2).2H(2)O (3), EtMe(4)dien = N'-ethyl-N,N,N",N"-tetramethylbis(2-aminoethane)amine; and {(&mgr;-CO(3))[Cu(2)(H(2)O)(Me(5)dien)(2)]}(ClO(4))(2).H(2)O (4), Me(5)dien = N,N,N',N",N"-pentamethylbis(2-aminoethane)amine. The crystal structures have been solved for 2, monoclinic system, space group P2(1)/n, formula [C(25)H(62)Cl(2)Cu(2)N(6)O(13)] with a = 12.763(6) Å, b = 25.125(8) Å, c = 13.261(4) Å, beta = 111.85(3) degrees, Z = 4, and for 3, triclinic system, space group P&onemacr;, formula [C(21)H(58)Cl(2)Cu(2)N(6)O(15)] with a = 8.412(3) Å, b = 14.667(4) Å, c = 16.555(5) Å, alpha = 99.66(2) degrees, beta = 102.14(2) degrees, gamma = 104.72(2) degrees, Z = 2. Susceptibility measurements show ferromagnetic behavior (J = +6.7(6) cm(-)(1)) for the trinuclear compound 1 whereas 2-4 are antiferromagnetically coupled with J = -17.8(8), -125.5(9), and -21.2(3) cm(-)(1) respectively. Certain synthetic aspects that may be related to the nuclearity of the copper(II) &mgr;-CO(3)(2-) compounds and the superexchange pathway for the different coordination modes of the carbonato bridge are discussed.

Mono- and tetra-substituted zinc(II) phthalocyanines containing morpholinyl moieties: Synthesis, antifungal photodynamic activities, and structure-activity relationships.

PubMed

Zheng, Bi-Yuan; Ke, Mei-Rong; Lan, Wen-Liang; Hou, Lu; Guo, Jun; Wan, Dong-Hua; Cheong, Ling-Zhi; Huang, Jian-Dong

2016-05-23

A series of zinc(II) phthalocyanines (ZnPcs) mono-substituted and tetra-substituted with morpholinyl moieties and their quaternized derivatives have been synthesized and evaluated for their antifungal photodynamic activities toward Candida albicans. The α-substituted, quaternized, and mono-substituted ZnPcs are found to have higher antifungal photoactivity than β-substituted, neutral, and tetra-substituted counterparts. The cationic α-mono-substituted ZnPc (6a) exhibits the highest photocytotoxicity. Moreover, it is more potent than axially di-substituted analogue. The different photocytotoxicities of these compounds have also been rationalized by investigating their spectroscopic and photochemical properties, aggregation trend, partition coefficients, and cellular uptake. The IC90 value of 6a against C. albicans cells is as low as 3.3 μM with a light dose of 27 J cm(-2), meaning that 6a is a promising candidate as the antifungal photosensitizer for future investigations. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

A Luminescent Zinc(II) Metal-Organic Framework (MOF) with Conjugated π-Electron Ligand for High Iodine Capture and Nitro-Explosive Detection.

PubMed

Yao, Ru-Xin; Cui, Xin; Jia, Xiao-Xia; Zhang, Fu-Qiang; Zhang, Xian-Ming

2016-09-19

A porous luminescent zinc(II) metal-organic framework (MOF) with a NbO net [Zn2(tptc)(apy)2-x(H2O)x]·H2O (1) (where x ≈ 1, apy = aminopyridine, H4tptc = terphenyl-3,3″,5,5″-tetracarboxylic acid), constructed using paddlewheel [Zn2(COO)4] clusters and π-electron-rich terphenyl-tetracarboxylic acid, has been solvothermally synthesized and characterized. Interestingly, the material displays efficient, reversible adsorption of radioactive I2 in vapor and in solution (up to 216 wt %). The strong affinity for I2 is mainly due to it having large porosity, a conjugated π-electron aromatic system, halogen bonds, and electron-donating aminos. Furthermore, luminescent study indicated that 1 exhibits high sensitivity to electron-deficient nitrobenzene explosives via fluorescence quenching.

Luminescence of five-coordinated nickel(ii) complexes with substituted-8-hydroxyquinolines and macrocyclic ligands.

PubMed

Santana, M Dolores; García-Bueno, Rocío; García, Gabriel; Pérez, José; García, Luis; Monge, Miguel; Laguna, Antonio

2010-02-21

A series of heteroleptic quinolinolate pentacoordinated nickel(ii) complexes, [Ni(mcN(3))(R(1),R(2),R(3)-8-hq)](PF(6)), were synthesized and characterized by spectroscopic methods. Single-crystal X-ray diffraction studies for [(Me(3)-mcN(3))Ni(N,O-2-CN-8-hq)][PF(6)] (6a), [(Me(4)-mcN(3))Ni(N,O-8-hq)][PF(6)] (2b) and [(Me(4)-mcN(3))Ni(N,O-5,7-I(2)-8-hq)][PF(6)] (5b) indicate that these complexes consist of a square-pyramidal ligand arrangement containing one chelating quinolinolate and one macrocyclic ligand (mcN(3)). Variation of the substituents on quinolinolate ligands imposes obvious electronic or structural effects on the nickel atom. These chromophores absorb moderately in the visible region and emit in the yellowish-green spectral region from a quinolinolate-centered intraligand charge-transfer excited state. The emission maxima are in the range 520-548 nm, with quantum yields between 0.11 and 1.63%, in deoxygenated organic solvents at room temperature. TD-DFT calculations allow exploration of the photophysical properties of complex [(Me(4)-mcN(3))Ni(N,O-8-hq)][PF(6)] and reveal the influence of the quinolinolate ligand on the HOMO/LUMO energies and oscillator strengths.

Catalytic fixation of atmospheric carbon dioxide by copper(ii) complexes of bidentate ligands.

PubMed

Muthuramalingam, Sethuraman; Khamrang, Themmila; Velusamy, Marappan; Mayilmurugan, Ramasamy

2017-11-28

New copper(ii) complexes, [Cu(L1) 2 (H 2 O)](ClO 4 ) 2 , 1 [L1 = 2-pyridin-2-yl-quinoline], [Cu(L2) 2 (H 2 O)](ClO 4 ) 2 , 2 [L2 = 2-pyridin-2-yl-quinoxaline], [Cu(L3) 2 (H 2 O)](ClO 4 ) 2 , 3 [L3 = 6,7-dimethyl-2-pyridin-2-yl-quinoxaline], [Cu(L4) 2 (H 2 O)](ClO 4 ) 2 , 4 [L4 = 4-phenyl-2-pyridin-2-yl-quinoline] and [Cu(L5) 2 (H 2 O)](ClO 4 ) 2 , 5 [L5 = 4-phenyl-2-pyridin-2-yl-quinazoline], were synthesized and characterized as catalysts for selective fixation of atmospheric CO 2 . The molecular structure of 2 was determined by single-crystal X-ray studies and shown to have an unusual trigonal bipyramid geometry (τ, 0.936) around the copper(ii) center, with the coordination of two ligand units and a water molecule. The Cu-N quin (2.040, 2.048 Å) bonds are slightly longer than the Cu-N pyr (1.987 Å) bonds but shorter than the Cu-O water bond (2.117 Å). Well-defined Cu(ii)/Cu(i) redox potentials of around 0.352 to 0.401 V were observed for 1-5 in acetonitrile. The electronic absorption spectra of 1-5 showed ligand-based transitions at around 208-286 nm with a visible shoulder at around 342-370 nm. The d-d transitions appeared at around 750-800 and 930-955 nm in acetonitrile. The rhombic EPR spectra of 1-5 exhibited three different g values g x , 2.27-2.34; g y , 2.06-2.09; and g z , 1.95-1.98 at 70 K. Atmospheric CO 2 was successfully fixed by 1-5 using Et 3 N as a sacrificial reducing agent, resulting in CO 3 2- -bound complexes of type [Cu(L)CO 3 (H 2 O)] that display an absorption band at around 614-673 nm and a ν st at 1647 cm -1 . This CO 3 2- -bound complex of 1 was crystallized from the reaction mixture and it displayed a distorted square pyramidal geometry (τ, 0.369) around the copper(ii) center via the coordination of only one ligand unit, a carbonate group, and water molecules. Furthermore, treatment of the carbonate-bound Cu(ii) complexes with one equivalent of H + under N 2 atmosphere resulted in the liberation of bicarbonate (HCO 3 - ) and

A Nanostructured Lipid System as a Strategy to Improve the in Vitro Antibacterial Activity of Copper(II) Complexes.

PubMed

da Silva, Patricia B; Bonifácio, Bruna V; Frem, Regina C G; Godoy Netto, Adelino V; Mauro, Antonio E; Ferreira, Ana M da Costa; Lopes, Erica de O; Raddi, Maria S G; Bauab, Tais M; Pavan, Fernando R; Chorilli, Marlus

2015-12-16

The aim of this study was to construct a nanostructured lipid system as a strategy to improve the in vitro antibacterial activity of copper(II) complexes. New compounds with the general formulae [CuX₂(INH)₂]·nH₂O (X = Cl(-) and n = 1 (1); X = NCS(-) and n = 5 (2); X = NCO(-) and n = 4 (3); INH = isoniazid, a drug widely used to treat tuberculosis) derived from the reaction between the copper(II) chloride and isoniazid in the presence or absence of pseudohalide ions (NCS(-) or NCO(-)) were synthesized and characterized by infrared spectrometry, electronic absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, elemental analysis, melting points and complexometry with 2,2',2'',2'''-(Ethane-1,2-diyldinitrilo)tetraacetic acid (EDTA). The characterization techniques allowed us to confirm the formation of the copper(II) complexes. The Cu(II) complexes were loaded into microemulsion (MEs) composed of 10% phase oil (cholesterol), 10% surfactant [soy oleate and Brij(®) 58 (1:2)] and 80% aqueous phase (phosphate buffer pH = 7.4) prepared by sonication. The Cu(II) complex-loaded MEs displayed sizes ranging from 158.0 ± 1.060 to 212.6 ± 1.539 nm, whereas the polydispersity index (PDI) ranged from 0.218 ± 0.007 to 0.284 ± 0.034. The antibacterial activity of the free compounds and those that were loaded into the MEs against Staphylococcus aureus ATCC(®) 25923 and Escherichia coli ATCC(®) 25922, as evaluated by a microdilution technique, and the cytotoxicity index (IC50) against the Vero cell line (ATCC(®) CCL-81(TM)) were used to calculate the selectivity index (SI). Among the free compounds, only compound 2 (MIC 500 μg/mL) showed activity for S. aureus. After loading the compounds into the MEs, the antibacterial activity of compounds 1, 2 and 3 was significantly increased against E. coli (MIC's 125, 125 and 500 μg/mL, respectively) and S. aureus (MICs 250, 500 and 125 μg/mL, respectively). The loaded compounds were less toxic against the

A Nanostructured Lipid System as a Strategy to Improve the in Vitro Antibacterial Activity of Copper(II) Complexes.

PubMed

Silva, Patricia B da; Bonifácio, Bruna V; Frem, Regina C G; Godoy Netto, Adelino V; Mauro, Antonio E; Ferreira, Ana M da Costa; Lopes, Erica de O; Raddi, Maria S G; Bauab, Tais M; Pavan, Fernando R; Chorilli, Marlus

2015-12-16

The aim of this study was to construct a nanostructured lipid system as a strategy to improve the in vitro antibacterial activity of copper(II) complexes. New compounds with the general formulae [CuX₂(INH)₂]·nH₂O (X = Cl(-) and n = 1 (1); X = NCS(-) and n = 5 (2); X = NCO(-) and n = 4 (3); INH = isoniazid, a drug widely used to treat tuberculosis) derived from the reaction between the copper(II) chloride and isoniazid in the presence or absence of pseudohalide ions (NCS(-) or NCO(-)) were synthesized and characterized by infrared spectrometry, electronic absorption spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, elemental analysis, melting points and complexometry with 2,2',2'',2'''-(Ethane-1,2-diyldinitrilo)tetraacetic acid (EDTA). The characterization techniques allowed us to confirm the formation of the copper(II) complexes. The Cu(II) complexes were loaded into microemulsion (MEs) composed of 10% phase oil (cholesterol), 10% surfactant [soy oleate and Brij® 58 (1:2)] and 80% aqueous phase (phosphate buffer pH = 7.4) prepared by sonication. The Cu(II) complex-loaded MEs displayed sizes ranging from 158.0 ± 1.060 to 212.6 ± 1.539 nm, whereas the polydispersity index (PDI) ranged from 0.218 ± 0.007 to 0.284 ± 0.034. The antibacterial activity of the free compounds and those that were loaded into the MEs against Staphylococcus aureus ATCC® 25923 and Escherichia coli ATCC® 25922, as evaluated by a microdilution technique, and the cytotoxicity index (IC50) against the Vero cell line (ATCC® CCL-81(TM)) were used to calculate the selectivity index (SI). Among the free compounds, only compound 2 (MIC 500 μg/mL) showed activity for S. aureus. After loading the compounds into the MEs, the antibacterial activity of compounds 1, 2 and 3 was significantly increased against E. coli (MIC's 125, 125 and 500 μg/mL, respectively) and S. aureus (MICs 250, 500 and 125 μg/mL, respectively). The loaded compounds were less toxic against the Vero

Computational studies on nonlinear optical property of novel Wittig-based Schiff-base ligands and copper(II) complex

NASA Astrophysics Data System (ADS)

Rajasekhar, Bathula; Patowary, Nidarshana; K. Z., Danish; Swu, Toka

2018-07-01

Hundred and forty-five novel molecules of Wittig-based Schiff-base (WSB), including copper(II) complex and precursors, were computationally screened for nonlinear optical (NLO) properties. WSB ligands were derived from various categories of amines and aldehydes. Wittig-based precursor aldehydes, (E)-2-hydroxy-5-(4-nitrostyryl)benzaldehyde (f) and 2-hydroxy-5-((1Z,3E)-4-phenylbuta-1,3-dien-1-yl) benzaldehyde (g) were synthesised and spectroscopically confirmed. Schiff-base ligands and copper(II) complex were designed, optimised and their NLO property was studied using GAUSSIAN09 computer program. For both optimisation and hyperpolarisability (finite-field approach) calculations, Density Functional Theory (DFT)-based B3LYP method was applied with LANL2DZ basis set for metal ion and 6-31G* basis set for C, H, N, O and Cl atoms. This is the first report to present the structure-activity relationship between hyperpolarisability (β) and WSB ligands containing mono imine group. The study reveals that Schiff-base ligands of the category N-2, which are the ones derived from the precursor aldehyde, 2-hydroxy-5-(4nitro-styryl)benzaldehyde and pre-polarised WSB coordinated with Cu(II), encoded as Complex-1 (β = 14.671 × 10-30 e.s.u) showed higher β values over other categories, N-1 and N-3, i.e. WSB derived from precursor aldehydes, 2-hydroxy-5-styrylbenzaldehyde and 2-hydroxy-5-((1Z,3E)-4-phenylbuta-1,3-dien-1-yl)benzaldehyde, respectively. For the first time here we report the geometrical isomeric effect on β value.

Antimalarial evaluation of copper(II) nanohybrid solids: inhibition of plasmepsin II, a hemoglobin-degrading malarial aspartic protease from Plasmodium falciparum.

PubMed

Mohapatra, Subash Chandra; Tiwari, Hemandra Kumar; Singla, Manisha; Rathi, Brijesh; Sharma, Arun; Mahiya, Kuldeep; Kumar, Mukesh; Sinha, Saket; Chauhan, Shyam Singh

2010-03-01

A new class of copper(II) nanohybrid solids, LCu(CH(3)COO)(2) and LCuCl(2), have been synthesized and characterized by transmission electron microscopy, dynamic light scattering, and IR spectroscopy, and have been found to be capped by a bis(benzimidazole) diamide ligand (L). The particle sizes of these nanohybrid solids were found to be in the ranges 5-10 and 60-70 nm, respectively. These nanohybrid solids were evaluated for their in vitro antimalarial activity against a chloroquine-sensitive isolate of Plasmodium falciparum (MRC 2). The interactions between these nanohybrid solids and plasmepsin II (an aspartic protease and a plausible novel target for antimalarial drug development), which is believed to be essential for hemoglobin degradation by the parasite, have been assayed by UV-vis spectroscopy and inhibition kinetics using Lineweaver-Burk plots. Our results suggest that these two compounds have antimalarial activities, and the IC(50) values (0.025-0.032 microg/ml) are similar to the IC(50) value of the standard drug chloroquine used in the bioassay. Lineweaver-Burk plots for inhibition of plasmepsin II by LCu(CH(3)COO)(2) and LCuCl(2) show that the inhibition is competitive with respect to the substrate. The inhibition constants of LCu(CH(3)COO)(2) and LCuCl(2) were found to be 10 and 13 microM, respectively. The IC(50) values for inhibition of plasmepsin II by LCu(CH(3)COO)(2) and LCuCl(2) were found to be 14 and 17 microM, respectively. Copper(II) metal capped by a benzimidazole group, which resembles the histidine group of copper proteins (galactose oxidase, beta-hydroxylase), could provide a suitable anchoring site on the nanosurface and thus could be useful for inhibition of target enzymes via binding to the S1/S3 pocket of the enzyme hydrophobically. Both copper(II) nanohybrid solids were found to be nontoxic against human hepatocellular carcinoma cells and were highly selective for plasmepsin II versus human cathepsin D. The pivotal mechanism of

Treatment of model and galvanic waste solutions of copper(II) ions using a lignin/inorganic oxide hybrid as an effective sorbent.

PubMed

Ciesielczyk, Filip; Bartczak, Przemysław; Klapiszewski, Łukasz; Jesionowski, Teofil

2017-04-15

A study was made concerning the removal of copper(II) ions from model and galvanic waste solutions using a new sorption material consisting of lignin in combination with an inorganic oxide system. Specific physicochemical properties of the material resulted from combining the activity of the functional groups present in the structure of lignin with the high surface area of the synthesized oxide system (585m 2 /g). Analysis of the porous structure parameters, particle size and morphology, elemental composition and characteristic functional groups confirmed the effective synthesis of the new type of sorbent. A key element of the study was a series of tests of adsorption of copper(II) ions from model solutions. It was determined how the efficiency of the adsorption process was affected by the process time, mass of sorbent, concentration of adsorbate, pH and temperature. Potential regeneration of adsorbent, which provides the possibility of its reusing and recovering the adsorbed copper, was also analyzed. The sorption capacity of the material was measured (83.98mg/g), and the entire process was described using appropriate kinetic models. The results were applied to the design of a further series of adsorption tests, carried out on solutions of real sewage from a galvanizing plant. Copyright © 2017 Elsevier B.V. All rights reserved.

Dual Nuclear/Fluorescence Imaging Potantial of Zinc(II) Phthalocyanine in MIA PaCa-2 Cell Line.

PubMed

Lambrecht, Fatma Yurt; Ince, Mine; Er, Ozge; Ocakoglu, Kasim; Sarı, Fatma Aslıhan; Kayabasi, Cagla; Gunduz, Cumhur

2016-01-01

Pancreatic cancer is very common and difficult to diagnose in early stage. Imaging systems for diagnosing cancer have many disadvantages. However, combining different imaging modalities offers synergistic advantages. Optical imaging is the most multidirectional and widely used imaging modality in both clinical practice and research. In present study, Zinc(II) phthalocyanine [Zn(II)Pc] was synthesized, labeled with iodine- 131 and in vitro study was carried out. The intracellular uptake studies of radiolabeled Zn(II)Pc were performed in WI-38 [ATCC CCL-75™, tissue: human fibroblast lung] and MIA PaCa-2 [ATCC CRL-1420™, tissue: human epithelial pancreas carcinoma] cell lines. The intracellular uptake efficiency of radiolabeled Zn(II)Pc in MIA PaCa-2 cells was determined two times higher than WI-38 cells. Also, fluorescence imaging (FI) efficiency of synthesized Zn(II)Pc was investigated in MIA PaCa-2 cells and significant uptake was observed. Zn(II)Pc might be used as a new agent for dual fluorescence/nuclear imaging for pancreatic cancer. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Synthesis, crystal structures and luminescent properties of zinc(II) metal–organic frameworks constructed from terpyridyl derivative ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiao-Le; Shangguan, Yi-Qing; Hu, Huai-Ming, E-mail: ChemHu1@NWU.EDU.CN

2014-08-15

Five zinc(II) metal–organic frameworks, [Zn{sub 3}(344-pytpy){sub 2}Cl{sub 6}]{sub n}·n(H{sub 2}O) (1), [Zn(344-pytpy)(ox)]{sub n} (2), [Zn{sub 2}(344-pytpy)(bdc){sub 2}]{sub n}·1.5n(H{sub 2}O) (3), [Zn{sub 2}(344-pytpy){sub 2} (sfdb){sub 2}]{sub n}·1.5n(H{sub 2}O) (4) and [Zn{sub 3}(344-pytpy){sub 2}(btc){sub 2}]{sub n}·2n(H{sub 2}O) (5), (344-pytpy=4′-(3-pyridyl)-4,2′:6′,4″-terpyridine, H{sub 2}ox=oxalic acid, H{sub 2}bdc=1,4-benzenedi-carboxylic acid, H{sub 2}sfdb=4,4′-sulfonyldibenzoic acid and H{sub 3}btc=1,3,5-benzene-tricarboxylic acid) have been prepared by hydrothermal reactions. Compound 1 is a 1D chain structure, in which 344-pytpy ligand links three Zn{sup II} centers through three of terminal N-donors. Compound 2 is a 4-connected 3D framework with the dia topological net and the Schläfli symbol of 6{sup 6}. Compound 3 displays amore » unusual 3-fold interpenetrating 3D coordination network which exhibits a new intriguing (3,3,4)-connected topological net with the Schläfli symbol of (4.8{sup 2})(4.8{sup 5})(8{sup 3}). Compound 4 features a two-fold interpenetrating 4-connected 2D framework with the sql topological net and the Schläfli symbol of (4{sup 4}.6{sup 2}). Compound 5 is a new self-interpenetrating (3,3,4,4)-connected topological net with the Schläfli symbol of (6.8{sup 2}){sub 2}(6{sup 2}.8{sup 2}.10.12)(6{sup 2}.8{sup 3}.10){sub 2}(6{sup 2}.8){sub 2}. The luminescence properties of 1–5 have been investigated by emission spectra and they possess great thermal stabilities which can be stable up to around 400 °C. - Graphical abstract: Five new Zn(II) metal–organic frameworks based on dicarboxylate and terpyridyl derivative ligands have been synthesized by hydrothermal reactions, giving networks from 1D to 3D structures. The thermal stability and luminescent property have been investigated. - Highlights: • Five zinc(II) metal–organic frameworks have been prepared under hydrothermal conditions. • Their crystal and

Synthesis of a zinc(II) complex with hexadentate N4S2 donor thioether ligand: X-ray structure, DNA binding study and DFT computation

NASA Astrophysics Data System (ADS)

Mondal, Apurba Sau; Jana, Mahendra Sekhar; Manna, Chandan Kumar; Naskar, Rahul; Mondal, Tapan Kumar

2018-07-01

A new zinc(II) complex, [Zn(L)](ClO4) with hexadentate N4S2 donor azo-thioether ligand (HL) was synthesized and characterized by several spectroscopic techniques. The structure was confirmed by single crystal X-ray analysis. The interaction of the complex with CT DNA was investigated by UV-vis method and binding constant is found to be 6.6 × 104 M-1. Competitive binding titration with ethidium bromide (EB) by fluorescence titration method reveals that the complex efficiently displaces EB from EB-DNA system and the Stern-Volmer dynamic quenching constant, Ksv is found to be 2.6 × 104 M-1. DFT and TDDFT calculations were carried out to interpret the electronic structure and electronic spectra of the complex.

Copper(II) complexes of alloferon 1 with point mutations (H1A) and (H9A) stability structure and biological activity.

PubMed

Matusiak, Agnieszka; Kuczer, Mariola; Czarniewska, Elżbieta; Rosiński, Grzegorz; Kowalik-Jankowska, Teresa

2014-09-01

Mono- and polynuclear copper(II) complexes of the alloferon 1 with point mutations (H1A) A(1)GVSGH(6)GQH(9)GVH(12)G (Allo1A) and (H9A) H(1)GVSGH(6)GQA(9)GVH(12)G (Allo9A) have been studied by potentiometric, UV-visible, CD, EPR spectroscopic and mass spectrometry (MS) methods. To obtain a complete complex speciation different metal-to-ligand molar ratios ranging from 1:1 to 4:1 for Allo1A and to 3:1 for Allo9A were studied. The presence of the His residue in first position of the peptide chain changes the coordination abilities of the Allo9A peptide in comparison to that of the Allo1A. Imidazole-N3 atom of N-terminal His residue of the Allo9A peptide forms stable 6-membered chelate with the terminal amino group. Furthermore, the presence of two additional histidine residues in the Allo9A peptide (H(6),H(12)) leads to the formation of the CuL complex with 4N {NH2,NIm-H(1),NIm-H(6),NIm-H(12)} binding site in wide pH range (5-8). For the Cu(II)-Allo1A system, the results demonstrated that at physiological pH7.4 the predominant complex the CuH-1L consists of the 3N {NH2,N(-),CO,NIm} coordination mode. The inductions of phenoloxidase activity and apoptosis in vivo in Tenebrio molitor cells by the ligands and their copper(II) complexes at pH7.4 were studied. The Allo1A, Allo1K peptides and their copper(II) complexes displayed the lowest hemocytotoxic activity while the most active was the Cu(II)-Allo9A complex formed at pH7.4. The results may suggest that the N-terminal-His(1) and His(6) residues may be more important for their proapoptotic properties in insects than those at positions 9 and 12 in the peptide chain. Copyright © 2014 Elsevier Inc. All rights reserved.

Zinc(II) complexes with potent cyclin-dependent kinase inhibitors derived from 6-benzylaminopurine: synthesis, characterization, X-ray structures and biological activity.

PubMed

Trávnícek, Zdenek; Krystof, Vladimír; Sipl, Michal

2006-02-01

The synthesis, characterization and biological activity of the first zinc(II) complexes with potent inhibitors of cyclin-dependent kinases (CDKs) derived from 6-benzylaminopurine are described. Based on the results following from elemental analyses, infrared, NMR and ES+MS (electrospray mass spectra in the positive ion mode) spectroscopies, conductivity data, thermal analysis and X-ray structures, the tetrahedral Zn(II) complexes of the compositions [Zn(Olo)Cl(2)](n) (1), [Zn(iprOlo)Cl(2)](n) (2), [Zn(BohH(+))Cl(3)] x H(2)O (3) and [Zn(iprOloH(+))Cl(3)] x H(2)O (4) have been prepared, where Olo=2-(2-hydroxyethylamino)-6-benzylamino-9-methylpurine (Olomoucine), iprOlo=2-(2-hydroxyethylamino)-6-benzylamino-9-isopropylpurine (i-propyl-Olomoucine), Boh=2-(3-hydroxypropylamino)-6-benzylamino-9-isopropylpurine (Bohemine). The 1D-polymeric chain structure for [Zn(Olo)Cl(2)](n) (1) as well as the monomeric one for [Zn(BohH(+))Cl(3)] x H(2)O (3) and [Zn(iprOloH(+))Cl(3)] x H(2)O (4) have been revealed unambiguously by single crystal X-ray analyses. The 1D-polymeric chain of 1 consists of Zn(Olo)Cl(2) monomeric units in which the Zn(II) ion is coordinated by two chlorine atoms and one oxygen atom of the 2-hydroxyethylamino group of Olomoucine. The next monomeric unit is bonded to Zn(II) through the N7 atom of a purine ring. Thus, each of Zn(II) ions is tetrahedrally coordinated and a ZnCl(2)NO chromophore occurs in the complex 1. The complexes 3 and 4 are mononuclear species with a distorted tetrahedral arrangement of donor atoms around the Zn(II) ion with a ZnCl(3)N chromophore. The corresponding CDK inhibitor, i.e., both Boh and iprOlo, is coordinated to Zn(II) via the N7 atom of the purine ring in 3 and 4. The cytotoxicity of the zinc(II) complexes against human melanoma, sarcoma, leukaemia and carcinoma cell lines has been determined as well as the inhibition of the CDK2/cyclin E kinase. A relationship between the structure and biological activity of the complexes is

Half a grid is better than no grid: competition between 2,2':6',2''-terpyridine and 3,6-di(pyrid-2-yl)pyridazine for copper(II).

PubMed

Constable, Edwin C; Decurtins, Silvio; Housecroft, Catherine E; Keene, Tony D; Palivan, Cornelia G; Price, Jason R; Zampese, Jennifer A

2010-03-07

The reaction between Cu(NO(3))(2).3H(2)O, 2,2':6',2''-terpyridine (tpy) and 3,6-di(pyrid-2-yl)pyridazine (1) in a 2 : 2 : 1 molar equivalent ratio in aqueous MeCN in the presence of excess NH(4)PF(6) leads to competition between the assembly of the dinuclear half-grid [Cu(2)(1)(tpy)(2)][PF(6)](4).2H(2)O and the mononuclear complex [Cu(1)(2)(OH(2))][PF(6)](2). The yield of [Cu(2)(1)(tpy)(2)][PF(6)](4).2H(2)O has been optimized using microwave conditions. [Cu(1)(2)(OH(2))][PF(6)](2) can be selectively produced by treating Cu(NO(3))(2).3H(2)O with 1 (1 : 2 molar equivalents) in aqueous MeCN in the presence of NH(4)PF(6). The single crystal structures of [Cu(2)(1)(tpy)(2)][PF(6)](4).4MeNO(2) and [Cu(1)(2)(OH(2))][PF(6)](2) are presented. In the [Cu(2)(1)(tpy)(2)](4+) cation, ligand 1 bridges the two copper(II) centres, each of which is further coordinated by a tpy ligand. The copper(II) coordination geometry is closely associated with the arrangement of the two tpy ligands which engage in efficient face-to-face pi-stacking. Magnetic data for crystalline [Cu(2)(1)(tpy)(2)][PF(6)](4).4MeNO(2) are consistent with a weak antiferromagnetic interaction between the two copper(II) centres. EPR spectroscopic data for a powder sample of [Cu(2)(1)(tpy)(2)][PF(6)](4).2H(2)O are consistent with the dinuclear structure, but in frozen DMF and DMSO solutions, the data indicate that the dinuclear structure of [Cu(2)(1)(tpy)(2)](4+) is not preserved.

A one-dimensional nickel(II) coordination polymer containing 2,6-dipicolinate and dipyrido[3,2-a:2',3'-c]phenazine.

PubMed

Ma, Yi; Zhang, Li-Tian; Wang, Xiao-Fang; He, Yong-Ke; Han, Zheng-Bo

2007-12-01

A new coordination polymer, catena-poly[[(dipyrido[3,2-a:2',3'-c]phenazine-kappa(2)N,N')nickel(II)]-mu-2,6-dipicolinato-kappa(4)O(2),N,O(6):O(2')], [Ni(C7H3NO4)(C18H10N4)]n, exhibits a one-dimensional structure in which 2,6-dipicolinate acts as a bridging ligand interconnecting adjacent nickel(II) centers to form a chain structure. The asymmetric unit contains one Ni(II) center, one dipyrido[3,2-a:2',3'-c]phenazine ligand and one 2,6-dipicolinate ligand. Each Ni(II) center is six-coordinated and surrounded by three N atoms and three O atoms from one dipyrido[3,2-a:2',3'-c]phenazine ligand and two different 2,6-dipicolinate ligands, leading to a distorted octahedral geometry. Adjacent chains are linked by pi-pi stacking interactions and weak interactions to form a three-dimensional supramolecular network.

Synthesis of mononuclear copper(II) complexes of N3O2 and N4O2 donors containing Schiff base ligands: Theoretical and biological observations

NASA Astrophysics Data System (ADS)

Mancha Madha, K.; Gurumoorthy, P.; Arul Antony, S.; Ramalakshmi, N.

2017-09-01

A new series of six mononuclear copper(II) complexes were synthesized from N3O2 and N4O2 donors containing Schiff base ligands, and characterized by various spectral methods. The geometry of the complexes was determined using UV-Vis, EPR and DFT calculations. The complexes of N3O2 donors (1-3) adopted square pyramidal geometry and the remaining complexes of N4O2 donors (4-6) show distorted octahedral geometry around copper(II) nuclei. Redox properties of the complexes show a one-electron irreversible reduction process in the cathodic potential (Epc) region from -0.74 to -0.98 V. The complexes show potent antioxidant activity against DPPH radicals. Molecular docking studies of complexes showed σ-π interaction, hydrogen bonding, electrostatic and van der Waals interactions with VEGFR2 kinase receptor. In vitro cytotoxicity of the complexes was tested against human breast cancer (MDA-MB-231) cell lines and one normal human dermal fibroblasts (NHDF) cell line through MTT assay. The morphological assessment data obtained by Hoechst 33258 and AO/EB staining revealed that the complexes induce apoptosis pathway of cell death.

Ferromagnetic interaction in an asymmetric end-to-end azido double-bridged copper(II) dinuclear complex: a combined structure, magnetic, polarized neutron diffraction and theoretical study.

PubMed

Aronica, Christophe; Jeanneau, Erwann; El Moll, Hani; Luneau, Dominique; Gillon, Béatrice; Goujon, Antoine; Cousson, Alain; Carvajal, Maria Angels; Robert, Vincent

2007-01-01

A new end-to-end azido double-bridged copper(II) complex [Cu(2)L(2)(N(3))2] (1) was synthesized and characterized (L=1,1,1-trifluoro-7-(dimethylamino)-4-methyl-5-aza-3-hepten-2-onato). Despite the rather long Cu-Cu distance (5.105(1) A), the magnetic interaction is ferromagnetic with J= +16 cm(-1) (H=-JS(1)S(2)), a value that has been confirmed by DFT and high-level correlated ab initio calculations. The spin distribution was studied by using the results from polarized neutron diffraction. This is the first such study on an end-to-end system. The experimental spin density was found to be localized mainly on the copper(II) ions, with a small degree of delocalization on the ligand (L) and terminal azido nitrogens. There was zero delocalization on the central nitrogen, in agreement with DFT calculations. Such a picture corresponds to an important contribution of the d(x2-y2) orbital and a small population of the d(z2) orbital, in agreement with our calculations. Based on a correlated wavefunction analysis, the ferromagnetic behavior results from a dominant double spin polarization contribution and vanishingly small ionic forms.

Unusual saccharin-N,O (carbonyl) coordination in mixed-ligand copper(II) complexes: Synthesis, X-ray crystallography and biological activity

NASA Astrophysics Data System (ADS)

Mokhtaruddin, Nur Shuhada Mohd; Yusof, Enis Nadia Md; Ravoof, Thahira B. S. A.; Tiekink, Edward R. T.; Veerakumarasivam, Abhi; Tahir, Mohamed Ibrahim Mohamed

2017-07-01

Three tridentate Schiff bases containing N and S donor atoms were synthesized via the condensation reaction between S-2-methylbenzyldithiocarbazate with 2-acetyl-4-methylpyridine (S2APH); 4-methyl-3-thiosemicarbazide with 2-acetylpyridine (MT2APH) and 4-ethyl-3-thiosemicarbazide with 2-acetylpyridine (ET2APH). Three new, binuclear and mixed-ligand copper(II) complexes with the general formula, [Cu(sac)(L)]2 (sac = saccharinate anion; L = anion of the Schiff base) were then synthesized, and subsequently characterized by IR and UV/Vis spectroscopy as well as by molar conductivity and magnetic susceptibility measurements. The Schiff bases were also spectroscopically characterized using NMR and MS to further confirm their structures. The spectroscopic data indicated that the Schiff bases behaved as a tridentate NNS donor ligands coordinating via the pyridyl-nitrogen, azomethine-nitrogen and thiolate-sulphur atoms. Magnetic data indicated a square pyramidal environment for the complexes and the conductivity values showed that the complexes were essentially non-electrolytes in DMSO. The X-ray crystallographic analysis of one complex, [Cu(sac)(S2AP)]2 showed that the Cu(II) atom was coordinated to the thiolate-S, azomethine-N and pyridyl-N donors of the S2AP Schiff base and to the saccharinate-N from one anion, as well as to the carbonyl-O atom from a symmetry related saccharinate anion yielding a centrosymmetric binuclear complex with a penta-coordinate, square pyramidal geometry. All the copper(II) saccharinate complexes were found to display strong cytotoxic activity against the MCF-7 and MDA-MB-231 human breast cancer cell lines.

Synthesis, spectral, and structural studies of porphyrins having sterically hindered [η(5)-CpCo(η(4)-C4Ph4)] cobalt sandwich units at the meso positions.

PubMed

Keshav, Karunesh; Kumar, Dheeraj; Elias, Anil J

2013-11-04

Synthesis, spectral, and structural studies of the first examples of porphyrins substituted at the meso positions with sterically hindered η(5)-CpCo(η(4)-C4Ph4) cobalt sandwich units are described. The novel dipyrromethane derived cobalt sandwich compound {η(5)-[(C4H4N)2CH]C5H4}Co(η(4)-C4Ph4) 1, as well as its parent aldehyde, η(5)-[C5H4(CHO)]Co(η(4)-C4Ph4), were used in the synthesis of porphyrins having one or two η(5)-CpCo(η(4)-C4Ph4) groups at their meso positions. 1,9-Diformyldipyrromethane derived η(5)-CpCo(η(4)-C4Ph4) 2 was synthesized using dipyrromethane 1 under Vilsmeier conditions. A reaction of 2 with unsubstituted dipyrromethane under basic conditions in the presence of Pd(C6H5CN)2Cl2 yielded an A-type palladium coordinated porphyrin 3 [where A = η(5)-CpCo(η(4)-C4Ph4)]. A similar reaction of 2 with meso aryl and ferrocenyl-substituted dipyrromethanes yielded trans-AB type palladium coordinated porphyrins 4-6 [where A = η(5)-CpCo(η(4)-C4Ph4) and B = 4-tert-butylphenyl 4, ferrocenyl 5, and pentafluorophenyl 6]. Reactions of 2 with 5-ferrocenyl dipyrromethane under the same reaction conditions in the presence of Ni(acac)2 and Zn(OAc)2 gave the trimetallic nickel(II) and zinc(II) complexed trans-AB type porphyrins 7 and 8 having both cobalt and iron sandwich units at the meso positions. Crystal structure of the Pd(II) porphyrin 5 and nickel(II) porphyrin 7 showed nonplanar structures having distinct ruffle type distortion of the porphyrin ring. Demetalation of the zinc(II) trans-AB type porphyrin 8 in the presence of trifluoroacetic acid gave the metal free base porphyrin 9. Reactions of the cobalt sandwich aldehyde [(η(5)-C5H4(CHO)]Co(η(4)-C4Ph4) with sterically hindered dipyrromethane derivatives under acid-catalyzed condensation reactions gave trans-A2B2 type porphyrins [where A = η(5)-CpCo(η(4)-C4Ph4) and B = pentafluorophenyl, 10 mesityl 11]. In contrast, reactions of [η(5)-C5H4(CHO)]Co(η(4)-C4Ph4) with sterically unhindered meso-4

A new approach for crystallization of copper(ii) oxide hollow nanostructures with superior catalytic and magnetic response

NASA Astrophysics Data System (ADS)

Singh, Inderjeet; Landfester, Katharina; Chandra, Amreesh; Muñoz-Espí, Rafael

2015-11-01

We report the synthesis of copper(ii) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow structures. The synthesis also leads to modification of physical properties such as magnetism.We report the synthesis of copper(ii) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow structures. The synthesis also leads to modification of physical properties such as magnetism. Electronic supplementary information (ESI) available: Associated structural and morphological analysis, XPS characterization, BET surface area, catalytic measurements, recycle tests of the catalyst, and magnetic characterizations. See DOI: 10.1039/c5nr05579b

Synthesis, structure, and magnetic properties of regular alternating μ-bpm/di-μ-X copper(II) chains (bpm = 2,2'-bipyrimidine; X = OH, F).

PubMed

Marino, Nadia; Armentano, Donatella; De Munno, Giovanni; Cano, Joan; Lloret, Francesc; Julve, Miguel

2012-04-02

The preparation and X-ray crystal structure of four 2,2'-bipyrimidine (bpm)-containing copper(II) complexes of formula {[Cu(2)(μ-bpm)(H(2)O)(4)(μ-OH)(2)][Mn(H(2)O)(6)](SO(4))(2)}(n) (1), {[Cu(2)(μ-bpm)(H(2)O)(4)(μ-OH)(2)]SiF(6)}(n) (2), {Cu(2)(μ-bpm)(H(2)O)(2)(μ-F)(2)F(2)}(n) (3), and [Cu(bpm)(H(2)O)(2)F(NO(3))][Cu(bpm)(H(2)O)(3)F]NO(3)·2H(2)O (4) are reported. The structures of 1-3 consist of chains of copper(II) ions with regular alternation of bis-bidentate bpm and di-μ-hydroxo (1 and 2) or di-μ-fluoro (3) groups, the electroneutrality being achieved by either hexaaqua manganese(II) cations plus uncoordinated sulfate anions (1), uncoordinated hexafluorosilicate anions (2), or terminally bound fluoride ligands (3). Each copper(II) ion in 1-4 is six-coordinated in elongated octahedral surroundings. 1 and 2 show identical, linear chain motifs with two bpm-nitrogen atoms and two hydroxo groups building the equatorial plane at each copper(II) ion and the axial position being filled by water molecules. In the case of 3, the axial sites at the copper atom are occupied by a bpm-nitrogen atom and a bis-monodentate fluoride anion, producing a "step-like" chain motif. The values of the angle at the hydroxo and fluoro bridges are 94.11(6) (1), 94.75(4) (2), and 101.43(4)° (3). In each case, the copper-copper separation through the bis-bidentate bpm [5.428(1) (1), 5.449(1) (2), and 5.9250(4) Å (3)] is considerably longer than that through the di-μ-hydroxo [2.8320(4) (1) and 2.824(1) Å (2)] or di-μ-fluoro [3.3027(4) Å (3)] bridges. Compound 4 is a mononuclear species whose structure is made up of neutral [Cu(bpm)(H(2)O)(2)F(NO(3))] units, [Cu(bpm)(H(2)O)(3)F](+) cations, uncoordinated nitrate anions, and crystallization water molecules, giving rise to a pseudo-helical, one-dimensional (1D) supramolecular motif. The magnetic properties of 1-3 have been investigated in the temperature range 1.9-300 K. Relatively large, alternating antiferro- [J = -149 (1) and

Synthesis, characterization and biological studies of copper(II) complexes with 2-aminobenzimidazole derivatives

NASA Astrophysics Data System (ADS)

Joseph, J.; Suman, A.; Nagashri, K.; Joseyphus, R. Selwin; Balakrishnan, Nisha

2017-06-01

Novel series of four copper(II) complexes with 2-aminobenzimidazole derivatives (obtained from the Knoevenagel condensate of acetylacetone (obtained from acetylacetone and halogen substituted benzaldehydes) and 2-aminobenzimidazole) were synthesized. They were structurally characterized using elemental analysis, molar conductance, FAB mass, FT- IR, 1H &13C-NMR, UV-Vis., and EPR techniques. On the basis of analytical and spectral studies, the distorted square planar geometry was assigned for all the complexes. The antibacterial screening of the ligands and their copper complexes indicated that all the complexes showed higher anti microbial activities than the free ligands. Superoxide dismutase and antioxidant activities of the copper complexes have also been performed. In the electrochemical technique, the shift in ΔEp, E1/2 and Ipc values were explored for the interaction of the complexes with CT-DNA. During the electrolysis process, the present ligand system stabilizes unusual oxidation state of copper in the complexes. It is believed that the copper complexes with curcumin analogs may enhance chemotherapeutic behavior.

Spectroscopic studies on Solvatochromism of mixed-chelate copper(II) complexes using MLR technique

NASA Astrophysics Data System (ADS)

Golchoubian, Hamid; Moayyedi, Golasa; Fazilati, Hakimeh

2012-01-01

Mixed-chelate copper(II) complexes with a general formula [Cu(acac)(diamine)]X where acac = acetylacetonate ion, diamine = N,N-dimethyl,N'-benzyl-1,2-diaminoethane and X = BPh 4-, PF 6-, ClO 4- and BF 4- have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, UV-vis and IR spectroscopies. The complexes are solvatochromic and their solvatochromism were investigated by visible spectroscopy. All complexes demonstrated the positive solvatochromism and among the complexes [Cu(acac)(diamine)]BPh 4·H 2O showed the highest Δ νmax value. To explore the mechanism of interaction between solvent molecules and the complexes, different solvent parameters such as DN, AN, α and β using multiple linear regression (MLR) method were employed. The statistical results suggested that the DN parameter of the solvent plays a dominate contribution to the shift of the d-d absorption band of the complexes.

Spectroscopic investigation of the noncovalent association of the nerve agent simulant diisopropyl methylphosphonate (DIMP) with zinc(II) porphyrins.

PubMed

Maza, William A; Vetromile, Carissa M; Kim, Chungsik; Xu, Xue; Zhang, X Peter; Larsen, Randy W

2013-11-07

Organophosphonates pose a significant threat as chemical warfare agents, as well as environmental toxins in the form of pesticides. Thus, methodologies to sense and decontaminate these agents are of significant interest. Porphyrins and metalloporphyrins offer an excellent platform to develop chemical threat sensors and photochemical degradation systems. These highly conjugated planar molecules exhibit relatively long-lived singlet and triplet states with high quantum yields and also form self-associated complexes with a wide variety of molecules. A significant aspect of porphyrins is the ability to functionalize the peripheral ring system either directly to the pyrrole rings or to the bridging methine carbons. In this report, steady-state absorption and fluorescence are utilized to probe binding affinities of a series of symmetric and asymmetric zinc(II) metalloporphyrins for the nerve agent simulant diisopropyl methylphosphonate (DIMP) in hexane. The red shifts in the absorption and emission spectra observed for all of the metalloporphyrins probed are discussed in the frame of Gouterman's four orbital model and a common binding motif involving coordination between the metalloporphyrin and DIMP via interaction between the zinc metal center of the porphyrin and phosphoryl oxygen of DIMP (Zn-O═P) is proposed.

Surface complexation model for multisite adsorption of copper(II) onto kaolinite

NASA Astrophysics Data System (ADS)

Peacock, Caroline L.; Sherman, David M.

2005-08-01

We measured the adsorption of Cu(II) onto kaolinite from pH 3-7 at constant ionic strength. EXAFS spectra show that Cu(II) adsorbs as (CuO 4H n) n-6 and binuclear (Cu 2O 6H n) n-8 inner-sphere complexes on variable-charge ≡AlOH sites and as Cu 2+ on ion exchangeable ≡X-H + sites. Sorption isotherms and EXAFS spectra show that surface precipitates have not formed at least up to pH 6.5. Inner-sphere complexes are bound to the kaolinite surface by corner-sharing with two or three edge-sharing Al(O,OH) 6 polyhedra. Our interpretation of the EXAFS data are supported by ab initio (density functional theory) geometries of analog clusters simulating Cu complexes on the {110} and {010} crystal edges and at the ditrigonal cavity sites on the {001}. Having identified the bidentate (≡AlOH) 2Cu(OH) 20, tridentate (≡Al 3O(OH) 2)Cu 2(OH) 30 and ≡X-Cu 2+ surface complexes, the experimental copper(II) adsorption data can be fit to the reactions

Antimalarial, antimicrobial, cytotoxic, DNA interaction and SOD like activities of tetrahedral copper(II) complexes

NASA Astrophysics Data System (ADS)

Mehta, Jugal V.; Gajera, Sanjay B.; Patel, Mohan N.

2015-02-01

The mononuclear copper(II) complexes with P, O-donor ligand and different fluoroquinolones have been synthesized and characterized by elemental analysis, electronic spectra, TGA, EPR, FT-IR and LC-MS spectroscopy. An antimicrobial efficiency of the complexes has been tested against five different microorganisms in terms of minimum inhibitory concentration (MIC) and displays very good antimicrobial activity. The binding strength and binding mode of the complexes with Herring Sperm DNA (HS DNA) have been investigated by absorption titration and viscosity measurement studies. The studies suggest the classical intercalative mode of DNA binding. Gel electrophoresis assay determines the ability of the complexes to cleave the supercoiled form of pUC19 DNA. Synthesized complexes have been tested for their SOD mimic activity using nonenzymatic NBT/NADH/PMS system and found to have good antioxidant activity. All the complexes show good cytotoxic and in vitro antimalarial activities.

Adsorption and photocatalytic properties of transition metal Zinc(II) complex based on 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid

NASA Astrophysics Data System (ADS)

Qiao, Yu; Ren, Shan-Shan; Liu, Li-Hui; Guan, Wei-Sheng; Li, Zhi-Min; Che, Guang-Bo; Liu, Chun-Bo; Wang, Yan-Yan; Wang, Qing-Wei; Li, Xiu-Ying; Zhu, En-Wei

2018-06-01

A new coordination polymeric zinc(II) complex, namely, [Zn2(L)(H2O)3]n·nNO3(1), (H3L = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid) has been synthesized under solvothermal conditions and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis and powder X-ray diffraction. Complex 1 exhibits a three-dimensional structure with a Schläfli symbol of 44•69•82 topologies, constructed from two crystallographically independent five and six coordinated mode with metal center and connected H3L ligands. The complex has good thermal stability and excellent photoluminescent property. Furthermore, by comparing the photoluminescent and photocatalytic mutation results induced by interconversion of metal ions, we confirm that the properties mutation induced by metal ions is much controllable and obvious. In addition, the complex exhibits significantly enhanced photocatalytic activity for methylene blue (MB) under UV light irradiation (λ < 400 nm), and the degradation rate could reach 75% in 80 min. Meanwhile trapping experiments indicated that the •O2- and h+ are the main activated species.

Photocatalyzed Hydrogen Evolution from Water by a Composite Catalyst of NH2 -MIL-125(Ti) and Surface Nickel(II) Species.

PubMed

Meyer, Kim; Bashir, Shahid; Llorca, Jordi; Idriss, Hicham; Ranocchiari, Marco; van Bokhoven, Jeroen A

2016-09-19

A composite of the metal-organic framework (MOF) NH 2 -MIL-125(Ti) and molecular and ionic nickel(II) species, catalyzed hydrogen evolution from water under UV light. In 95 v/v % aqueous conditions the composite produced hydrogen in quantities two orders of magnitude higher than that of the virgin framework and an order of magnitude greater than that of the molecular catalyst. In a 2 v/v % water and acetonitrile mixture, the composite demonstrated a TOF of 28 mol H 2  g(Ni) -1  h -1 and remained active for up to 50 h, sustaining catalysis for three times longer and yielding 20-fold the amount of hydrogen. Appraisal of physical mixtures of the MOF and each of the nickel species under identical photocatalytic conditions suggest that similar surface localized light sensitization and proton reduction processes operate in the composite catalyst. Both nickel species contribute to catalytic conversion, although different activation behaviors are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of bis nitrato[4-hydroxyacetophenonesemicarbazone) nickel(II) complex as ionophore for thiocyanate-selective electrode.

PubMed

Chandra, Sulekh; Hooda, Sunita; Tomar, Praveen Kumar; Malik, Amrita; Kumar, Ankit; Malik, Sakshi; Gautam, Seema

2016-05-01

The PVC based-ion selective electrode viz., bis nitrato[4-hydroxyacetophenone semicarbazone] nickel(II) as an ionophore was prepared for the determination of thiocyanate ion. The ionophore was characterized by FT-IR, UV-vis, XRD, magnetic moment and elemental analysis (CHN). On the basis of spectral studies an octahedral geometry has been assigned. The best performance was obtained with a membrane composition of 31% PVC, 63% 2-nitrophenyl octylether, 4.0% ionophore and 2.0% trioctylmethyl ammonium chloride. The electrode exhibited an excellent Nernstian response to SCN(-) ion ranging from 1.0 × 10(-7) to 1.0 × 10(-1)M with a detection limit of 8.6 × 10(-8)M and a slope of -59.4 ± 0.2 mV/decade over a wide pH range (1.8-10.7) with a fast response time (6s) at 25 °C. The proposed electrode showed high selectivity for thiocyanate ion over a number of common inorganic and organic anions. It was successfully applied to direct determination of thiocyanate in biological (urine and saliva) samples in order to distinguish between smokers and non-smokers, environmental samples and as an indicator electrode for titration of thiocyanate ions with AgNO3 solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Reactivity of dinuclear copper(II) complexes towards melanoma cells: Correlation with its stability, tyrosinase mimicking and nuclease activity.

PubMed

Nunes, Cléia Justino; Borges, Beatriz Essenfelder; Nakao, Lia Sumie; Peyroux, Eugénie; Hardré, Renaud; Faure, Bruno; Réglier, Marius; Giorgi, Michel; Prieto, Marcela Bach; Oliveira, Carla Columbano; Da Costa Ferreira, Ana M

2015-08-01

In this work, the influence of two new dinuclear copper(II) complexes in the viability of melanoma cells (B16F10 and TM1MNG3) was investigated, with the aim of verifying possible correlations between their cytotoxicity and their structure. One of the complexes had a polydentate dinucleating amine-imine ligand (complex 2), and the other a tridentate imine and a diamine-bridging ligand (complex 4). The analogous mononuclear copper(II) species (complexes 1 and 3, respectively) were also prepared for comparative studies. Crystal structure determination of complex 2 indicated a square-based pyramidal geometry around each copper, coordinated to three N atoms from the ligand and the remaining sites being occupied by either solvent molecules or counter-ions. Complex 4 has a tetragonal geometry. Interactions of these complexes with human albumin protein (HSA) allowed an estimation of their relative stabilities. Complementary studies of their reactivity towards DNA indicated that all of them are able of causing significant oxidative damage, with single and double strand cleavages, in the presence of hydrogen peroxide. However, nuclease activity of the dinuclear species was very similar and much higher than that of the corresponding mononuclear compounds. Although complex 2, with a more flexible structure, exhibits a much higher tyrosinase activity than complex 4, having a more rigid environment around the metal ion, both complexes showed comparable cytotoxicity towards melanoma cells. Corresponding mononuclear complexes showed to be remarkably less reactive as tyrosinase mimics as well as cytotoxic agents. Moreover, the dinuclear complexes showed higher cytotoxicity towards more melanogenic cells. The obtained results indicated that the structure of these species is decisive for its activity towards the malignant tumor cells tested. Copyright © 2015 Elsevier Inc. All rights reserved.

The binding of manganese(II) and zinc(II) to the synthetic oligonucleotide d(C-G-C-G-A-A-T-T-C-G-C-G)2. A 1H NMR study.

PubMed

Frøystein, N A; Sletten, E

1991-03-01

The interaction of the synthetic oligonucleotide d(C-G-C-G-A-A-T-T-C-G-C-G)2 with two different transition-metal ions has been investigated in aqueous solution by means of 1H NMR spectroscopy. The effects on the DNA due to the presence of manganese(II) or zinc(II) have been monitored by observing the paramagnetic broadening and diamagnetic shifts of the non-exchangeable proton resonance lines, respectively. The 1H NMR spectra acquired during the course of the manganese(II) titration show very distinct broadening effects on certain DNA resonance lines. Primarily, the H8 resonance of G4 is affected, but also the H5 and H6 resonances of C3 are clearly affected by the metal. The results imply that the binding of manganese(II) to DNA is sequence specific. The 1H spectra obtained during the zinc(II) titration reveal diamagnetic shift effects which largely conform with the paramagnetic broadening effects due to the presence of manganese(II), although this picture is somewhat more complex. The H8 resonance of G4 displays a clearly visible high-field shift, while for the other guanosine H8 protons this effect is absent. The H1' and H2' protons of C3 show an effect of similar strength, although in the opposite direction, while H5 and H6 of C3 are only slightly affected. Local differences in the structure of the DNA and the basicities of potential binding sites on different base steps in the sequence might account for the observed sequence selectivity.

Adlayer structure of octa-alkoxy-substituted copper(II) phthalocyanine on Au(111) by electrochemical scanning tunneling microscopy.

PubMed

Wang, Li; Ou-Yang, Liangyue; Yau, Shueh-Lin

2008-01-01

Electrochemical scanning tunneling microscopy (ECSTM) has been used to examine the adlayer of octa-alkoxy-substituted copper(II) phthalocyanines (CuPc(OC(8)H(17))(8)) on Au(111) in 0.1 M HClO(4), where the molecular adlayer was prepared by spontaneous adsorption from a benzene solution containing this molecule. Topography STM scans revealed long-range ordered, interweaved arrays of CuPc(OC(8)H(17))(8) with coexistent rectangular and hexagonal symmetries. High-quality STM molecular resolution yielded the internal molecular structure and the orientation of CuPc(OC(8)H(17))(8) admolecules. These STM results could shed insight into the method of generating ordered molecular assemblies of phthalocyanine molecules with long-chained substitutes on metal surface. 2007 Wiley-Liss, Inc

Facile synthesis of gold coated copper(II) hydroxide pine-needle-like micro/nanostructures for surface-enhanced Raman scattering

NASA Astrophysics Data System (ADS)

Long, Kailin; Du, Deyang; Luo, Xiaoguang; Zhao, Weiwei; Wu, Zhangting; Si, Lifang; Qiu, Teng

2014-08-01

This work reports a facile method to fabricate gold coated copper(II) hydroxide pine-needle-like micro/nanostructures for surface-enhanced Raman scattering (SERS) application. The effects of reaction parameters on the shape, size and surface morphology of the products are systematically investigated. The as-prepared 3D hierarchical structures have the advantage of a large surface area available for the formation of hot spots and the adsorption of target analytes, thus dramatically improving the Raman signals. The finite difference time domain calculations indicate that the pine-needle-like model pattern may demonstrate a high quality SERS property owing to the high density and abundant hot spot characteristic in closely spaced needle-like arms.

Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, {sup 57}Fe Moessbauer spectroscopy and thermal studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Travnicek, Zdenek, E-mail: zdenek.travnicek@upol.c; Herchel, Radovan; Mikulik, Jiri

2010-05-15

Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN){sub 5}NO].H{sub 2}O (1), where tet=N,N'-bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN){sub 5}NO].2H{sub 2}O (2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]octadecane and [Cu(nme){sub 2}Fe(CN){sub 5}NO].H{sub 2}O (3), where nme=N-methylethylenediamine, were synthesized and characterized by elemental analyses, {sup 57}Fe Moessbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, {sup 57}Fe Moessbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe{sub 2}O{sub 4} and CuO. - Three heterobimetallic cyano-bridged copper(II) nitroprusside-based complexes of the general compositions of [Cu(L)Fe(CN){sub 5}NO].xH{sub 2}O, wheremore » L=N,N'-bis(3-aminopropyl)ethylenediamine (complex 1), 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1{sup 6,9}]-octadecane (complex 2) and N-methylethylenediamine (complex 3), were synthesized, and fully structurally and magnetically characterized. SEM, EDS, XRD and {sup 57}Fe Moessbauer experiments were used for characterization of thermal decomposition products of complexes 2 and 3.« less

Crystal structures and catalytic performance of three new methoxy substituted salen type nickel(II) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine

NASA Astrophysics Data System (ADS)

Ghaffari, Abolfazl; Behzad, Mahdi; Pooyan, Mahsa; Amiri Rudbari, Hadi; Bruno, Giuseppe

2014-04-01

Three new nickel(II) complexes of a series of methoxy substituted salen type Schiff base ligands were synthesized and characterized by IR, UV-Vis and 1H NMR spectroscopy and elemental analysis. The ligands were synthesized from the condensation of meso-1,2-diphenyl-1,2-ethylenediamine with n-methoxysalicylaldehyde (n = 3, 4 and 5). Crystal structures of these complexes were determined. Electrochemical behavior of the complexes was studied by means of cyclic voltammetry in DMSO solutions. Catalytic performance of the complexes was studied in the epoxidation of cyclooctene using tert-butylhydroperoxide (TBHP) as oxidant under various conditions to find the optimum operating parameters. Low catalytic activity with moderate epoxide selectivity was observed in in-solvent conditions but in the solvent-free conditions, enhanced catalytic activity with high epoxide selectivity was achieved.

pH-Responsive Dimeric Zinc(II) Phthalocyanine in Mesoporous Silica Nanoparticles as an Activatable Nanophotosensitizing System for Photodynamic Therapy.

PubMed

Wong, Roy C H; Chow, Sun Y S; Zhao, Shirui; Fong, Wing-Ping; Ng, Dennis K P; Lo, Pui-Chi

2017-07-19

An acid-cleavable acetal-linked zinc(II) phthalocyanine dimer with an azido terminal group (cPc) was prepared and conjugated to alkyne-modified mesoporous silica nanoparticles via copper(I)-catalyzed alkyne-azide cycloaddition reaction. For comparison, an amine-linked analogue (nPc) was also prepared as a non-acid-cleavable counterpart. These dimeric phthalocyanines were significantly self-quenched due to the close proximity of the phthalocyanine units inside the mesopores, resulting in much weaker fluorescence emission and singlet oxygen generation, both in N,N-dimethylformamide and in phosphate-buffered saline (PBS), compared with the free molecular counterparts. Under acidic conditions in PBS, the cPc-encapsulated nanosystem was activated in terms of fluorescence emission and singlet oxygen production. After internalization into human colon adenocarcinoma HT29 cells, it exhibited much higher intracellular fluorescence and photocytotoxicity compared to the nanosystem entrapped with nPc. The activation of this nanosystem was also demonstrated in tumor-bearing nude mice. The intratumoral fluorescence intensity increased gradually over 24 h, while for the nPc counterpart the fluorescence remained very weak. The results suggest that this nanosystem serves as a promising activatable nanophotosensitizing agent for photodynamic therapy.

Synthesis of New Five Coordinated Copper(II) and Nickel(II) Complexes of L-Valine and Kinetic Study of Copper(II) with Calf Thymus DNA

PubMed Central

Tak, Aijaz Ahmad; Arjmand, Farukh

2002-01-01

Five coordinated novel complexes of Cu II and Ni II have been synthesized from benzil and 1,3- diaminopropane- Cu II / Ni II complex and characterized by elemental analysis, i.r., n.m.r., e.p.r, molar conductance and u.v-vis, spectroscopy. The complexes are ionic in nature and exhibit pentaeoordinated geometry around the metal ion. The reaction kinetics of C 25 H 36 N 5 O 2 CuCl with calf thymus DNA was studied by u.v-vis, spectroscopy in aqueous medium. The complex after interaction with calf thymus DNA shows shift in the absorption spectrum and hypochromicity indicating an intercalative binding mode. The K obs values have been calculated under pseudo-first order conditions. The redox behaviour of complex C 25 H 36 N 5 O 2 CuCl in the presence and in the absence of calf thymus DNA in the aqueous solution has been investigated by cyclic voltammetry. The cyclic voitammogram exhibits one quasi-reversible redox wave corresponding to Cu II / Cu I redox couple with E 1 / 2 values of -0.377 and -0.237 V respectively at a scan rate of 0.1V s - 1 .On interaction with calf thymus DNA, the complex C 25 H 36 N 5 O 2 CuCl exhibits shifts in both E p as well as in E 1 / 2 values, indicating strong binding of the complex to the calf thymus DNA. PMID:18475428

Nonlinear optical and G-Quadruplex DNA stabilization properties of novel mixed ligand copper(II) complexes and coordination polymers: Synthesis, structural characterization and computational studies

NASA Astrophysics Data System (ADS)

Rajasekhar, Bathula; Bodavarapu, Navya; Sridevi, M.; Thamizhselvi, G.; RizhaNazar, K.; Padmanaban, R.; Swu, Toka

2018-03-01

The present study reports the synthesis and evaluation of nonlinear optical property and G-Quadruplex DNA Stabilization of five novel copper(II) mixed ligand complexes. They were synthesized from copper(II) salt, 2,5- and 2,3- pyridinedicarboxylic acid, diethylenetriamine and amide based ligand (AL). The crystal structure of these complexes were determined through X-ray diffraction and supported by ESI-MAS, NMR, UV-Vis and FT-IR spectroscopic methods. Their nonlinear optical property was studied using Gaussian09 computer program. For structural optimization and nonlinear optical property, density functional theory (DFT) based B3LYP method was used with LANL2DZ basis set for metal ion and 6-31G∗ for C,H,N,O and Cl atoms. The present work reveals that pre-polarized Complex-2 showed higher β value (29.59 × 10-30e.s.u) as compared to that of neutral complex-1 (β = 0.276 × 10-30e.s.u.) which may be due to greater advantage of polarizability. Complex-2 is expected to be a potential material for optoelectronic and photonic technologies. Docking studies using AutodockVina revealed that complex-2 has higher binding energy for both G-Quadruplex DNA (-8.7 kcal/mol) and duplex DNA (-10.1 kcal/mol). It was also observed that structure plays an important role in binding efficiency.

A threefold interpenetrated two-dimensional zinc(II) supramolecular architecture based on 3-nitrobenzoic acid and 4,4'-bipyridine.

PubMed

Tang, Long; Wang, Ji-Jiang; Fu, Feng; Wang, Sheng-Wen; Liu, Qi-Rui

2016-02-01

With regard to crystal engineering, building block or modular assembly methodologies have shown great success in the design and construction of metal-organic coordination polymers. The critical factor for the construction of coordination polymers is the rational choice of the organic building blocks and the metal centre. The reaction of Zn(OAc)2·2H2O (OAc is acetate) with 3-nitrobenzoic acid (HNBA) and 4,4'-bipyridine (4,4'-bipy) under hydrothermal conditions produced a two-dimensional zinc(II) supramolecular architecture, catena-poly[[bis(3-nitrobenzoato-κ(2)O,O')zinc(II)]-μ-4,4'-bipyridine-κ(2)N:N'], [Zn(C7H4NO4)2(C10H8N2)]n or [Zn(NBA)2(4,4'-bipy)]n, which was characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction analysis. The Zn(II) ions are connected by the 4,4'-bipy ligands to form a one-dimensional zigzag chain and the chains are decorated with anionic NBA ligands which interact further through aromatic π-π stacking interactions, expanding the structure into a threefold interpenetrated two-dimensional supramolecular architecture. The solid-state fluorescence analysis indicates a slight blue shift compared with pure 4,4'-bipyridine and HNBA.

Tetranuclear copper(II) complexes bridged by alpha-D-glucose-1-phosphate and incorporation of sugar acids through the Cu4 core structural changes.

PubMed

Kato, Merii; Sah, Ajay Kumar; Tanase, Tomoaki; Mikuriya, Masahiro

2006-08-21

Tetranuclear copper(II) complexes containing alpha-D-glucose-1-phosphate (alpha-D-Glc-1P), [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(bpy)4(H2O)2]X3 [X = NO3 (1a), Cl (1b), Br (1c)], and [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(phen)4(H2O)2](NO3)3 (2) were prepared by reacting the copper(II) salt with Na2[alpha-D-Glc-1P] in the presence of diimine ancillary ligands, and the structure of 2 was characterized by X-ray crystallography to comprise four {Cu(phen)}2+ fragments connected by the two sugar phosphate dianions in 1,3-O,O' and 1,1-O mu4-bridging fashion as well as a mu-hydroxo anion. The crystal structure of 2 involves two chemically independent complex cations in which the C2 enantiomeric structure for the trapezoidal tetracopper(II) framework is switched according to the orientation of the alpha-D-glucopyranosyl moieties. Temperature-dependent magnetic susceptibility data of 1a indicated that antiferromagnetic spin coupling is operative between the two metal ions joined by the hydroxo bridge (J = -52 cm(-1)) while antiferromagnetic interaction through the Cu-O-Cu sugar phosphate bridges is weak (J = -13 cm(-1)). Complex 1a readily reacted with carboxylic acids to afford the tetranuclear copper(II) complexes, [Cu4{mu-(alpha-D-Glc-1P)}2(mu-CA)2(bpy)4](NO3)2 [CA = CH3COO (3), o-C6H4(COO)(COOH) (4)]. Reactions with m-phenylenediacetic acid [m-C6H4(CH2COOH)2] also gave the discrete tetracopper(II) cationic complex [Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)(CH2COOH))2(bpy)4](NO3)2 (5a) as well as the cluster polymer formulated as {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)2)(bpy)4](NO3)2}n (5b). The tetracopper structure of 1a is converted into a symmetrical rectangular core in complexes 3, 4, and 5b, where the hydroxo bridge is dissociated and, instead, two carboxylate anions bridge another pair of Cu(II) ions in a 1,1-O monodentate fashion. The similar reactions were applied to incorporate sugar acids onto the tetranuclear copper(II) centers. Reactions of 1a with delta

X-Ray absorption spectroscopy quantitative analysis of biomimetic copper(II) complexes with tridentate nitrogen ligands mimicking the tris(imidazole) array of protein centres.

PubMed

Borghi, Elena; Casella, Luigi

2010-02-21

In this study copper(ii) complexes with the tridentate nitrogen ligand bis[2-(1-methylbenzimidazol-2-yl)ethyl]amine (2-BB) are considered as model compounds for the Cu-tris(imidazole) array found in several copper proteins. 2-BB chelates copper(ii) forming two six-membered rings and the complexes contain methanol, nitrite, azide and water as ancillary ligands; both the coordination numbers and stereochemistries differ in these complexes. Their key structural features were investigated by using full multiple-scattering theoretical analysis of the copper K-edge X-ray absorption spectrum with the MXAN code. We showed that using cluster sizes large enough to include all atoms of the ligand, the analysis of the XANES region can give both a structural model of the metal centre and map the structure of the 2-BB complexes. Complex [Cu(2-BB)(N(3))](+) provided a critical test through the comparison of the XANES simulation results with crystallographic data, thus permitting the extension of the method to the complex [Cu(2-BB)(H(2)O)(n)](+) (n = 1 or 2), for which crystallographic data are not available but is expected to bear a five-coordinated Cu(3N)(2O) core (n = 2). The structural data of [Cu(2-BB)(MeOH)(ClO(4))](+) and [Cu(2-BB)(NO(2))](+), both with a Cu(3N)(2O) core but with a different stereochemistry, were used as the starting parameters for two independent simulations of the XANES region of the [Cu(2-BB)(H(2)O)(2)](+) cation. The two structural models generated by simulation converge towards a structure for the aqua-cation with a lower coordination number. New calculations, where four-coordinated Cu(3N)(O) cores were considered as the starting structures, validated that the structure of the aqua-complex in the powder state has a copper(ii) centre with a four-coordinated Cu(3N)(O) core and a molecular formula [Cu(2-BB)(H(2)O)](ClO(4)).(H(2)O). A water solvation molecule, presumed to be disordered from the simulations with the two Cu(3N)(2O) cores, is present. The

Binding selectivity of vitamin K3 based chemosensors towards nickel(II) and copper(II) metal ions

NASA Astrophysics Data System (ADS)

Patil, Amit; Lande, Dipali N.; Nalkar, Archana; Gejji, Shridhar P.; Chakrovorty, Debamitra; Gonnade, Rajesh; Moniz, Tânia; Rangel, Maria; Pereira, Eulália; Salunke-Gawali, Sunita

2017-09-01

The vitamin K3 derivatives 2-methyl-3-[(pyridin-2-ylmethyl)-amino]-1,4-naphthoquinone (M-1), 2-methyl-3-[(pyridin-2-ylethyl)-amino]-1,4-naphthoquinone (M-2), 2-methyl-3-((2-(thiophen-2-yl)methyl)amino)naphthalene-1,4-dione (M-3) and 2-methyl-3-((2-(thiophen-2-yl)ethyl)amino)naphthalene-1,4-dione (M-4) have been synthesized, characterized and studied for their chemosensor abilities towards transition metal ions. Crystal structures of M-1 to M-4 revealed a variety of Nsbnd H⋯O, Csbnd H⋯O, Csbnd H⋯π and π⋯π interactions. Minor variations in such interactions by chemical stimuli such as metal ions, results in change in color that can be visualized by naked eyes. It has been shown that electronic structure and 1H NMR, vibrational as well as electronic spectra from the density functional theory agree well with the experiments. The metal ion binding in ethanol, ethanol-water and in mild base triethylamine brings forth recognizing ability of M-1 toward Ni2+ whereas M-2 exhibits large sensing ability for Cu2+ ion. Interestingly M-1 display varying metal ion binding specificity in different solvents with the association constant in ethanol being 11,786 M-1 for Ni2+ compared to 9462 M-1 for the Cu2+. A reversal in preferential binding of M-2 with the respective association constants being 4190 M-1 and 6370 M-1 is discernible.

Investigation of copper(II) binding to the protein precursor of Non-Amyloid-Beta Component of Alzheimer Disease Amyloid Plaque

NASA Astrophysics Data System (ADS)

Rose, Francis; Hodak, Miroslav; Bernholc, Jerry

2007-03-01

The Non-Amyloid-Beta Component Precursor (NACP) is a natively unfolded synaptic protein that is implicated in Alzheimers and Parkinsons diseases. Its aggregation into fibrillar structures is accelerated by the binding of copper(II). Experimental studies suggest that the dominant copper binding site is located at the histidine residue in NACP. Based on this evidence we assembled a model fragment of the binding site and used DFT to analyze the conformational details of the most probable binding motifs. We investigated the overall conformational effects with classical MD by constraining the copper binding site to the most energetically favorable geometry obtained from the DFT calculations. These results are compared and contrasted with those of the unbound NACP.

Oligo-m-phenyleneoxalamide copper(II) mesocates as electro-switchable ferromagnetic metal-organic wires.

PubMed

Pardo, Emilio; Ferrando-Soria, Jesús; Dul, Marie-Claire; Lescouëzec, Rodrigue; Journaux, Yves; Ruiz-García, Rafael; Cano, Joan; Julve, Miguel; Lloret, Francesc; Cañadillas-Delgado, Laura; Pasán, Jorge; Ruiz-Pérez, Catalina

2010-11-15

Double-stranded copper(II) string complexes of varying nuclearity, from di- to tetranuclear species, have been prepared by the Cu(II)-mediated self-assembly of a novel family of linear homo- and heteropolytopic ligands that contain two outer oxamato and either zero (1 b), one (2 b), or two (3 b) inner oxamidato donor groups separated by rigid 2-methyl-1,3-phenylene spacers. The X-ray crystal structures of these Cu(II) (n) complexes (n=2 (1 d), 3 (2 d), and 4 (3 d)) show a linear array of metal atoms with an overall twisted coordination geometry for both the outer CuN(2)O(2) and inner CuN(4) chromophores. Two such nonplanar all-syn bridging ligands 1 b-3 b in an anti arrangement clamp around the metal centers with alternating M and P helical chiralities to afford an overall double meso-helicate-type architecture for 1 d-3 d. Variable-temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 d-3 d show the occurrence of S=nS(Cu) (n=2-4) high-spin ground states that arise from the moderate ferromagnetic coupling between the unpaired electrons of the linearly disposed Cu(II) ions (S(Cu)=1/2) through the two anti m-phenylenediamidate-type bridges (J values in the range of +15.0 to 16.8 cm(-1)). Density functional theory (DFT) calculations for 1 d-3 d evidence a sign alternation of the spin density in the meta-substituted phenylene spacers in agreement with a spin polarization exchange mechanism along the linear metal array with overall intermetallic distances between terminal metal centers in the range of 0.7-2.2 nm. Cyclic voltammetry (CV) and rotating-disk electrode (RDE) electrochemical measurements for 1 d-3 d show several reversible or quasireversible one- or two-electron steps that involve the consecutive metal-centered oxidation of the inner and outer Cu(II) ions (S(Cu)=1/2) to diamagnetic Cu(III) ones (S(Cu)=0) at relatively low formal potentials (E values in the range of

Nickel(II) and palladium(II) triphenylphosphine complexes incorporating tridentate Schiff base ligands: Synthesis, characterization and biocidal activities

NASA Astrophysics Data System (ADS)

Shabbir, Muhammad; Akhter, Zareen; Ashraf, Ahmad Raza; Ismail, Hammad; Habib, Anum; Mirza, Bushra

2017-12-01

Nickel(II) and palladium(II) triphenylphosphine complexes incorporating tridentate Schiff bases have been prepared and characterized by elemental analysis as well as by spectroscopic techniques (FTIR & NMR). The synthesized compounds were assessed to check their potential biocidal activity by using different biological assays (brine shrimp cytotoxicity, antimicrobial, antioxidant, antitumor and drug-DNA interaction). Results of brine shrimp cytotoxicity assay showed that ligand molecules are more bioactive than metal complexes with LD50 as low as 12.4 μg/mL. The prominent antitumor activity was shown by nickel complexes while the palladium complexes exhibited moderate activity. The synthesized compounds have shown high propensity for DNA binding either through intercalation or groove binding which represents the mechanism of antitumor effect of these compounds. Additionally, ligand molecules and nickel metal complexes showed significant antioxidant activity with IC50 values as low as 3.1 μg/mL and 18.9 μg/mL respectively while palladium complexes exhibited moderate activity. Moreover, in antimicrobial assays H2L1, Ni(L1)PPh3 and H2L3 showed dual inhibition against bacterial and fungal strains while for the rest of the compounds varying degree of activity was recorded against different strains. Overall comparison of results suggests that the synthesized compounds can be promising candidate for drug formulation and development.

Copper(II) complexes of N-(2-{[(2E)-2-(2-Hydroxy-(5-substituted)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide ligands and heterocyclic coligands

NASA Astrophysics Data System (ADS)

Chavan, S. S.; Sawant, V. A.; Jadhav, A. N.

2014-01-01

Some copper(II) complexes of the type [Cu(L1-3)(phen]ṡCH2Cl2 (1a-3a) and [Cu(L1-3) (bipy)]ṡCH2Cl2 (1b-3b) (where L1 = N-(2-{[(2E)-2-(2-Hydroxy-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L2 = N-(2-{[(2E)-2-(2-Hydroxy-(5-bromo)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L3 = N-(2-{[(2E)-2-(2-Hydroxy-(5-methoxy)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide; phen = 1,10-phenanthroline, bipy = 2,2‧-bipyridine) have been prepared and characterized on the basis of elemental analyses, IR, UV-Vis and EPR spectral studies. IR spectra indicate that the ligand L1-3 exists in the keto form in the solid state, while at the time of complexation, it tautomerises into enol form. The single crystal X-ray diffraction study of the representative complex [Cu(L1) (phen)]ṡCH2Cl2 (1a) reveals the distorted square pyramidal geometry around copper(II). Crystal data of (1a): space group = P21/n, a = 11.5691(16) Å, b = 11.0885(15) Å, c = 24.890(4) Å, V = 3166.2(8) Å3, Z = 4. The electrochemical behavior of all the complexes indicate that the phen complexes appears at more positive potential as compared to those for bipy complexes, as a consequence of its stronger π acidic character. All the complexes exhibit blue-green emission as a result of the fluorescence from the intra-ligand (π → π∗) emission excited state.

Location of Varying Hydrophobicity Zinc(II) Phthalocyanine-Type Photosensitizers in Methoxy Poly(ethylene oxide) and Poly(l-lactide) Block Copolymer Micelles Using 1H NMR and XPS Techniques.

PubMed

Lamch, Łukasz; Tylus, Włodzimierz; Jewgiński, Michał; Latajka, Rafał; Wilk, Kazimiera A

2016-12-15

Hydrophobic zinc(II) phthalocyanine-type derivatives, solubilized in polymeric micelles (PMs), provide a befitting group of so-called nanophotosensitizers, suitable for a variety of photodynamic therapy (PDT) protocols. The factors that influence the success of such products in PDT are the location of the active cargo in the PMs and the nanocarrier-enhanced ability to safely interact with biological systems and fulfill their therapeutic functions. Therefore, the aim of this work was to determine the solubilization loci of three phthalocyanines of varying hydrophobicity, i.e., zinc(II) phthalocyanine (ZnPc), along with its tetrasulfonic acid (ZnPc-sulfo 4 ) and perfluorinated (ZnPcF 16 ) derivatives, loaded in polymeric micelles of methoxy poly(ethylene oxide)-b-poly(l-lactide) (mPEG-b-PLLA), by means of 1 H nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) combined with ion sputtering. Furthermore, the microenvironment influence upon the chemical and physical status of the solubilized cargo in PMs, expressed by photobleaching and reactive oxygen species (ROS) generation comparing to the same properties of native cargoes in solution, was also evaluated and discussed in regards to the probing location data. The studied phthalocyanine-loaded PMs exhibited good physical stability, high drug-loading efficiency, and a size of less than ca. 150 nm with low polydispersity indices. The formation of polymeric micelles and the solubilization locus were investigated by 1 H NMR and XPS. ZnPc localized within the PM core, whereas both ZnPcF 16 and ZnPc-sulfo 4 - in the corona of PMs. We proved that the cargo locus is crucial for the photochemical properties of the studied phthalocyanines; the increase in photostability and ability to generate ROS in micellar solution compared to free photosensitizer was most significant for the photosensitizer in the PM core. Our results indicate the role of the cargo location in the PM microenvironment and demonstrate

Variation of M···H-C Interactions in Square-Planar Complexes of Nickel(II), Palladium(II), and Platinum(II) Probed by Luminescence Spectroscopy and X-ray Diffraction at Variable Pressure.

PubMed

Poirier, Stéphanie; Lynn, Hudson; Reber, Christian; Tailleur, Elodie; Marchivie, Mathieu; Guionneau, Philippe; Probert, Michael R

2018-06-12

Luminescence spectra of isoelectronic square-planar d 8 complexes with 3d, 4d, and 5d metal centers show d-d luminescence with an energetic order different from that of the spectrochemical series, indicating that additional structural effects, such as different ligand-metal-ligand angles, are important factors. Variable-pressure luminescence spectra of square-planar nickel(II), palladium(II), and platinum(II) complexes with dimethyldithiocarbamate ({CH 3 } 2 DTC) ligands and their deuterated analogues show unexpected variations of the shifts of their maxima. High-resolution crystal structures and crystal structures at variable pressure for [Pt{(CH 3 ) 2 DTC} 2 ] indicate that intermolecular M···H-C interactions are at the origin of these different shifts.

Topological study of diverse hydrogen-bonded patterns found in a system of a nickel(II) complex and the sulfate anion.

PubMed

Harvey, Miguel Angel; Suarez, Sebastián; Zolotarev, Pavel N; Proserpio, Davide M; Baggio, Ricardo

2018-03-01

A nickel(II) coordination complex, bis[2,6-bis(1H-benzimidazol-2-yl-κN 3 )pyridine-κN]nickel(II) sulfate, [Ni(C 19 H 13 N 5 ) 2 ]SO 4 or [Ni(H 2 L) 2 ]SO 4 , having four peripheral tetrahedrally oriented N-H donor units, combines with sulfate bridges to create hydrogen-bonded structures of varied dimensionality. The three crystal structures reported herein in the space groups P2 1 2 1 2 1 , I-4 and Pccn are defined solely by strong charge-assisted N-H...O hydrogen bonds and contain disordered guests (water and dimethylformamide) that vary in size, shape and degree of hydrophilicity. Two of the compounds are channelled solids with three-dimensional structures, while the third is one-dimensional in nature. In spite of their differences, all three present a striking resemblance to the previously reported anhydrous relative [Guo et al. (2011). Chin. J. Inorg. Chem. 27, 1517-1520], which is considered as the reference framework from which all three title compounds are derived. The hydrogen-bonded frameworks are described and compared using crystallographic and topological approaches.

Synthesis, thermogravimetric, spectroscopic and theoretical characterization of copper(II) complex with 4-chloro-2-nitrobenzenosulfonamide

NASA Astrophysics Data System (ADS)

Camí, G.; Chacón Villalba, E.; Di Santi, Y.; Colinas, P.; Estiu, G.; Soria, D. B.

2011-05-01

4-Chloro-2-nitrobenzenesulfonamide (ClNbsa) was purified and characterized. A new copper(II) complex, [Cu(ClNbsa) 2(NH 3) 2], has been prepared using the sulfonamide as ligand. The thermal behavior of both, the ligand and the Cu(II) complex, was investigated by thermogravimetric analyses (TG) and differential thermal analysis (DT), and the electronic characteristics analyzed by UV-VIS, FTIR, Raman and 1H NMR spectroscopies. The experimental IR, Raman and UV-VIS spectra have been assigned on the basis of DFT calculations at the B3LYP level of theory using the standard (6-31 + G ∗∗) basis set. The geometries have been fully optimized in vacuum and in modeled dimethylsulfoxide (DMSO) solvent, using for the latter a continuum solvation model that reproduced the experimental conditions of the UV-VIS spectroscopy. The theoretical results converged to stable conformations for the free sulfonamide and for the complex, suggesting for the latter a distorted square planar geometry in both environments.

The crystal structure of paramagnetic copper(II) oxalate (CuC₂O₄): formation and thermal decomposition of randomly stacked anisotropic nano-sized crystallites.

PubMed

Christensen, Axel Nørlund; Lebech, Bente; Andersen, Niels Hessel; Grivel, Jean-Claude

2014-11-28

Synthetic copper(II) oxalate, CuC2O4, was obtained in a precipitation reaction between a copper(II) solution and an aqueous solution of oxalic acid. The product was identified from its conventional X-ray powder patterns which match that of the copper mineral Moolooite reported to have the composition CuC2O4·0.44H2O. Time resolved in situ investigations of the thermal decomposition of copper(II) oxalate using synchrotron X-ray powder diffraction showed that in air the compound converts to Cu2O at 215 °C and oxidizes to CuO at 345 °C. Thermo gravimetric analysis performed in an inert Ar-gas reveals that the material contains no crystal water and reduces to pure Cu at 295 °C. Magnetic susceptibility measurements in the temperature range from 2 K to 300 K show intriguing paramagnetic behaviour with no sign of magnetic order down to 2 K. A crystal structure investigation is made based on powder diffraction data using one neutron diffraction pattern obtained at 5 K (λ = 1.5949(1) Å) combined with one conventional and two synchrotron X-ray diffraction patterns obtained at ambient temperature using λ = 1.54056, 1.0981 and λ = 0.50483(1) Å, respectively. Based on the X-ray synchrotron data the resulting crystal structure is described in the monoclinic space group P2₁/c (#14) in the P12₁/n1 setting with unit cell parameters a = 5.9598(1) Å, b = 5.6089(1) Å, c = 5.1138 (1) Å, β = 115.320(1)°. The composition is CuC2O4 with atomic coordinates determined by FullProf refinement of the neutron diffraction data. The crystal structure consists of a random stacking of CuC2O4 micro-crystallites where half the Cu-atoms are placed at (2a) and the other half at (2b) positions with the corresponding oxalate molecules centred around the corresponding (2b) and (2a) site positions, respectively. The diffraction patterns obtained for both kinds of radiation show considerable broadening of several Bragg peaks caused by highly anisotropic microstructural size and strain

Facile control of nanoporosity in Cellulose Acetate using Nickel(II) nitrate additive and water pressure treatment for highly efficient battery gel separators.

PubMed

Lee, Woong Gi; Kim, Do Hyeong; Jeon, Woo Cheol; Kwak, Sang Kyu; Kang, Seok Ju; Kang, Sang Wook

2017-04-28

We succeed in fabricating nearly straight nanopores in cellulose acetate (CA) polymers for use as battery gel separators by utilizing an inorganic hexahydrate (Ni(NO 3 ) 2 ·6H 2 O) complex and isostatic water pressure treatment. The continuous nanopores are generated when the polymer film is exposed to isostatic water pressure after complexing the nickel(II) nitrate hexahydrate (Ni(NO 3 ) 2 ·6H 2 O) with the CA. These results can be attributed to the manner in which the polymer chains are weakened because of the plasticization effect of the Ni(NO 3 ) 2 ·6H 2 O that is incorporated into the CA. Furthermore, we performed extensive molecular dynamics simulation for confirming the interaction between electrolyte and CA separator. The well controlled CA membrane after water pressure treatment enables fabrication of highly reliable cell by utilizing 2032-type coin cell structure. The resulting cell performance exhibits not only the effect of the physical morphology of CA separator, but also the chemical interaction of electrolyte with CA polymer which facilitates the Li-ion in the cell.

Synthesis, molecular docking and DNA binding studies of phthalimide-based copper(II) complex: In vitro antibacterial, hemolytic and antioxidant assessment

NASA Astrophysics Data System (ADS)

Arif, Rizwan; Nayab, Pattan Sirajuddin; Ansari, Istikhar A.; Shahid, M.; Irfan, Mohammad; Alam, Shadab; Abid, Mohammad; Rahisuddin

2018-05-01

In the present research work, we prepared N-substituted phthalimide, 2-(-(2-(2-(2-(1,3-dioxoisoindoline-2-yl-ethylamino)ethylamino)ethyl)isoindoline-1,3-dione (DEEI) and its copper(II) complex. The ligand (DEEI) and its Cu(II) complex were structurally identified using absorption, FTIR, NMR, electron spin resonance, X-ray diffraction spectral studies, thermogravimetric and elemental analyses. The electronic spectrum and magnetic moment value proposed that Cu(II) complex has square planar geometry. The DNA interaction ability of the ligand (DEEI) and Cu(II) complex was studied by means of absorption and fluorescence spectrophotometer, viscosity measurements, cyclic voltammetery, and circular dichroism methods. The extent of DNA binding (Kb) with Calf thymus (Ct-DNA) follows the order of Cu(II) complex (1.11 × 106 M-1) > DEEI (1.0 × 105 M-1), indicating that Cu(II) complex interact with Ct-DNA through groove binding mode and more sturdily than ligand (DEEI). Interestingly, in silico predictions were corroborated with in vitro DNA binding studies. The antibacterial evaluation of these compounds was screened against a panel of bacterial strains Pseudomonas aeruginosa (MTCC 2453), Salmonella enterica (MTCC 3224), Streptococcus pneumoniae (MTCC 655), Enterococcus faecalis (MTCC 439), Klebsiella pneumonia and Escherichia coli (ATCC 25922). The results showed that the copper(II) complex has significant antibacterial potential (IC50 = 0.0019 μg/mL) against Salmonella enteric comparable with ligand (DEEI) and standard drug ciprofloxacin. Growth curve study of Cu(II) complex against only three bacterial strains S. enterica, E. faecalis and S. pneumoniae showed its bactericidal nature. Cu(II) complex showed less than 2% hemolysis on human RBCs indicating its non toxic nature. The results of antioxidant assay demonstrated that scavenging activity of Cu(II) complex is higher as compared to ligand and ascorbic acid as standard.

Synthesis and spectroscopic studies of binuclear metal complexes of a tetradentate N2O2 Schiff base ligand derived from 4,6-diacetylresorcinol and benzylamine.

PubMed

Shebl, Magdy

2008-09-01

A tetradentate N2O2 donor Schiff base ligand, H2L, was synthesized by the condensation of 4,6-diacetylresorcinol with benzylamine. The structure of the ligand was elucidated by elemental analyses, IR, 1H NMR, electronic and mass spectra. Reaction of the Schiff base ligand with nickel(II), cobalt(II), iron(III), cerium(III), vanadyl(IV) and uranyl(VI) ions in 1:2 molar ratio afforded binuclear metal complexes. Also, reaction of the ligand with several copper(II) salts, including Cl-, NO3-, AcO-, ClO4- and SO42- afforded different metal complexes that reflect the non-coordinating or weakly coordinating power of the ClO(4)(-) anion as compared to the strongly coordinating power of SO42- and Cl- anions. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, 1H NMR, electronic, mass and ESR spectra as well as magnetic susceptibility measurements. The metal complexes exhibited different geometrical arrangements such as square planar, octahedral, square pyramidal and pentagonal bipyramidal arrangements. The variety in the geometrical arrangements depends on the nature of both the anion and the metal ion.

In Situ Observations of UV-Induced Restructuring of Self-Assembled Porphyrin Monolayer on Liquid/Au(111) Interface at Molecular Level.

PubMed

Kim, Yongman; Doh, Won Hui; Kim, Jeongjin; Park, Jeong Young

2018-05-29

Porphyrin-derived molecules have received much attention for use in solar energy conversion devices, such as artificial leaves and dye-sensitized solar cells. Because of their technological importance, a molecular-level understanding of the mechanism for supramolecular structure formation in a liquid, as well as their stability under ultraviolet (UV) irradiation, is important. Here, we observed the self-assembled structure of free-base, copper(II), and nickel(II) octaethylporphyrin formed on Au(111) in a dodecane solution using scanning tunneling microscopy (STM). As evident in the STM images, the self-assembled monolayers (SAMs) of these three porphyrins on the Au(111) surface showed hexagonal close-packed structures when in dodecane solution. Under UV irradiation (λ = 365 nm), the porphyrin molecules in the SAM or the dodecane solution move extensively and form new porphyrin clusters on the Au sites that have a high degree of freedom. Consequently, the Au(111) surface was covered with disordered porphyrin clusters. However, we found that the porphyrin molecules decomposed under UV irradiation at 254 nm. Molecular-scale observation of the morphological evolution of the porphyrin SAM under UV irradiation can provide a fundamental understanding of the degradation processes of porphyrin-based energy conversion devices.

Copper(II) catalysis in cyanide conversion into ethyl carbamate in spirits and relevant reactions.

PubMed

Aresta, M; Boscolo, M; Franco, D W

2001-06-01

The role of copper(II) species in the oxidation of inorganic cyanide to cyanate and in the conversion of cyanate or urea into ethyl carbamate was investigated. The oxidation process has been shown to be independent from the dissolved oxygen. Elemental analysis and infrared spectroscopy have shown the formation of a mixed copper carbonate/hydroxide in the process of oxidation of cyanide to cyanate in water/ethanol. The complexation to Cu(II) of cyanate formed upon cyanide oxidation makes the former more susceptible to nucleophilic attack from ethanol, with conversion into ethyl carbamate. Comparatively, urea has a minor role with respect to cyanide in the formation of ethyl carbamate. Therefore, the urea present in some samples of Brazilian sugar cane spirit (cachaça) has been shown to have almost no influence on the ethyl carbamate content of cachaças, which comes essentially from cyanide. Fe(II,III) affords results similar to those found with Cu(II). Some suggestions are presented to avoid ethyl carbamate formation in spirits during distillation.

Free metal ion depletion by "Good's" buffers. III. N-(2-acetamido)iminodiacetic acid, 2:1 complexes with zinc(II), cobalt(II), nickel(II), and copper(II); amide deprotonation by Zn(II), Co(II), and Cu(II).

PubMed

Lance, E A; Rhodes, C W; Nakon, R

1983-09-01

Potentiometric, visible, infrared, electron spin, and nuclear magnetic resonance studies of the complexation of N-(2-acetamido)iminodiacetic acid (H2ADA) by Ca(II), Mg(II), Mn(II), Zn(II), Co(II), Ni(II), and Cu(II) are reported. Ca(II) and Mg(II) were found not to form 2:1 ADA2- to M(II) complexes, while Mn(II), Cu(II), Ni(II), Zn(II), and Co(II) did form 2:1 metal chelates at or below physiological pH values. Co(II) and Zn(II), but not Cu(II), were found to induce stepwise deprotonation of the amide groups to form [M(H-1ADA)4-(2)]. Formation (affinity) constants for the various metal complexes are reported, and the probable structures of the various metal chelates in solution are discussed on the basis of various spectral data.

Synthesis and characterization of an N-(2-hydroxyethyl)-ethylenediaminetriacetic acid resin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Yuet Fan

1977-10-01

A chelating ion-exchange resin with N-(2-hydroxyethyl)ethylene-diaminetriacetic acid (HEDTA) used as the ligand chemically bonded to XAD-4 by an ester linkage, HEDTA-4, was synthesized. It is stable under normal experimental conditions with the liquid chromatograph. The structure of the resin was confirmed by an infrared spectrum, and by potentiometric titrations. The capacity of the resin was also obtained by potentiometric titration and by a nitrogen analysis. The resin was used to pack a column of 5 mm internal diameter and 5 cm long. The effect of pH on the retention of different metal ions on the resin was studied. It wasmore » found that the resin was most selective for chromium(III), copper(II), lead(II), mercury(II), uranium(VI), zirconium(IV) and zinc(II) at a pH of less than 3. Furthermore, the resin proves to be functioning with a chelating mechanism rather than ion-exchange, and it can concentrate trace metal ions in the presence of a large excess of calcium and magnesium. This makes the resin potentially useful for purifying and analyzing drinking water.« less

Fluorescence and electron paramagnetic resonance studies of norfloxacin and N-donor mixed-ligand ternary copper(II) complexes: Stability and interaction with SDS micelles

NASA Astrophysics Data System (ADS)

Vignoli Muniz, Gabriel S.; Incio, Jimmy Llontop; Alves, Odivaldo C.; Krambrock, Klaus; Teixeira, Letícia R.; Louro, Sonia R. W.

2018-01-01

The stability of ternary copper(II) complexes of a heterocyclic ligand, L (L being 2,2‧-bipyridine (bipy) or 1,10-phenanthroline (phen)) and the fluorescent antibacterial agent norfloxacin (NFX) as the second ligand was studied at pH 7.4 and different ionic strengths. Fluorescence quenching upon titration of NFX with the binary complexes allowed to obtain stability constants for NFX binding, Kb, as a function of ionic strength. The Kb values vary by more than two orders of magnitude when buffer concentration varies from 0.5 to 100 mM. It was observed that previously synthesized ternary complexes dissociate in buffer according with the obtained stability constants. This shows that equimolar solutions of NFX and binary complexes are equivalent to solutions of synthesized ternary complexes. The interaction of the ternary copper complexes with anionic SDS (sodium dodecyl sulfate) micelles was studied by fluorescence and electron paramagnetic resonance (EPR). Titration of NFX-loaded SDS micelles with the complexes Cu:L allowed to determine the stability constants inside the micelles. Fluorescence quenching demonstrated that SDS micelles increase the stability constants by factors around 50. EPR spectra gave details of the copper(II) local environment, and demonstrated that the structure of the ternary complexes inside SDS micelles is different from that in buffer. Mononuclear ternary complexes formed inside the micelles, while in buffer most ternary complexes are binuclear. The results show that anionic membrane interfaces increase formation of copper fluoroquinolone complexes, which can influence bioavailability, membrane diffusion, and mechanism of action of the antibiotics.

Biosorption Performance of Encapsulated Candida krusei for the removal of Copper(II).

PubMed

Luk, Chi Him Jim; Yip, Joanne; Yuen, Chun Wah Marcus; Pang, Siu Kwong; Lam, Kim Hung; Kan, Chi Wai

2017-05-19

The use of microorganisms in biosorption is one of the most promising ways to remove trace amounts of heavy metal ions. Nevertheless, the enhancement of the successful removal of heavy metal ions by using different combinations of biosorbents is not generally guaranteed which leaves room to explore the application of the technique. In this study, the performance of free and immobilized forms of a yeast strain, Candida krusei (C. krusei), and calcium alginate (CaAlg) are evaluated for their ability to remove copper(II). Infrared spectroscopy, studies on the effects of pH and temperature, and kinetics and isotherm modelling are carried out to evaluate the biosorption. The infrared spectroscopy shows that the primary biosorption sites on the biosorbents are carboxylate groups. In addition, a higher pH and higher temperatures promote biosorption while a decline in biosorption ability is observed for C. krusei at 50 °C. The kinetics study shows that C. krusei, CaAlg and immobilized C. krusei (MCaAlg) conform with good correlation to pseudo-second order kinetics. MCaAlg and CaAlg fit well to the Langmuir isotherm while C. krusei fits well to the Temkin isotherm. From the experimental data, encapsulating C. krusei showed improved biosoprtion and address clogging in practical applications.

Copper(II) complexes of N-(2-{[(2E)-2-(2-Hydroxy-(5-substituted)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide ligands and heterocyclic coligands.

PubMed

Chavan, S S; Sawant, V A; Jadhav, A N

2014-01-03

Some copper(II) complexes of the type [Cu(L1-3)(phen]·CH2Cl2 (1a-3a) and [Cu(L1-3) (bipy)]·CH2Cl2 (1b-3b) (where L1=N-(2-{[(2E)-2-(2-Hydroxy-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L2=N-(2-{[(2E)-2-(2-Hydroxy-(5-bromo)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L3=N-(2-{[(2E)-2-(2-Hydroxy-(5-methoxy)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide; phen=1,10-phenanthroline, bipy=2,2'-bipyridine) have been prepared and characterized on the basis of elemental analyses, IR, UV-Vis and EPR spectral studies. IR spectra indicate that the ligand L1-3 exists in the keto form in the solid state, while at the time of complexation, it tautomerises into enol form. The single crystal X-ray diffraction study of the representative complex [Cu(L1) (phen)]·CH2Cl2 (1a) reveals the distorted square pyramidal geometry around copper(II). Crystal data of (1a): space group=P21/n, a=11.5691(16) Å, b=11.0885(15) Å, c=24.890(4) Å, V=3166.2(8) Å(3), Z=4. The electrochemical behavior of all the complexes indicate that the phen complexes appears at more positive potential as compared to those for bipy complexes, as a consequence of its stronger π acidic character. All the complexes exhibit blue-green emission as a result of the fluorescence from the intra-ligand (π→π(*)) emission excited state. Copyright © 2013 Elsevier B.V. All rights reserved.

Spectral characterization of novel ternary zinc(II) complexes containing 1,10-phenanthroline and Schiff bases derived from amino acids and salicylaldehyde-5-sulfonates

NASA Astrophysics Data System (ADS)

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2007-07-01

A series of new ternary zinc(II) complexes [Zn(L 1-10)(phen)], where phen is 1,10-phenanthroline and H 2L 1-10 = tridentate Schiff base ligands derived from the condensation of amino acids (glycine, L-phenylalanine, L-valine, L-alanine, and L-leucine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5-sulfonate), have been synthesized. The complexes were characterized by elemental analysis, IR, UV-vis, 1H NMR, and 13C NMR spectra. The IR spectra of the complexes showed large differences between νas(COO) and νs(COO), Δ ν ( νas(COO) - νs(COO)) of 191-225 cm -1, indicating a monodentate coordination of the carboxylate group. Spectral data showed that in these ternary complexes the zinc atom is coordinated with the Schiff base ligand acts as a tridentate ONO moiety, coordinating to the metal through its phenolic oxygen, imine nitrogen, and carboxyl oxygen, and also with the neutral planar chelating ligand, 1,10-phenanthroline, coordinating through nitrogens.

XAFS Study of the Ferro- and Antiferromagnetic Binuclear Copper(II) Complexes of Azomethine Based Tridentate Ligands

NASA Astrophysics Data System (ADS)

Vlasenko, Valery G.; Vasilchenko, Igor S.; Pirog, Irina V.; Shestakova, Tatiana E.; Uraev, Ali I.; Burlov, Anatolii S.; Garnovskii, Alexander D.

2007-02-01

Binuclear copper complexes are known to be models for metalloenzymes containing copper active sites, and some of them are of considerable interest due to their magnetic and charge transfer properties. The reactions of the complex formation of bibasic tridentate heterocyclic imines with copper acetate leads to two types of chelates with mono deprotonated ligands and with totally deprotonated ligands. Cu K-edge EXAFS has been applied to determine the local structure around the metal center in copper(II) azomethine complexes with five tridentate ligands: 1-(salycilideneimino)- or 1-(2-tosylaminobenzilideneimino)-2-amino(oxo, thio)benzimidazoles. It has been found that some of the chelates studied are bridged binuclear copper complexes, and others are mononuclear complexes. The copper-copper interatomic distances in the bridged binuclear copper complexes were found to be 2.85-3.01 Å. Variable temperature magnetic susceptibility data indicate the presence of both ferromagnetic and antiferromagnetic interactions within the dimer, the former is dominating at low temperatures and the latter at high temperatures.

Dimensional modulation and magnetic properties of triazole- and bis(triazole)-based copper(II) coordination polymers tuned by aromatic polycarboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ju-Wen; Zhao, Wei; Lu, Qi-Lin

2014-04-01

Five new metal–organic coordination polymers ([Cu{sub 3}(μ{sub 2}-OH){sub 2}(atrz){sub 2}(nph){sub 2}(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (1), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)]·2H{sub 2}O){sub n} (2), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)(H{sub 2}O)]·H{sub 2}O){sub n} (3), [Cu(dth){sub 0.5}(nph)(H{sub 2}O)]{sub n} (4) and [Cu(dth)(Hnip){sub 2}]{sub n} (5) [atrz=4-amino-1,2,4-triazole, dth=N,N'-di(4H-1,2,4-triazole)hexanamide, H{sub 2}nph=3-nitrophthalic acid, 1,2,4-H{sub 3}btc=1,2,4-benzenetricarboxylic acid and H{sub 2}nip=5-nitroisophthalic acid] were hydrothermally synthesized and structurally characterized. Polymer 1 shows a one-dimensional (1D) chain. Polymers 2 and 3 exhibit similar tetranuclear Cu{sup II}{sub 4} cluster-based three-dimensional (3D) frameworks with the same components. Polymer 4 possesses a 3D framework with a 4{sup 12}·6{sup 3}-pcu topology. Polymer 5 displays a 3D frameworkmore » with a 4{sup 4}·6{sup 10}·8-mab topology. The magnetic properties of 1–4 were investigated. - Graphical abstract: Five triazole-based copper(II) polymers modulated by polycarboxylates were synthesized. Bis-triazole-bis-amide ligand and polycarboxylates play important roles in tuning dimensionality of polymers. Magnetic properties of polymers were investigated. - Highlights: • Five triazole- and bis(triazole)-based copper(II) coordination polymers tuned by aromatic polycarboxylates were obtained. • The aromatic polycarboxylates have an important influence on the dimensionality of five polymers. • The magnetic properties of four polymers were investigated.« less

Effective cleavage of phosphodiester promoted by the zinc(II) and copper(II) inclusion complexes of β-cyclodextrin.

PubMed

Zhou, Ying-Hua; Chen, Li-Qing; Tao, Jun; Shen, Jun-Li; Gong, Dao-Yu; Yun, Rui-Rui; Cheng, Yong

2016-10-01

To construct the model of metallohydrolase, two inclusion complexes [MLCl 2 (β-CD)] (1, M=Zn(II); 2, M=Cu(II); L=N,N'-bis(2-pyridylmethyl)amantadine; β-CD=β-cyclodextrin) were synthesized by mixing β-CDs with the pre-synthesized complexes G1, [ZnLCl 2 ] and G2, [CuLCl 2 ]. Structures of G1, G2, 1 and 2 were characterized by X-ray crystallography, respectively. In solution, two chloride anions of G1 and G2 underwent ligand exchange with solvent molecules according to ESI-MS analysis. The chemical equilibrium constants were determined by potentiometric pH titration. The kinetics of bis(4-nitrophenyl) phosphate (BNPP) hydrolysis catalyzed by G1, G2, 1 and 2 were examined at pHs ranging from 7.50 to 10.50 at 308±0.1K. The pH profile of rate constant of BNPP hydrolysis catalyzed by 1 exhibited an exponential increase with the second-order rate constant of 2.68×10 -3 M -1 s -1 assigned to the di-hydroxo species, which was approximately an order of magnitude higher than those of reported mono-Zn(II)-hydroxo species. The high reactivity was presumably hydroxyl-rich microenvironment provided by β-CDs, which might effect in stabilizing either the labile zinc-hydroxo species or the catalytic transition state. Copyright © 2016 Elsevier Inc. All rights reserved.

Competitive adsorption of copper(II), cadmium(II), lead(II) and zinc(II) onto basic oxygen furnace slag.

PubMed

Xue, Yongjie; Hou, Haobo; Zhu, Shujing

2009-02-15

Polluted and contaminated water can often contain more than one heavy metal species. It is possible that the behavior of a particular metal species in a solution system will be affected by the presence of other metals. In this study, we have investigated the adsorption of Cd(II), Cu(II), Pb(II), and Zn(II) onto basic oxygen furnace slag (BOF slag) in single- and multi-element solution systems as a function of pH and concentration, in a background solution of 0.01M NaNO(3). In adsorption edge experiments, the pH was varied from 2.0 to 13.0 with total metal concentration 0.84mM in the single element system and 0.21mM each of Cd(II), Cu(II), Pb(II), and Zn(II) in the multi-element system. The value of pH(50) (the pH at which 50% adsorption occurs) was found to follow the sequence Zn>Cu>Pb>Cd in single-element systems, but Pb>Cu>Zn>Cd in the multi-element system. Adsorption isotherms at pH 6.0 in the multi-element systems showed that there is competition among various metals for adsorption sites on BOF slag. The adsorption and potentiometric titrations data for various slag-metal systems were modeled using an extended constant-capacitance surface complexation model that assumed an ion-exchange process below pH 6.5 and the formation of inner-sphere surface complexes at higher pH. Inner-sphere complexation was more dominant for the Cu(II), Pb(II) and Zn(II) systems.

Axial coordination and conformational heterogeneity of nickel(II) tetraphenylprophyrin complexes with nitrogenous bases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, S.L.; Song, X.Z.; Ma, J.G.

1998-08-24

Axial ligation of nickel(II) 5,10,15,20-tetraphenylporphyrin (NiTPP) with pyrrolidine or piperidine has been investigated using X-ray crystallography, UV-visible spectroscopy, resonance Raman spectroscopy, and molecular mechanics (MM) calculations. Distinct v{sub 4} Raman lines are found for the 4-, 5-, and 6-coordinate species of NiTPP. The equilibrium constants for addition of the first and second pyrrolidine axial ligands are 1.1 and 3.8 M{sup {minus}1}, respectively. The differences in the calculated energies of the conformers having different ligand rotational angles are small so they may coexist in solution. Because of the similarity in macrocyclic structural parameters of these conformers and the free rotation ofmore » the axial ligands, narrow and symmetric v{sub 2} and v{sub 8} Raman lines are observed. Nonetheless, the normal-coordinate structural-decomposition analysis of the nonplanar distortions of the calculated structures and the crystal structure of the bis(piperidine) complex reveals a relationship between the orientations of axial ligand(s) and the macrocyclic distortions. For the 5-coordinate complex with the plane of the axial ligand bisecting the Ni-N{sub pyrrole} bonds, a primarily ruffled deformation results. With the ligand plane eclipsing the Ni-N{sub pyrrole} bonds, a mainly saddled deformation occurs. With the addition of the second axial ligand, the small doming of the 5-coordinate complexes disappears, and ruffling or saddling deformations change depending on the relative orientation of the two axial ligands. The crystal structure of the NiTPP bis(piperidine) complex shows a macrocycle distortion composed of wav(x) and wav(y) symmetric deformations, but no ruffling, saddling, or doming. The difference in the calculated and observed distortions results partly from the phenyl group orientation imposed by crystal packing forces. MM calculations predict three stable conformers (ruf, sad, and planar) for 4-coordinate NiTPP, and resonance

DNA binding, antioxidant, cytotoxicity (MTT, lactate dehydrogenase, NO), and cellular uptake studies of structurally different nickel(II) thiosemicarbazone complexes: synthesis, spectroscopy, electrochemistry, and X-ray crystallography.

PubMed

Prabhakaran, R; Kalaivani, P; Huang, R; Poornima, P; Vijaya Padma, V; Dallemer, F; Natarajan, K

2013-02-01

Three new nickel(II) thiosemicarbazone complexes have been synthesized and characterized by analytical, spectral, and single-crystal X-ray diffraction studies. In complex 1, the ligand 2-hydroxy-1-naphthaldehydethiosemicarbazone coordinated as a monobasic tridentate donor, whereas in complexes 2 and 3, the ligands salicylaldehyde-4(N)-ethylthiosemicarbazone and 2-hydroxy-1-naphthaldehyde-4(N)-ethylthiosemicarbazone coordinated as a dibasic tridentate donor. The DNA binding ability of the complexes in calf thymus DNA was explored by absorption and emission titration experiments. The antioxidant property of the new complexes was evaluated to test their free-radical scavenging ability. In vitro cytotoxicity assays were performed for the new complexes in A549 and HepG2 cell lines. The new compounds overcome cisplatin resistance in the A549 cell line and they were also active in the HepG2 cell line. The cellular uptake study showed the accumulation of the complexes in tumor cells depended on the nature of the ligand attached to the nickel ion.

Concomitant polymorphism of an octahedral, homoleptic zinc(II) bis complex of an N,N,O donor hydrazone

NASA Astrophysics Data System (ADS)

Patra, Shanti G.; Shee, Nirmal K.; Mitra, Partha; Drew, Michael G. B.; Datta, Dipankar

2018-03-01

Using the 1:1 condensate of benzil and 2-hydrazinopyridine as the ligand HL (H: a dissociable proton), a new zinc(II) complex ZnL2 is synthesized. It is obtained as a mixture of three types of deep red crystals - diamond shaped (1a), rectangular (1b) and pointed tetragonal (1c) which can be separated manually. Their different crystal structures have been determined. 1a crystallizes in the space group P21/c, 1b in Pbca and 1c in P-1. The asymmetric unit of 1c contains two independent molecules labeled A and B. Thus ZnL2 can assume at least four different molecular conformations in the solid state, namely 1a, 1b, 1c-A and 1c-B. But in the DFT calculations at the B3LYP/6-311++G (2d,p) and BP86/LanL2DZ levels 1a, 1b, 1c-A and 1c-B converge to a single structure in the gas phase. The DFT structure is found to possess a C2 axis though no symmetry constraint was imposed in the calculations. Interestingly 1a, 1b, 1c-A and 1c-B yield the same NMR spectra in solution revealing a C2 axis. So it is concluded that the gas phase DFT structure is realized experimentally only in solution. Further, our DFT calculations show that the four species are distributed along a "potential energy curve" of ZnL2. Anyway, our ZnL2 presents a case of concomitant polymorphism.

Experimental Investigation on the Mechanism of Chelation-Assisted, Copper(II) Acetate-Accelerated Azide-Alkyne Cycloaddition

PubMed Central

Kuang, Gui-Chao; Guha, Pampa M.; Brotherton, Wendy S.; Simmons, J. Tyler; Stankee, Lisa A.; Nguyen, Brian T.; Clark, Ronald J.; Zhu, Lei

2011-01-01

A mechanistic model is formulated to account for the high reactivity of chelating azides (organic azides capable of chelation-assisted metal coordination at the alkylated azido nitrogen position) and copper(II) acetate (Cu(OAc)2) in copper(II)-mediated azide-alkyne cycloaddition (AAC) reactions. Fluorescence and 1H NMR assays are developed for monitoring the reaction progress in two different solvents – methanol and acetonitrile. Solvent kinetic isotopic effect and pre-mixing experiments give credence to the proposed different induction reactions for converting copper(II) to catalytic copper(I) species in methanol (methanol oxidation) and acetonitrile (alkyne oxidative homocoupling), respectively. The kinetic orders of individual components in a chelation-assisted, copper(II)-accelerated AAC reaction are determined in both methanol and acetonitrile. Key conclusions resulting from the kinetic studies include (1) the interaction between copper ion (either in +1 or +2 oxidation state) and a chelating azide occurs in a fast, pre-equilibrium step prior to the formation of the in-cycle copper(I)-acetylide, (2) alkyne deprotonation is involved in several kinetically significant steps, and (3) consistent with prior experimental and computational results by other groups, two copper centers are involved in the catalysis. The X-ray crystal structures of chelating azides with Cu(OAc)2 suggest a mechanistic synergy between alkyne oxidative homocoupling and copper(II)-accelerated AAC reactions, in which both a bimetallic catalytic pathway and a base are involved. The different roles of the two copper centers (a Lewis acid to enhance the electrophilicity of the azido group and a two-electron reducing agent in oxidative metallacycle formation, respectively) in the proposed catalytic cycle suggest that a mixed valency (+2 and +1) dinuclear copper species be a highly efficient catalyst. This proposition is supported by the higher activity of the partially reduced Cu(OAc)2 in

Nickel-quinolones interaction. Part 4. Structure and biological evaluation of nickel(II)-enrofloxacin complexes compared to zinc(II) analogues.

PubMed

Skyrianou, Kalliopi C; Psycharis, Vassilis; Raptopoulou, Catherine P; Kessissoglou, Dimitris P; Psomas, George

2011-01-01

The nickel(II) complexes with the second-generation quinolone antibacterial agent enrofloxacin in the presence or absence of the nitrogen-donor heterocyclic ligands 1,10-phenanthroline, 2,2'-bipyridine or pyridine have been synthesized and characterized. Enrofloxacin acts as bidentate ligand coordinated to Ni(II) ion through the ketone oxygen and a carboxylato oxygen. The crystal structure of (1,10-phenanthroline)bis(enrofloxacinato)nickel(II) has been determined by X-ray crystallography. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that they bind to CT DNA and bis(pyridine)bis(enrofloxacinato)nickel(II) exhibits the highest binding constant to CT DNA. The cyclic voltammograms of the complexes have shown that in the presence of CT DNA the complexes can bind to CT DNA by the intercalative binding mode which has also been verified by DNA solution viscosity measurements. Competitive study with ethidium bromide (EB) has shown that the complexes can displace the DNA-bound EB indicating that they bind to DNA in strong competition with EB. The complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values. The biological properties of the complexes have been evaluated in comparison to the corresponding Zn(II) enrofloxacinato complexes as well as Ni(II) complexes with the first-generation quinolone oxolinic acid. Copyright © 2010 Elsevier Inc. All rights reserved.

Synthesis, structure and electrochemical behavior of a 3D crystalline copper(II) metal-organic framework

NASA Astrophysics Data System (ADS)

Bai, Hong-Ye; Fan, Wei-Qiang; Liu, Chun-Bo; Shi, Wei-Dong; Yan, Yong-Sheng

2014-05-01

Using an flexible amide-type tripodal ligand N,N‧,N″-tris(3-pyridyl)-1,3,5-benzenetricarboxamide (L) and 1,4-benzenedicarboxylic acid (H2bdc), a three-dimensional copper(II) metal-organic framework (MOF) formulated as [Cu(bdc)(L)]n has been hydrothermally synthesized and structurally characterized by IR, elemental, X-ray single-crystal diffraction and thermal analysis. The complex crystallizes in the triclinic, space group P - 1, a = 8.891(2) Å, b = 11.760(2) Å, c = 15.348(3) Å, α = 96.73(3)°, β = 105.96(3)°, γ = 106.47(3)°, V = 1446.2(5) Å3, Mr = 666.10, Dc = 1.530 g/cm3, Z = 2, F(000) = 682, GOOF = 1.0560, μ(MoKα) = 0.817 mm-1, R = 0.0366 and wR = 0.0885. The structural analyses reveal that the title compound consists of one Cu(II) atom, two halves of bdc, and one L ligand. Each Cu(II) atom is linked by two bdc ligands and three L ligands to form a three-dimensional network. In addition, the electrochemical behavior of title compound has been studied. CCDC No. 990526.

New Cu (II), Co(II) and Ni(II) complexes of chalcone derivatives: Synthesis, X-ray crystal structure, electrochemical properties and DFT computational studies

NASA Astrophysics Data System (ADS)

Tabti, Salima; Djedouani, Amel; Aggoun, Djouhra; Warad, Ismail; Rahmouni, Samra; Romdhane, Samir; Fouzi, Hosni

2018-03-01

The reaction of nickel(II), copper(II) and cobalt(II) with 4-hydroxy-3-[(2E)-3-(1H-indol-3-yl)prop-2-enoyl]-6-methyl-2H-pyran-2-one (HL) leads to a series of new complexes: Ni(L)2(NH3), Cu(L)2(DMF)2 and Co(L)2(H2O). The crystal structure of the Cu(L)2(DMF)2 complex have been determined by X-ray diffraction methods. The Cu(II) lying on an inversion centre is coordinated to six oxygen atoms forming an octahedral elongated. Additionally, the electrochemical behavior of the metal complexes were investigated by cyclic voltammetry at a glassy carbon electrode (GC) in CH3CN solutions, showing the quasi-reversible redox process ascribed to the reduction of the MII/MI couples. The X-ray single crystal structure data of the complex was matched excellently with the optimized monomer structure of the desired compound; Hirschfeld surface analysis supported the packed crystal lattice 3D network intermolecular forces. HOMO/LUMO energy level and the global reactivity descriptors quantum parameters are also calculated. The electrophilic and nucleophilic potions in the complex surface are theoretically evaluated by molecular electrostatic potential and Mulliken atomic charges analysis.

Synthesis, spectroscopic characterization, DNA interaction and biological activities of Mn(II), Co(II), Ni(II) and Cu(II) complexes with [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol

NASA Astrophysics Data System (ADS)

Gaber, Mohamed; El-Wakiel, Nadia A.; El-Ghamry, Hoda; Fathalla, Shaimaa K.

2014-11-01

Manganese(II), cobalt(II), nickel(II) and copper(II) complexes of [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol have been synthesized. The structure of complexes have been characterized by elemental analysis, molar conductance, magnetic moment measurements and spectral (IR, 1H NMR, EI-mass, UV-Vis and ESR), and thermal studies. The results showed that the chloro and nitrato Cu(II) complexes have octahedral geometry while Ni(II), Co(II) and Mn(II) complexes in addition to acetato Cu(II) complex have tetrahedral geometry. The possible structures of the metal complexes have been computed using the molecular mechanic calculations using the hyper chem. 8.03 molecular modeling program to confirm the proposed structures. The kinetic and thermodynamic parameters of the thermal decomposition steps were calculated from the TG curves. The binding modes of the complexes with DNA have been investigated by UV-Vis absorption titration. The results showed that the mode of binding of the complexes to DNA is intercalative or non-intercalative binding modes. Schiff base and its metal complexes have been screened for their in vitro antimicrobial activities against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli and Pesudomonas aeruginosa), fungi (Asperigllus flavus and Mucer) and yeast (Candida albicans and Malassezia furfur).

Electroless Cu Plating on Anodized Al Substrate for High Power LED.

PubMed

Rha, Sa-Kyun; Lee, Youn-Seoung

2015-03-01

Area-selective copper deposition on screen printed Ag pattern/anodized Al/Al substrate was attempted using a neutral electroless plating processes for printed circuit boards (PCBs), according to a range of variation of pH 6.5-pH 8 at 70 °C. The utilized basic electroless solution consisted of copper(II) sulfate pentahydrate, sodium phosphinate monohydrate, sodium citrate tribasic dihydrate, ammonium chloride, and nickel(II) sulfate hexahydrate. The pH of the copper plating solutions was adjusted from pH 6.5 to pH 8 using NH4OH. Using electroless plating in pH 6.5 and pH 7 baths, surface damage to the anodized Al layer hardly occurred; the structure of the plated Cu-rich films was a typical fcc-Cu, but a small Ni component was co-deposited. In electroless plating at pH 8, the surface of the anodized Al layer was damaged and the Cu film was composed of a lot of Ni and P which were co-deposited with Cu. Finally, in a pH 7 bath, we can make a selectively electroless plated Cu film on a PCB without any lithography and without surface damage to the anodized Al layer.

Investigate the ultrasound energy assisted adsorption mechanism of nickel(II) ions onto modified magnetic cobalt ferrite nanoparticles: Multivariate optimization.

PubMed

Mehrabi, Fatemeh; Alipanahpour Dil, Ebrahim

2017-07-01

In present study, magnetic cobalt ferrite nanoparticles modified with (E)-N-(2-nitrobenzylidene)-2-(2-(2-nitrophenyl)imidazolidine-1-yl) ethaneamine (CoFe 2 O 4 -NPs-NBNPIEA) was synthesized and applied as novel adsorbent for ultrasound energy assisted adsorption of nickel(II) ions (Ni 2+ ) from aqueous solution. The prepared adsorbent characterized by Fourier transforms infrared spectroscopy (FT-IR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). The dependency of adsorption percentage to variables such as pH, initial Ni 2+ ions concentration, adsorbent mass and ultrasound time were studied with response surface methodology (RSM) by considering the desirable functions. The quadratic model between the dependent and independent variables was built. The proposed method showed good agreement between the experimental data and predictive value, and it has been successfully employed to adsorption of Ni 2+ ions from aqueous solution. Subsequently, the experimental equilibrium data at different concentration of Ni 2+ ions and 10mg amount of adsorbent mass was fitted to conventional isotherm models like Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich and it was revealed that the Langmuir is best model for explanation of behavior of experimental data. In addition, conventional kinetic models such as pseudo-first and second-order, Elovich and intraparticle diffusion were applied and it was seen that pseudo-second-order equation is suitable to fit the experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis, crystal structure, fluorescence and electrochemical studies of a new tridentate Schiff base ligand and its nickel(II) and palladium(II) complexes

NASA Astrophysics Data System (ADS)

Shafaatian, Bita; Soleymanpour, Ahmad; Kholghi Oskouei, Nasim; Notash, Behrouz; Rezvani, Seyyed Ahmad

2014-07-01

A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1 M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1 M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s-1 scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, 1H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction.

Trace level voltammetric determination of heavy metals and total mercury in tea matrices (Camellia sinensis).

PubMed

Melucci, Dora; Locatelli, Marcello; Locatelli, Clinio

2013-12-01

An analytical procedure regarding the voltammetric determination of mercury(II), copper(II), lead(II), cadmium(II) and zinc(II) by square wave anodic stripping voltammetry (SWASV) in matrices involved in food chain is proposed. In particular, tea leaves were analyzed as real samples. The digestion of each matrix was carried out using a concentrated HCl-HNO3-H2SO4 acidic attack mixture; 0.01 mol L(-1) EDTA-Na2+ 0.15 mol L(-1) NaCl + 0.5 mol L(-1) HCl was employed as the supporting electrolyte. The voltammetric measurements were carried out using a conventional three electrode cell, employing, as working electrodes, a gold electrode (GE) and a stationary hanging mercury drop electrode (HMDE). The analytical procedure has been verified on the standard reference materials Spinach Leaves NIST-SRM 1570a, Tomato Leaves NIST-SRM 1573a and Apple Leaves NIST-SRM 1515. For all the elements, the precision as repeatability, expressed as relative standard deviation (sr) was of the order of 3-5%, while the trueness, expressed as relative error (e) was of the order of 3-7%. Once set up on the standard reference materials, the analytical procedure was applied to commercial tea leaves samples. A critical comparison with spectroscopic measurements is also discussed.

New fluorescent azo-Schiff base Cu(II) and Zn(II) metal chelates; spectral, structural, electrochemical, photoluminescence and computational studies

NASA Astrophysics Data System (ADS)

Purtas, Fatih; Sayin, Koray; Ceyhan, Gokhan; Kose, Muhammet; Kurtoglu, Mukerrem

2017-06-01

A new Schiff base containing azo chromophore group obtained by condensation of 2-hydroxy-4-[(E)-phenyldiazenyl]benzaldehyde with 3,4-dimethylaniline (HL) are used for the syntheses of new copper(II) and zinc(II) chelates, [Cu(L)2], and [Zn(L)2], and characterized by physico-chemical and spectroscopic methods such as 1H and 13C NMR, IR, UV.-Vis. and elemental analyses. The solid state structure of the ligand was characterized by single crystal X-ray diffraction study. X-ray diffraction data was then used to calculate the harmonic oscillator model of aromaticity (HOMA) indexes for the rings so as to investigate of enol-imine and keto-amine tautomeric forms in the solid state. The phenol ring C10-C15 shows a considerable deviation from the aromaticity with HOMA value of 0.837 suggesting the shift towards the keto-amine tautomeric form in the solid state. The analytical data show that the metal to ligand ratio in the chelates was found to be 1:2. Theoretical calculations of the possible isomers of the ligand and two metal complexes are performed by using B3LYP method. Electrochemical and photoluminescence properties of the synthesized azo-Schiff bases were also investigated.

Binary and ternary copper(II) complexes of a new Schiff base ligand derived from 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone: Synthesis, spectral, thermal, antimicrobial and antitumor studies

NASA Astrophysics Data System (ADS)

Shebl, Magdy; Adly, Omima M. I.; Abdelrhman, Ebtesam M.; El-Shetary, B. A.

2017-10-01

A new Schiff base ligand was synthesized by the reaction of 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone with ethylenediamine. A series of binary copper(II) Schiff base complexes have been synthesized by using various copper(II) salts; AcO-, NO3-, ClO4-, Cl- and Br-. Ternary complexes were synthesized by using auxiliary ligands (L‧) [N,O-donor; 8-hydroxyquinoline and glycine or N,N-donor; 1,10-phenanthroline, bipyridyl and 2-aminopyridine]. The structures of the Schiff base and its complexes were characterized by elemental and thermal analyses, IR, electronic, mass, 1H NMR and ESR spectra in addition to conductivity and magnetic susceptibility measurements. The obtained complexes include neutral binuclear complexes as well as neutral and cationic mononuclear complexes according to the anion used and the experimental conditions. The ESR spin Hamiltonian parameters of some complexes were calculated and discussed. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages were evaluated using Coats-Redfern equations. The antimicrobial activity of the Schiff base and its complexes was screened against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). The antitumor activity of the Schiff base and some of its Cu(II) complexes was investigated against HepG-2 cell line.

Ternary copper(II) complex: NCI60 screening, toxicity studies, and evaluation of efficacy in xenograft models of nasopharyngeal carcinoma.

PubMed

Ahmad, Munirah; Suhaimi, Shazlan-Noor; Chu, Tai-Lin; Abdul Aziz, Norazlin; Mohd Kornain, Noor-Kaslina; Samiulla, D S; Lo, Kwok-Wai; Ng, Chew-Hee; Khoo, Alan Soo-Beng

2018-01-01

Copper(II) ternary complex, [Cu(phen)(C-dmg)(H2O)]NO3 was evaluated against a panel of cell lines, tested for in vivo efficacy in nasopharyngeal carcinoma xenograft models as well as for toxicity in NOD scid gamma mice. The Cu(II) complex displayed broad spectrum cytotoxicity against multiple cancer types, including lung, colon, central nervous system, melanoma, ovarian, and prostate cancer cell lines in the NCI-60 panel. The Cu(II) complex did not cause significant induction of cytochrome P450 (CYP) 3A and 1A enzymes but moderately inhibited CYP isoforms 1A2, 2C9, 2C19, 2D6, 2B6, 2C8 and 3A4. The complex significantly inhibited tumor growth in nasopharyngeal carcinoma xenograft bearing mice models at doses which were well tolerated without causing significant or permanent toxic side effects. However, higher doses which resulted in better inhibition of tumor growth also resulted in toxicity.

Copper(II) complexes as catalyst for the aerobic oxidation of o-phenylenediamine to 2,3-diaminophenazine

NASA Astrophysics Data System (ADS)

Khattar, Raghvi; Yadav, Anjana; Mathur, Pavan

2015-05-01

Two new mononuclear copper(II) complexes [Cu (L) (NO3)2] (1) and [Cu (L) Br2] (2) where (L = bis(1-(pyridin-2-ylmethyl)-benzimidazol-2-ylmethyl)ether) are synthesized and characterized by single-crystal X-ray diffraction analysis, elemental analysis, UV-Visible, IR spectroscopy, EPR and cyclic voltammetry. The complexes exhibit different coordination structures; the E1/2 value of the complex (1) is found to be relatively more cathodic than that of complex (2). X-band EPR spectra at low temperature in DMF supports a tetragonally distorted complex (1) while complex (2) shows three different g values suggesting a rhombic geometry. These complexes were utilized as a catalyst for the aerobic oxidation of o-phenylenediamine to 2,3-diaminophenazine assisted by molecular oxygen. The initial rate of reaction is dependent on the concentration of Cu(II) complex as well as substrate, and was found to be higher for the nitrate bound complex, while presence of acetate anion acts as a mild inhibitor of the reaction, as it is likely to pick up protons generated during the course of reaction. The inhibition suggests that the generated protons are further required in another important catalytic step.

Copper(II) complexes of tridentate N, N, N', N″, N″-pentamethyldiethylenetriamine: Superoxide dismutase and inhibitory activity against bacteria and fungi

NASA Astrophysics Data System (ADS)

Patel, R. N.; Singh, Nripendra; Gundla, V. L. N.; Chauhan, U. K.

2007-03-01

A series of ternary copper(II) complexes containing same coordination sphere but difference in the counter ions, viz., [Cu(PMDT)(OAc)]PF 6(1); [Cu(PMDT)(OAc)]ClO 4(2); [Cu(PMDT)(OAc)]BF 4(3) and [Cu(PMDT)(OAc)]BPh 4(4) where PMDT = N, N, N', N″, N″-pentamethyldiethylenetriamine, OAc = Acetate ion were synthesized and characterized by means of spectroscopic, magnetic and cyclic voltammetric measurements. In frozen solution e.p.r. spectra, an interesting relation g|| > g⊥ has been observed which is a typical of the axially symmetric d 9 Cu II ( SCu = 1/2) having an unpaired electron in a d orbital. Single crystal X-ray analysis of (1) has revealed the presence of distorted square planar geometry. The influence of the counter ion on the complexes has been examined by performing some biological experiments like superoxide dismutase and anti-microbial activity.

Zinc(II) and lead(II) metal-organic networks driven by a multifunctional pyridine-carboxylate building block: Hydrothermal synthesis, structural and topological features, and luminescence properties

NASA Astrophysics Data System (ADS)

Yang, Ling; Li, Yu; You, Ao; Jiang, Juan; Zou, Xun-Zhong; Chen, Jin-Wei; Gu, Jin-Zhong; Kirillov, Alexander M.

2016-09-01

4-(5-Carboxypyridin-2-yl)isophthalic acid (H3L) was applied as a flexible, multifunctional N,O-building block for the hydrothermal self-assembly synthesis of two novel coordination compounds, namely 2D [Zn(μ3-HL)(H2O)]n·nH2O (1) and 3D [Pb2(μ5-HL)(μ6-HL)]n (2) coordination polymers (CPs). These compounds were obtained in aqueous medium from a mixture containing zinc(II) or lead(II) nitrate, H3L, and sodium hydroxide. The products were isolated as stable crystalline solids and were characterized by IR spectroscopy, elemental, thermogravimetric (TGA), powder (PXRD) and single-crystal X-ray diffraction analyses. Compound 1 possesses a 2D metal-organic layer with the fes topology, which is further extended into a 3D supramolecular framework via hydrogen bonds. In contrast, compound 2 features a very complex network structure, which was topologically classified as a binodal 5,6-connected net with the unique topology defined by the point symbol of (47.63)(49.66). Compounds 1 and 2 disclose an intense blue or green luminescent emission at room temperature.

Synthesis, characterization, single crystal X-ray determination, fluorescence and electrochemical studies of new dinuclear nickel(II) and oxovanadium(IV) complexes containing double Schiff base ligands

NASA Astrophysics Data System (ADS)

Shafaatian, Bita; Ozbakzaei, Zahra; Notash, Behrouz; Rezvani, S. Ahmad

2015-04-01

A series of new bimetallic complexes of nickel(II) and vanadium(IV) have been synthesized by the reaction of the new double bidentate Schiff base ligands with nickel acetate and vanadyl acetylacetonate in 1:1 M ratio. In nickel and also vanadyl complexes the ligands were coordinated to the metals via the imine N and enolic O atoms. The complexes have been found to possess 1:1 metals to ligands stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The nickel and vanadyl complexes exhibited distorted square planar and square pyramidal coordination geometries, respectively. The emission spectra of the ligands and their complexes were studied in methanol. Electrochemical properties of the ligands and their metal complexes were also investigated in DMSO solvent at 150 mV s-1 scan rate. The ligands and metal complexes showed both quasi-reversible and irreversible processes at this scan rate. The Schiff bases and their complexes have been characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis and conductometry. The crystal structure of the nickel complex has been determined by single crystal X-ray diffraction.

Trapping of muscle relaxant methocarbamol degradation product by complexation with copper(II) ion: Spectroscopic and quantum chemical studies

NASA Astrophysics Data System (ADS)

Mansour, Ahmed M.; Shehab, Ola R.

2014-07-01

Structural properties of methocarbamol (Mcm) were extensively studied both experimentally and theoretically using FT IR, 1H NMR, UV-Vis., geometry optimization, Mulliken charge, and molecular electrostatic potential. Stability arises from hyper-conjugative interactions, charge delocalization and H-bonding was analyzed using natural bond orbital (NBO) analysis. Mcm was decomposed in ethanol/water mixture at 80 °C to guaifenesin [(RS)-3-(2-methoxyphenoxy)propane-1,2-diol] and carbamate ion [NH2COO-], where the degradation mechanism was explained by trapping the carbamate ion via the complexation with copper(II) ion. The structure of the isolated complex ([Cu(NH2COO)2(H2O)]ṡ4H2O) was elucidated by spectral, thermal, and magnetic tools. Electronic spectra were discussed by TD-DFT and the descriptions of frontier molecular orbitals and the relocations of the electron density were determined. Calculated g-tensor values showed best agreement with experimental values from EPR when carried out using both the B3LYP and B3PW91 functional.

One-electron oxidation of electronically diverse manganese(III) and nickel(II) salen complexes: transition from localized to delocalized mixed-valence ligand radicals.

PubMed

Kurahashi, Takuya; Fujii, Hiroshi

2011-06-01

Ligand radicals from salen complexes are unique mixed-valence compounds in which a phenoxyl radical is electronically linked to a remote phenolate via a neighboring redox-active metal ion, providing an opportunity to study electron transfer from a phenolate to a phenoxyl radical mediated by a redox-active metal ion as a bridge. We herein synthesize one-electron-oxidized products from electronically diverse manganese(III) salen complexes in which the locus of oxidation is shown to be ligand-centered, not metal-centered, affording manganese(III)-phenoxyl radical species. The key point in the present study is an unambiguous assignment of intervalence charge transfer bands by using nonsymmetrical salen complexes, which enables us to obtain otherwise inaccessible insight into the mixed-valence property. A d(4) high-spin manganese(III) ion forms a Robin-Day class II mixed-valence system, in which electron transfer is occurring between the localized phenoxyl radical and the phenolate. This is in clear contrast to a d(8) low-spin nickel(II) ion with the same salen ligand, which induces a delocalized radical (Robin-Day class III) over the two phenolate rings, as previously reported by others. The present findings point to a fascinating possibility that electron transfer could be drastically modulated by exchanging the metal ion that bridges the two redox centers. © 2011 American Chemical Society

Optically active red-emitting Cu nanoclusters originating from complexation and redox reaction between copper(ii) and d/l-penicillamine

NASA Astrophysics Data System (ADS)

Long, Tengfei; Guo, Yanjia; Lin, Min; Yuan, Mengke; Liu, Zhongde; Huang, Chengzhi

2016-05-01

Despite a significant surge in the number of investigations into both optically active Au and Ag nanostructures, there is currently only limited knowledge about optically active Cu nanoclusters (CuNCs) and their potential applications. Here, we have succeeded in preparing a pair of optically active red-emitting CuNCs on the basis of complexation and redox reaction between copper(ii) and penicillamine (Pen) enantiomers, in which Pen serves as both a reducing agent and a stabilizing ligand. Significantly, the CuNCs feature unique aggregation induced emission (AIE) characteristics and therefore can serve as pH stimuli-responsive functional materials. Impressively, the ligand chirality plays a dramatic role for the creation of brightly emissive CuNCs, attributed to the conformation of racemic Pen being unfavorable for the electrostatic interaction, and thus suppressing the formation of cluster aggregates. In addition, the clusters display potential toward cytoplasmic staining and labelling due to the high photoluminescence (PL) quantum yields (QYs) and remarkable cellular uptake, in spite that no chirality-dependent effects in autophagy and subcellular localization are observed in the application of chiral cluster enantiomer-based cell imaging.Despite a significant surge in the number of investigations into both optically active Au and Ag nanostructures, there is currently only limited knowledge about optically active Cu nanoclusters (CuNCs) and their potential applications. Here, we have succeeded in preparing a pair of optically active red-emitting CuNCs on the basis of complexation and redox reaction between copper(ii) and penicillamine (Pen) enantiomers, in which Pen serves as both a reducing agent and a stabilizing ligand. Significantly, the CuNCs feature unique aggregation induced emission (AIE) characteristics and therefore can serve as pH stimuli-responsive functional materials. Impressively, the ligand chirality plays a dramatic role for the creation of

Dinuclear Nickel(II) Complexes as Models for the Active Site of Urease.

PubMed

Volkmer, Dirk; Hommerich, Birgit; Griesar, Klaus; Haase, Wolfgang; Krebs, Bernt

1996-06-19

Dinuclear nickel(II) complexes of the ligands 2,6-bis[bis((2-benzimidazolylmethyl)amino)methyl]-p-cresol (bbapOH), N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane (tbpOH), N-methyl-N,N',N'-tris(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane (m-tbpOH) and 1-[N,N-bis(2-benzimidazolylmethyl)amino]-3-[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethoxy]-2-hydroxypropane (bpepOH) were prepared in order to model the active site of urease. The novel asymmetric structures of the dinuclear complexes were characterized by X-ray structure analysis. The complex [Ni(2)(bbapO)(ClO(4))(H(2)O)(MeOH)](ClO(4))(2).Et(2)O, 1, crystallizes in the monoclinic space group P2(1)/c, with a = 10.258(2) Å, b = 19.876(3) Å, c = 25.592(4) Å, and beta = 97.12(2) degrees. The nickel ions in 1 are bridged by the phenoxy donor of the ligand and a perchlorate anion. The complexes [Ni(2)(tbpO)(MeCOO)(H(2)O)](ClO(4))(2).H(2)O.Et(2)O, 2, [Ni(2)(m-tbpO)(PhCOO)(EtOH)(2)](ClO(4))(2).EtOH, 3, and [Ni(2)(bpepO)(MeCOO)(H(2)O)(2)](ClO(4))(2).H(2)O.Et(2)O.2EtOH, 4, also crystallize in the monoclinic crystal system with the following unit cell parameters: 2, C2/c, a = 35.360(13) Å, b = 10.958(3) Å, c = 24.821(10) Å, beta = 103.55(3) degrees; 3, Cc, a = 14.663(5) Å, b = 32.630(13) Å, c = 9.839(3) Å, beta = 92.49(2) degrees; 4, C2/c, a = 27.689(13) Å, b = 12.187(5) Å, c = 31.513(14) Å, beta = 115.01(3) degrees. The dinuclear centers of all these complexes are bridged by the alkoxy donor of the ligand and a carboxylate function. Compounds 2 and 3 have one of the nickel ions in a five-coordinated, trigonal bipyramidal coordination environment and thus show a high structural similarity to the dinuclear active site of urease from Klebsiella aerogenes. Furthermore, their magnetic and spectroscopic properties were determined and related to those of the urease enzymes. Activity toward hydrolysis of test substrates (4-nitrophenyl)urea, 4-nitroacetanilide, 4-nitrophenyl phosphate or bis(4

Removal of copper(II) from some environmental samples by sorptive-flotation using powdered marble wastes as sorbents and oleic acid as surfactant.

PubMed

Ghazy, S E; Samra, S E; Mahdy, A F M; El-Morsy, S M

2004-11-01

A simple and economic experimental sorptive -flotation procedure is presented for the removal of copper(II) species from aqueous solutions. It is based on using powdered marble wastes (PMW), which are widespread and inexpensive and may represent an environmental problem, as the effective inorganic sorbent and oleic (HOL) as the surfactant. The main parameters (i.e. initial solution pH, sorbent, surfactant and copper concentrations, stirring times, ionic strength, temperature and the presence of foreign ions) influencing the flotation of PMW and /or Cu(II) were examined. Nearly, 100% of PMW and Cu(II) were removed from aqueous solutions at pH7 after stirring for 10 min and at room temperature, (approximately 25 degrees C). The procedure was successfully applied to recover Cu(II) spiked to some natural water samples. A mechanism for sorption and flotation is suggested.

Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, 57Fe Mössbauer spectroscopy and thermal studies

NASA Astrophysics Data System (ADS)

Trávníček, Zdeněk; Herchel, Radovan; Mikulík, Jiří; Zbořil, Radek

2010-05-01

Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN) 5NO]·H 2O ( 1), where tet= N,N' -bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN) 5NO]·2H 2O ( 2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1 6,9]octadecane and [Cu(nme) 2Fe(CN) 5NO]·H 2O ( 3), where nme= N-methylethylenediamine, were synthesized and characterized by elemental analyses, 57Fe Mössbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, 57Fe Mössbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe 2O 4 and CuO.

Synthesis and structure elucidation of a copper(II) Schiff-base complex: in vitro DNA binding, pBR322 plasmid cleavage and HSA binding studies.

PubMed

Tabassum, Sartaj; Ahmad, Musheer; Afzal, Mohd; Zaki, Mehvash; Bharadwaj, Parimal K

2014-11-01

New copper(II) complex with Schiff base ligand 4-[(2-Hydroxy-3-methoxy-benzylidene)-amino]-benzoic acid (H₂L) was synthesized and characterized by spectroscopic and analytical and single crystal X-ray diffraction studies which revealed that the complex 1 exist in a distorted octahedral environment. In vitro CT-DNA binding studies were performed by employing different biophysical technique which indicated that the 1 strongly binds to DNA in comparison to ligand via electrostatic binding mode. Complex 1 cleaves pBR322 DNA via hydrolytic pathway and recognizes minor groove of DNA double helix. The HSA binding results showed that ligand and complex 1 has ability to quench the fluorescence emission intensity of Trp 214 residue available in the subdomain IIA of HSA. Copyright © 2014 Elsevier B.V. All rights reserved.

Selective flotation-spectrophotometric determination of trace copper(II) in natural waters, human blood and drug samples using phenanthraquinone monophenylthiosemicarbazone.

PubMed

Khalifa, M E; Akl, M A; Ghazy, S E

2001-06-01

Copper(II) forms 1:1 and 1:2 intense red complexes with phenanthraquinone monophenylthiosemicarbazone (PPT) at pH 3-3.5 and > or =6.5, respectively. These complexes exhibit maximal absorbance at 545 and 517 nm, the molar absorptivity being 2.3 x 10(4) and 4.8 x 10(4) l mol(-1) cm(-1), respectively. However, the 1:1 complex was quantitatively floated with oleic acid (HOL) surfactant in the pH range 4.5-5.5, providing a highly selective and sensitive procedure for the spectrophotometric determination of CuII. The molar absorptivity of the floated Cu-PPT complex was 1.5 x 10(5) l mol)(-1) cm(-1). Beer's law was obeyed over the range 3-400 ppb at 545 nm. The analytical parameters affecting the flotation process and hence the determination of copper traces were reported. Also, the structure of the isolated solid complex and the mechanism of flotation were suggested. Moreover, the procedure was successfully applied to the analysis of CuII in natural waters, serum blood and some drug samples.

Mesoporous silica nanoparticles supported copper(II) and nickel(II) Schiff base complexes: Synthesis, characterization, antibacterial activity and enzyme immobilization

NASA Astrophysics Data System (ADS)

Tahmasbi, Leila; Sedaghat, Tahereh; Motamedi, Hossein; Kooti, Mohammad

2018-02-01

Mesoporous silica nanoparticles (MSNs) were prepared by sol-gel method and functionalized with 3-aminopropyltriethoxysilane. Schiff base grafted mesoporous silica nanoparticle was synthesized by the condensation of 2-hydroxy-3-methoxybenzaldehyde and amine-functionalized MSNs. The latter material was then treated with Cu(II) and Ni(II) salts separately to obtain copper and nickel complexes anchored mesoporous composites. The newly prepared hybrid organic-inorganic nanocomposites have been characterized by several techniques such as FT-IR, LA-XRD, FE-SEM, TEM, EDS, BET and TGA. The results showed all samples have MCM-41 type ordered mesoporous structure and functionalization occurs mainly inside the mesopore channel. The presence of all elements in synthesized nanocomposites and the coordination of Schiff base via imine nitrogen and phenolate oxygen were confirmed. MSNs and all functionalized MSNs have uniform spherical nanoparticles with a mean diameter less than 100 nm. The as-synthesized mesoporous nanocomposites were investigated for antibacterial activity against Gram-positive (B. subtilis and S. aureus) and Gram-negative (E. coli and P. aeruginosa) bacteria, as carrier for gentamicin and also for immobilization of DNase, coagulase and amylase enzymes. MSN-SB-Ni indicated bacteriocidal effect against S.aureus and all compounds were found to be good carrier for gentamicin. Results of enzyme immobilization for DNase and coagulase and α-amylase revealed that supported metal complexes efficiently immobilized enzymes.

Metal stabilization of collagen and de novo designed mimetic peptides

PubMed Central

Parmar, Avanish S.; Xu, Fei; Pike, Douglas H.; Belure, Sandeep V.; Hasan, Nida F.; Drzewiecki, Kathryn E.; Shreiber, David I.; Nanda, Vikas

2017-01-01

We explore the design of metal binding sites to modulate triple-helix stability of collagen and collagen-mimetic peptides. Globular proteins commonly utilize metals to connect tertiary structural elements that are well separated in sequence, constraining structure and enhancing stability. It is more challenging to engineer structural metals into fibrous protein scaffolds, which lack the extensive tertiary contacts seen in globular proteins. In the collagen triple helix, the structural adjacency of the carboxy-termini of the three chains makes this region an attractive target for introducing metal binding sites. We engineered His3 sites based on structural modeling constraints into a series of designed homotrimeric and heterotrimeric peptides, assessing the capacity of metal binding to improve stability and in the case of heterotrimers, affect specificity of assembly. Notable enhancements in stability for both homo and heteromeric systems were observed upon addition of zinc(II) and several other metal ions only when all three histidine ligands were present. Metal binding affinities were consistent with the expected Irving-Williams series for imidazole. Unlike other metals tested, copper(II) also bound to peptides lacking histidine ligands. Acetylation of the peptide N-termini prevented copper binding, indicating proline backbone amide metal-coordination at this site. Copper similarly stabilized animal extracted Type I collagen in a metal specific fashion, highlighting the potential importance of metal homeostasis within the extracellular matrix. PMID:26225466

The Application of Curve Fitting on the Voltammograms of Various Isoforms of Metallothioneins–Metal Complexes

PubMed Central

Merlos Rodrigo, Miguel Angel; Molina-López, Jorge; Jimenez Jimenez, Ana Maria; Planells Del Pozo, Elena; Adam, Pavlina; Eckschlager, Tomas; Zitka, Ondrej; Richtera, Lukas; Adam, Vojtech

2017-01-01

The translation of metallothioneins (MTs) is one of the defense strategies by which organisms protect themselves from metal-induced toxicity. MTs belong to a family of proteins comprising MT-1, MT-2, MT-3, and MT-4 classes, with multiple isoforms within each class. The main aim of this study was to determine the behavior of MT in dependence on various externally modelled environments, using electrochemistry. In our study, the mass distribution of MTs was characterized using MALDI-TOF. After that, adsorptive transfer stripping technique with differential pulse voltammetry was selected for optimization of electrochemical detection of MTs with regard to accumulation time and pH effects. Our results show that utilization of 0.5 M NaCl, pH 6.4, as the supporting electrolyte provides a highly complicated fingerprint, showing a number of non-resolved voltammograms. Hence, we further resolved the voltammograms exhibiting the broad and overlapping signals using curve fitting. The separated signals were assigned to the electrochemical responses of several MT complexes with zinc(II), cadmium(II), and copper(II), respectively. Our results show that electrochemistry could serve as a great tool for metalloproteomic applications to determine the ratio of metal ion bonds within the target protein structure, however, it provides highly complicated signals, which require further resolution using a proper statistical method, such as curve fitting. PMID:28287470

Metal Stabilization of Collagen and de Novo Designed Mimetic Peptides.

PubMed

Parmar, Avanish S; Xu, Fei; Pike, Douglas H; Belure, Sandeep V; Hasan, Nida F; Drzewiecki, Kathryn E; Shreiber, David I; Nanda, Vikas

2015-08-18

We explore the design of metal binding sites to modulate triple-helix stability of collagen and collagen-mimetic peptides. Globular proteins commonly utilize metals to connect tertiary structural elements that are well separated in sequence, constraining structure and enhancing stability. It is more challenging to engineer structural metals into fibrous protein scaffolds, which lack the extensive tertiary contacts seen in globular proteins. In the collagen triple helix, the structural adjacency of the carboxy-termini of the three chains makes this region an attractive target for introducing metal binding sites. We engineered His3 sites based on structural modeling constraints into a series of designed homotrimeric and heterotrimeric peptides, assessing the capacity of metal binding to improve stability and in the case of heterotrimers, affect specificity of assembly. Notable enhancements in stability for both homo- and heteromeric systems were observed upon addition of zinc(II) and several other metal ions only when all three histidine ligands were present. Metal binding affinities were consistent with the expected Irving-Williams series for imidazole. Unlike other metals tested, copper(II) also bound to peptides lacking histidine ligands. Acetylation of the peptide N-termini prevented copper binding, indicating proline backbone amide metal-coordination at this site. Copper similarly stabilized animal extracted Type I collagen in a metal-specific fashion, highlighting the potential importance of metal homeostasis within the extracellular matrix.

The DFT Calculations of Structures and EPR Parameters for the Dinuclear Paddle-Wheel Copper(II) Complex {Cu2(μ2-O2CCH3)4}(OCNH2CH3) as Powder or Single Crystal

NASA Astrophysics Data System (ADS)

Ding, Chang-Chun; Wu, Shao-Yi; Xu, Yong-Qiang; Zhang, Li-Juan; Zhang, Zhi-Hong; Zhu, Qin-Sheng; Wu, Ming-He; Teng, Bao-Hua

2017-10-01

Density functional theory (DFT) calculations of the structures and the Cu2+ g factors (gx, gy and gz ) and hyperfine coupling tensor A (Ax , Ay and Az ) were performed for the paddle-wheel (PW)-type binuclear copper(II) complex {Cu2(μ2-O2CCH3)4}(OCNH2CH3) powder and single crystal. Calculations were carried out with the ORCA software using the functionals BHandHlyp, B3P86 and B3LYP with five different basis sets: 6-311g, 6-311g(d,p), VTZ, def-2 and def2-TZVP. Results were tested by the MPAD analysis to find the most suitable functional and basis sets. The electronic structure and covalency between copper and oxygen were investigated by the electron localisation function and the localised orbital locator as well as the Mayer bond order for the [CuO5] group. The optical spectra were theoretically calculated by the time-dependent DFT module and plotted by the Multiwfn program for the [CuO5] group and reasonably associated with the local structure in the vicinity of the central ion copper. In addition, the interactions between the OCNH2CH3, NH3 and H2O molecules and the uncoordinated PW copper(II) complex were studied, and the corresponding adsorption energies, the frequency shifts with respect to the free molecules and the changes of the Cu-Cu distances were calculated and compared with the relevant systems.

Synthesis, characterization, DNA-binding and cleavage studies of polypyridyl copper(II) complexes

NASA Astrophysics Data System (ADS)

Gubendran, Ammavasi; Rajesh, Jegathalaprathaban; Anitha, Kandasamy; Athappan, Periyakaruppan

2014-10-01

Six new mixed-ligand copper(II) complexes were synthesized namely [Cu(phen)2OAc]ClO4ṡH2O(1), [Cu(bpy)2OAc]ClO4ṡH2O(2), [Cu(o-ampacac)(phen)]ClO4(3), [Cu(o-ampbzac)(phen)]ClO4(4), [Cu(o-ampacac)(bpy)]ClO4(5), and [Cu(o-ampbzac)(bpy)]ClO4(6) (phen = 1,10-phenanthroline, bpy = 2, 2‧-bipyridine, o-ampacac = (Z)-4-(2-hydroxylamino)pent-3-ene-2-one,o-ampbzac = (Z)-4-(2-hydroxylamino)-4-phenylbut-3-ene-2-one)and characterized by UV-Vis, IR, EPR and cyclic voltammetry. Ligands were characterized by NMR spectra. Single crystal X-ray studies of the complex 1 shows Cu(II) ions are located in a highly distorted octahedral environment. Absorption spectral studies reveal that the complexes 1-6 exhibit hypochromicity during the interaction with DNA and binding constant values derived from spectral and electrochemical studies indicate that complexes 1, 2 and 3 bind strongly with DNA possibly by an intercalative mode. Electrochemical studies reveal that the complexes 1-4 prefer to bind with DNA in Cu(I) rather than Cu(II) form. The shift in the formal potentials E1/2 and CD spectral studies suggest groove or electrostatic binding mode for the complexes 4-6. Complex 1 can cleave supercoiled (SC) pUC18 DNA efficiently into nicked form II under photolytic conditions and into an open circular form (form II) and linear form (form III) in the presence of H2O2 at pH 8.0 and 37 °C, while the complex 2 does not cleave DNA under similar conditions.

Synthesis, structure and photoluminescence of (PLAGH){sub 2}[ZnCl{sub 4}] and comparative analysis of photoluminescence properties with tris(2,2′-bipyridine)ruthenium(II)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radanović, Mirjana M.; Jelić, Miodrag G., E-mail: jelicmgm@uns.ac.rs; Romčević, Nebojša Ž.

Highlights: • New zinc(II) complex with pyridoxalaminoguanidine was synthesized. • The enhancement of the photoluminescence due to the compound formation was achieved. • Very high photoluminescence of Zn(II) compound was noticed. • Comparative analysis of photoluminescence with tris(2,2′-bipyridine) ruthenium(II) was provided. - Abstract: The first compound of zinc(II) containing pyridoxalaminoguanidine has been synthesized and characterized by elemental analysis, infrared spectra, conductometric measurements and X-ray crystallography. Single crystals of the compound were obtained in the reaction of methanolic solution of zinc(II) chloride and pyridoxalaminoguanidine hydrochloride. In this compound the coordination of chelate ligand is absent and tetrachlorido complex of zinc(II) withmore » pyridoxalaminuguanidinium cation as contraion is obtained. Photoluminescence spectra were measured. Lorentzian multipeak technique was used to determine peak wavelengths and their intensities. Photoluminescence spectroscopy upon 325, 488 and 514 nm laser excitation light was used to obtain results. This novel compound of zinc(II) was compared to the well-known organic light emitting diode material—ruthenium(II) complex with bypiridine i.e., tris(2,2′-bipyridine)ruthenium(II), under the same circumstances and the identical experimental setup. A scheme of energy levels and transitions is proposed to explain the obtained experimental results.« less

Uniqueness of Zinc as a Bioelement: Principles and Applications in Bioinorganic Chemistry--III.

ERIC Educational Resources Information Center

Ochiai, Ei-Ichiro

1988-01-01

Attempts to delineate certain basic principles and applications of bioinorganic chemistry to oxidation-reduction reactions. Examines why zinc(II) is so uniquely suited to enzymated reactions of the acid-base type. Suggests the answer may be in the natural abundance and the basic physicochemical properties of zinc(II). (MVL)

Clinical Variants of New Delhi Metallo-β-Lactamase Are Evolving To Overcome Zinc Scarcity.

PubMed

Stewart, Alesha C; Bethel, Christopher R; VanPelt, Jamie; Bergstrom, Alex; Cheng, Zishuo; Miller, Callie G; Williams, Cameron; Poth, Robert; Morris, Matthew; Lahey, Olivia; Nix, Jay C; Tierney, David L; Page, Richard C; Crowder, Michael W; Bonomo, Robert A; Fast, Walter

2017-12-08

Use and misuse of antibiotics have driven the evolution of serine β-lactamases to better recognize new generations of β-lactam drugs, but the selective pressures driving evolution of metallo-β-lactamases are less clear. Here, we present evidence that New Delhi metallo-β-lactamase (NDM) is evolving to overcome the selective pressure of zinc(II) scarcity. Studies of NDM-1, NDM-4 (M154L), and NDM-12 (M154L, G222D) demonstrate that the point mutant M154L, contained in 50% of clinical NDM variants, selectively enhances resistance to the penam ampicillin at low zinc(II) concentrations relevant to infection sites. Each of the clinical variants is shown to be progressively more thermostable and to bind zinc(II) more tightly than NDM-1, but a selective enhancement of penam turnover at low zinc(II) concentrations indicates that most of the improvement derives from catalysis rather than stability. X-ray crystallography of NDM-4 and NDM-12, as well as bioinorganic spectroscopy of dizinc(II), zinc(II)/cobalt(II), and dicobalt(II) metalloforms probe the mechanism of enhanced resistance and reveal perturbations of the dinuclear metal cluster that underlie improved catalysis. These studies support the proposal that zinc(II) scarcity, rather than changes in antibiotic structure, is driving the evolution of new NDM variants in clinical settings.

Antimicrobial and mutagenic activity of some carbono- and thiocarbonohydrazone ligands and their copper(II), iron(II) and zinc(II) complexes.

PubMed

Bacchi, A; Carcelli, M; Pelagatti, P; Pelizzi, C; Pelizzi, G; Zani, F

1999-06-15

Several mono- and bis- carbono- and thiocarbonohydrazone ligands have been synthesised and characterised; the X-ray diffraction analysis of bis(phenyl 2-pyridyl ketone) thiocarbonohydrazone is reported. The coordinating properties of the ligands have been studied towards Cu(II), Fe(II), and Zn(II) salts. The ligands and the metal complexes were tested in vitro against Gram positive and Gram negative bacteria, yeasts and moulds. In general, the bisthiocarbonohydrazones possess the best antimicrobial properties and Gram positive bacteria are the most sensitive microorganisms. Bis(ethyl 2-pyridyl ketone) thiocarbonohydrazone, bis(butyl 2-pyridyl ketone)thiocarbonohydrazone and Cu(H2nft)Cl2 (H2nft, bis(5-nitrofuraldehyde)thiocarbonohydrazone) reveal a strong activity with minimum inhibitory concentrations of 0.7 microgram ml-1 against Bacillus subtilis and of 3 micrograms ml-1 against Staphylococcus aureus. Cu(II) complexes are more effective than Fe(II) and Zn(II) ones. All bisthiocarbono- and carbonohydrazones are devoid of mutagenic properties, with the exception of the compounds derived from 5-nitrofuraldehyde. On the contrary a weak mutagenicity, that disappears in the copper complexes, is exhibited by monosubstituted thiocarbonohydrazones.

Templated synthesis of copper(II) azacyclam complexes using urea as a locking fragment and their metal-enhanced binding tendencies towards anions.

PubMed

Boiocchi, Massimo; Fabbrizzi, Luigi; Garolfi, Mauro; Licchelli, Maurizio; Mosca, Lorenzo; Zanini, Cristina

2009-10-26

Copper(II) azacyclam complexes 3(2+) and 4(2+) were obtained through a metal-templated procedure involving the pertinent open-chain tetramine, formaldehyde and a phenylurea derivative as a locking fragment. Both metal complexes can establish interactions with anions through the metal centre and the amide NH group. Equilibrium studies in DMSO by a spectrophotometric titration technique were carried out to assess the affinity of 3(2+) and 4(2+) towards anions. While the NH group of an amide model compound and the metal centre of the plain Cu(II)(azacyclam)(2+) complex do not interact at all with anions, 3(2+) and 4(2+) establish strong interactions with oxo anions, profiting from a pronounced cooperative effect. In particular, 1) they form stable 1:1 and 1:2 complexes with H(2)PO(4) (-) ions in a stepwise mode with both hydrogen-bonding and metal-ligand interactions, and 2) in the presence of CH(3)COO(-), they undergo deprotonation of the amido NH group and thus profit from axial coordination of the partially negatively charged carbonyl oxygen atom in a scorpionate binding mode.

Perchlorate mixed-ligand copper(II) complexes of beta-diketone and ethylene diamine derivatives: thermal, spectroscopic and biochemical studies.

PubMed

El-Ayaan, Usama; El-Metwally, Nashwa M; Youssef, Magdy M; El Bialy, Serry A A

2007-12-31

The present work carried out a study on perchlorate mixed-ligand copper(II) complexes which have been synthesized from ethylenediamine derivatives (3a-c) and beta-diketones. These complexes, namely [Cu(DA-Cl)(acac)H(2)O]ClO(4)4, [Cu(DA-Cl)(bzac)H(2)O]H(2)O.ClO(4)5, [Cu(DA-OMe)(acac)H(2)O]ClO(4)6, [Cu(DA-OMe)(bzac)H(2)O]ClO(4)7, [Cu(DA-H)(acac)H(2)O]2H(2)O.ClO(4)8 and [Cu(DA-H)(bzac)H(2)O]ClO(4)9 (where acac, acetylacetonate and bzac, benzoylacetonate) were characterized by elemental analysis, spectral (IR and UV-vis) and magnetic moment measurements. Thermal properties and decomposition kinetics of all complexes are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters (E, A, DeltaH, DeltaS and DeltaG) of all thermal decomposition stages have been evaluated using Coats-Redfern equation. The biochemical studies showed that, the diamines 3a-c have powerful effects on degradation of DNA and protein. The antibacterial screening demonstrated that, the diamine (DA-Cl), 3b has the maximum and broad activities against Gram +ve and Gram -ve bacterial strains.

Binary adsorption of copper(II) and cadmium(II) from aqueous solutions by biomass of marine alga Durvillaea potatorum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Q.; Kaewsarn, P.

1999-06-01

Much work on the biosorption of heavy metals by low-cost, natural biomass has been on the uptake of single metals. In practice, wastewaters often contain multiple heavy metal ions. In this paper the binary adsorption of copper(II) and cadmium(II) by a pretreated biomass of the marine alga Durvillaea potatorum from aqueous solutions was studied. The results showed that the uptake capacities for each heavy metal of the binary system were lower when compared with the single metal biosorption for copper and cadmium, respectively, but the total capacities for the binary system were similar to those obtained for single metal biosorption.more » The uptake capacities for copper and cadmium increased as the equilibrium pH increased and reached a plateau at a pH around 5.0. The uptake process was relatively fast, with 90% of the adsorption completed within 10 minutes for copper and 30 minutes for cadmium, and equilibrium reached after about 60 minutes of stirring. The biosorption isotherms of binary systems were not significantly affected by equilibrium temperature. The presence of light metal ions in solution also did not affect adsorption significantly. The binary adsorption was successfully predicted by the extended Langmuir model, using parameters and capacities obtained from single component systems.« less

Redox chemistry of nickel(II) complexes supported by a series of noninnocent β-diketiminate ligands.

PubMed

Takaichi, June; Morimoto, Yuma; Ohkubo, Kei; Shimokawa, Chizu; Hojo, Takayuki; Mori, Seiji; Asahara, Haruyasu; Sugimoto, Hideki; Fujieda, Nobutaka; Nishiwaki, Nagatoshi; Fukuzumi, Shunichi; Itoh, Shinobu

2014-06-16

Nickel complexes of a series of β-diketiminate ligands ((R)L(-), deprotonated form of 2-substituted N-[3-(phenylamino)allylidene]aniline derivatives (R)LH, R = Me, H, Br, CN, and NO2) have been synthesized and structurally characterized. One-electron oxidation of the neutral complexes [Ni(II)((R)L(-))2] by AgSbF6 or [Ru(III)(bpy)3](PF6)3 (bpy = 2,2'-bipyridine) gave the corresponding metastable cationic complexes, which exhibit an EPR spectrum due to a doublet species (S = 1/2) and a characteristic absorption band in near IR region ascribable to a ligand-to-ligand intervalence charge-transfer (LLIVCT) transition. DFT calculations have indicated that the divalent oxidation state of nickel ion (Ni(II)) is retained, whereas one of the β-diketiminate ligands is oxidized to give formally a mixed-valence complex, [Ni(II)((R)L(-))((R)L(•))](+). Thus, the doublet spin state of the oxidized cationic complex can be explained by taking account of the antiferromagnetic interaction between the high-spin nickel(II) ion (S = 1) and the organic radical (S = 1/2) of supporting ligand. A single-crystal structure of one of the cationic complexes (R = H) has been successfully determined to show that both ligands in the cationic complex are structurally equivalent. On the basis of theoretical analysis of the LLIVCT band and DFT calculations as well as the crystal structure, the mixed-valence complexes have been assigned to Robin-Day class III species, where the radical spin is equally delocalized between the two ligands to give the cationic complex, which is best described as [Ni(II)((R)L(0.5•-))2](+). One-electron reduction of the neutral complexes with decamethylcobaltocene gave the anionic complexes when the ligand has the electron-withdrawing substituent (R = CN, NO2, Br). The generated anionic complexes exhibited EPR spectra due to a doublet species (S = 1/2) but showed no LLIVCT band in the near-IR region. Thus, the reduced complexes are best described as the d(9) nickel

Luminescent zinc(ii) and copper(i) complexes for high-performance solution-processed monochromic and white organic light-emitting devices† †Electronic supplementary information (ESI) available: Experimental procedures, device performances, and computational details. CCDC 1054456, 1400003 and 1400004. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03161j Click here for additional data file. Click here for additional data file.

PubMed Central

Cheng, Gang; So, Gary Kwok-Ming; To, Wai-Pong; Chen, Yong; Kwok, Chi-Chung; Ma, Chensheng; Guan, Xiangguo; Chang, Xiaoyong; Kwok, Wai-Ming

2015-01-01

The synthesis and spectroscopic properties of luminescent tetranuclear zinc(ii) complexes of substituted 7-azaindoles and a series of luminescent copper(i) complexes containing 7,8-bis(diphenylphosphino)-7,8-dicarba-nido-undecaborate ligand are described. These complexes are stable towards air and moisture. Thin film samples of the luminescent copper(i) complexes in 2,6-dicarbazolo-1,5-pyridine and zinc(ii) complexes in poly(methyl methacrylate) showed emission quantum yields of up to 0.60 (for Cu-3) and 0.96 (for Zn-1), respectively. Their photophysical properties were examined by ultrafast time-resolved emission spectroscopy, temperature dependent emission lifetime measurements and density functional theory calculations. Monochromic blue and orange solution-processed OLEDs with these Zn(ii) and Cu(i) complexes as light-emitting dopants have been fabricated, respectively. Maximum external quantum efficiency (EQE) of 5.55% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.16, 0.19) were accomplished with the optimized Zn-1-OLED while these values were, respectively 15.64% and (0.48, 0.51) for the optimized Cu-3-OLED. Solution-processed white OLEDs having maximum EQE of 6.88%, CIE coordinates of (0.42, 0.44), and colour rendering index of 81 were fabricated by using these luminescent Zn(ii) and Cu(i) complexes as blue and orange light-emitting dopant materials, respectively. PMID:29142704

Nickel(II) Complex of Polyhydroxybenzaldehyde N4-Thiosemicarbazone Exhibits Anti-Inflammatory Activity by Inhibiting NF-κB Transactivation

PubMed Central

Loh, Sheng Wei; Looi, Chung Yeng; Hassandarvish, Pouya; Phan, Alicia Yi Ling; Wong, Won Fen; Wang, Hao; Paterson, Ian C.; Ea, Chee Kwee; Mustafa, Mohd Rais; Maah, Mohd Jamil

2014-01-01

Background The biological properties of thiosemicarbazone have been widely reported. The incorporation of some transition metals such as Fe, Ni and Cu to thiosemicarbazone complexes is known to enhance its biological effects. In this study, we incorporated nickel(II) ions into thiosemicarbazone with N4-substitution groups H3L (H; H3L1, CH3; H3L2, C6H5; H3L3 and C2H5; H3L4) and examined its potential anti-inflammatory activity. Methodology/Principal Findings Four ligands (1–4) and their respective nickel-containing complexes (5–8) were synthesized and characterized. The compounds synthesized were tested for their effects on NF-κB nuclear translocation, pro-inflammatory cytokines secretion and NF-κB transactivation activity. The active compound was further evaluated on its ability to suppress carrageenan-induced acute inflammation in vivo. A potential binding target of the active compound was also predicted by molecular docking analysis. Conclusions/Significance Among all synthesized compounds tested, we found that complex [Ni(H2L1)(PPh3)]Cl (5) (complex 5), potently inhibited IκBα degradation and NF-κB p65 nuclear translocation in LPS-stimulated RAW264.7 cells as well as TNFα-stimulated HeLa S3 cells. In addition, complex 5 significantly down-regulated LPS- or TNFα-induced transcription of NF-κB target genes, including genes that encode the pro-inflammatory cytokines TNFα, IFNβ and IL6. Luciferase reporter assays confirmed that complex 5 inhibited the transactivation activity of NF-κB. Furthermore, the anti-inflammatory effect of complex 5 was also supported by its suppressive effect on carrageenan-induced paw edema formation in wild type C57BL/6 mice. Interestingly, molecular docking study showed that complex 5 potentially interact with the active site of IKKβ. Taken together, we suggest complex 5 as a novel NF-κB inhibitor with potent anti-inflammatory effects. PMID:24977407

Ammonia, phosphate, phenol, and copper(II) removal from aqueous solution by subsurface and surface flow constructed wetland.

PubMed

Mojiri, Amin; Ahmad, Zakiah; Tajuddin, Ramlah Mohd; Arshad, Mohd Fadzil; Gholami, Ali

2017-07-01

Water pollution is a global problem. During current study, ammonia, phosphate, phenol, and copper(II) were removed from aqueous solution by subsurface and surface flow constructed wetland. In current investigation, distilled water was polluted with four contaminants including ammonia, phosphate, copper (Cu), and phenol. Response surface methodology and central composite design were applied to optimize pollutant removal during treatment by subsurface flow constructed wetland (SSFCW). Contact time (12 to 80 h) and initial pollutant concentration (20 to 85 mg/L) were selected as independent factors; some upper and lower ranges were also monitored for accuracy. In SSFCW, water hyacinth transplanted in two substrate layers, namely zeolite and cockle shell. SSFCW removed 87.7, 81.4, 74.7, and 54.9% of ammonia, phosphate, Cu, and phenol, respectively, at optimum contact time (64.5 h) and initial pollutant concentration (69.2 mg/L). Aqueous solution was moved to a surface flow constructed wetland (SFCW) after treating via SSFCW at optimum conditions. In SFCW, Typha was transplanted to a fixed powdered substrate layer, including bentonite, zeolite, and cockle shell. SFCW could develop performance of this combined system and could improve elimination efficacy of the four contaminants to 99.99%. So this combined CW showed a good performance in removing pollutants. Graphical abstract Wetlands arrangement for treating aqueous solution in current study.

Powder X-ray diffraction, infrared and 13C NMR spectroscopic studies of the homologous series of some solid-state zinc(II) and sodium(I) n-alkanoates

NASA Astrophysics Data System (ADS)

Nelson, Peter N.; Taylor, Richard A.

2015-03-01

A comparative study of the room temperature molecular packing and lattice structures for the homologous series of zinc(II) and sodium(I) n-alkanoates adduced from Fourier transform infrared and solid-state 13C NMR spectroscopic data in conjunction with X-ray powder diffraction measurements is carried out. For zinc carboxylates, metal-carboxyl bonding is via asymmetric bridging bidentate coordination whilst for the sodium adducts, coordination is via asymmetric chelating bidentate bonding. All compounds are packed in a monoclinic crystal system. Furthermore, the fully extended all-trans hydrocarbon chains are arranged as lamellar bilayers. For zinc compounds, there is bilayer overlap, for long chain adducts (nc > 8) but not for sodium compounds where methyl groups from opposing layers in the lamellar are only closely packed. Additionally, the hydrocarbon chains are extended along the a-axis of the unit cell for zinc compounds whilst for sodium carboxylates they are extended along the c-axis. These packing differences are responsible for different levels of Van der Waals effects in the lattices of these two series of compounds, hence, observed odd-even alternation is different. The significant difference in lattice packing observed for these two series of compounds is proposed to be due to the difference in metal-carboxyl coordination mode, arising from the different electronic structure of the central metal ions.

Investigation and Control of "Sphere-Like" Buckminsterfullerene C60 and "Disk-Like" Copper(II) Phthalocyanine

NASA Astrophysics Data System (ADS)

McAfee, Terry Richard

Due to the growing global need for cheap, flexible, and portable electronics, numerous research groups from mechanical and electrical engineering, material science, chemistry, and physics have increasingly turned to organic electronics research over the last ˜5--10 years. Largely, the focus of researchers in this growing field have sought to obtain the next record holding device, allowing a heuristic approach of trial and error to become dominant focus of research rather than a fundamental understanding. Rather than working with the latest high performance organic semiconducting materials and film processing techniques, I have chosen to investigate and control the fundamental self-assembly interactions of organic photovoltaic thin films using simplified systems. Specifically, I focus on organic photovoltaic research using two of the oldest and well studies semiconducting materials, namely "sphere-like" electron donor material Buckminsterfullerene C60 and "disklike" electron acceptor material Copper(II) Phthalocyanine. I manufactured samples using the well-known technique of physical vapor deposition using a high vacuum chamber that I designed and built to accommodate my need of precise material deposition control, with codeposition capability. Films were characterized using microscopy and spectroscopy techniques locally at NCSU, including Atomic Force Microscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy, and Ultraviolet-visible spectroscopy, as well as at National Laboratory based synchrotron x-ray techniques, including Carbon and Nitrogen k-edge Total Electron Yield and Transmission Near Edge X-ray absorption fine structure spectroscopy, Carbon k-edge Resonant Soft x-ray Microscopy, Resonant Soft x-ray reflectivity, and Grazing Incidence Wide-Angle X-ray scattering.

Synthesis, electronic and ESR spectral studies on copper(II) nitrate complexes with some acylhydrazines and hydrazones.

PubMed

Singh, Vinod P

2008-11-01

This paper describes the preparation of [Cu(bh)2(H2O)2](NO3)2], [Cu(ibh)2(NO3)2], [Cu(ibh)2(H2O)2](NO3)2 and [Cu(iinh)2(NO3)2] (bh = benzoyl hydrazine (C6H5CONHNH2); ibh = isonicotinoyl hydrazine (NC5H4CONHNH2); ibh = isopropanone benzoyl hydrazone (C6H5CONHN=C(CH3)2; iinh = isopropanone isonicotinoyl hydrazone (NC5H4CONHN=C(CH3)2). These copper(II) complexes are characterized by elemental analyses, molar conductances, dehydration studies, ESR, IR and electronic spectral studies. The electronic and ESR spectra indicate that each complex exhibits a six-coordinate tetragonally distorted octahedral geometry in the solid state and in DMSO solution. The ESR spectra of most of the complexes are typically isotropic type at room temperature (300 K) in solid state as well as in DMSO solution. However, all the complexes exhibit invariably axial signals at 77 K in DMSO solution. The trend g(||) > g(perpendicular) > g(e,) observed in all the complexes suggests the presence of an unpaired electron in the d x2-y2 orbital of the Cu(II). The bh and inh ligands bond to Cu(II) through the >C=O and -NH2 groups whereas, ibh and iinh bond through >C=O and >C=N- groups. The IR spectra of bh and ibh complexes also show H-O-H stretching and bending modes of coordinated water.

Synthesis, structure, and DNA cleavage properties of copper(II) complexes of 1,4,7-triazacyclononane ligands featuring pairs of guanidine pendants.

PubMed

Tjioe, Linda; Joshi, Tanmaya; Brugger, Joël; Graham, Bim; Spiccia, Leone

2011-01-17

Two new ligands, L(1) and L(2), have been prepared via N-functionalization of 1,4,7-triazacyclononane (tacn) with pairs of ethyl- or propyl-guanidine pendants, respectively. The X-ray crystal structure of [CuL(1)](ClO4)2 (C1) isolated from basic solution (pH 9) indicates that a secondary amine nitrogen from each guanidine pendants coordinates to the copper(II) center in addition to the nitrogen atoms in the tacn macrocycle, resulting in a five-coordinate complex with intermediate square-pyramidal/trigonal bipyramidal geometry. The guanidines adopt an unusual coordination mode in that their amine nitrogen nearest to the tacn macrocycle binds to the copper(II) center, forming very stable five-membered chelate rings. A spectrophotometric pH titration established the pK(app) for the deprotonation and coordination of each guanidine group to be 3.98 and 5.72, and revealed that [CuL(1)](2+) is the only detectable species present in solution above pH ∼ 8. The solution speciation of the CuL(2) complex (C2) is more complex, with at least 5 deprotonation steps over the pH range 4-12.5, and mononuclear and binuclear complexes coexisting. Analysis of the spectrophotometric data provided apparent deprotonation constants, and suggests that solutions at pH ∼ 7.5 contain the maximum proportion of polynuclear complexes. Complex C1 exhibits virtually no cleavage activity toward the model phosphate diesters, bis(p-nitrophenyl)phosphate (BNPP) and 2-hydroxypropyl-p-nitrophenyl phosphate (HPNPP), while C2 exhibits moderate activity. For C2, the respective kobs values measured at pH 7.0 (7.24 (± 0.08) × 10(-5) s(-1) (BNPP at 50 °C) and 3.2 (± 0.3) × 10(-5) s(-1) (HPNPP at 25 °C)) are 40- and 10-times faster than [Cu(tacn)(OH2)2](2+) complex. Both complexes cleave supercoiled pBR 322 plasmid DNA, indicating that the guanidine pendants of [CuL(1)](2+) may have been displaced from the copper coordination sphere to allow for DNA binding and subsequent cleavage. The rate of DNA

Synthesis, characterization, and antipathogenic studies of some transition metal complexes with N,O-chelating Schiff's base ligand incorporating azo and sulfonamide Moieties

NASA Astrophysics Data System (ADS)

Alaghaz, Abdel-Nasser M. A.; Bayoumi, Hoda A.; Ammar, Yousry A.; Aldhlmani, Sharah A.

2013-03-01

Chromium(III), Manganese(II), Cobalt(II), nickel(II), copper(II) and cadmium(II) complexes of 4-[4-hydroxy-3-(phenyliminomethyl)-phenylazo]benzenesulfonamide, were prepared and characterized on the basis of elemental analyses, spectral, magnetic, molar conductance and thermal analysis. Square planar, tetrahedral and octahedral geometries have been assigned to the prepared complexes. Dimeric complexes are obtained with 2:2 molar ratio except chromium(III) complex is monomeric which is obtained with 1:1 molar ratios. The IR spectra of the prepared complexes were suggested that the Schiff base ligand(HL) behaves as a bi-dentate ligand through the azomethine nitrogen atom and phenolic oxygen atom. The crystal field splitting, Racah repulsion and nepheloauxetic parameters and determined from the electronic spectra of the complexes. Thermal studies suggest a mechanism for degradation of HL and its metal complexes as function of temperature supporting the chelation modes. Also, the activation thermodynamic parameters, such as ΔE*, ΔH*, ΔS* and ΔG* for the different thermal decomposition steps of HL and its metal complexes were calculated. The pathogenic activities of the synthesized compounds were tested in vitro against the sensitive organisms Staphylococcus aureus (RCMB010027), Staphylococcus epidermidis (RCMB010024) as Gram positive bacteria, Klebsiella pneumonia (RCMB 010093), Shigella flexneri (RCMB 0100542), as Gram negative bacteria and Aspergillus fumigates (RCMB 02564), Aspergillus clavatus (RCMB 02593) and Candida albicans (RCMB05035) as fungus strain, and the results are discussed.

Development of Novel DNA Cleavage Systems Based on Copper Complexes. Synthesis and Characterisation of Cu(II) Complexes of Hydroxyflavones

PubMed Central

el Amrani, F. Ben-Allal; Perelló, L.; Torres, L.

2000-01-01

Copper(II) complexes of several hydroxyflavones were prepared and characterised through their physico-chemical properties. The nuclease activity of three synthesised complexes is reported. These copper(II) complexes present more nuclease activity than the ligands and the copper(II) ion. PMID:18475969

Phase-dependent ultrafast third-order optical nonlinearities in metallophthalocyanine thin films

NASA Astrophysics Data System (ADS)

Kumar, Samir; Anil Kumar, K. V.; Dharmaprakash, S. M.; Das, Ritwick

2016-09-01

We present a comprehensive study on the impact of phase transformations of metallophthalocyanine thin films on their third-order nonlinear optical (NLO) properties. The metallophthalocyanine thin films are prepared by thermally evaporating the commercially available Copper(II)2,9,16,23-Tetra-tert-butyl-29H,31H-phthalocyanine (CuPc) and Zinc(II) 2,9,16,23-Tetra-tert-butyl-29H,31H-phthalocyanine (ZnPc) powder on glass substrate. Thermal annealing causes a phase transformation which has a distinct signature in powder X-ray diffraction and UV-Vis-NIR spectroscopy. The NLO characteristics which include nonlinear refractive index n2, as well as nonlinear absorption coefficient (βeff), were measured by using a single beam Z-scan technique. An ultrashort pulsed fiber laser emitting femtosecond pulses (Δτ ≈ 250 fs) at 1064 nm central wavelength is used as a source for the Z-scan experiment. The βeff values in as prepared thin films were ascertained to be smaller as compared to the annealed one due to the smaller value of saturation intensity (Is) which, in turn, is a consequence of ground-state bleaching in the thermally unstable amorphous state of the molecule. Interestingly, the nonlinear refractive indices bear opposite sign for CuPc and ZnPc. The variations in the third-order nonlinearity in CuPc and ZnPc are discussed in terms of molecular packing and geometries of metallophthalocyanine molecules.

Copper(ii) oxide nanoparticles penetrate into HepG2 cells, exert cytotoxicity via oxidative stress and induce pro-inflammatory response

NASA Astrophysics Data System (ADS)

Piret, Jean-Pascal; Jacques, Diane; Audinot, Jean-Nicolas; Mejia, Jorge; Boilan, Emmanuelle; Noël, Florence; Fransolet, Maude; Demazy, Catherine; Lucas, Stéphane; Saout, Christelle; Toussaint, Olivier

2012-10-01

The potential toxic effects of two types of copper(ii) oxide (CuO) nanoparticles (NPs) with different specific surface areas, different shapes (rod or spheric), different sizes as raw materials and similar hydrodynamic diameter in suspension were studied on human hepatocarcinoma HepG2 cells. Both CuO NPs were shown to be able to enter into HepG2 cells and induce cellular toxicity by generating reactive oxygen species. CuO NPs increased the abundance of several transcripts coding for pro-inflammatory interleukins and chemokines. Transcriptomic data, siRNA knockdown and DNA binding activities suggested that Nrf2, NF-κB and AP-1 were implicated in the response of HepG2 cells to CuO NPs. CuO NP incubation also induced activation of MAPK pathways, ERKs and JNK/SAPK, playing a major role in the activation of AP-1. In addition, cytotoxicity, inflammatory and antioxidative responses and activation of intracellular transduction pathways induced by rod-shaped CuO NPs were more important than spherical CuO NPs. Measurement of Cu2+ released in cell culture medium suggested that Cu2+ cations released from CuO NPs were involved only to a small extent in the toxicity induced by these NPs on HepG2 cells.The potential toxic effects of two types of copper(ii) oxide (CuO) nanoparticles (NPs) with different specific surface areas, different shapes (rod or spheric), different sizes as raw materials and similar hydrodynamic diameter in suspension were studied on human hepatocarcinoma HepG2 cells. Both CuO NPs were shown to be able to enter into HepG2 cells and induce cellular toxicity by generating reactive oxygen species. CuO NPs increased the abundance of several transcripts coding for pro-inflammatory interleukins and chemokines. Transcriptomic data, siRNA knockdown and DNA binding activities suggested that Nrf2, NF-κB and AP-1 were implicated in the response of HepG2 cells to CuO NPs. CuO NP incubation also induced activation of MAPK pathways, ERKs and JNK/SAPK, playing a major

Zinc complexes as fluorescent chemosensors for nucleic acids: new perspectives for a "boring" element.

PubMed

Terenzi, Alessio; Lauria, Antonino; Almerico, Anna Maria; Barone, Giampaolo

2015-02-28

Zinc(II) complexes are effective and selective nucleic acid-binders and strongly fluorescent molecules in the low energy range, from the visible to the near infrared. These two properties have often been exploited to quantitatively detect nucleic acids in biological samples, in both in vitro and in vivo models. In particular, the fluorescent emission of several zinc(II) complexes is drastically enhanced or quenched by the binding to nucleic acids and/or upon visible light exposure, in a different fashion in bulk solution and when bound to DNA. The twofold objective of this perspective is (1) to review recent utilisations of zinc(II) complexes as selective fluorescent probes for nucleic acids and (2) to highlight their novel potential applications as diagnostic tools based on their photophysical properties.

Stimulation and Inhibition of Anaerobic Digestion by Nickel and Cobalt: A Rapid Assessment Using the Resazurin Reduction Assay.

PubMed

Chen, Jian Lin; Steele, Terry W J; Stuckey, David C

2016-10-03

Stimulation of anaerobic digestion by essential trace metals is beneficial from a practical point of view to enhance the biodegradability and degradation rate of wastes. Hence, a quick method to determine which metal species, and at what concentration, can optimize anaerobic digestion is of great interest to both researchers and operators. In this present study, we investigated the effect of nickel(II), cobalt(II), and their mixture, on the anaerobic digestion of synthetic municipal wastewater. Using a volumetric method, that is, measuring methane production over time, revealed that anaerobic digestion was stimulated by the addition of 5 mg L -1 nickel(II), and cobalt(II), and their mixture in day(s). However, using a novel resazurin reduction assay, and based on its change in rate over time, we evaluated both inhibition at 250 mg L -1 nickel(II) and cobalt(II), and also the stimulatory effect of 5 mg L -1 nickel(II), and cobalt(II), and their mixture, in just 6 h. By investigating the dynamic distribution of these metals in the liquid phase of the anaerobic system and kinetics of resazurin reduction by nickel spiked anaerobic sludge, the concentration of nickel(II) on anaerobic digestion performance was profiled. Three critical concentrations were determined; stimulation starting (around 1 mg L -1 ), stimulation ending (around 100 mg L -1 ) and stimulation maximizing (around 10 mg L -1 ). Hence, we propose that the resazurin reduction assay is a novel and quick protocol for studying the stimulation of anaerobic bioprocesses by bioavailable essential trace metals.

5-Arylvinyl-2,2′-bipyridyls: Bright “push–pull” dyes as components in fluorescent indicators for zinc ions

PubMed Central

Zhu, Lei; Younes, Ali H.; Yuan, Zhao; Clark, Ronald J.

2015-01-01

This article reviews the zinc(II)-dependent photophysical properties of arylvinylbipyridines (AVBs), a class of fluoroionophores in which 2,2′-bipyridyl and an aryl moiety are electronically conjugated. Zinc(II) binding of an AVB may lead to an emission bathochromic shift of the fluoroionophore without diminishing its fluorescence quantum yield. This observation can be explained using the excited state model of electron donor–π bridge–electron acceptor “push–pull” fluorophores, in which the bipy moiety acts as an electron acceptor, and zinc(II)-coordination strengthens its electron affinity. The spectral sensitivity of bipy-containing fluoroionophores, such as AVBs, to zinc(II) can be exploited to prepare fluorescent indicators for this ion. In several cases, AVB moieties are incorporated in fluorescent heteroditopic ligands, so that the variation of zinc(II) concentration over a relatively large range can be correlated to fluorescence changes in either intensity or color. AVB fluoroionophores are also used to introduce an intramolecular Förster resonance energy transfer (FRET) strategy for creating zinc(II) indicators with high photostability and a narrow emission band, two desired characteristics of dyes used in fluorescence microscopy. PMID:26190906

Ferromagnetic coupling by spin polarization in a trinuclear copper(II) metallacyclophane with a triangular cage-like structure.

PubMed

Dul, Marie-Claire; Ottenwaelder, Xavier; Pardo, Emilio; Lescouëzec, Rodrigue; Journaux, Yves; Chamoreau, Lise-Marie; Ruiz-García, Rafael; Cano, Joan; Julve, Miguel; Lloret, Francesc

2009-06-15

A series of trinuclear copper(II) complexes of general formula A(6)[Cu(3)L(2)] x nH(2)O [L = benzene-1,3,5-tris(oxamate); A = Li(+) (n = 8), 1a; Na(+) (n = 11.5), 1b; and K(+) (n = 8.5), 1c] have been synthesized, and they have been structurally and magnetically characterized. X-ray diffraction on single crystals of 1c shows the presence of three square-planar copper(II)-bis(oxamato) moieties which are connected by a double benzene-1,3,5-triyl skeleton to give a unique metallacyclophane-type triangular cage. The copper basal planes are virtually orthogonal to the two benzene rings, which adopt an almost perfect face-to-face alignment. Complexes 1a-c exhibit a quartet (S = 3/2) ground spin state resulting from the moderate ferromagnetic coupling (J values in the range of +7.3 to +16.5 cm(-1)) between the three Cu(II) ions across the two benzene-1,3,5-tris(amidate) bridges [H = -J(S(1) x S(2) + S(2) x S(3) + S(3) x S(1)) with S(1) = S(2) = S(3) = S(Cu) = 1/2]. Density functional theory calculations on the S = 3/2 Cu(II)(3) ground spin state of 1c support the occurrence of a spin polarization mechanism for the propagation of the exchange interaction, as evidenced by the sign alternation of the spin density in the 1,3,5-substituted benzene spacers.

A combination of experimental and computational studies on a new oxamido bridged dinuclear copper(II) complex

NASA Astrophysics Data System (ADS)

Bhattacharya, Arnab; Saha, Pinki; Saha, Baptu; Maiti, Debasish; Mitra, Partha; Naskar, Jnan Prakash; Chowdhury, Shubhamoy

2017-10-01

Reaction of N,N‧-bis(2-pyridylmethyl)oxamide (H2L), and copper(II)nitrate trihydrate in 1:2 M proportion in methanol generates oxamido bridged dimeric copper(II) compound, [Cu2L(H2O)2(NO3)2]H2O (1a.H2O) in good yield. 1a.H2O has been characterized by C, H and N microanalyses, copper estimation, FT-IR, UV-Vis and room temperature magnetic susceptibility measurements. The X-ray crystal structure of 1a.H2O has been determined. Bond Valence Sum (BVS) analysis was undertaken to assign the oxidation state of each copper center in 1a. Thermal behavior of 1a.H2O has been studied by TGA. Electrochemical studies on 1a.H2O shows single electron two step sequential reductions of Cu(II) to Cu(I) in dimethyl sulphoxide. Our optimized geometry of 1a as obtained through conceptual Density Functional Theory (DFT) corroborates well with that obtained from single crystal X-ray diffraction. TD-DFT method was also adopted to delve into the electronic properties of 1a. We have taken recourse to employ our optimized structure of 1a to investigate systematically the relative stabilities of various dimeric Cu(II) complexes obtained through variation of ligands bearing uni-donor anion through substitution of nitrate in 1a. The in vitro antibacterial potentiality of 1a.H2O was also tested against some bacterial cell lines, pathogenic to mankind.

Studies on Some Biologically Cobalt(II), Copper(II) and Zinc(II) Complexes With ONO, NNO and SNO Donor Pyrazinoylhydrazine-Derived Ligands

PubMed Central

Praveen, Marapaka; Sherazi, Syed K. A.

1998-01-01

Biologically active complexes of Co(II), Ni(II), Cu(II) and Zn(II) with novel ONO, NNO and SNO donor pyrazinoylhydrazine-derived compounds have been prepared and characterized on the basis of analytical data and various physicochemical studies. Distorted octahedral structures for all the complexes have been proposed. The synthesized ligands and their complexes have been screened for their antibacterial activity against bacterial species Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumonae. The activity data show the metal complexes to be more active than the parent free ligands against one or more bacterial species. PMID:18475857

Theoretical (in B3LYP/6-3111++G** level), spectroscopic (FT-IR, FT-Raman) and thermogravimetric studies of gentisic acid and sodium, copper(II) and cadmium(II) gentisates.

PubMed

Regulska, E; Kalinowska, M; Wojtulewski, S; Korczak, A; Sienkiewicz-Gromiuk, J; Rzączyńska, Z; Swisłocka, R; Lewandowski, W

2014-11-11

The DFT calculations (B3LYP method with 6-311++G(d,p) mixed with LanL2DZ for transition metals basis sets) for different conformers of 2,5-dihydroxybenzoic acid (gentisic acid), sodium 2,5-dihydroxybenzoate (gentisate) and copper(II) and cadmium(II) gentisates were done. The proposed hydrated structures of transition metal complexes were based on the results of experimental findings. The theoretical geometrical parameters and atomic charge distribution were discussed. Moreover Na, Cu(II) and Cd(II) gentisates were synthesized and the composition of obtained compounds was revealed by means of elemental and thermogravimetric analyses. The FT-IR and FT-Raman spectra of gentisic acid and gentisates were registered and the effect of metals on the electronic charge distribution of ligand was discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

In vitro Solubility of Copper(II) Sulfate and Dicopper Chloride Trihydroxide for Pigs.

PubMed

Park, C S; Kim, B G

2016-11-01

This study was conducted to determine the solubility of copper (Cu) in two sources of copper(II) sulfate (CuSO 4 ) including monohydrate and pentahydrate and three sources of dicopper chloride trihydroxide (dCCTH) including α-form (dCCTH-α), β-form (dCCTH-β), and a mixture of α- and β-form (dCCTH-αβ) at different pH and a 3-step in vitro digestion assay for pigs. In Exp. 1, Cu sources were incubated in water-based buffers at pH 2.0, 3.0, 4.8, and 6.8 for 4 h using a shaking incubator at 39°C. The CuSO 4 sources were completely dissolved within 15 min except at pH 6.8. The solubility of Cu in dCCTH-α was greater (p<0.05) than dCCTH-β but was not different from dCCTH-αβ during 3-h incubation at pH 2.0 and during 2-h incubation at pH 3.0. At pH 4.8, there were no significant differences in solubility of Cu in dCCTH sources. Copper in dCCTH sources were non-soluble at pH 6.8. In Exp. 2, the solubility of Cu was determined during the 3-step in vitro digestion assay for pigs. All sources of Cu were completely dissolved in step 1 which simulated digestion in the stomach. In Exp. 3, the solubility of Cu in experimental diets including a control diet and diets containing 250 mg/kg of additional Cu from five Cu sources was determined during the in vitro digestion assay. The solubility of Cu in diets containing additional Cu sources were greater (p<0.05) than the control diet in step 1. In conclusion, the solubility of Cu was influenced by pH of digesta but was not different among sources based on the in vitro digestion assay.

In vitro Solubility of Copper(II) Sulfate and Dicopper Chloride Trihydroxide for Pigs

PubMed Central

Park, C. S.; Kim, B. G.

2016-01-01

This study was conducted to determine the solubility of copper (Cu) in two sources of copper(II) sulfate (CuSO4) including monohydrate and pentahydrate and three sources of dicopper chloride trihydroxide (dCCTH) including α-form (dCCTH-α), β-form (dCCTH-β), and a mixture of α- and β-form (dCCTH-αβ) at different pH and a 3-step in vitro digestion assay for pigs. In Exp. 1, Cu sources were incubated in water-based buffers at pH 2.0, 3.0, 4.8, and 6.8 for 4 h using a shaking incubator at 39°C. The CuSO4 sources were completely dissolved within 15 min except at pH 6.8. The solubility of Cu in dCCTH-α was greater (p<0.05) than dCCTH-β but was not different from dCCTH-αβ during 3-h incubation at pH 2.0 and during 2-h incubation at pH 3.0. At pH 4.8, there were no significant differences in solubility of Cu in dCCTH sources. Copper in dCCTH sources were non-soluble at pH 6.8. In Exp. 2, the solubility of Cu was determined during the 3-step in vitro digestion assay for pigs. All sources of Cu were completely dissolved in step 1 which simulated digestion in the stomach. In Exp. 3, the solubility of Cu in experimental diets including a control diet and diets containing 250 mg/kg of additional Cu from five Cu sources was determined during the in vitro digestion assay. The solubility of Cu in diets containing additional Cu sources were greater (p<0.05) than the control diet in step 1. In conclusion, the solubility of Cu was influenced by pH of digesta but was not different among sources based on the in vitro digestion assay. PMID:27456425

Synthesis and Crystal Structure of Dibromido{2-[(4-tert-butylmethylphenyl) iminomethyl]pyridine-κ2 N, N'}Zinc

NASA Astrophysics Data System (ADS)

Khalaj, M.; Ghazanfarpour-Darjani, M.; Seftejani, F. B.; Lalegani, A.

2017-12-01

The title compound [Zn( dip)Br2] was synthesized using the Schiff base bidentate ligand (E)-4- tert-butyl- N-(pyridine-2-ylmethylene)benzeneamine ( dip) and zinc(II) bromide salts. It has been characterized by elemental analysis, X-ray diffraction, and optical spectroscopy. The X-ray diffraction analysis demonstrates that in this structure, the zinc(II) ion is located on an inversion center and exhibits a ZnN2Br2 tetrahedral geometry. In this structure the dip ligand is coordinated with zinc(II) ion in a cyclic-bidentate fashion forming a five-membered metallocyclic ring. The compound crystallizes in the monoclinic sp. gr. P21/ m with a = 9.2700(13) Å, b = 7.6128(11) Å, c = 12.3880(17) Å, and β = 97.021(3)°.

Synthesis, Structure and Electrochemistry of Tetranuclear Oxygen-Centered Copper(II) Clusters with Acetylacetone and Benz-pyrazole Hydrolyzed Derivatives as Ligand.

PubMed

Vafazadeh, Rasoul; Willis, Anthony C

2016-01-01

Two copper(II) clusters Cu(4)OCl(6)(pyrazole)4, 1, and Cu(4)OBr(6)(Br-pyrazole)4, 2, have been synthesized by reacting acetylacetone and benzohydrazide (1:1 ratio) with CuX(2) (X = Cl for 1 and X= Br for 2) in methanol solutions. The structures of both clusters have been established by X-ray crystallography. The clusters contain four Cu, one O, six μ(2)-X atoms, and four pyrazole ligands. The pyrazoles was prepared in situ by the reaction of acetylacetone with benzohydrazide in methanol under reflux. In 2, the methine hydrogens of the pyrazole ligands have been replaced by bromine atoms. The four copper atoms encapsulate the central O atom in a tetrahedral arrangement. All copper atoms are five-coordinate and have similar coordination environments with slightly distorted trigonal bipyramidal geometry. The cyclic voltammogram of the clusters 1 and 2 show a one-electron quasi-reversible reduction wave in the region 0.485 to 0.731 V, and a one-electron quasi-reversible oxidation wave in the region 0.767 to 0.898 V. In 1, one irreversible oxidative response is observed on the positive of side of the voltammogram at 1.512 V and this can be assigned to Cu(II) to Cu(III) oxidation.

Synthesis and synergistic antifungal activities of a pyrazoline based ligand and its copper(II) and nickel(II) complexes with conventional antifungals.

PubMed

Ali, Imran; Wani, Waseem A; Khan, Amber; Haque, Ashanul; Ahmad, Aijaz; Saleem, Kishwar; Manzoor, Nikhat

2012-08-01

A pyrazoline based ligand; (5-(4-chlorophenyl)-3-phenyl-4, 5-dihydro-1H-pyrazole-1-carbothioamide) has been synthesized by Claisen-Schmidt condensation of acetophenone with p-chlorobenzaldehyde, followed by sodium hydroxide assisted cyclization of the resulting chalcone with thiosemicarbazide. Metal ion complexes of the synthesized ligand were prepared with Cu(II) and Ni(II) metal ions, separately and respectively. Ligand and the metal complexes were characterized by elemental analysis, FT-IR, UV-Vis, (1)HNMR, ESI-MS and (13)CNMR spectroscopic techniques. Molar conductance measurements in DMSO suggested non-electrolytic nature of the complexes. Tetragonally distorted octahedral geometry for copper and octahedral geometry for the nickel complexes was proposed on the basis of UV-Vis spectroscopic studies and magnetic moment measurements. The complexes were investigated for their ability to kill human fungal pathogen Candida by determining MICs (Minimum inhibitory concentrations), inhibition in solid media and ability to produce a possible synergism with conventional most clinically practiced antifungals by disc diffusion assay and FICI (fractional inhibitory concentration index). Copyright © 2012 Elsevier Ltd. All rights reserved.

Visual and portable strategy for copper(II) detection based on a striplike poly(thymine)-caged and microwell-printed hydrogel.

PubMed

Qing, Zhihe; Mao, Zhengui; Qing, Taiping; He, Xiaoxiao; Zou, Zhen; He, Dinggeng; Shi, Hui; Huang, Jin; Liu, Jianbo; Wang, Kemin

2014-11-18

Due to its importance to develop strategies for copper(II) (Cu(2+)) detection, we here report a visual and portable strategy for Cu(2+) detection based on designing and using a strip-like hydrogel. The hydrogel is functionalized through caging poly(thymine) as probes, which can effectively template the formation of fluorescent copper nanoparticles (CuNPs) in the presence of the reductant (ascorbate) and Cu(2+). On the hydrogel's surface, uniform wells of microliter volume (microwells) are printed for sample-injection. When the injected sample is stained by Cu(2+), fluorescent CuNPs will be in situ templated by poly T in the hydrogel. With ultraviolet (UV) irradiation, the red fluorescence of CuNPs can be observed by naked-eye and recorded by a common camera without complicated instruments. Thus, the strategy integrates sample-injection, reaction and indication with fast signal response, providing an add-and-read manner for visual and portable detection of Cu(2+), as well as a strip-like strategy. Detection ability with a detectable minimum concentration of 20 μM and practically applicable properties have been demonstrated, such as resistance to environmental interference and good constancy, indicating that the strategy holds great potential and significance for popular detection of Cu(2+), especially in remote regions. We believe that the strip-like hydrogel-based methodology is also applicable to other targets by virtue of altering probes.

New glycoside derivatives of carnosine and analogs resistant to carnosinase hydrolysis: synthesis and characterization of their copper(II) complexes.

PubMed

Lanza, Valeria; Bellia, Francesco; D'Agata, Roberta; Grasso, Giuseppe; Rizzarelli, Enrico; Vecchio, Graziella

2011-02-01

Carnosine (β-alanyl-L-histidine) is an endogenous dipeptide widely and abundantly distributed in muscle and nervous tissues of several animal species. Many functions have been proposed for this compound, such as antioxidant and metal ion-chelator properties. However, the main limitation on therapeutic use of carnosine on pathologies related to increased oxidative stress and/or metal ion dishomeostasis is associated with the hydrolysis by the specific dipeptidase carnosinase. Several attempts have been made to overcome this limitation. On this basis, we functionalized carnosine and its amide derivative with small sugars such as glucose and lactose. The resistance of these derivatives to the carnosinase hydrolysis was tested and compared with that of carnosine. We found that the glycoconjugation protects the dipeptide moiety from carnosinase hydrolysis, thus potentially improving the availability of carnosine. The copper(II) binding properties of all the new synthesized compounds were investigated by spectroscopic (UV-Visible and circular dichroism) and ESI-MS studies. Particularly, the new family of amide derivatives that are not significantly hydrolyzed by carnosinase is a very promising class of carnosine derivatives. The sugar moiety can act as a recognition element. These new derivatives are potentially able to act as chelating agents in the development of clinical approaches for the regulation of metal homeostasis in the field of medicinal inorganic chemistry. Copyright © 2010 Elsevier Inc. All rights reserved.

Equilibrium and kinetic studies of copper biosorption by dead Ceriporia lacerata biomass isolated from the litter of an invasive plant in China.

PubMed

Li, Xiaona; Li, Airong; Long, Mingzhong; Tian, Xingjun

2015-01-01

Ceriporia lacerata, a strain of white-rot fungus isolated from the litter of an invasive plant (Solidago canadensis) in China, was little known about its properties and utilization. In this work, the copper(II) biosorption characteristics of formaldehyde inactivated C. lacerata biomass were examined as a function of initial pH, initial copper(II) concentration and contact time, and the adsorptive equilibrium and kinetics were simulated, too. The optimum pH was found to be 6.0 at experimental conditions of initial copper(II) concentration 100 mg/L, biomass dose 2 g/L, contact time 12 h, shaking rate 150 r/min and temperature 25°C. Biosorption equilibrium cost about 1 hour at experimental conditions of pH 6.0, initial copper(II) concentration 100 mg/L, C. lacerata dose 2 g/L, shaking rate 150 r/min and temperature 25°C. At optimum pH 6.0, highest copper(II) biosorption amounts were 6.79 and 7.76 mg/g for initial copper(II) concentration of 100 and 200 mg/L, respectively (with other experimental parameters of C. lacerata dose 2 g/L, shaking rate 150 r/min and temperature 25°C). The pseudo second-order adsorptive model gave the best adjustment for copper(II) biosorption kinetics. The equilibrium data fitted very well to both Langmuir and Freundlich adsorptive isotherm models. Without further acid or alkali treatment for improving adsorption properties, formaldehyde inactivated C. lacerata biomass possesses good biosorption characteristics on copper(II) removal from aqueous solutions.

Study on the interaction of a copper(II) complex containing the artificial sweetener aspartame with human serum albumin.

PubMed

Shahabadi, Nahid; Khodaei, Mohammad Mehdi; Kashanian, Soheila; Kheirdoosh, Fahimeh; Filli, Soraya Moradi

2014-05-01

A copper(II) complex containing aspartame (APM) as ligand, Cu(APM)2Cl2·2H2O, was synthesized and characterized. In vitro binding interaction of this complex with human serum albumin (HSA) was studied at physiological pH. Binding studies of this complex with HSA are useful for understanding the Cu(APM)2Cl2·2H2O-HSA interaction mechanism and providing guidance for the application and design of new and more efficient artificial sweeteners drive. The interaction was investigated by spectrophotometric, spectrofluorometric, competition experiment and circular dichroism. Hyperchromicity observed in UV absorption band of Cu(APM)2Cl2·2H2O. A strong fluorescence quenching reaction of HSA to Cu(APM)2Cl2·2H2O was observed and the binding constant (Kf) and corresponding numbers of binding sites (n) were calculated at different temperatures. Thermodynamic parameters, enthalpy change (∆H) and entropy change (∆S) were calculated to be -458.67 kJ mol(-1) and -1,339 J mol(-1 )K(-1) respectively. According to the van't Hoff equation, the reaction is predominantly enthalpically driven. In conformity with experimental results, we suggest that Cu(APM)2Cl2·2H2O interacts with HSA. In comparison with previous study, it is found that the Cu(II) complex binds stronger than aspartame.

Comparative Investigation of Peripheral and Nonperipheral Zinc Phthalocyanine-Based Polycarbazoles in Terms of Optical, Electrical, and Sensing Properties.

PubMed

Soganci, Tugba; Baygu, Yasemin; Kabay, Nilgün; Gök, Yaşar; Ak, Metin

2018-06-15

In this study, nonperipherally alkyl-linked carbazole conjugated novel zinc(II) phthalocyanine was synthesized by cyclotetramerization reaction of 6-(9 H-carbazol-9-yl)hexane-1-thiol and 3,6-bis(tosyloxy) phthalonitrile in a one-step reaction. Optical, electrical, and sensing properties of this super structured polycarbazole obtained by electropolymerization are compared with peripherally alkyl-linked polycarbazole-based zinc(II) phthalocyanine. It has been found that the attachment of alkyl-linked carbazoles to the phthalocyanine molecule in either peripheral or nonperipheral positions has a great effect on the optical and electrical properties and sensing ability of the resulting polycarbazole derivatives. P(n-ZnPc) has the highest electrochromic contrast (70.5%) among the derivatives of zinc(II) phthalocyanines in the literature. In addition to these, the sensor platform has been successfully established, and analytical optimizations have been carried out. When the sensors prepared with zinc(II) phthalocyanine are examined, it was specified that the n-ZnPc- co-TP/GOx was ranked first in the literature with high sensor response and stability. As a result, by changing of the peripheral and nonperipheral position of phthalocyanines, their physical properties can be tuned to meet the requirements of desired technological application.

Optimization and validation of a method for the determination of the refractive index of milk serum based on the reaction between milk and copper(II) sulfate to detect milk dilutions.

PubMed

Rezende, Patrícia Sueli; Carmo, Geraldo Paulo do; Esteves, Eduardo Gonçalves

2015-06-01

We report the use of a method to determine the refractive index of copper(II) serum (RICS) in milk as a tool to detect the fraudulent addition of water. This practice is highly profitable, unlawful, and difficult to deter. The method was optimized and validated and is simple, fast and robust. The optimized method yielded statistically equivalent results compared to the reference method with an accuracy of 0.4% and quadrupled analytical throughput. Trueness, precision (repeatability and intermediate precision) and ruggedness are determined to be satisfactory at a 95.45% confidence level. The expanded uncertainty of the measurement was ±0.38°Zeiss at the 95.45% confidence level (k=3.30), corresponding to 1.03% of the minimum measurement expected in adequate samples (>37.00°Zeiss). Copyright © 2015 Elsevier B.V. All rights reserved.

A Novel Pentadentate Coordination Mode for the Carbonato Bridge: Synthesis, Crystal Structure, and Magnetic Behavior of (&mgr;(3)-CO(3))[Ni(3)(Medpt)(3)(NCS)(4)], a New Trinuclear Nickel(II) Carbonato-Bridged Complex with Strong Antiferromagnetic Coupling.

PubMed

Escuer, Albert; Vicente, Ramon; Kumar, Sujit B.; Solans, Xavier; Font-Bardía, Mercé; Caneschi, Andrea

1996-05-22

The trinuclear complex (&mgr;(3)-CO(3))[Ni(3)(Medpt)(3)(NCS)(4)] was obtained by reaction of basic solutions of nickel(II), Medpt (bis(3aminopropyl)methylamine) and thiocyanate ligand with atmospheric CO(2) or by simple reaction with carbonate anion. (&mgr;(3)-CO(3))[Ni(3)(Medpt)(3)(NCS)(4)] crystallizes in the triclinic system, space group P&onemacr;, with a = 12.107(5) Å, b = 12.535(7) Å, c = 16.169(9) Å, alpha = 102.69(5) degrees, beta = 92.91(5) degrees, gamma = 118.01(4) degrees, Z = 2, and R = 0.043. The three nickel atoms are asymmetrically bridged by one pentadentate carbonato ligand, which shows a novel coordination mode. The (&mgr;(3)-CO(3))[Ni(3)(Medpt)(3)(NCS)(4)] compound shows a very strong antiferromagnetic coupling. Fit as irregular triangular arrangement gave J(1) = -88.4, J(2) = -57.7, and J(3) = -9.6 cm(-)(1), which is the strongest AF coupling observed to date for Ni(3) compounds. The magnetic behavior of the carbonato bridge is discussed.

Copper(II) complexes with naringenin and hesperetin: cytotoxic activity against A 549 human lung adenocarcinoma cells and investigation on the mode of action.

PubMed

Tamayo, Lenka V; Gouvea, Ligiane R; Sousa, Anna C; Albuquerque, Ronniel M; Teixeira, Sarah Fernandes; de Azevedo, Ricardo Alexandre; Louro, Sonia R W; Ferreira, Adilson Kleber; Beraldo, Heloisa

2016-02-01

Copper(II) complexes [Cu(H2O)2 (L1)(phen)](ClO4) (1) and [Cu(H2O)(L2)(phen)](ClO4) (2) (HL1 = naringenin; HL2 = hesperetin) were obtained, in which an anionic flavonoid ligand is attached to the metal center along with 1,10-phenanthroline (phen) as co-ligand. Complexes (1) and (2) were assayed for their cytotoxic activity against A549 lung carcinoma and against normal lung fibroblasts (LL-24) and human umbilical vein endothelial cells (HUVEC). We found IC50 = 16.42 µM (1) and IC50 = 5.82 µM (2) against A549 tumor cells. Complexes (1) and (2) exhibited slight specificity, being more cytotoxic against malignant than against non-malignant cells. 1 and 2 induced apoptosis on A549 cells in a mitochondria-independent pathway, and showed antioxidant activity. The antioxidant effect of the complexes could possibly improve their apoptotic action, most likely by a PI3K-independent reduction of autophagy. Complexes (1) and (2) interact in vitro with calf thymus DNA by an intercalative binding mode. EPR data indicated that 1 and 2 interact with human serum albumin (HSA) forming mixed ligand species.

Synthesis, characterization and investigation of electrochemical and spectroelectrochemical properties of non-peripherally tetra-5-methyl-1,3,4-thiadiazole substituted copper(II) iron(II) and oxo-titanium (IV) phthalocyanines

NASA Astrophysics Data System (ADS)

Demirbaş, Ümit; Akyüz, Duygu; Akçay, Hakkı Türker; Barut, Burak; Koca, Atıf; Kantekin, Halit

2017-09-01

In this study novel substituted phthalonitrile (3) and non-peripherally tetra 5-Methyl-1,3,4-thiadiazole substituted copper(II) (4), iron(II) (5) and oxo-titanium (IV) (6) phthalocyanines were synthesized. These novel compounds were fully characterized by FT-IR, 1H NMR, UV-vis and MALDI-TOF mass spectroscopic techniques. Voltammetric and in situ spectroelectrochemical measurements were performed for metallo-phthalocyanines (4-6). TiIVOPc and FeIIPc showed metal-based and ligand-based electron transfer reactions while CuIIPc shows only ligand-based electron transfer reaction. Voltammetric measurements indicated that the complexes have reversible, diffusion controlled and one-electron redox reactions. The assignments of the redox processes and color of the electrogenerated species of the complexes were determined with in-situ spectroelectrochemical and electrocolorimetric measurements. These measurements showed that the complexes can be used as the electrochromic materials for various display technologies.

Indirect spectrophotometric determination of sodium ceftriaxone with n-propyl alcohol-ammonium sulfate-water system by extraction flotation of copper(II).

PubMed

Zhao, Wei; Zhang, Yan; Li, Quanmin

2008-05-01

Although the determination methods of sodium ceftriaxone has been increasingly reported, these methods have their inherent limits preventing them from being broadly applied in common laboratories. In order to circumvent this problem, a rapid and simple method for the indirect spectrophotometric determination of sodium ceftriaxone is reported. Sodium ceftriaxone was degraded completely in the presence of 0.20 mol/l sodium hydroxide in boiling water bath for 20 min. The thiol group (-SH) of the degradation product (I) of sodium ceftriaxone could reduce cupric to cuprous ions, and the resulting which was precipitated with the thiol group (-SH) of the degradation product (II) at pH 4.0. By determining the residual amount of copper (II), the indirect determination of sodium ceftriaxone can be achieved. Standard curve of sodium ceftriaxone versus the flotation yield of copper(II) showed that sodium ceftriaxone could be determined in low concentrations. The linear range of sodium ceftriaxone was 0.70-32 microg/ml and the detection limit evaluated by calibration curve (3sigma/k) was found to be 0.60 microg/ml. A simple and efficient method was developed and it has been successfully applied to the determination of sodium ceftriaxone in human serum and urine samples, respectively. It is expected that this method will find broad applications in the detection of cephalosporin derivatives with similar structure.

Hierarchical nanostructures of copper(II) phthalocyanine on electrospun TiO(2) nanofibers: controllable solvothermal-fabrication and enhanced visible photocatalytic properties.

PubMed

Zhang, Mingyi; Shao, Changlu; Guo, Zengcai; Zhang, Zhenyi; Mu, Jingbo; Cao, Tieping; Liu, Yichun

2011-02-01

In the present work, 2,9,16,23-tetranitrophthalocyanine copper(II) (TNCuPc)/TiO(2) hierarchical nanostructures were successfully fabricated by a simple combination method of electrospinning technique and solvothermal processing. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), UV-vis diffuse reflectance (DR), Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric and differential thermal analysis (TG-DTA) were used to characterize the as-synthesized TNCuPc/TiO(2) hierarchical nanostructures. The results showed that the secondary TNCuPc nanostructures were not only successfully grown on the primary TiO(2) nanofibers substrates but also uniformly distributed without aggregation. By adjusting the solvothermal fabrication parameters, the TNCuPc nanowires or nanoflowers were facilely fabricated, and also the loading amounts of TNCuPc could be controlled on the TNCuPc/TiO(2) hierarchical nanostructural nanofibers. And, there might exist the interaction between TNCuPc and TiO(2). A possible mechanism for the formation of TNCuPc/TiO(2) hierarchical nanostructures was suggested. The photocatalytic studies revealed that the TNCuPc/TiO(2) hierarchical nanostructures exhibited enhanced photocatalytic efficiency of photodegradation of Rhodamine B (RB) compared with the pure TNCuPc or TiO(2) nanofibers under visible-light irradiation.

Supramolecular Complexes Formed by the Self-assembly of Hydrophobic Bis(Zn(2+)-cyclen) Complexes, Copper, and Di- or Triimide Units for the Hydrolysis of Phosphate Mono- and Diesters in Two-Phase Solvent Systems (Cyclen=1,4,7,10-Tetraazacyclododecane).

PubMed

Hisamatsu, Yosuke; Miyazawa, Yuya; Yoneda, Kakeru; Miyauchi, Miki; Zulkefeli, Mohd; Aoki, Shin

2016-01-01

We previously reported on supramolecular complexes 4 and 5, formed by the 4 : 4 : 4 or 2 : 2 : 2 assembly of a dimeric zinc(II) complex (Zn2L(1)) having 2,2'-bipyridyl linker, dianion of cyanuric acid (CA) or 5,5-diethylbarbituric acid (Bar), and copper(II) ion (Cu(2+)) in an aqueous solution. The supermolecule 4 possesses Cu2(μ-OH)2 centers and catalyzes hydrolysis of phosphate monoester dianion, mono(4-nitrophenyl)phosphate (MNP), at neutral pH. In this manuscript, we report on design and synthesis of hydrophobic supermolecules 9 and 10 by 4 : 4 : 4 and 2 : 2 : 2 self-assembly of hydrophobic Zn2L(2) and Zn2L(3) containing long alkyl chains, CA or Bar, and Cu(2+) and their phosphatase activity for the hydrolysis of MNP and bis(4-nitrophenyl)phosphate (BNP) in two-phase solvent systems. We assumed that the Cu2(μ-OH)2 active sites of 9 and 10 would be more stable in organic solvent than in aqueous solution and that product inhibition of the supermolecules might be avoided by the release of HPO4(2-) into the aqueous layer. The findings indicate that 9 and 10 exhibit phosphatase activity in the two-phase solvent system, although catalytic turnover was not observed. Furthermore, the hydrolysis of BNP catalyzed by the hydrophobic 2 : 2 : 2 supermolecules in the two-phase solvent system is described.

Non-rigid molecule of copper(II) diiminate Cu[CF3C(NH)C(F)C(NH)CF3]2, its conformational polymorphism in crystal and structure in solutions (Raman, UV-vis and quantum chemistry study)

NASA Astrophysics Data System (ADS)

Bukalov, Sergey S.; Aysin, Rinat R.; Leites, Larissa A.; Kurykin, Mikhail A.; Khrustalev, Victor N.

2015-10-01

Calculation of potential energy surface (PES) of isolated molecule of copper(II) diiminate Cu[CF3С(NH)C(F)C(NH)CF3]2 (1) resulted a double-well curve with the minima corresponding to equivalent screwed conformations. The low barrier leads to molecular non-rigidity which seems to be the reason of conformational polymorphism in crystals, reported in [1]. For one of newly found polymorphs, the X-ray structure was determined. The differences in the Raman and UV-vis spectra between differently colored species and their solutions were revealed, they are determined by different geometries of Cu(II) coordination polyhedron and different systems of intermolecular interactions in crystals. Transformations of the polymorphs under thermal, mechanical and photo exposures were studied.

The effectiveness of 1H decoupling in the 13C MAS NMR of paramagnetic solids: An experimental case study incorporating copper(II) amino acid complexes

NASA Astrophysics Data System (ADS)

Willans, Mathew J.; Sears, Devin N.; Wasylishen, Roderick E.

2008-03-01

The use of continuous-wave (CW) 1H decoupling has generally provided little improvement in the 13C MAS NMR spectroscopy of paramagnetic organic solids. Recent solid-state 13C NMR studies have demonstrated that at rapid magic-angle spinning rates CW decoupling can result in reductions in signal-to-noise and that 1H decoupling should be omitted when acquiring 13C MAS NMR spectra of paramagnetic solids. However, studies of the effectiveness of modern 1H decoupling sequences are lacking, and the performance of such sequences over a variety of experimental conditions must be investigated before 1H decoupling is discounted altogether. We have studied the performance of several commonly used advanced decoupling pulse sequences, namely the TPPM, SPINAL-64, XiX, and eDROOPY sequences, in 13C MAS NMR experiments performed under four combinations of the magnetic field strength (7.05 or 11.75 T), rotor frequency (15 or 30 kHz), and 1H rf-field strength (71, 100, or 140 kHz). The effectiveness of these sequences has been evaluated by comparing the 13C signal intensity, linewidth at half-height, LWHH, and coherence lifetimes, T2', of the methine carbon of copper(II) bis( DL-alanine) monohydrate, Cu(ala) 2·H 2O, and methylene carbon of copper(II) bis( DL-2-aminobutyrate), Cu(ambut) 2, obtained with the advanced sequences to those obtained without 1H decoupling, with CW decoupling, and for fully deuterium labelled samples. The latter have been used as model compounds with perfect 1H decoupling and provide a measure of the efficiency of the 1H decoupling sequence. Overall, the effectiveness of 1H decoupling depends strongly on the decoupling sequence utilized, the experimental conditions and the sample studied. Of the decoupling sequences studied, the XiX sequence consistently yielded the best results, although any of the advanced decoupling sequences strongly outperformed the CW sequence and provided improvements over no 1H decoupling. Experiments performed at 7.05 T demonstrate

Synthesis, structures and Helicobacter pylori urease inhibitory activity of copper(II) complexes with tridentate aroylhydrazone ligands.

PubMed

Pan, Lin; Wang, Cunfang; Yan, Kai; Zhao, Kedong; Sheng, Guihua; Zhu, Hailiang; Zhao, Xinlu; Qu, Dan; Niu, Fang; You, Zhonglu

2016-06-01

A series of new copper(II) complexes were prepared. They are [CuL(1)(NCS)] (1), [CuClL(1)]·CH3OH (2), [CuClL(2)]·CH3OH (3), [CuL(3)(NCS)]·CH3OH (4), [CuL(4)(NCS)]·0.4H2O (5), and [CuL(5)(bipy)] (6), where L(1), L(2), L(3) and L(4) are the deprotonated form of N'-(2-hydroxybenzylidene)-3-methylbenzohydrazide, 4-bromo-N'-(2-hydroxy-5-methoxybenzylidene)benzohydrazide, N'-(2-hydroxy-5-methoxybenzylidene)-3-methylbenzohydrazide and 2-chloro-N'-(2-hydroxy-5-methoxybenzylidene)benzohydrazide, respectively, L(5) is the dianionic form of N'-(2-hydroxybenzylidene)-3-methylbenzohydrazide, and bipy is 2,2'-bipyridine. The complexes were characterized by infrared and UV-Vis spectra and single crystal X-ray diffraction. The Cu atoms in complexes 1, 2, 3, 4 and 5 are coordinated by the NOO donor set of the aroylhydrazone ligands, and one Cl or thiocyanate N atom, forming square planar coordination. The Cu atom in complex 6 is in a square pyramidal coordination, with the NOO donor set of L(1), and one N atom of bipy defining the basal plane, and with the other N atom of bipy occupying the apical position. Complexes 1, 2, 3, 4 and 5 show effective urease inhibitory activities, with IC50 values of 5.14, 0.20, 4.06, 5.52 and 0.26μM, respectively. Complex 6 has very weak activity against urease, with IC50 value over 100μM. Molecular docking study of the complexes with the Helicobacter pylori urease was performed. The relationship between structures and urease inhibitory activities indicated that copper complexes with square planar coordination are better models for urease inhibition. Copyright © 2016 Elsevier Inc. All rights reserved.

Halochromism, ionochromism, solvatochromism and density functional study of a synthesized copper(II) complex containing hemilabile amide derivative ligand.

PubMed

Golchoubian, Hamid; Moayyedi, Golasa; Reisi, Neda

2015-03-05

This study investigates chromotropism of newly synthesized 3,3'-(ethane-1,2-diylbis(benzylazanediyl))dipropanamide copper(II) perchlorate complex. The compound was structurally characterized by physico-chemical and spectroscopic methods. X-ray crystallography of the complex showed that the copper atom achieved a distorted square pyramidal environment through coordination of two amine N atoms and two O atoms of the amide moieties. The pH effect on the visible absorption spectrum of the complex was studied which functions as pH-induced "off-on-off" switches through protonation and deprotonation of amide moieties along with the CuO to CuN bond rearrangement at room temperature. The complex was also observed to show solvatochromism and ionochromism. The distinct solution color changes mainly associated with hemilability of the amide groups. The solvatochromism of the complex was investigated with different solvent parameter models using stepwise multiple linear regression method. The results suggested that the basicity power of the solvent has a dominant contribution to the shift of the d-d absorption band of the complex. Density functional theory, DFT calculations were performed in order to study the electronic structure of the complex, the relative stabilities of the CuN/CuO isomers, and to understand the nature of the halochromism processes taking place. DFT computational results buttressed the experimental observations indicating that in the natural pH (5.8) the CuO isomer is more stable than its linkage isomer and conversely in alkaline aqueous solution. Copyright © 2014 Elsevier B.V. All rights reserved.

Nickel(II) and copper(II) complexes of N,N-dialkyl-N‧-3-chlorobenzoylthiourea: Synthesis, characterization, crystal structures, Hirshfeld surfaces and antimicrobial activity

NASA Astrophysics Data System (ADS)

Binzet, Gun; Gumus, Ilkay; Dogen, Aylin; Flörke, Ulrich; Kulcu, Nevzat; Arslan, Hakan

2018-06-01

We synthesized four new N,N-dialkyl-N‧-3-chlorobenzoylthiourea ligands (Alkyl: Dimethyl, diethyl, di-n-propyl and di-n-butyl) and their metal complexes with copper and nickel atoms. The structure of all synthesized compounds was fully characterized by physicochemical, spectroscopic and single crystal X-ray diffraction analysis techniques. The physical, spectral and analytical data of the newly synthesized metal complexes have shown the formation of 1:2 (metal:ligand) ratio. The benzoylthiourea ligands coordinate with metal atoms through oxygen and sulphur atoms. The metal atoms are in slightly distorted square-planar coordination geometry in Ni(II) or Cu(II) complex. Two oxygen and two sulphur atoms are mutually cis to each other in Ni(II) or Cu(II) complex. The intermolecular contacts in the compounds, which are HL1 and HL3, were examined by Hirshfeld surfaces and fingerprint plots using the data obtained from X-ray single crystal diffraction measurement. Besides these, their antimicrobial activities against Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, Streptococcus pyogenes and Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and anti-yeast activity (Candida glabrata, Candida parapsilosis and Candida albicans) were investigated. This exhibited some promising results towards testing organism. Among all the compounds, Ni(L1)2 complex showed high activity against Bacillus subtilis with MIC values at 7.81 μg/mL.

Activation of heteroallenes by coordinatively unsaturated nickel(ii) alkyl complexes supported by the hydrotris(3-phenyl-5-methyl)pyrazolyl borate (Tp(Ph,Me)) ligand.

PubMed

Abubekerov, Mark; Eymann, Léonard Y M; Gianetti, Thomas L; Arnold, John

2016-10-07

Activation of sulfur containing heteroallenes by nickel(ii) alkyl complexes supported by the bulky hydrotris(3-phenyl-5-methylpyrazolyl)borate (Tp(Ph,Me)) ligand is described. Exposure of Tp(Ph,Me)NiCH2Ph (1a) and Tp(Ph,Me)NiCH2Si(CH3)3 (1b) to CS2 resulted in formation of the insertion products Tp(Ph,Me)Ni(η(2)-CS2)CH2Ph (2a) and Tp(Ph,Me)Ni(η(2)-CS2)CH2Si(CH3)3 (2b) in moderate yields. Reaction of 1a and MeNCS produced two species in a 1 : 1 ratio, identified as Tp(Ph,Me)Ni(η(2)-MeNC)CH2Ph (3) and Tp(Ph,Me)Ni(η(2)-MeNCS)SCH2Ph (4). Isolation of the unexpected insertion product (3) prompted an investigation into the activity of 1a-b in the presence of isocyanides (i.e.(t)BuNC), which resulted in isolation of Tp(Ph,Me)Ni(η(2-t)BuNC)CH2Ph (5a) and Tp(Ph,Me)Ni(η(2-t)BuNC)CH2Si(CH3)3 (5b). Similarly, reaction of 1a with OCS led to the isolation of a rare example of a Ni(i) carbonyl species Tp(Ph,Me)NiCO (6). Alternatively, complex 6 was also formed by exposure of 1a-b to an atmosphere of CO. Isolation of the intermediate species (Tp(Ph,Me)Ni(η(2)-CO)CH2TMS (7b) and Tp(Ph,Me)Ni(CO)(C(O)R, (8a-b) with R = Ph, TMS)) shed light on the formation of such species.

Structural characterization of a hydroperoxo nickel complex and its autoxidation: mechanism of interconversion between peroxo, superoxo, and hydroperoxo species.

PubMed

Rettenmeier, Christoph A; Wadepohl, Hubert; Gade, Lutz H

2015-04-13

Pincer-stabilized nickel(I) complexes readily react with molecular oxygen to form dinuclear 1,2-μ-peroxo-bridged nickel(II) complexes, which are the major components of a dynamic equilibrium with the corresponding mononuclear superoxo species. The peroxo complexes further react with hydrogen peroxide to give the corresponding nickel(II) hydroperoxides. One of these hitherto elusive species was characterized by X-ray diffraction for the first time [O-O bond length: 1.492(2) Å]. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Study on solid phase extraction spectrophotometric determination of zinc with 2-(2-quinolylazo)-5-dimthylaminophenol].

PubMed

Zhou, Shi-ping; Duan, Chang-qun; Liu, Hong-cheng; Hu, Qiu-fen

2005-10-01

A highly sensitive, selective and rapid method for the determination of zinc based on the rapid reaction of zinc(II) with 2-(2-quinolylazo)-5-dimthylaminophenol (QADMAP) and the solid phase extraction of zinc ion with anion exchange resin cartridge was developed. In the presence of pH 8.5 buffer solution and Triton X-100 medium, QADMAP can react with zinc(II) to form a stable 2 :1 complex (QADMAP:Zn(II)). The molar absorptivity is 1.22 x 10(5)L x moL(-1) x cm(-1) at 590 nm. Beer's law is obeyed in the range of 0-1.0 microg x mL(-1). The zinc ions in the samples can be enriched and separated by solid phase extraction with anion exchange resincartridge. Testing results show that recovery for zinc(II) was from 95% to 104%, and RSD was below 3%. This method was applied to the determination of zinc in water and food with good results.

Two novel copper(II) complexes constructed from dicarboxylate ligands with different spacer lengths and 2-phenylimidazo[4,5- f]1,10-phenanthroline (PIP): Synthesis, structures and properties

NASA Astrophysics Data System (ADS)

Wang, X.-L.; Chen, Yongqiang; Liu, Guocheng; Lin, Hongyan; Zhang, Jinxia

2009-09-01

Two novel metal-organic coordination polymers [Cu(PIP)(bpea)(H 2O)]·H 2O ( 1) and [Cu(PIP)(1,4-bdc)] ( 2) have been obtained from hydrothermal reaction of copper(II) with the mixed ligands [biphenylethene-4,4'-dicarboxylic acid (bpea) for 1, benzene-1,4-dicarboxylic acid (1,4-H 2bdc) for 2, and 2-phenylimidazo[4,5- f]1,10-phenanthroline (PIP)]. Both complexes have been structurally characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. Structural analyses reveal that complex 1 possesses infinite one-dimensional zigzag chain, 2 exhibits a two-dimensional (4,4) network, both of which are extended into three-dimensional supramolecular network by weak interactions. The different structures of the title complexes illustrate the influence of the flexibility (the spacer length of carboxyl groups and the structural rigidity of the spacer) of organic dicarboxylate ligands on the formation of such coordination architectures. Moreover, the thermal properties and the voltammetric behavior of complexes 1 and 2 have been reported.

Synthesis and characterization of bis-(2-cyano-1-methyl-3-{2- {{(5-methylimidazol-4-yl)methyl}thio}ethyl)guanidine copper(II) sulfate tetrahydrate

NASA Astrophysics Data System (ADS)

Rahardjo, Sentot B.; Endah Saraswati, Teguh; Pramono, Edy; Fitriana, Nur

2016-02-01

Complex of copper(II) with 2-cyano-1-methyl-3-{2-{{(5-methylimidazol-4- yl)methyl}thio}ethyl)guanidin(xepamet) had been synthesized in 1 : 4 mole ratio of metal to the ligand in methanol. The complex was characterized by metal analysis, thermal gravimetry/differential thermal analyzer (TG/DTA), molar conductivity meter, (Fourier transform infrared spectroscopy) FT-IR, UV-Vis spectroscopy, and magnetic susceptibility balance. The molar conductivity measurement shows that the complex was 2: 1 for electrolyte and SO42- which was acting as a counter ion. The thermal analysis by Thermogravimetric (TG) indicates that the complex contained four molecules of H2O. The Infrared spectral data indicates that functional groups of (C=N) imidazole and (C-S) are coordinated to the center ion Cu2+. Magnetic moment measurement shows that the complex is paramagnetic with peff = 1.78 ± 0.01 BM. Electronic spectra of the complex show a broad band at 608 nm (16447.23 cm-1) are due to Eg→T2g transition. Based on those of characteristics, The complex formula was estimated as [Cu(xepamet)2]SO4.4H2O. The structure of [Cu(xepamet)2]SO4.4H2O complex is probably square planar.

A ruthenium(II) complex as turn-on Cu(II) luminescent sensor based on oxidative cyclization mechanism and its application in vivo

NASA Astrophysics Data System (ADS)

Zhang, Yunfei; Liu, Zonglun; Yang, Kui; Zhang, Yi; Xu, Yongqian; Li, Hongjuan; Wang, Chaoxia; Lu, Aiping; Sun, Shiguo

2015-02-01

Copper ions play a vital role in a variety of fundamental physiological processes not only in human beings and plants, but also for extensive insects and microorganisms. In this paper, a novel water-soluble ruthenium(II) complex as a turn-on copper(II) ions luminescent sensor based on o-(phenylazo)aniline was designed and synthesized. The azo group would undergo a specific oxidative cyclization reaction with copper(II) ions and turn into high luminescent benzotriazole, triggering significant luminescent increasements which were linear to the concentrations of copper(II) ions. The sensor distinguished by its high sensitivity (over 80-fold luminescent switch-on response), good selectivity (the changes of the emission intensity in the presence of other metal ions or amino acids were negligible) and low detection limit (4.42 nM) in water. Moreover, the copper(II) luminescent sensor exhibited good photostability under light irradiation. Furthermore, the applicability of the proposed sensor in biological samples assay was also studied and imaged copper(II) ions in living pea aphids successfully.

Syntheses of vanadyl and zinc(II) complexes of 1-hydroxy-4,5,6-substituted 2(1H)-pyrimidinones and their insulin-mimetic activities.

PubMed

Yamaguchi, Mika; Wakasugi, Kei; Saito, Ryota; Adachi, Yusuke; Yoshikawa, Yutaka; Sakurai, Hiromu; Katoh, Akira

2006-02-01

Control of the glucose level in the blood plasma has been achieved in vitro and in vivo by administration of vanadium and zinc in form of inorganic salts. It has been shown that elements are poorly absorbed in their inorganic forms and required high doses which have been associated with undesirable side effects. Many researchers, therefore, have focused on metal complexes that were prepared from VOSO(4) or ZnSO(4) and low-molecular-weight bidentate ligands. Seven kinds of 1-hydroxy-4,6-disubstituted and 1-hydroxy-4,5,6-trisubstituted-2(1H)-pyrimidinones were synthesized by reaction of N-benzyloxyurea and beta-diketones and subsequent removal of the protecting group. Six kinds of 1-hydroxy-4-(substituted)amino-2(1H)-pyrimidinones were synthesized by the substitution reaction of 1-benzyloxy-4-(1',2',4'-triazol-1'-yl)-2(1H)-pyrimidinone with various alkyl amines or amino acids. Treatment with VOSO(4) and ZnSO(4) or Zn(OAc)(2) afforded vanadyl(IV) and zinc(II) complexes which were characterized by means of (1)H NMR, IR, EPR, and UV-vis spectroscopies, and combustion analysis. The in vitro insulin-mimetic activity of these complexes was evaluated from 50% inhibitory concentrations (IC(50)) on free fatty acid (FFA) release from isolated rat adipocytes treated with epinephrine. Vanadyl complexes of 4,6-disubstituted-2(1H)-pyrimidinones showed higher insulin-mimetic activities than those of 4,5,6-trisubstituted ones. On the other hand, Zn(II) complexes showed lower insulin-mimetic activities than VOSO(4) and ZnSO(4) as positive controls. It was found that the balance of the hydrophilicity and/or hydrophobicity is important for higher insulin-mimetic activity. The in vivo insulin-mimetic activity was evaluated with streptozotocin (STZ)-induced diabetic rats. Blood glucose levels were lowered from hyperglycemic to normal levels after the treatment with bis(1,2-dihydro-4,6-dimethyl-2-oxo-1-pyrimidinolato)oxovanadium(IV) by daily intraperitoneal injections. The improvement in

Subneurotoxic copper(II)-induced NF-κB-dependent microglial activation is associated with mitochondrial ROS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Zhuqin; Yu, Fengxiang; Gong, Ping

2014-04-15

Microglia-mediated neuroinflammation and the associated neuronal damage play critical roles in the pathogenesis of neurodegenerative disorders. Evidence shows an elevated concentration of extracellular copper(II) in the brains of these disorders, which may contribute to neuronal death through direct neurotoxicity. Here we explored whether extracellular copper(II) triggers microglial activation. Primary rat microglia and murine microglial cell line BV-2 cells were cultured and treated with copper(II). The content of tumor necrosis factor-α (TNF-α) and nitric oxide in the medium was determined. Extracellular hydrogen peroxide was quantified by a fluorometric assay with Amplex Red. Mitochondrial superoxide was measured by MitoSOX oxidation. At subneurotoxicmore » concentrations, copper(II) treatment induced a dose- and time-dependent release of TNF-α and nitric oxide from microglial cells, and caused an indirect, microglia-mediated neurotoxicity that was blocked by inhibition of TNF-α and nitric oxide production. Copper(II)-initiated microglial activation was accompanied with reduced IkB-α expression as well as phosphorylation and translocation of nuclear factor-κB (NF-κB) p65 and was blocked by NF-κB inhibitors (BAY11-7082 and SC-514). Moreover, copper(II) treatment evoked a rapid release of hydrogen peroxide from microglial cells, an effect that was not affected by NADPH oxidase inhibitors. N-acetyl-cysteine, a scavenger of reactive oxygen species (ROS), abrogated copper(II)-elicited microglial release of TNF-α and nitric oxide and subsequent neurotoxicity. Importantly, mitochondrial production of superoxide, paralleled to extracellular release of hydrogen peroxide, was induced after copper(II) stimulation. Our findings suggest that extracellular copper(II) at subneurotoxic concentrations could trigger NF-κB-dependent microglial activation and subsequent neurotoxicity. NADPH oxidase-independent, mitochondria-derived ROS may be involved in this activation

Microporous Materials of Metal Carboxylates

NASA Astrophysics Data System (ADS)

Mori, Wasuke; Takamizawa, Satoshi

2000-06-01

Copper(II) terephthalate absorbs a large amount of gases such as N2, Ar, O2, and Xe. The maximum amounts of absorption of gases were 1.8, 1.9, 2.2, and 0.9 mole per mole of the copper(II) salt for N2, Ar, O2, and Xe, respectively, indicating that the gases were not adsorbed on the surface but occluded within the solid. Other microporous copper(II) dicarboxylates are also reviewed. The porous structure of copper(II) terephthalate, in which the gas is occluded, is deduced from the temperature dependence of magnetic susceptibilities and the linear structure of terephthalate. Microporous molybdenum(II) and ruthenium(II, III) dicarboxylates are discussed. We describe that rhodium(II) monocarboxylate bridged by pyrazine form stable micropores by self-assembly of infinite linear chain complexes.

Hydroxyethyl cellulose doped with copper(II) phthalocyanine-tetrasulfonic acid tetrasodium salt as an effective dual functional hole-blocking layer for polymer light-emitting diodes

NASA Astrophysics Data System (ADS)

Wu, Cheng-Liang; Chen, Yun

2017-07-01

We report a doping method to improve the performance of solution-processed polymer light-emitting diodes (PLEDs). Doping 12 wt% copper(II) phthalocyanine-tetrasulfonated acid tetrasodium salt (TS-CuPc) into hydroxyethyl cellulose (HEC) as a dual functional hole-blocking layer (df-HBL) of multilayer PLED (glass/ITO/PEDOT:PSS/HY-PPV/TS-CuPc-doped HEC/LiF/Al) significantly enhanced maximum luminance, maximum current and power efficiency over that without the df-HBL (10,319 cd/m2, 2.98 cd/A and 1.24 lm/W) to (29,205 cd/m2, 13.27 cd/A and 9.56 lm/W). CV measurements reveal that HEC possesses a powerful hole-blocking capability. Topography and conductivity AFM images show that doping TS-CuPc increases the interfacial contact area and interfacial conductivity, which can overcome the insulating nature of HEC and thus further facilitate electron injection. Enhancements in device performance are attributed to the improved carrier balance and recombination in the presence of df-HBL, confirmed in electron-only and hole-only devices. Moreover, apparently raised open-circuit voltages provide further evidence that enhanced electron injection is indeed realized by the df-HBL. This study demonstrates an effective approach to develop highly efficient PLEDs.

Biosorption of Nickel from Industrial Wastewater using Zygnema sp.

NASA Astrophysics Data System (ADS)

Sivaprakash, Kanchana; Blessi T. L., Adlin; Madhavan, Jeyanthi

2015-12-01

Contamination of water sources with heavy metals is a very important pollution problem in the current scenario. Biosorption is an effective method for the removal of heavy metal ions from wastewaters. In this study, the removal of Nickel(II) ions from electroplating industrial wastewater using biosorbent prepared from fresh water algal biomass Zygnema was investigated under batch mode. The sorption efficiency of nickel on Zygnema sp. was evaluated as a function of time, pH and sorbent dosage. The Nickel(II) uptake was dependent on initial pH with pH 3 being the optimum value. For 100 mg/L initial Nickel(II) concentration, sorption equilibrium was attained at a contact time of 100 min. The sorbent dosage affected the biosorption efficiency and maximum removal of 76.4 % was obtained at a dosage of 7.5 g/L. From the performance studies, algal biosorbent Zygnema is found to be a valuable material for the removal of Nickel from industrial wastewater and a better substitute for the conventional adsorbents.

Developing Anticancer Copper(II) Pro-drugs Based on the Nature of Cancer Cells and the Human Serum Albumin Carrier IIA Subdomain.

PubMed

Gou, Yi; Qi, Jinxu; Ajayi, Joshua-Paul; Zhang, Yao; Zhou, Zuping; Wu, Xiaoyang; Yang, Feng; Liang, Hong

2015-10-05

To synergistically enhance the selectivity and efficiency of anticancer copper drugs, we proposed and built a model to develop anticancer copper pro-drugs based on the nature of human serum albumin (HSA) IIA subdomain and cancer cells. Three copper(II) compounds of a 2-hydroxy-1-naphthaldehyde benzoyl hydrazone Schiff-base ligand in the presence pyridine, imidazole, or indazole ligands were synthesized (C1-C3). The structures of three HSA complexes revealed that the Cu compounds bind to the hydrophobic cavity in the HSA IIA subdomain. Among them, the pyridine and imidazole ligands of C1 and C2 are replaced by Lys199, and His242 directly coordinates with Cu(II). The indazole and Br ligands of C3 are replaced by Lys199 and His242, respectively. Compared with the Cu(II) compounds alone, the HSA complexes enhance cytotoxicity in MCF-7 cells approximately 3-5-fold, but do not raise cytotoxicity levels in normal cells in vitro through selectively accumulating in cancer cells to some extent. We find that the HSA complex has a stronger capacity for cell cycle arrest in the G2/M phase of MCF-7 by targeting cyclin-dependent kinase 1 (CDK1) and down-regulating the expression of CDK1 and cyclin B1. Moreover, the HSA complex promotes MCF-7 cell apoptosis possibly through the intrinsic reactive oxygen species (ROS) mediated mitochondrial pathway, accompanied by the regulation of Bcl-2 family proteins.

Biologically active Schiff bases containing thiophene/furan ring and their copper(II) complexes: Synthesis, spectral, nonlinear optical and density functional studies

NASA Astrophysics Data System (ADS)

Gündüzalp, Ayla Balaban; Özsen, İffet; Alyar, Hamit; Alyar, Saliha; Özbek, Neslihan

2016-09-01

Schiff bases; 1,8-bis(thiophene-2-carboxaldimine)-p-menthane (L1) and 1,8-bis(furan-2-carboxaldimine)-p-menthane (L2) have been synthesized and characterized by elemental analysis, 1Hsbnd 13C NMR, UV-vis, FT-IR and LC-MS methods. 1H and 13C shielding tensors for L1 and L2 were calculated with GIAO/DFT/B3LYP/6-311++G(d,p) methods in CDCl3. The vibrational band assignments, nonlinear optical (NLO) activities, frontier molecular orbitals (FMOs) and absorption spectrum have been investigated by the same basis set. Schiff base-copper(II) complexes have been synthesized and structurally characterized with spectroscopic methods, magnetic and conductivity measurements. The spectroscopic data suggest that Schiff base ligands coordinate through azomethine-N and thiophene-S/furan-O donors (as SNNS and ONNO chelating systems) to give a tetragonal geometry around the copper(II) ions. Schiff bases and Cu(II) complexes have been screened for their biological activities on different species of pathogenic bacteria, those are, Gram positive bacteria: Bacillus subtitilus, Yersinia enterotica, Bacillus cereus, Listeria monocytogenes, Micrococcus luteus and Gram negative bacteria: Escherichia coli, Pseudomonas aeroginosa, Shigella dysenteriae, Salmonella typhi, Klebsiella pseudomonas by using microdilution technique (MIC values in mM). Biological activity results show that Cu(II) complexes have higher activities than parent ligands and metal chelation may affect significantly the antibacterial behavior of the organic ligands.

Spectroscopic, structural, electrochemical and computational studies of some new 2-thienyl-containing β-diketonate complexes of cobalt(II), nickel(II) and copper(II)

NASA Astrophysics Data System (ADS)

Ahumada, Guillermo; Fuentealba, Mauricio; Roisnel, Thierry; Kahlal, Samia; Córdova, Ricardo; Carrillo, David; Saillard, Jean-Yves; Hamon, Jean-René; Manzur, Carolina

2017-12-01

In this work, we present the synthesis of the unsymmetrical β-diketone 1-(2-thienyl)-3-(4-fluorophenyl)-propane-1,3-dione (HL) and its corresponding Co(II), Ni(II) and Cu(II) bis(β-diketonato) complexes 1-3, respectively. The four new compounds were isolated in good yields (65-70%), and characterized by mass spectrometry, elemental analysis, FT-IR and UV-Vis spectroscopy and, in the case of HL, by 1H, 13C and 19F NMR spectroscopy. In addition, the molecular identities and the geometries of the β-diketone HL and complex 3 were confirmed by X-ray diffraction analysis. The dicarbonyl derivative HL does exist as the diketo tautomeric form in DMSO solution and as its keto-enol tautomer in the solid-state with the sbnd OH group adjacent to the 4-fluorophenyl unit. The keto-enol isomer was computed to be more stable by 8.2 kcal/mol in free energy at room temperature. In 3, the Cu(II) center adopts a perfect square-planar geometry. Two reduction processes were observed in the cyclovoltammogram of 3 at -1.30 and -1.80 V vs. Fc/Fc+, with copper deposit on the surface of the electrode. DFT and TD-DFT calculations on HL and complex 3 allow rationalizing their stability, bonding and properties.

An Octanuclear Metallosupramolecular Cage Designed To Exhibit Spin-Crossover Behavior.

PubMed

Struch, Niklas; Bannwarth, Christoph; Ronson, Tanya K; Lorenz, Yvonne; Mienert, Bernd; Wagner, Norbert; Engeser, Marianne; Bill, Eckhard; Puttreddy, Rakesh; Rissanen, Kari; Beck, Johannes; Grimme, Stefan; Nitschke, Jonathan R; Lützen, Arne

2017-04-24

By employing the subcomponent self-assembly approach utilizing 5,10,15,20-tetrakis(4-aminophenyl)porphyrin or its zinc(II) complex, 1H-4-imidazolecarbaldehyde, and either zinc(II) or iron(II) salts, we were able to prepare O-symmetric cages having a confined volume of ca. 1300 Å 3 . The use of iron(II) salts yielded coordination cages in the high-spin state at room temperature, manifesting spin-crossover in solution at low temperatures, whereas corresponding zinc(II) salts led to the corresponding diamagnetic analogues. The new cages were characterized by synchrotron X-ray crystallography, high-resolution mass spectrometry, and NMR, Mössbauer, IR, and UV/Vis spectroscopy. The cage structures and UV/Vis spectra were independently confirmed by state-of-the-art DFT calculations. A remarkably high-spin-stabilizing effect through encapsulation of C 70 was observed. The spin-transition temperature T 1/2 is lowered by 20 K in the host-guest complex. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Copper(II) complex with 6-methylpyridine-2-carboxyclic acid: Experimental and computational study on the XRD, FT-IR and UV-Vis spectra, refractive index, band gap and NLO parameters

NASA Astrophysics Data System (ADS)

Altürk, Sümeyye; Avcı, Davut; Başoğlu, Adil; Tamer, Ömer; Atalay, Yusuf; Dege, Necmi

2018-02-01

Crystal structure of the synthesized copper(II) complex with 6-methylpyridine-2-carboxylic acid, [Cu(6-Mepic)2·H2O]·H2O, was determined by XRD, FT-IR and UV-Vis spectroscopic techniques. Furthermore, the geometry optimization, harmonic vibration frequencies for the Cu(II) complex were carried out by using Density Functional Theory calculations with HSEh1PBE/6-311G(d,p)/LanL2DZ level. Electronic absorption wavelengths were obtained by using TD-DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ level with CPCM model and major contributions were determined via Swizard/Chemissian program. Additionally, the refractive index, linear optical (LO) and non-nonlinear optical (NLO) parameters of the Cu(II) complex were calculated at HSEh1PBE/6-311G(d,p) level. The experimental and computed small energy gap shows the charge transfer in the Cu(II) complex. Finally, the hyperconjugative interactions and intramolecular charge transfer (ICT) were studied by performing of natural bond orbital (NBO) analysis.

Copper(II) complex with 6-methylpyridine-2-carboxyclic acid: Experimental and computational study on the XRD, FT-IR and UV-Vis spectra, refractive index, band gap and NLO parameters.

PubMed

Altürk, Sümeyye; Avcı, Davut; Başoğlu, Adil; Tamer, Ömer; Atalay, Yusuf; Dege, Necmi

2018-02-05

Crystal structure of the synthesized copper(II) complex with 6-methylpyridine-2-carboxylic acid, [Cu(6-Mepic) 2 ·H 2 O]·H 2 O, was determined by XRD, FT-IR and UV-Vis spectroscopic techniques. Furthermore, the geometry optimization, harmonic vibration frequencies for the Cu(II) complex were carried out by using Density Functional Theory calculations with HSEh1PBE/6-311G(d,p)/LanL2DZ level. Electronic absorption wavelengths were obtained by using TD-DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ level with CPCM model and major contributions were determined via Swizard/Chemissian program. Additionally, the refractive index, linear optical (LO) and non-nonlinear optical (NLO) parameters of the Cu(II) complex were calculated at HSEh1PBE/6-311G(d,p) level. The experimental and computed small energy gap shows the charge transfer in the Cu(II) complex. Finally, the hyperconjugative interactions and intramolecular charge transfer (ICT) were studied by performing of natural bond orbital (NBO) analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-assembled copper(II) metallacycles derived from asymmetric Schiff base ligands: efficient hosts for ADP/ATP in phosphate buffer.

PubMed

Kumar, Amit; Pandey, Rampal; Kumar, Ashish; Gupta, Rakesh Kumar; Dubey, Mrigendra; Mohammed, Akbar; Mobin, Shaikh M; Pandey, Daya Shankar

2015-10-21

Novel asymmetric Schiff base ligands 2-{[3-(3-hydroxy-1-methyl-but-2-enylideneamino)-2,4,6-trimethylphenylimino]-methyl}-phenol (H2L(1)) and 1-{[3-(3-hydroxy-1-methyl-but-2-enylideneamino)-2,4,6-trimethylphenylimino]-methyl}-naphthalen-2-ol (H2L(2)) possessing dissimilar N,O-chelating sites and copper(ii) metallacycles (CuL(1))4 (1) and (CuL(2))4 (2) based on these ligands have been described. The ligands and complexes have been thoroughly characterized by satisfactory elemental analyses, and spectral (IR, (1)H, (13)C NMR, ESI-MS, UV/vis) and electrochemical studies. Structures of H2L(2) and 1 have been unambiguously determined by X-ray single crystal analyses. The crystal structure of H2L(2) revealed the presence of two distinct N,O-chelating sites on dissimilar cores (naphthalene and β-ketoaminato groups) offering a diverse coordination environment. Metallacycles 1 and 2 having a cavity created by four Cu(ii) centres coordinated in a homo- and heteroleptic fashion with respective ligands act as efficient hosts for adenosine-5'-diphosphate (ADP) and adenosine-5'-triphosphate (ATP) respectively, over other nucleoside polyphosphates (NPPs). The disparate sensitivity of these metallacycles toward ADP and ATP has been attributed to the size of the ligands assuming diverse dimensions and spatial orientations. These are attuned for π-π stacking and electrostatic interactions suitable for different guest molecules under analogous conditions, metallacycle 1 offers better orientation for ADP, while 2 for ATP. The mechanism of the host-guest interaction has been investigated by spectral and electrochemical studies and supported by molecular docking studies.

Permanganate-assisted removal of PCR inhibitors during the DNA Chelex extraction from stained denim samples.

PubMed

Pîrlea, Sorina; Puiu, Mihaela; Răducan, Adina; Oancea, Dumitru

2017-03-01

In this study, it was demonstrated that the DNA Chelex extraction combined with the permanganate assisted-oxidation is highly efficient in removing the PCR inhibitors often found in clothing materials, such as phthalocyanine. The extraction assays were conducted in saliva, blood and epithelial cells samples mixed with three oxidation-resistant dye copper(II) α-phthalocyanine, copper(II) β-phthalocyanine and tetrasulfonated copper(II) β-phthalocyanine. After DNA amplification, all samples were able to provide full DNA profiles. The permanganate/Chelex system was tested further on denim-stained samples and displayed the same ability to remove the PCR inhibitors from the commercial textile materials.

Copper(II) complexes with 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid: Syntheses, crystal structures and antifungal activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, Pingping; Li, Jie; Bu, Huaiyu, E-mail: 7213792@qq.com

2014-07-01

Reaction of Cu(II) with an asymmetric semi-rigid organic ligand 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid (HL), yielded five compounds, [Cu{sub 0.5}L]{sub n} (1), [Cu(HL){sub 2}Cl{sub 2}]{sub n} (2), [Cu(HL){sub 2}Cl{sub 2}(H{sub 2}O)] (3), [Cu(L){sub 2}(H{sub 2}O)]{sub n} (4) and [Cu(L)(phen)(HCO{sub 2})]{sub n} (5), which have been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. As for compounds 1, 2 and 5, Cu(II) is bridged through HL, Cl{sup -}, and formic acid, respectively, featuring 1D chain-structure. In compound 3, Cu(II) with hexahedral coordination sphere is assembled through hydrogen-bonding into 3D supramolecular framework. In compound 4, 1D chain units –Cu–O–Cu–O–more » are ligand-bridged into a 3D network. All compounds were tested on fungi (Fusarium graminearum, Altemaria solani, Macrophoma kawatsukai, Alternaria alternata and Colletotrichum gloeosporioides). Compound 1 exhibits a better antifungal effect compared to other compounds. An effect of structure on the antifungal activity has also been correlated. - Graphical abstract: Copper(II) compounds with 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid, were prepared, structurally characterized and investigated for antifungal activity. - Highlights: • The title compounds formed by thermodynamics and thermokinetics. • The five compounds show higher inhibition percentage than reactants. • The structure effect on the antifungal activity.« less

Hydrolysis mechanisms of BNPP mediated by facial copper(II) complexes bearing single alkyl guanidine pendants: cooperation between the metal centers and the guanidine pendants.

PubMed

Zhang, Xuepeng; Liu, Xueping; Phillips, David Lee; Zhao, Cunyuan

2016-01-28

The hydrolysis mechanisms of DNA dinucleotide analogue BNPP(-) (bis(p-nitrophenyl) phosphate) catalyzed by mononuclear/dinuclear facial copper(ii) complexes bearing single alkyl guanidine pendants were investigated using density functional theory (DFT) calculations. Active catalyst forms have been investigated and four different reaction modes are proposed accordingly. The [Cu2(L(1))2(μ-OH)](3+) (L(1) is 1-(2-guanidinoethyl)-1,4,7-triazacyclononane) complex features a strong μ-hydroxo mediated antiferromagnetic coupling between the bimetallic centers and the corresponding more stable open-shell singlet state. Three different reaction modes involving two catalysts and a substrate were proposed for L(1) entries and the mode 1 in which an inter-complex nucleophilic attack by a metal bound hydroxide was found to be more favorable. In the L(3)-involved reactions (L(3) is 1-(4-guanidinobutyl)-1,4,7-triazacyclononane), the reaction mode in which an in-plane intracomplex scissoring-like nucleophilic attack by a Cu(ii)-bound hydroxide was found to be more competitive. The protonated guanidine pendants in each proposed mechanism were found to play crucial roles in stabilizing the reaction structures via hydrogen bonds and in facilitating the departure of the leaving group via electrostatic attraction. The calculated results are consistent with the experimental observations that the Cu(ii)-L(3) complexes are hydrolytically more favorable than their L(1)-involved counterparts.

In-vivo evaluation of the response of Galleria mellonella larvae to novel copper(II) phenanthroline-phenazine complexes.

PubMed

Rochford, Garret; Molphy, Zara; Browne, Niall; Surlis, Carla; Devereux, Michael; McCann, Malachy; Kellett, Andrew; Howe, Orla; Kavanagh, Kevin

2018-06-01

Herein we report the in-vivo characterisation and metabolic changes in Galleria mellonella larvae to a series of bis-chelate copper(II) phenanthroline-phenazine cationic complexes of [Cu(phen) 2 ] 2+ (Cu-Phen), [Cu(DPQ)(Phen)] 2+ (Cu-DPQ-Phen) and [Cu(DPPZ)(Phen)] 2+ (Cu-DPPZ-Phen) (where phen = 1,10-phenanthroline, DPQ = dipyrido[3,2-ƒ:2',3'-h]quinoxaline and DPPZ = dipyrido[3,2-a:2',3'-c]phenazine). Our aim was to investigate the influence of the systematic extension of the ligated phenazine ligand in the G. mellonella model as a first step towards assessing the in-vivo tolerance and mode of action of the complex series with respect to the well-studied oxidative chemical nuclease, Cu-Phen. The Lethal Dose 50 (LD 50 ) values were established over dose ranges of 2 - 30 μg at 4-, 24-, 48- and 72 h by mortality assessment, with Cu-Phen eliciting the highest mortality at 4 h (Cu-Phen, 12.62 μg < Cu-DPQ-Phen, 21.53 μg < Cu-DPPZ-Phen, 26.07 μg). At other timepoints, a similar profile was observed as the phenazine π-backbone within the complex scaffold was extended. Assessment of both cellular response and related gene expression demonstrated that the complexes did not initiate an immune response. However, Label-Free Quantification proteomic data indicated the larval response was associated with upregulation of key proteins such as Glutathione S-transferase, purine synthesis and glycolysis/gluconeogenesis (e.g. fructose-bisphosphate aldolase and glyceraldehyde-3-phosphate). Both Cu-Phen and Cu-DPQ-Phen elicited a similar in-vivo response in contrast to Cu-DPPZ-Phen, which displayed a substantial increase in nitrogen detoxification proteins and proteins with calcium binding sites. Overall, the response of G. mellonella larvae exposure to the complex series is dominated by detoxification and metabolic proteome response mechanisms. Copyright © 2018 Elsevier Inc. All rights reserved.

Separation and Precipitation of Nickel from Acidic Sulfate Leaching Solution of Molybdenum-Nickel Black Shale by Potassium Nickel Sulfate Hexahydrate Crystallization

NASA Astrophysics Data System (ADS)

Deng, Zhigan; Wei, Chang; Fan, Gang; Li, Xingbin; Li, Minting; Li, Cunxiong

2018-02-01

Nickel was separated and precipitated with potassium nickel sulfate hexahydrate [K2Ni(SO4)2·6H2O] from acidic sulfate solution, a leach solution from molybdenum-nickel black shale. The effects of the potassium sulfate (K2SO4) concentration, crystallization temperature, solution pH, and crystallization time on nickel(II) recovery and iron(III) precipitation were investigated, revealing that nickel and iron were separated effectively. The optimum parameters were K2SO4 concentration of 200 g/L, crystallization temperature of 10°C, solution pH of 0.5, and crystallization time of 24 h. Under these conditions, 97.6% nickel(II) was recovered as K2Ni(SO4)2·6H2O crystals while only 2.0% of the total iron(III) was precipitated. After recrystallization, 98.4% pure K2Ni(SO4)2·6H2O crystals were obtained in the solids. The mother liquor was purified by hydrolysis-precipitation followed by cooling, and more than 99.0% K2SO4 could be crystallized. A process flowsheet was developed to separate iron(III) and nickel(II) from acidic-sulfate solution.

Synthesis, characterization and biological activity of complexes of 2-hydroxy-3,5-dimethylacetophenoneoxime (HDMAOX) with copper(II), cobalt(II), nickel(II) and palladium(II)

NASA Astrophysics Data System (ADS)

Singh, Bibhesh K.; Jetley, Umesh K.; Sharma, Rakesh K.; Garg, Bhagwan S.

2007-09-01

A new series of complexes of 2-hydroxy-3,5-dimethyl acetophenone oxime (HDMAOX) with Cu(II), Co(II), Ni(II) and Pd(II) have been prepared and characterized by different physical techniques. Infrared spectra of the complexes indicate deprotonation and coordination of the phenolic OH. It also confirms that nitrogen atom of the oximino group contributes to the complexation. Electronic spectra and magnetic susceptibility measurements reveal square planar geometry for Cu(II), Ni(II) and Pd(II) complexes and tetrahedral geometry for Co(II) complex. The elemental analyses and mass spectral data have justified the ML 2 composition of complexes. Kinetic and thermodynamic parameters were computed from the thermal decomposition data using Coats and Redfern method. The geometry of the metal complexes has been optimized with the help of molecular modeling. The free ligand (HDMAOX) and its metal complexes have been tested in vitro against Alternarie alternate, Aspergillus flavus, Aspergillus nidulans and Aspergillus niger fungi and Streptococcus, Staph, Staphylococcus and Escherchia coli bacteria in order to assess their antimicrobial potential. The results indicate that the ligand and its metal complexes possess antimicrobial properties.

Design, synthesis, spectral characterization, DNA interaction and biological activity studies of copper(II), cobalt(II) and nickel(II) complexes of 6-amino benzothiazole derivatives

NASA Astrophysics Data System (ADS)

Daravath, Sreenu; Kumar, Marri Pradeep; Rambabu, Aveli; Vamsikrishna, Narendrula; Ganji, Nirmala; Shivaraj

2017-09-01

Two novel Schiff bases, L1 = (2-benzo[d]thiazol-6-ylimino)methyl)-4,6-dichlorophenol), L2 = (1-benzo[d]thiazol-6-ylimino)methyl)-6-bromo-4-chlorophenol) and their bivalent transition metal complexes [M(L1)2] and [M(L2)2], where M = Cu(II), Co(II) and Ni(II) were synthesized and characterized by elemental analysis, NMR, IR, UV-visible, mass, magnetic moments, ESR, TGA, SEM, EDX and powder XRD. Based on the experimental data a square planar geometry around the metal ion is assigned to all the complexes (1a-2c). The interaction of synthesized metal complexes with calf thymus DNA was explored using UV-visible absorption spectra, fluorescence and viscosity measurements. The experimental evidence indicated that all the metal complexes strongly bound to CT-DNA through an intercalation mode. DNA cleavage experiments of metal(II) complexes with supercoiled pBR322 DNA have also been explored by gel electrophoresis in the presence of H2O2 as well as UV light, and it is found that the Cu(II) complexes cleaved DNA more effectively compared to Co(II), Ni(II) complexes. In addition, the ligands and their metal complexes were screened for antimicrobial activity and it is found that all the metal complexes were more potent than free ligands.

Synthesis, characterization and biological activity of complexes of 2-hydroxy-3,5-dimethylacetophenoneoxime (HDMAOX) with copper(II), cobalt(II), nickel(II) and palladium(II).

PubMed

Singh, Bibhesh K; Jetley, Umesh K; Sharma, Rakesh K; Garg, Bhagwan S

2007-09-01

A new series of complexes of 2-hydroxy-3,5-dimethyl acetophenone oxime (HDMAOX) with Cu(II), Co(II), Ni(II) and Pd(II) have been prepared and characterized by different physical techniques. Infrared spectra of the complexes indicate deprotonation and coordination of the phenolic OH. It also confirms that nitrogen atom of the oximino group contributes to the complexation. Electronic spectra and magnetic susceptibility measurements reveal square planar geometry for Cu(II), Ni(II) and Pd(II) complexes and tetrahedral geometry for Co(II) complex. The elemental analyses and mass spectral data have justified the ML(2) composition of complexes. Kinetic and thermodynamic parameters were computed from the thermal decomposition data using Coats and Redfern method. The geometry of the metal complexes has been optimized with the help of molecular modeling. The free ligand (HDMAOX) and its metal complexes have been tested in vitro against Alternarie alternate, Aspergillus flavus, Aspergillus nidulans and Aspergillus niger fungi and Streptococcus, Staph, Staphylococcus and Escherchia coli bacteria in order to assess their antimicrobial potential. The results indicate that the ligand and its metal complexes possess antimicrobial properties.

Preparation and Analysis of Libethenite: A Project for the First-Year Laboratory

ERIC Educational Resources Information Center

Ginion, Kelly E.; Yoder, Claude H.

2004-01-01

The preparation of libethenite, a double salt of copper(II) phosphate and copper(II) hydroxide presents the opportunity to discuss the prevalence of double salts in the environment, the relationship between solubility and stability in aqueous solution, the origin of the color of transition metal compounds and gravimetric analyses. Typical results…

Copper(II) sorption onto goethite, hematite and lepidocrocite: a surface complexation model based on ab initio molecular geometries and EXAFS spectroscopy

NASA Astrophysics Data System (ADS)

Peacock, Caroline L.; Sherman, David M.

2004-06-01

We measured the adsorption of Cu(II) onto goethite (α-FeOOH), hematite (α-Fe 2O 3) and lepidocrocite (γ-FeOOH) from pH 2-7. EXAFS spectra show that Cu(II) adsorbs as (CuO 4H n) n-6 and binuclear (Cu 2O 6H n) n-8 complexes. These form inner-sphere complexes with the iron (hydr)oxide surfaces by corner-sharing with two or three edge-sharing Fe(O,OH) 6 polyhedra. Our interpretation of the EXAFS data is supported by ab initio (density functional theory) geometries of analogue Fe 2(OH) 2(H 2O) 8Cu(OH) 4and Fe 3(OH) 4(H 2O) 10Cu 2(OH) 6 clusters. We find no evidence for surface complexes resulting from either monodentate corner-sharing or bidentate edge-sharing between (CuO 4H n) n-6 and Fe(O,OH) 6 polyhedra. Sorption isotherms and EXAFS spectra show that surface precipitates have not formed even though we are supersaturated with respect to CuO and Cu(OH) 2. Having identified the bidentate (FeOH) 2Cu(OH) 20 and tridentate (Fe 3O(OH) 2)Cu 2(OH) 30 surface complexes, we are able to fit the experimental copper(II) adsorption data to the reactions 3( FeOH)+2 Cu2++3 H2O=( Fe3O( OH) 2) Cu2( OH) 30+4 H+ and 2( FeOH)+ Cu2++2 H2O=( FeOH) 2Cu( OH) 20+2 H+. The two stability constants are similar for the three iron (hydr)oxide phases investigated.

A luminescent zinc(ii) coordination polymer with unusual (3,4,4)-coordinated self-catenated 3D network for selective detection of nitroaromatics and ferric and chromate ions: a versatile luminescent sensor.

PubMed

Zhang, Ya-Qian; Blatov, Vladislav A; Zheng, Tian-Rui; Yang, Chang-Hao; Qian, Lin-Lu; Li, Ke; Li, Bao-Long; Wu, Bing

2018-05-01

A zinc(ii) coordination polymer {[Zn3(mtrb)3(btc)2]·3H2O}n (1) was synthesized and characterized (mtrb = 1,3-bis(1,2,4-triazole-4-ylmethyl)benzene, btc = 1,3,5-benzenetricarboxylate). The polymer 1 shows an unusual (3,4,4)-coordinated self-catenated 3D network with the point symbol of {63}2{62·82·102}{64·82}2. The polymer 1 is the first luminescent sensor for the detection of 2-amino-4-nitrophenol (ANP). The polymer 1 is also a good luminescence sensor for detection of TNP, 2,4-DNP, 4-NP, ANP and 2-NP in MeOH, particularly for TNP. The order of detection efficiency is TNP > 2,4-DNP > 4-NP > ANP > 2-NP. The polymer 1 also exhibits high sensitivity and selectivity as a luminescence sensor for the detection of Fe3+, Cr2O72- and CrO42- in aqueous solution. Our experiments showed that the presence of interfering ions had no significant effect on the sensing of Fe3+, Cr2O72- or CrO42- ions. The detection limits for TNP, ANP, Fe3+, Cr2O72- and CrO42- are 0.22 μM, 4.12 μM, 1.78 μM, 2.83 μM, and 4.52 μM, respectively. The luminescence sensor is stable and can be recycled for detection at least five times. The possible quenching mechanisms are discussed. The polymer 1 is also an effective photocatalyst for degradation of methylene blue (MB) under visible or UV light irradiation.

Synthesis, and structural characterization of mixed ligand copper(II) complexes of N,N,N‧,N'-tetramethylethylenediamine incorporating carboxylates

NASA Astrophysics Data System (ADS)

Batool, Syeda Shahzadi; Gilani, Syeda Rubina; Tahir, Muhammad Nawaz; Rüffer, Tobias

2017-11-01

Two ternary copper(II) complexes of N,N,N‧,N'-tetramethylethylenediamine (tmen = C6H16N2) with benzoic acid and p-aminobenzoic acid, having the formula [Cu(tmen)(BA)2(H2O)2] (1), and [Cu(tmen)(pABA)2]. 1/2 CH3OH (2) {(Where BA1- = benzoate1- (C6H5CO21-), pABA1- = p-aminobenzoate1- (p-H2NC6H5CO21-)} have been prepared and characterized by elemental combustion analysis, Uv-Visible spectroscopy, FT-IR spectroscopy, thermal, and single crystal X-ray diffraction analyses. The complex 1 is a monomer with distorted octahedral geometry. In its CuN2O4 chromophore, the Cu(II) centre is coordinated by two N atoms of a symmetrically chelating tmen ligand, by two carboxylate-O atoms from two monodentate benzoate1- anions, and by two apical aqua-O atoms, which define the distorted octahedral structure. The complex 2 is a monomer with a distorted square planar coordination geometry. In CuN2O2 chromophore, tmen is coordinated to Cu(II) ion in a chelating bidentate fashion, while the two p-aminobenzoate1- anions coordinate to Cu(II) centre through their carboxylate-O atoms in a monodentate manner, forming a square planar structure. The observed difference between asymmetric ѵas(OCO) and symmetric ѵs(OCO) stretching IR vibrations of the carboxylate moieties for 1 and 2 is 220 cm-1 and 232 cm-1, respectively, which suggests monodentate coordination mode (Δν OCO>200) of the carboxylate groups to Cu(II) ion. Thermogravimetric studies of 1 indicates removal of two water molecules at 171 °C, elimination of a tmen upto 529 °C and of two benzoate groups upto 931 °C. In tga curve of 2, methanol is lost upto 212 °C, while tmen is lost from 212 to 993 °C. The antibacterial activities of these new compounds against various bacterial strains were also investigated.

Hole transport in pure and doped hematite

NASA Astrophysics Data System (ADS)

Liao, Peilin; Carter, Emily A.

2012-07-01

Hematite (α-Fe2O3) is a promising candidate for use in photovoltaic (PV) and photoelectrochemical devices. Its poor conductivity is one major drawback. Doping hematite either p-type or n-type greatly enhances its measured conductivity and is required for potential p-n junctions in PVs. Here, we study hole transport in pure and doped hematite using an electrostatically embedded cluster model with ab initio quantum mechanics (unrestricted Hartree-Fock theory). Consistent with previous work, the model suggests that hole hopping is via oxygen anions for pure hematite. The activation energy for hole mobility is predicted to be at least 0.1 eV higher than the activation energy for electron mobility, consistent with the trend observed in experiments. We examine four dopants—magnesium(II), nickel(II), copper(II), and manganese(II/III) in direct cation substitution sites—to gain insight into the mechanism by which conductivity is improved. The activation energies are used to assess qualitative effects of different dopants. The hole carriers are predicted to be attracted to O anions near the dopants. The magnitude of the trapping effect is similar among the four dopants in their +2 oxidation states. The multivalent character of Mn doping facilitates local hole transport around Mn centers via a low-barrier O-Mn-O pathway, which suggests that higher hole mobility can be achieved with increasing Mn doping concentration, especially when a network of these low-barrier pathways is produced. Our results suggest that the experimentally observed conductivity increase in Mg-, Ni-, and Cu-doped p-type hematite is mostly due to an increase in hole carriers rather than improved mobility, and that Mg-, Ni-, and Cu-doping perform similarly, while the conductivity of Mn-doped hematite might be significantly improved in the high doping concentration limit.

Charge and Spin States in Schiff Base Metal Complexes with a Disiloxane Unit Exhibiting a Strong Noninnocent Ligand Character: Synthesis, Structure, Spectroelectrochemistry, and Theoretical Calculations.

PubMed

Cazacu, Maria; Shova, Sergiu; Soroceanu, Alina; Machata, Peter; Bucinsky, Lukas; Breza, Martin; Rapta, Peter; Telser, Joshua; Krzystek, J; Arion, Vladimir B

2015-06-15

Mononuclear nickel(II), copper(II), and manganese(III) complexes with a noninnocent tetradentate Schiff base ligand containing a disiloxane unit were prepared in situ by reaction of 3,5-di-tert-butyl-2-hydroxybenzaldehyde with 1,3-bis(3-aminopropyl)tetramethyldisiloxane followed by addition of the appropriate metal(II) salt. The ligand H2L resulting from these reactions is a 2:1 condensation product of 3,5-di-tert-butyl-2-hydroxybenzaldehyde with 1,3-bis(3-aminopropyl)tetramethyldisiloxane. The resulting metal complexes, NiL·0.5CH2Cl2, CuL·1.5H2O, and MnL(OAc)·0.15H2O, were characterized by elemental analysis, spectroscopic methods (IR, UV-vis, X-band EPR, HFEPR, (1)H NMR), ESI mass spectrometry, and single crystal X-ray diffraction. Taking into account the well-known strong stabilizing effects of tert-butyl groups in positions 3 and 5 of the aromatic ring on phenoxyl radicals, we studied the one-electron and two-electron oxidation of the compounds using both experimental (chiefly spectroelectrochemistry) and computational (DFT) techniques. The calculated spin-density distribution and localized orbitals analysis revealed the oxidation locus and the effect of the electrochemical electron transfer on the molecular structure of the complexes, while time-dependent DFT calculations helped to explain the absorption spectra of the electrochemically generated species. Hyperfine coupling constants, g-tensors, and zero-field splitting parameters have been calculated at the DFT level of theory. Finally, the CASSCF approach has been employed to theoretically explore the zero-field splitting of the S = 2 MnL(OAc) complex for comparison purposes with the DFT and experimental HFEPR results. It is found that the D parameter sign strongly depends on the metal coordination geometry.

Ferrate(VI)-prompted removal of metals in aqueous media: mechanistic delineation of enhanced efficiency via metal entrenchment in magnetic oxides.

PubMed

Prucek, Robert; Tuček, Jiří; Kolařík, Jan; Hušková, Ivana; Filip, Jan; Varma, Rajender S; Sharma, Virender K; Zbořil, Radek

2015-02-17

The removal efficiency of heavy metal ions (cadmium(II), Cd(II); cobalt(II), Co(II); nickel(II), Ni(II); copper(II), Cu(II)) by potassium ferrate(VI) (K2FeO4, Fe(VI)) was studied as a function of added amount of Fe(VI) (or Fe) and varying pH. At pH = 6.6, the effective removal of Co(II), Ni(II), and Cu(II) from water was observed at a low Fe-to-heavy metal ion ratio (Fe/M(II) = 2:1) while a removal efficiency of 70% was seen for Cd(II) ions at a high Fe/Cd(II) weight ratio of 15:1. The role of ionic radius and metal valence state was explored by conducting similar removal experiments using Al(III) ions. The unique combination of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), in-field Mössbauer spectroscopy, and magnetization measurements enabled the delineation of several distinct mechanisms for the Fe(VI)-prompted removal of metal ions. Under a Fe/M weight ratio of 5:1, Co(II), Ni(II), and Cu(II) were removed by the formation of MFe2O4 spinel phase and partially through their structural incorporation into octahedral positions of γ-Fe2O3 (maghemite) nanoparticles. In comparison, smaller sized Al(III) ions got incorporated easily into the tetrahedral positions of γ-Fe2O3 nanoparticles. In contrast, Cd(II) ions either did not form the spinel ferrite structure or were not incorporated into the lattic of iron(III) oxide phase due to the distinct electronic structure and ionic radius. Environmentally friendly removal of heavy metal ions at a much smaller dosage of Fe than those of commonly applied iron-containing coagulants and the formation of ferrimagnetic species preventing metal ions leaching back into the environment and allowing their magnetic separation are highlighted.

Characterization of recombinant E. coli expressing arsR from Rhodopseudomonas palustris CGA009 that displays highly selective arsenic adsorption.

PubMed

Ke, Changdong; Zhao, Chungui; Rensing, Christopher; Yang, Suping; Zhang, Yi

2018-05-22

Innovative methods to lower arsenic (As) exposure are sought. The As regulatory protein (ArsR) is reported of having high affinity and specificity to arsenite [As(III)]. Rhodopseudomonas palustris CGA009 is a good model organism for studying As detoxification due to at least three ars operons and four diverse arsR RP1-4 on the genome. In this study, four Escherichia coli harboring arsR RP1-4 derived from CGA009 were engineered and tested regarding their As resistance. The results showed that E. coli (arsR RP2 ) displayed robust As(III) resistance, and its growth inhibition rate was only 2.9% when exposed to 3.0 mmol/L As(III). At pH 7.0, E. coli (arsR RP2 ) showed an enhanced As adsorption capacity. As(III) (2.32 mg/g (dry weight, dw)) and 1.47 mg/g arsenate [As(V)] was adsorbed representing a 4.2-fold and 1.3-fold increase respectively compared to the control strain. The adsorption process was well fitted to Langmuir isothermal mode. E. coli (arsR RP2 ) (1.0~12.0 g/L) could remove 30.3~82.2% of As (III) when exposed to 10 μg/L As(III). No increase in absorption to copper(II), zinc(II), chromium(III), and lead(II) could be detected. Our studies revealed that arsR RP1-4 from CGA009 could confer As(III) resistance; E. coli (arsR RP2 ) displayed the highest As resistance, selectivity, and adsorption capacity within a wider pH (5.0~9.0) and salinity (0~15.0 g/L NaCl) range, especially important as it could remove As(III) from low concentration As-containing water.

Evaluation of exchange-correlation functionals for time-dependent density functional theory calculations on metal complexes.

PubMed

Holland, Jason P; Green, Jennifer C

2010-04-15

The electronic absorption spectra of a range of copper and zinc complexes have been simulated by using time-dependent density functional theory (TD-DFT) calculations implemented in Gaussian03. In total, 41 exchange-correlation (XC) functionals including first-, second-, and third-generation (meta-generalized gradient approximation) DFT methods were compared in their ability to predict the experimental electronic absorption spectra. Both pure and hybrid DFT methods were tested and differences between restricted and unrestricted calculations were also investigated by comparison of analogous neutral zinc(II) and copper(II) complexes. TD-DFT calculated spectra were optimized with respect to the experimental electronic absorption spectra by use of a Matlab script. Direct comparison of the performance of each XC functional was achieved both qualitatively and quantitatively by comparison of optimized half-band widths, root-mean-squared errors (RMSE), energy scaling factors (epsilon(SF)), and overall quality-of-fit (Q(F)) parameters. Hybrid DFT methods were found to outperform all pure DFT functionals with B1LYP, B97-2, B97-1, X3LYP, and B98 functionals providing the highest quantitative and qualitative accuracy in both restricted and unrestricted systems. Of the functionals tested, B1LYP gave the most accurate results with both average RMSE and overall Q(F) < 3.5% and epsilon(SF) values close to unity (>0.990) for the copper complexes. The XC functional performance in spin-restricted TD-DFT calculations on the zinc complexes was found to be slightly worse. PBE1PBE, mPW1PW91 and B1LYP gave the most accurate results with typical RMSE and Q(F) values between 5.3 and 7.3%, and epsilon(SF) around 0.930. These studies illustrate the power of modern TD-DFT calculations for exploring excited state transitions of metal complexes. 2009 Wiley Periodicals, Inc.

Removal of Heavy Metal Ions with Acid Activated Carbons Derived from Oil Palm and Coconut Shells

PubMed Central

Rahman, Mokhlesur M.; Adil, Mohd; Yusof, Alias M.; Kamaruzzaman, Yunus B.; Ansary, Rezaul H.

2014-01-01

In this work, batch adsorption experiments were carried out to investigate the suitability of prepared acid activated carbons in removing heavy metal ions such as nickel(II), lead(II) and chromium(VI). Acid activated carbons were obtained from oil palm and coconut shells using phosphoric acid under similar activation process while the differences lie either in impregnation condition or in both pretreatment and impregnation conditions. Prepared activated carbons were modified by dispersing hydrated iron oxide. The adsorption equilibrium data for nickel(II) and lead(II) were obtained from adsorption by the prepared and commercial activated carbons. Langmuir and Freundlich models fit the data well. Prepared activated carbons showed higher adsorption capacity for nickel(II) and lead(II). The removal of chromium(VI) was studied by the prepared acid activated, modified and commercial activated carbons at different pH. The isotherms studies reveal that the prepared activated carbon performs better in low concentration region while the commercial ones in the high concentration region. Thus, a complete adsorption is expected in low concentration by the prepared activated carbon. The kinetics data for Ni(II), Pb(II) and Cr(VI) by the best selected activated carbon fitted very well to the pseudo-second-order kinetic model. PMID:28788640

Copper complexes as a source of redox active MRI contrast agents.

PubMed

Dunbar, Lynsey; Sowden, Rebecca J; Trotter, Katherine D; Taylor, Michelle K; Smith, David; Kennedy, Alan R; Reglinski, John; Spickett, Corinne M

2015-10-01

The study reports an advance in designing copper-based redox sensing MRI contrast agents. Although the data demonstrate that copper(II) complexes are not able to compete with lanthanoids species in terms of contrast, the redox-dependent switch between diamagnetic copper(I) and paramagnetic copper(II) yields a novel redox-sensitive contrast moiety with potential for reversibility.

Cationic Zn-Porphyrin Polymer Coated onto CNTs as a Cooperative Catalyst for the Synthesis of Cyclic Carbonates.

PubMed

Jayakumar, Sanjeevi; Li, He; Chen, Jian; Yang, Qihua

2018-01-24

The development of solid catalysts containing multiple active sites that work cooperatively is very attractive for biomimetic catalysis. Herein, we report the synthesis of bifunctional catalysts by supporting cationic porphyrin-based polymers on carbon nanotubes (CNTs) using the direct reaction of 5,10,15,20-tetrakis(4-pyridyl)porphyrin zinc(II), di(1H-imidazol-1-yl)methane, and 1,4-bis(bromomethyl)benzene in the presence of CNTs. The bifunctional catalysts could efficiently catalyze the cycloaddition reaction of epoxides and CO 2 under solvent-free conditions with porphyrin zinc(II) as the Lewis acid site and a bromine anion as a nucleophilic agent working in a cooperative way. Furthermore, a relative amount of porphyrin zinc(II) and quaternary ammonium bromide could be facilely adjusted for facilitating cooperative behavior. The bifunctional catalyst with a TOF up to 2602 h -1 is much more active than the corresponding homogeneous counterpart and is one of the most active heterogeneous catalysts ever reported under cocatalyst-free conditions. The high activity is mainly attributed to the enhanced cooperation effect of the bifunctional catalyst. With a wide substrate scope, the bifunctional catalyst could be stably recycled. This work demonstrates a new approach for the generation of a cooperative activation effect for solid catalysts.

Syntheses, characterization and antioxidant activity studies of mixed-ligand copper(II) complexes of 2,2‧-bipyridine and glycine: The X-ray crystal structure of [Cu(BPy)(Gly)]ClO4

NASA Astrophysics Data System (ADS)

Ibrahim, Mohamed M.; Ramadan, Abd El-Motaleb M.; Shaban, Shaban Y.; Mersal, Gaber A. M.; El-Shazly, Samir A.; Al-Juaid, Salih

2017-04-01

A series of mixed-ligand complexes, viz., [CuLL'X]Y {L = bipyridine; L' = glycine; X = 0, Y = ClO4- (1); X = Cl, Y = 2H2O (2); X = H2O, Y = NO3- (3); X = CH3COO-, Y = H2O (4)} and {[Cu(Gly)(BPy)]2-μ-(SO4)}(5)} have been synthesized and characterized by means of elemental analysis, spectroscopic (FT-IR, UV-Vis and ESR), and thermal analysis, as well as magnetic moment measurements. Spectral and X-ray structural features led to the conclusion that complexes 2-5 have square-pyramidal environments around copper(II) center with coordination chromophores CuN3OCl and CuN3O2, respectively. Whereas complex 1 displays square planar geometry. The quasi-reversible CuII/CuI redox couple slightly improves its reversibility with considerable decrease in current intensity. Additionally, the antioxidant (superoxide dismutase and catalase) biomimetic catalytic activities of the obtained complexes have been tested and found to be promising candidates as dual functional mimic enzyme to serve for complete reactive oxygen species (ROS) detoxification, both with respect to the superoxide radicals and the related peroxides.

Synthesis, structure and catechol-oxidase activity of copper(II) complexes of 17-hydroxy-16-(N-3-oxo-prop-1-enyl)amino steroids.

PubMed

Wegner, Rainer; Dubs, Manuela; Görls, Helmar; Robl, Christian; Schönecker, Bruno; Jäger, Ernst-G

2002-09-01

Copper is next to iron the most important element in the biological transport, storage and in redox reactions of dioxygen. A bioanalogous activation of dioxygen with copper complexes is used for catalytical epoxidation, allylic hydroxylation and oxidative coupling of aromatic substrates, for example. With stereochemical information in form of chiral ligands, enantioselective reactions may be possible. Another aspect of interest on copper catalyzed reactions with dioxygen is that the exact mechanism and biological function of some enzymes (especially catechol oxidase) is yet not fully clear. For studies mimicking the copper-containing catechol oxidase appropriate chiral steroid ligands with defined stereochemistry and conformation have been synthesized. The four diastereomeric 16,17-aminoalcohols of the 3-methoxy-estra-1,3,5(10)-triene series have been condensed with salicylic aldehyde and different beta-ketoenols to the chiral ligand types 1-5. These compounds with different steric and electronic properties and different arrangements of the neighboring hydroxy and nitrogen functions were reacted with copper(II) acetate to copper complexes. The structure of these complexes will be discussed. The bioanalogous oxidation of 3,5-di-tbutyl-catechol (dtbc) to the corresponding quinone was catalyzed by most of the complexes, indicating their ability to activate dioxygen. The trans configurations c and d showed an activity one magnitude higher than the cis configurations a and b. Comparing compounds with the same diastereomeric configuration, the main influence was that of the peripheral R(1-3) substituents at the beta-ketoenaminic group which are useful for the fine-tuning of the properties of the copper atoms like redox potential and Lewis acidity.

Stability of coordination compounds of Ni2+ and Co2+ ions with succinic acid anion in water-ethanol solvents

NASA Astrophysics Data System (ADS)

Tukumova, N. V.; Dieu Thuan, Tran Thi; Usacheva, T. R.; Koryshev, N. E.; Sharnin, V. A.

2017-04-01

Stability constants of the coordination compounds of nickel(II) and cobalt(II) ions with succinic acid anion in water-ethanol solvents are determined via potentiometric titration at ionic strength of 0.1 and at T = 298.15 K. It is found that logβ values of monoligand complexes of these ions and succinic acid anions rise along with the content of ethanol in solution ( X EtOH = 0-0.7 mole fractions). Based on an analysis of the thermodynamic characteristics of the solvation of the reagents involved in complex formation, it is found that the increased stability of succinate complexes of nickel(II) and cobalt(II) ions in water-ethanol solvents is mainly determined by the weakening of the solvation of succinic acid anion (Y2-).

Synthesis, structural characterization and DFT calculation on a square-planar Ni(II) complex of a compartmental Schiff base ligand

NASA Astrophysics Data System (ADS)

Biswas, Surajit; Dolai, Malay; Dutta, Arpan; Ali, Mahammad

2016-12-01

Reaction of a symmetric compartmental Schiff-base ligand, (H2L) with nickel(II) perchlorate hexahydrate in 1:1 M ratio in methanol gives rise to a mononuclear nickel(II) compound, NiL (1). The compound has been characterized by C, H, N microanalyses and UV-Vis spectra. The single crystal X-ray diffraction studies reveal a square planar geometry around the Ni(II) center. The compound crystallizes in monoclinic system with space group C2/c with a = 21.6425(6), b = 9.9481(3), c = 13.1958(4) Å, β = 107.728(2)°, V = 2706.16(14) Å3 and Z = 4. Ground state DFT optimization and TDDFT calculations on the ligand and complex were performed to get their UV-Vis spectral pattern.

Synthesis and Spectroscopic Evaluation of Two Novel Glycosylated Zinc(II)-Phthalocyanines.

PubMed

Bächle, Felix; Hanack, Michael; Ziegler, Thomas

2015-10-09

In continuation of our work on glycoconjugated phthalocyanines, two new water soluble, non-ionic zinc(II) phthalocyanines have been prepared and fully characterized by means of ¹H-NMR, 13C-NMR, MALDI-TOF, ESI-TOF, UV-Vis spectroscopy, emission spectroscopy and fluorescence lifetime measurements. The carbohydrate-containing phthalonitrile precursors were synthesized through a copper-catalyzed azide-alkyne cycloaddition (CuAAC). The 2-methoxyethoxymethyl protecting group (MEM) was used to protect the carbohydrate moieties. It resisted the harsh basic cyclotetramerization conditions and could be easily cleaved under mild acidic conditions. The glycoconjugated zinc(II) phthalocyanines described here have molar extinction coefficents εmax>10⁵ m(-1) cm(-1) and absorption maxima λ>680 nm, which make them attractive photosensitizers for photo-dynamic therapy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hang; Ha, Emmeline; Donaldson, Robert P.

Native electrospray ionization (ESI) mass spectrometry (MS) is often used to monitor noncovalent complex formation between peptides and ligands. The relatively low throughput of this technique, however, is not compatible with extensive screening. Laser ablation electrospray ionization (LAESI) MS combined with ion mobility separation (IMS) can analyze complex formation and provide conformation information within a matter of seconds. Islet amyloid polypeptide (IAPP) or amylin, a 37-amino acid residue peptide, is produced in pancreatic beta-cells through proteolytic cleavage of its prohormone. Both amylin and its precursor can aggregate and produce toxic oligomers and fibrils leading to cell death in the pancreasmore » that can eventually contribute to the development of type 2 diabetes mellitus. The inhibitory effect of the copper(II) ion on amylin aggregation has been recently discovered, but details of the interaction remain unknown. Finding other more physiologically tolerated approaches requires large scale screening of potential inhibitors. In this paper, we demonstrate that LAESI-IMS-MS can reveal the binding stoichiometry, copper oxidation state, and the dissociation constant of human amylin–copper(II) complex. The conformations of hIAPP in the presence of copper(II) ions were also analyzed by IMS, and preferential association between the β-hairpin amylin monomer and the metal ion was found. The copper(II) ion exhibited strong association with the —HSSNN– residues of the amylin. In the absence of copper(II), amylin dimers were detected with collision cross sections consistent with monomers of β-hairpin conformation. When copper(II) was present in the solution, no dimers were detected. Thus, the copper(II) ions disrupt the association pathway to the formation of β-sheet rich amylin fibrils. Using LAESI-IMS-MS for the assessment of amylin–copper(II) interactions demonstrates the utility of this technique for the high-throughput screening of

In Vitro Activity of Copper(II) Complexes, Loaded or Unloaded into a Nanostructured Lipid System, against Mycobacterium tuberculosis.

PubMed

Silva, Patricia B da; Souza, Paula C de; Calixto, Giovana Maria Fioramonti; Lopes, Erica de O; Frem, Regina C G; Netto, Adelino V G; Mauro, Antonio E; Pavan, Fernando R; Chorilli, Marlus

2016-05-17

Tuberculosis (TB) is an infectious disease caused mainly by the bacillus Mycobacterium tuberculosis (Mtb), presenting 9.5 million new cases and 1.5 million deaths in 2014. The aim of this study was to evaluate a nanostructured lipid system (NLS) composed of 10% phase oil (cholesterol), 10% surfactant (soy phosphatidylcholine, sodium oleate), and Eumulgin(®) HRE 40 ([castor oil polyoxyl-40-hydrogenated] in a proportion of 3:6:8), and an 80% aqueous phase (phosphate buffer pH = 7.4) as a tactic to enhance the in vitro anti-Mtb activity of the copper(II) complexes [CuCl₂(INH)₂]·H₂O (1), [Cu(NCS)₂(INH)₂]·5H₂O (2) and [Cu(NCO)₂(INH)₂]·4H₂O (3). The Cu(II) complex-loaded NLS displayed sizes ranging from 169.5 ± 0.7095 to 211.1 ± 0.8963 nm, polydispersity index (PDI) varying from 0.135 ± 0.0130 to 0.236 ± 0.00100, and zeta potential ranging from -0.00690 ± 0.0896 to -8.43 ± 1.63 mV. Rheological analysis showed that the formulations behave as non-Newtonian fluids of the pseudoplastic and viscoelastic type. Antimycobacterial activities of the free complexes and NLS-loaded complexes against Mtb H37Rv ATCC 27294 were evaluated by the REMA methodology, and the selectivity index (SI) was calculated using the cytotoxicity index (IC50) against Vero (ATCC(®) CCL-81), J774A.1 (ATCC(®) TIB-67), and MRC-5 (ATCC(®) CCL-171) cell lines. The data suggest that the incorporation of the complexes into NLS improved the inhibitory action against Mtb by 52-, 27-, and 4.7-fold and the SI values by 173-, 43-, and 7-fold for the compounds 1, 2 and 3, respectively. The incorporation of the complexes 1, 2 and 3 into the NLS also resulted in a significant decrease of toxicity towards an alternative model (Artemia salina L.). These findings suggest that the NLS may be considered as a platform for incorporation of metallic complexes aimed at the treatment of TB.

Theoretical Proposal for the Whole Phosphate Diester Hydrolysis Mechanism Promoted by a Catalytic Promiscuous Dinuclear Copper(II) Complex.

PubMed

Esteves, Lucas F; Rey, Nicolás A; Dos Santos, Hélio F; Costa, Luiz Antônio S

2016-03-21

The catalytic mechanism that involves the cleavage of the phosphate diester model BDNPP (bis(2,4-dinitrophenyl) phosphate) catalyzed through a dinuclear copper complex is investigated in the current study. The metal complex was originally designed to catalyze catechol oxidation, and it showed an interesting catalytic promiscuity case in biomimetic systems. The current study investigates two different reaction mechanisms through quantum mechanics calculations in the gas phase, and it also includes the solvent effect through PCM (polarizable continuum model) single-point calculations using water as solvent. Two mechanisms are presented in order to fully describe the phosphate diester hydrolysis. Mechanism 1 is of the S(N)2 type, which involves the direct attack of the μ-OH bridge between the two copper(II) ions toward the phosphorus center, whereas mechanism 2 is the process in which hydrolysis takes place through proton transfer between the oxygen atom in the bridging hydroxo ligand and the other oxygen atom in the phosphate model. Actually, the present theoretical study shows two possible reaction paths in mechanism 1. Its first reaction path (p1) involves a proton transfer that occurs immediately after the hydrolytic cleavage, so that the proton transfer is the rate-determining step, which is followed by the entry of two water molecules. Its second reaction path (p2) consists of the entry of two water molecules right after the hydrolytic cleavage, but with no proton transfer; thus, hydrolytic cleavage is the rate-limiting step. The most likely catalytic path occurs in mechanism 1, following the second reaction path (p2), since it involves the lowest free energy activation barrier (ΔG(⧧) = 23.7 kcal mol(-1), in aqueous solution). A kinetic analysis showed that the experimental k(obs) value of 1.7 × 10(-5) s(-1) agrees with the calculated value k1 = 2.6 × 10(-5) s(-1); the concerted mechanism is kinetically favorable. The KIE (kinetic isotope effect) analysis

Binding Selectivity of Methanobactin from Methylosinus trichosporium OB3b for Copper(I), Silver(I), Zinc(II), Nickel(II), Cobalt(II), Manganese(II), Lead(II), and Iron(II)

NASA Astrophysics Data System (ADS)

McCabe, Jacob W.; Vangala, Rajpal; Angel, Laurence A.

2017-12-01

Methanobactin (Mb) from Methylosinus trichosporium OB3b is a member of a class of metal binding peptides identified in methanotrophic bacteria. Mb will selectively bind and reduce Cu(II) to Cu(I), and is thought to mediate the acquisition of the copper cofactor for the enzyme methane monooxygenase. These copper chelating properties of Mb make it potentially useful as a chelating agent for treatment of diseases where copper plays a role including Wilson's disease, cancers, and neurodegenerative diseases. Utilizing traveling wave ion mobility-mass spectrometry (TWIMS), the competition for the Mb copper binding site from Ag(I), Pb(II), Co(II), Fe(II), Mn(II), Ni(II), and Zn(II) has been determined by a series of metal ion titrations, pH titrations, and metal ion displacement titrations. The TWIMS analyses allowed for the explicit identification and quantification of all the individual Mb species present during the titrations and measured their collision cross-sections and collision-induced dissociation patterns. The results showed Ag(I) and Ni(II) could irreversibly bind to Mb and not be effectively displaced by Cu(I), whereas Ag(I) could also partially displace Cu(I) from the Mb complex. At pH ≈ 6.5, the Mb binding selectivity follows the order Ag(I)≈Cu(I)>Ni(II)≈Zn(II)>Co(II)>>Mn(II)≈Pb(II)>Fe(II), and at pH 7.5 to 10.4 the order is Ag(I)>Cu(I)>Ni(II)>Co(II)>Zn(II)>Mn(II)≈Pb(II)>Fe(II). Breakdown curves of the disulfide reduced Cu(I) and Ag(I) complexes showed a correlation existed between their relative stability and their compact folded structure indicated by their CCS. Fluorescence spectroscopy, which allowed the determination of the binding constant, compared well with the TWIMS analyses, with the exception of the Ni(II) complex. [Figure not available: see fulltext.

Binding Selectivity of Methanobactin from Methylosinus trichosporium OB3b for Copper(I), Silver(I), Zinc(II), Nickel(II), Cobalt(II), Manganese(II), Lead(II), and Iron(II).

PubMed

McCabe, Jacob W; Vangala, Rajpal; Angel, Laurence A

2017-12-01

Methanobactin (Mb) from Methylosinus trichosporium OB3b is a member of a class of metal binding peptides identified in methanotrophic bacteria. Mb will selectively bind and reduce Cu(II) to Cu(I), and is thought to mediate the acquisition of the copper cofactor for the enzyme methane monooxygenase. These copper chelating properties of Mb make it potentially useful as a chelating agent for treatment of diseases where copper plays a role including Wilson's disease, cancers, and neurodegenerative diseases. Utilizing traveling wave ion mobility-mass spectrometry (TWIMS), the competition for the Mb copper binding site from Ag(I), Pb(II), Co(II), Fe(II), Mn(II), Ni(II), and Zn(II) has been determined by a series of metal ion titrations, pH titrations, and metal ion displacement titrations. The TWIMS analyses allowed for the explicit identification and quantification of all the individual Mb species present during the titrations and measured their collision cross-sections and collision-induced dissociation patterns. The results showed Ag(I) and Ni(II) could irreversibly bind to Mb and not be effectively displaced by Cu(I), whereas Ag(I) could also partially displace Cu(I) from the Mb complex. At pH ≈ 6.5, the Mb binding selectivity follows the order Ag(I)≈Cu(I)>Ni(II)≈Zn(II)>Co(II)>Mn(II)≈Pb(II)>Fe(II), and at pH 7.5 to 10.4 the order is Ag(I)>Cu(I)>Ni(II)>Co(II)>Zn(II)>Mn(II)≈Pb(II)>Fe(II). Breakdown curves of the disulfide reduced Cu(I) and Ag(I) complexes showed a correlation existed between their relative stability and their compact folded structure indicated by their CCS. Fluorescence spectroscopy, which allowed the determination of the binding constant, compared well with the TWIMS analyses, with the exception of the Ni(II) complex. Graphical abstract ᅟ.

Evidence for Alkene cis-Aminocupration, an Aminooxygenation Case Study: Kinetics, EPR Spectroscopy, and DFT Calculations

PubMed Central

Paderes, Monissa C.; Belding, Lee; Fanovic, Branden; Dudding, Travis; Keister, Jerome B.

2012-01-01

Alkene difunctionalization reactions are important in organic synthesis. We have recently shown that copper(II) complexes can promote and catalyze intramolecular alkene aminooxygenation, carboamination, and diamination reactions. In this contribution, we report a combined experimental and theoretical examination of the mechanism of the copper(II)-promoted olefin aminooxygenation reaction. Kinetics experiments revealed a mechanistic pathway involving an equilibrium reaction between a copper(II) carboxylate complex and the γ-alkenyl sulfonamide substrate and a rate-limiting intramolecular cis-addition of N–Cu across the olefin. Kinetic isotope effect studies support that the cis-aminocupration is the rate-determining step. UV/Vis spectra support a role for the base in the break-up of copper(II) carboxylate dimer to monomeric species. Electron paramagnetic resonance (EPR) spectra provide evidence for a kinetically competent N–Cu intermediate with a CuII oxidation state. Due to the highly similar stereochemical and reactivity trends among the CuII-promoted and catalyzed alkene difunctionalization reactions we have developed, the cis-aminocupration mechanism can reasonably be generalized across the reaction class. The methods and findings disclosed in this report should also prove valuable to the mechanism analysis and optimization of other copper(-II) carboxylate promoted reactions, especially those that take place in aprotic organic solvents. PMID:22237868

The CULTEX RFS: A Comprehensive Technical Approach for the In Vitro Exposure of Airway Epithelial Cells to the Particulate Matter at the Air-Liquid Interface

PubMed Central

Aufderheide, Michaela; Hochrainer, Dieter

2013-01-01

The EU Regulation on Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) demands the implementation of alternative methods for analyzing the hazardous effects of chemicals including particulate formulations. In the field of inhalation toxicology, a variety of in vitro models have been developed for such studies. To simulate the in vivo situation, an adequate exposure device is necessary for the direct exposure of cultivated lung cells at the air-liquid interface (ALI). The CULTEX RFS fulfills these requirements and has been optimized for the exposure of cells to atomized suspensions, gases, and volatile compounds as well as micro- and nanosized particles. This study provides information on the construction and functional aspects of the exposure device. By using the Computational Fluid Dynamics (CFD) analysis, the technical design was optimized to realize a stable, reproducible, and homogeneous deposition of particles. The efficiency of the exposure procedure is demonstrated by exposing A549 cells dose dependently to lactose monohydrate, copper(II) sulfate, copper(II) oxide, and micro- and nanoparticles. All copper compounds induced cytotoxic effects, most pronounced for soluble copper(II) sulfate. Micro- and nanosized copper(II) oxide also showed a dose-dependent decrease in the cell viability, whereby the nanosized particles decreased the metabolic activity of the cells more severely. PMID:23509768

β-Ketoiminato-based copper(ii) complexes as CVD precursors for copper and copper oxide layer formation.

PubMed

Pousaneh, Elaheh; Korb, Marcus; Dzhagan, Volodymyr; Weber, Marcus; Noll, Julian; Mehring, Michael; Zahn, Dietrich R T; Schulz, Stefan E; Lang, Heinrich

2018-06-19

The synthesis of ketoiminato copper(ii) complexes [Cu(OCRCHC(CH3)NCH2CH2X)(μ-OAc)]2 (X = NMe2: 4a, R = Me; 4b, R = Ph. X = OMe: 5, R = Me) and [Cu(OCRCHCMeNCH2CH2NEt2)(OAc)] (6, R = Me) from RC(O)CHC(CH3)N(H)CH2CH2X (X = NMe2: 1a, R = Me; 1b, R = Ph. X = NEt2: 1c, R = Me. X = OMe: 2, R = Me) and [Cu(OAc)2·H2O] (3) is reported. The molecular solid-state structures of 4-6 were determined by single crystal X-ray diffraction studies, showing that 4a,b and 5 are dimers which are set up by two [{Cu(μ-OAc)L}] (L = ketoiminato ligand) units featuring a square-planar Cu2O2 core with a distorted square-pyramidal geometry at Cu(ii). In contrast, 6 is monomeric with a tridentate-coordinated OCMeCHCMeNCH2CH2NEt2 ligand and a σ-bonded acetate group, thus inducing a square-planar environment around Cu(ii). The thermal behavior of all complexes was studied by TG (Thermogravimetry) and DSC (Differential Scanning Calorimetry) under an atmosphere of Ar and O2. Complex 4b shows the highest first onset temperature at 213 °C (under O2) and 239 °C (Ar). PXRD studies confirmed the formation of CuO under an atmosphere of O2 and Cu/Cu2O under Ar. TG-MS studies, exemplarily carried out with 4a, indicate the elimination of the ketoiminato ligands with detectable fragments such as m/z = 15, 28, 43, 44, 45, and 60 at a temperature above 250 °C. Vapor pressure measurements displayed that 5 shows the highest volatility of 3.6 mbar at 70 °C (for comparison, 4a, 1.4; 4b, 1.3; 6, 0.4 mbar) and hence 4a and 5 were used as MOCVD precursors for Cu/Cu2O deposition on Si/SiO2 at substrate temperatures of 450 °C and 510 °C. The deposition experiments were carried out under an atmosphere of nitrogen as well as oxygen. The as-obtained layers were characterized by SEM, EDX, XPS, and PXRD, showing that with oxygen as the reactive gas a mixture of metallic copper and copper(i) oxide without carbon impurities was formed, while under N2 Cu films with 53-68 mol% C contamination were produced. In a

Variation of the ground spin state in homo- and hetero-octanuclear copper(II) and nickel(II) double-star complexes with a meso-helicate-type metallacryptand core.

PubMed

Pardo, Emilio; Dul, Marie-Claire; Lescouëzec, Rodrigue; Chamoreau, Lise-Marie; Journaux, Yves; Pasán, Jorge; Ruiz-Pérez, Catalina; Julve, Miguel; Lloret, Francesc; Ruiz-García, Rafael; Cano, Joan

2010-05-28

Homo- and heterometallic octanuclear complexes of formula Na₂{[Cu₂(mpba)₃][Cu(Me₅dien)]₆}-(ClO₄)₆·12H₂O (1), Na₂{[Cu₂(Mempba)₃][Cu(Me₅dien)]₆}(ClO₄)₆·12H₂O (2), Na₂{[Ni₂(mpba)₃]-[Cu(Me₅dien)]₆}(ClO₄)₆·12H₂O (3), Na₂{[Ni₂(Mempba)₃][Cu(Me₅dien)]₆}(ClO₄)₆·9H₂O (4), {[Ni₂(mpba)₃][Ni(dipn)(H₂O)]₆}(ClO₄)₄·12.5H₂O (5), and {[Ni₂(Mempba)₃][Ni(dipn)-(H₂O)]₆}(ClO₄)₄·12H₂O (6) [mpba = 1,3-phenylenebis(oxamate), Mempba = 4-methyl-1,3-phenylenebis(oxamate), Me₅dien = N,N,N',N'',N''-pentamethyldiethylenetriamine, and dipn = dipropylenetriamine] have been synthesized through the "complex-as-ligand/complex-as-metal" strategy. Single-crystal X-ray diffraction analyses of 1, 3, and 5 show cationic M(II)₂M'(II)₆ entities (M, M' = Cu and Ni) with an overall double-star architecture, which is made up of two oxamato-bridged M(II)M'(II)₃ star units connected through three meta-phenylenediamidate bridges between the two central metal atoms leading to a binuclear metallacryptand core of the meso-helicate-type. Dc magnetic susceptibility data for 1-6 in the temperature range 2-300 K have been analyzed through a "dimer-of-tetramers" model [H = - J(S(1A)·S(3A) + S(1A)·S(4A) + S(1A)·S(5A) + S(2B)·S(6B) + S(2B)·S(7B) + S(2B)·S(8B)) - J'S(1A)·S(2B), with S(1A) = S(2B) = S(M) and S(3A) = S(4A) = S(5A) = S(6B) = S(7B) = S(8B) = S(M')]. The moderate to strong antiferromagnetic coupling between the M(II) and M'(II) ions through the oxamate bridge in 1-6 (-J(Cu-Cu) = 52.0-57.0 cm⁻¹, -J(Ni-Cu) = 39.1-44.7 cm⁻¹, and -J(Ni-Ni) = 26.3-26.6 cm⁻¹) leads to a non-compensation of the ground spin state for the tetranuclear M(II)M'(II)₃ star units [S(A) = S(B) = 3S(M') - S(M) = 1 (1 and 2), 1/2 (3 and 4), and 2 (5 and 6)]. Within the binuclear M(II)₂ meso-helicate cores of 1-4, a moderate to weak antiferromagnetic coupling between the M(II) ions (-J'(Cu-Cu) = 28.0-48.0 cm⁻¹ and -J'(Ni-Ni) = 0.16-0.97 cm⁻¹) is mediated by the triple m-phenylenediamidate bridge to give a ground spin singlet (S = S(A) - S(B) = 0) state for the octanuclear M(II)₂Cu(II)₆ molecule. Instead, a weak ferromagnetic coupling between the Ni(II) ions (J'(Ni-Ni) = 2.07-3.06 cm⁻¹) operates in the binuclear Ni(II)₂ meso-helicate core of 5 and 6 leading thus to a ground spin nonet (S = S(A) + S(B) = 4) state for the octanuclear Ni(II)₈ molecule. Dc magnetization data for 5 reveal a small but non-negligible axial magnetic anisotropy (D = -0.23 cm⁻¹) of the S = 4 Ni(II)₈ ground state with an estimated value of the energy barrier for magnetization reversal of 3.7 cm⁻¹ (U = -DS²). Ac magnetic susceptibility data for 5 show an unusual slow magnetic relaxation behaviour at low temperatures which is typical of "cluster glasses". The temperature dependence of the relaxation time for 5 has been interpreted on the basis of the Vogel-Fulcher law for weakly interacting clusters, with values of 2.5 K, 1.4 × 10⁻⁶ s, and 4.0 cm⁻¹ for the intermolecular interaction parameter (T₀), the pre-exponential factor (τ₀), and the effective energy barrier (U(eff)), respectively.

Capped Mesoporous Silica Nanoparticles for the Selective and Sensitive Detection of Cyanide.

PubMed

Sayed, Sameh El; Licchelli, Maurizio; Martínez-Máñez, Ramón; Sancenón, Félix

2017-10-18

The development of easy and affordable methods for the detection of cyanide is of great significance due to the high toxicity of this anion and the potential risks associated with its pollution. Herein, optical detection of cyanide in water has been achieved by using a hybrid organic-inorganic nanomaterial. Mesoporous silica nanoparticles were loaded with [Ru(bipy) 3 ] 2+ , functionalized with macrocyclic nickel(II) complex subunits, and capped with a sterically hindering anion (hexametaphosphate). Cyanide selectively induces demetallation of nickel(II) complexes and the removal of capping anions from the silica surface, allowing the release of the dye and the consequent increase in fluorescence intensity. The response of the capped nanoparticles in aqueous solution is highly selective and sensitive towards cyanide with a limit of detection of 2 μm. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

C-H oxidation and chelation of a dipyrromethane mediated rapid colorimetric naked-eye Cu(ii) chemosensor.

PubMed

Rajmohan, Rajamani; Ayaz Ahmed, Khan Behlol; Sangeetha, Sampathkumar; Anbazhagan, Veerappan; Vairaprakash, Pothiappan

2017-09-08

Copper(ii) ion mediated C-H oxidation of dipyrromethanes (DPMs) to the corresponding dipyrrins followed by complexation invoked the selective sensing of copper(ii) ions in aqueous solutions. On the addition of copper, the colour of the DPM solution instantaneously changes from yellow to pink with the detection limit of 0.104 μM measured by absorption spectroscopy, whereas visible colour changes could be observed by the naked eye for concentrations as low as 3 μM.

Mixed-ligand copper(II) complexes activate aryl hydrocarbon receptor AhR and induce CYP1A genes expression in human hepatocytes and human cell lines.

PubMed

Kubešová, Kateřina; Dořičáková, Aneta; Trávníček, Zdeněk; Dvořák, Zdeněk

2016-07-25

The effects of four copper(II) mixed-ligand complexes [Cu(qui1)(L)]NO3·H2O (1-3) and [Cu(qui2)(phen)]NO3 (4), where qui1=2-phenyl-3-hydroxy-4(1H)-quinolinone, Hqui2=2-(4-amino-3,5-dichlorophenyl)-N-propyl-3-hydroxy-4(1H)-quinolinone-7-carboxamide, L=1,10-phenanthroline (phen) (1), 5-methyl-1,10-phenanthroline (mphen) (2), bathophenanthroline (bphen) (3), on transcriptional activities of steroid receptors, nuclear receptors and xenoreceptors have been studied. The complexes (1-4) did not influence basal or ligand-inducible activities of glucocorticoid receptor, androgen receptor, thyroid receptor, pregnane X receptor and vitamin D receptor, as revealed by gene reporter assays. The complexes 1 and 2 dose-dependently induced luciferase activity in stable gene reporter AZ-AhR cell line, and this induction was reverted by resveratrol, indicating involvement of aryl hydrocarbon receptor (AhR) in the process. The complexes 1, 2 and 3 induced CYP1A1 mRNA in LS180 cells and CYP1A1/CYP1A2 in human hepatocytes through AhR. Electrophoretic mobility shift assay EMSA showed that the complexes 1 and 2 transformed AhR in its DNA-binding form. Collectively, we demonstrate that the complexes 1 and 2 activate AhR and induce AhR-dependent genes in human hepatocytes and cancer cell lines. In conclusion, the data presented here might be of toxicological importance, regarding the multiple roles of AhR in human physiology and pathophysiology. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Synthesis, structure, and magnetic properties of two 1-D helical coordination polymeric Cu(II) complexes

NASA Astrophysics Data System (ADS)

Bian, He-Dong; Yang, Xiao-E.; Yu, Qing; Chen, Zi-Lu; Liang, Hong; Yan, Shi-Ping; Liao, Dai-Zheng

2008-01-01

Two helical coordination polymeric copper(II) complexes bearing amino acid Schiff bases HL or HL', which are condensed from 2-hydroxy-1-naphthaldehyde with 2-aminobenzoic acid or L-valine, respectively, have been prepared and characterised by X-ray crystallography. In [CuL] n ( 1) the copper(II) atoms are bridged by syn- anti carboxylate groups giving infinite 1-D right-handed helical chains which are further connected by weak C-H⋯Cu interactions to build a 2-D network. While in [CuL'] n ( 2) the carboxylate group acts as a rare monatomic bridge to connect the adjacent copper(II) atoms leading to the formation of a left-handed helical chain. Magnetic susceptibility measurements indicate that 1 exhibits weak ferromagnetic interactions whereas an antiferromagnetic coupling is established for 2. The magnetic behavior can be satisfactorily explained on the basis of the structural data.

A review on methods of recovery of acid(s) from spent pickle liquor of steel industry.

PubMed

Ghare, N Y; Wani, K S; Patil, V S

2013-04-01

Pickling is the process of removal of oxide layer and rust formed on metal surface. It also removes sand and corrosion products from the surface of metal. Acids such as sulfuric acid, hydrochloric acid are used for pickling. Hydrofluoric acid-Nitric acid mixture is used for stainless steel pickling. Pickling solutions are spent when acid concentration in pickling solutions decreases by 75-85%, which also has metal content up to 150-250 g/ dm3. Spent pickling liquor (SPL) should be dumped because the efficiency of pickling decreases with increasing content of dissolved metal in the bath. The SPL content depends on the plant of origin and the pickling method applied there. SPL from steel pickling in hot-dip galvanizing plants contains zinc(II), iron, traces of lead, chromium. and other heavy metals (max. 500 mg/dm3) and hydrochloric acid. Zinc(II) passes tothe spent solution after dissolution of this metal from zinc(II)-covered racks, chains and baskets used for transportation of galvanized elements. Unevenly covered zinc layers are usually removed in another pickling bath. Due to this, zinc(II) concentration increases even up to 110 g/dm3, while iron content may reach or exceed even 80 g/dm3 in the same solution. This review presents an overview on different aspects of generation and treatment of SPL with recourse to recovery of acid for recycling. Different processes are described in this review and higher weightage is given to membrane processes.

Reactions of the melatonin metabolite N(1)-acetyl-5-methoxykynuramine with carbamoyl phosphate and related compounds.

PubMed

Kuesel, Jana T; Hardeland, Rüdiger; Pfoertner, Henrike; Aeckerle, Nelia

2010-01-01

N-[2-(6-methoxyquinazolin-4-yl)-ethyl] acetamide (MQA) is a compound formed from the melatonin metabolite N(1)-acetyl-5-methoxykynuramine (AMK). We followed MQA production in reaction systems containing various putative reaction partners, in the absence and presence of hydrogen peroxide and/or copper(II). Although MQA may be formally described as a condensation product of either N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) with ammonia, or AMK with formamide, none of these combinations led to substantial quantities of MQA. However, MQA formation was observed in mixtures containing AMK, hydrogen peroxide, hydrogen carbonate and ammonia, or AMK, hydrogen peroxide, copper(II) and potentially carbamoylating agents, such as potassium cyanate or, more efficiently, carbamoyl phosphate. In the presence of hydrogen peroxide, copper(II) and carbamoyl phosphate, MQA was the major product obtained from AMK, but the omission of copper(II) mainly led to another metabolite, 3-acetamidomethyl-6-methoxycinnolinone (AMMC). This was caused by nitric oxide (NO) generated under oxidative conditions from carbamoyl phosphate, as shown by an NO spin trap. MQA formation with carbamoyl phosphate was not due to the possible decomposition product, formamide. The reaction of AMK with carbamoyl phosphate under oxidative conditions, in which inorganic phosphate and water are released and which differs from the typical process of carbamoylation via isocyanate, may be considered as a new physiological route of MQA formation.

Carbonate formation within a nickel dimer: synthesis of a coordinatively unsaturated bis(mu-hydroxo) dinickel complex and its reactivity toward carbon dioxide.

PubMed

Wikstrom, Jeffrey P; Filatov, Alexander S; Mikhalyova, Elena A; Shatruk, Michael; Foxman, Bruce M; Rybak-Akimova, Elena V

2010-03-14

The tridentate aminopyridine ligand bearing a bulky tert-butyl substituent at the amine nitrogen, tert-butyl-dipicolylamine (tBuDPA), occupies three coordination sites in six-coordinate complexes of nickel(ii), leaving the remaining three sites available for additional ligand binding and activation. New crystallographically characterized complexes include two mononuclear species with 1:1 metal:ligand complexation: a trihydrate solvate (1.3H(2)O) and a monohydrate biacetonitrile solvate (1.H(2)O.2CH(3)CN). Complexation in the presence of sodium hydroxide results in a bis(mu-hydroxo) complex (2), the bridging hydroxide anions of which are labile and become displaced by methoxide anions in methanol solvent, affording bis-methoxo-bridged (4). Nickel(II) centers in 2 are five-coordinate and antiferromagnetically coupled (with J = -31.4(5) cm(-1), H = -2JS(1)S(2), in agreement with Ni-O-Ni angle of 103.7 degrees). Bridging hydroxide or alkoxide anions in coordinatively unsaturated dinuclear nickel(II) complexes with tBuDPA react as active nucleophiles. 2 readily performs carbon dioxide fixation, resulting in the formation of a bis(mu-carbonato) tetrameric complex (3), which features a novel binding geometry in the form of an inverted butterfly-type nickel-carbonate core. Temperature-dependent magnetic measurements of tetranuclear carbonato-bridged revealed relatively weak antiferromagnetic coupling (J(1) = -3.1(2) cm(-1)) between the two nickel centers in the core of the cluster, as well as weak antiferromagnetic pairwise interactions (J(2) = J(3) = -4.54(5) cm(-1)) between central and terminal nickel ions.

Correlation between ionic radii of metals and thermal decomposition of supramolecular structure of azodye complexes

NASA Astrophysics Data System (ADS)

El-Sonbati, A. Z.; Diab, M. A.; El-Bindary, A. A.; Eldesoky, A. M.; Morgan, Sh. M.

2015-01-01

An interesting azodye heterocyclic ligand of copper(II), cobalt(II), nickel(II) and uranyl(II) complexes have been synthesized by the reaction of metal salts with 5-(2,3-dimethyl-1-phenylpyrazol-5-one azo)-2-thioxo-4-thiazolidinone (HL) yields 1:1 and 1:2 (M:L) complexes depending on the reaction conditions. The elemental analysis, magnetic moments, spectral (UV-Vis, IR, 1H and 13C NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structures of the ligand tautomers are optimized theoretically and the quantum chemical parameters are calculated. The IR spectra showed that the ligand (HL) act as monobasic tridentate/neutral bidentate through the (sbnd Ndbnd N), enolic (Csbnd O)- and/or oxygen keto moiety groups forming a five/six-membered structures. According to intramolecular hydrogen bond leads to increasing of the complexes stability. The molar conductivities show that all the complexes are non-electrolytes. The ESR spectra indicate that the free electron is in dxy orbital. The calculated bonding parameter indicates that in-plane σ-bonding is more covalent than in-plane π-bonding. The coordination geometry is five/six-coordinated trigonal bipyramidal for complex (1) and octahedral for complexes (2-6). The value of covalency factor β12 and orbital reduction factor K accounts for the covalent nature of the complexes. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The synthesized ligand (HL) and its Cu(II) complexes (1, 2 and 4) are screened for their biological activity against bacterial and fungal species. The ligand (HL) showed antimicrobial activities against Escherichia coli. The ligand (HL) and its Cu(II) complexes (2 and 4) have very high antifungal activity against Penicillium italicum. The inhibitive action of ligand (HL), against the corrosion of C-steel in 2 M HCl solution has been investigated using potentiodynamic polarization and electrochemical

Zinc Enzymes.

ERIC Educational Resources Information Center

Bertini, I.; And Others

1985-01-01

Discusses the role of zinc in various enzymes concerned with hydration, hydrolysis, and redox reactions. The binding of zinc to protein residues, properties of noncatalytic zinc(II) and catalytic zinc, and the reactions catalyzed by zinc are among the topics considered. (JN)

Electrophilic-Nucleophilic Dualism of Nickel(II) toward Ni···I Noncovalent Interactions: Semicoordination of Iodine Centers via Electron Belt and Halogen Bonding via σ-Hole.

PubMed

Bikbaeva, Zarina M; Ivanov, Daniil M; Novikov, Alexander S; Ananyev, Ivan V; Bokach, Nadezhda A; Kukushkin, Vadim Yu

2017-11-06

The nitrosoguanidinate complex [Ni{NH═C(NMe 2 )NN(O)} 2 ] (1) was cocrystallized with I 2 and sym-trifluorotriiodobenzene (FIB) to give associates 1·2I 2 and 1·2FIB. Structures of these solid species were studied by XRD followed by topological analysis of the electron density distribution within the framework of Bader's approach (QTAIM) at the M06/DZP-DKH level of theory and Hirshfeld surface analysis. Our results along with inspection of XRD (CCDC) data, accompanied by the theoretical calculations, allowed the identification of three types of Ni···I contacts. The Ni···I semicoordination of the electrophilic nickel(II) center with electron belt of I 2 was observed in 1·2I 2 , the metal-involving halogen bonding between the nucleophilic nickel(II)-d z 2 center and σ-hole of iodine center was recognized and confirmed theoretically in the structure of [FeNi(CN) 4 (IPz)(H 2 O)] n (IPz = 4-N-coordinated 2-I-pyrazine), whereas the arrangement of FIB in 1·2FIB provides a boundary case between the semicoordination and the halogen Ni···I bondings. In 1·2I 2 and 1·2FIB, noncovalent interactions were studied by variable temperature XRD detecting the expansion of noncovalent contacts with preservation of covalent bond lengths upon the temperature increase from 100 to 300 K. The nature and energies of all identified types of the Ni···I noncovalent interactions in the obtained (1·2I 2 and 1·2FIB) and in the previously reported ([FeNi(CN) 4 (IPz)(H 2 O)] n , [NiL 2 ](I 3 ) 2 ·2I 2 (L = o-phenylene-bis(dimethylphosphine), [NiL]I 2 (L = 1,4,8,11-tetra-azacyclotetradecane), Ni(en) 2 ] n [AgI 2 ] 2n (en = ethylenediamine), and [NiL](ClO 4 ) (L = 4-iodo-2-((2-(2-(2-pyridyl)ethylsulfanyl)ethylimino)methyl)-phenolate)) structures were studied theoretically. The estimated strengths of these Ni···I noncovalent contacts vary from 1.6 to 4.1 kcal/mol and, as expected, become weaker on heating. This work is the first emphasizing electrophilic-nucleophilic dualism

DNA binding studies of a new dicationic porphyrin. Insights into interligand interactions.

PubMed

Shelton, Alexander H; Rodger, Alison; McMillin, David R

2007-08-07

Cationic porphyrins have an affinity for DNA and potential for applications in the fields of photodynamic therapy and cellular imaging. This report describes a new dicationic porphyrin, 5,15-dimethyl-10,20-di(N-methylpyridinium-4-yl)porphyrin, abbreviated H2tMe2D4. Although tetrasubstituted, H2tMe2D4 presents modest steric requirements and forms in reasonable yield by a "2+2" synthetic method. Accordingly, studies of the zinc(II)- and copper(II)-containing derivatives, Zn(tMe2D4) and Cu(tMe2D4), have also been possible. Methods used to characterize DNA-binding motifs include absorption, emission, linear, and circular dichroism spectroscopies, as well as viscometry. An unusually detailed picture of porphyrin uptake emerges. As the ratio of DNA to porphyrin increases during a typical titration, H2tMe2D4 or Cu(tMe2D4) initially aggregates on the host and then shifts to intercalative binding at close quarters before finally dispersing into non-interacting intercalation sites of the host. Emission studies of the copper(II) porphyrin have been very valuable. The existence of a measurable signal is diagnostic of intercalative binding, and the saturation behavior establishes that internalization typically monopolizes approximately three base pairs. In the moderate loading regime, emission data are most telling because dipole-dipole interactions between near-neighbor porphyrins tend to confuse other spectroscopic assays. The third ligand, Zn(tMe2D4), behaves differently in that the uptake is a strictly cooperative process. The mode of binding also varies with the base content of the DNA host. When the DNA is rich in A=T base pairs, the porphyrin remains five-coordinate and binds externally; however, Zn(tMe2D4) loses its axial ligand and binds by intercalation if the host contains only G[triple bond]C base pairs.

In vitro photodynamic activity of lipid vesicles with zinc phthalocyanine derivative against Enterococcus faecalis.

PubMed

Sobotta, Lukasz; Dlugaszewska, Jolanta; Kasprzycki, Piotr; Lijewski, Sebastian; Teubert, Anna; Mielcarek, Jadwiga; Gdaniec, Maria; Goslinski, Tomasz; Fita, Piotr; Tykarska, Ewa

2018-06-01

Zinc(II) phthalocyanine bearing eight non-peripheral 2-propoxy substituents was subjected to physicochemical study and, after incorporation in lipid vesicles, assessed as a potential photosensitizer for antibacterial photodynamic therapy. The phthalocyanine derivative obtained in the macrocyclization reaction was characterized by MS and NMR techniques. Moreover, its chemical purity was confirmed by HPLC analysis. X-ray structural analysis revealed that overcrowding of the phthalocyanine derivative leads to a strong out-of-plane distortion of the π-system of the macrocycle core. In the UV-Vis absorption spectra of zinc(II) phthalocyanine two characteristic bands were found: the Soret (300-450 nm) and the Q band (600-800 nm). Photophysical properties of mono- and diprotonated forms of phthalocyanine derivative were studied with time-resolved fluorescence spectroscopy. Its tri- and tetraprotonated forms could not be obtained, because compound decomposes in higher acid concentrations. The presented zinc(II) phthalocyanine showed values of singlet oxygen generation Φ Δ  = 0.18 and 0.16, the quantum yield of the photodecomposition Φ P  = 3.06∙10 -4 and 1.23∙10 -5 and the quantum yield of fluorescence Φ FL  = 0.005 and 0.004, designated in DMF and DMSO, respectively. For biological studies, phthalocyanine has been incorporated into modified liposome vesicles containing ethanol. In vitro bacteria photoinactivation study revealed no activity against Escherichia coli and 5.7 log reduction of the Enterococcus faecalis growth. Copyright © 2018 Elsevier B.V. All rights reserved.

Zinc Biochemistry: From a Single Zinc Enzyme to a Key Element of Life12

PubMed Central

Maret, Wolfgang

2013-01-01

The nutritional essentiality of zinc for the growth of living organisms had been recognized long before zinc biochemistry began with the discovery of zinc in carbonic anhydrase in 1939. Painstaking analytical work then demonstrated the presence of zinc as a catalytic and structural cofactor in a few hundred enzymes. In the 1980s, the field again gained momentum with the new principle of “zinc finger” proteins, in which zinc has structural functions in domains that interact with other biomolecules. Advances in structural biology and a rapid increase in the availability of gene/protein databases now made it possible to predict zinc-binding sites from metal-binding motifs detected in sequences. This procedure resulted in the definition of zinc proteomes and the remarkable estimate that the human genome encodes ∼3000 zinc proteins. More recent developments focus on the regulatory functions of zinc(II) ions in intra- and intercellular information transfer and have tantalizing implications for yet additional functions of zinc in signal transduction and cellular control. At least three dozen proteins homeostatically control the vesicular storage and subcellular distribution of zinc and the concentrations of zinc(II) ions. Novel principles emerge from quantitative investigations on how strongly zinc interacts with proteins and how it is buffered to control the remarkably low cellular and subcellular concentrations of free zinc(II) ions. It is fair to conclude that the impact of zinc for health and disease will be at least as far-reaching as that of iron. PMID:23319127

The Difference Se Makes: A Bio-Inspired Dppf-Supported Nickel Selenolate Complex Boosts Dihydrogen Evolution with High Oxygen Tolerance.

PubMed

Pan, Zhong-Hua; Tao, Yun-Wen; He, Quan-Feng; Wu, Qiao-Yu; Cheng, Li-Ping; Wei, Zhan-Hua; Wu, Ji-Huai; Lin, Jin-Qing; Sun, Di; Zhang, Qi-Chun; Tian, Dan; Luo, Geng-Geng

2018-06-12

Inspired by the metal active sites of [NiFeSe]-hydrogenases, a dppf-supported nickel(II) selenolate complex (dppf=1,1'-bis(diphenylphosphino)ferrocene) shows high catalytic activity for electrochemical proton reduction with a remarkable enzyme-like H 2 evolution turnover frequency (TOF) of 7838 s -1 under an Ar atmosphere, which markedly surpasses the activity of a dppf-supported nickel(II) thiolate analogue with a low TOF of 600 s -1 . A combined study of electrochemical experiments and DFT calculations shed light on the catalytic process, suggesting that selenium atom as a bio-inspired proton relay plays a key role in proton exchange and enhancing catalytic activity of H 2 production. For the first time, this type of Ni selenolate-containing electrocatalyst displays a high degree of O 2 and H 2 tolerance. Our results should encourage the development of the design of highly efficient oxygen-tolerant Ni selenolate molecular catalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evidence of desulfurization in the oxidative cyclization of thiosemicarbazones. Conversion to 1,3,4-oxadiazole derivatives.

PubMed

Gómez-Saiz, Patricia; García-Tojal, Javier; Maestro, Miguel A; Arnaiz, Francisco J; Rojo, Teófilo

2002-03-25

The addition of pyridine-2-carbaldehyde 4N-methylthiosemicarbazone (C8H10N4S) to an aqueous solution of copper(II) nitrate yields [[Cu(C8H9N4S)(NO3)]2] (1). This complex consists of centrosymmetric dinuclear entities containing square-pyramidal copper(II) ions bridged through the sulfur thioamide atoms. The oxidation of 1 with KBrO3 or KIO3 gives rise to a compound with formula [[Cu(C8H8N4O)(H2O)2(SO4)]2]*2H2O (2) (C8H8N4O = 2-methylamino-5-pyridin-2-yl-1,3,4-oxadiazole). The structure of 2 is made up of centrosymmetric dimers where the copper(II) ions exhibit a distorted octahedral coordination and are connected by the oxadiazole moiety. The metal ions in 2 can be removed by addition of K4[Fe(CN)6], and then the oxadiazole ligand can be isolated and recrystallized as (C8H8N4O)*3H2O (3).

Copper-mercury film electrode for cathodic stripping voltammetric determination of Se(IV).

PubMed

Sladkov, Vladimir; David, François; Fourest, Blandine

2003-01-01

The copper-mercury film electrode has been suggested for the determination of Se(IV) in a wide range of concentration from 1x10(-9) to 1x10(-6) mol L(-1)by square-wave cathodic stripping voltammetry. Insufficient reproducibility and sensitivity of the mercury film electrode have been overcome by using copper(II) ions during the plating procedure. Copper(II) has been found to be reduced and form a reproducible copper-mercury film on a glassy carbon electrode surface. The plating potential and time, the concentration of copper(II) and the concentration of the supporting electrolyte have been optimised. Microscopy has been used for a study of the morphology of the copper-mercury film. It has been found that it is the same as for the mercury one. The preconcentration step consists in electrodeposition of copper selenide on the copper-mercury film. The relative standard deviation is 4.3% for 1x10(-6) mol L(-1) of Se(IV). The limit of detection is 8x10(-10) mol L(-1) for 5 min of accumulation.

Crystal structures, DFT calculations, and Hirshfeld surface analyses of two new copper(II) and nickel(II) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine

NASA Astrophysics Data System (ADS)

Seifikar Ghomi, Leila; Behzad, Mahdi; Tarahhomi, Atekeh; Arab, Ali

2017-12-01

Two new Ni(II) and Cu(II) complexes of a tetradentate Schiff base ligand (1 and 2, respectively), derived from the condensation of meso-1,2-diphenyl-1,2-ethylenediamine with 2-hydroxy-6-methoxy benzaldehyde, were synthesized and characterized by IR, UV-Vis, 1H NMR spectroscopy, and X-Ray crystallography. The central metal ions in both complexes are coordinated via the N2O2 coordination sphere of the ligand with square-planar geometry. DFT results revealed that the Msbnd N and Msbnd O interactions (M = Ni, Cu) are weaker than the typical covalent single bond indicating that ionic and electrostatic interactions are dominated in Msbnd N and Msbnd O bonds. Hirshfeld surface (HS) analyses of the studied structures 1 and 2 have been performed. The study using 3D HSs and 2D fingerprint plots (FPs) highlighted the dominant contacts H⋯H, C⋯H/H⋯C and O⋯H/H⋯O in both structures, and H⋯Cl in 2. The molecular assemblies held by C⋯O/O⋯C (in 1) and C⋯C (in 1 and 2) type dipole-dipole interactions are also found in the crystal packing contributing towards stability. The significant contributions arising from the mentioned interactions in crystal packing are also revealed from the Hirshfeld surface FPs showing a major contribution to total HS area for the H⋯H contacts for both structures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shardin, Rosidah; Pui, Law Kung; Yamin, Bohari M.

A simple mononuclear octahedral copper(II) complex was attempted from the reaction of three moles of 1-benzoyl-3-(pyridin-2-yl)-1H-pyrazole and one mole of copper(II) perchlorate hexahydrate in methanol. However, the product of the reaction was confirmed to be a dinuclear copper(II) complex with μ-(3-(pyridin-2-yl)-pyrazolato) and 3-(pyridin-2-yl)-1H-pyrazole ligands attached to each of the Cu(II) centre atom. The copper(II) ion assisted the cleavage of the C{sub benzoyl}N bond afforded a 3-(pyridin-2-yl)-1H-pyrazole molecule. Deprotonation of the 3-(pyridin-2-yl)-1H-pyrazole gave a 3-(pyridin-2-yl)-pyrazolato, which subsequently reacted with the Cu(II) ion to give the (3-(pyridin-2-yl)-pyrazolato)(3-(pyridin-2-yl)-1H-pyrazole)Cu(II) product moiety. The structure of the dinuclear complex was confirmed by x-ray crystallography. The complexmore » crystallized in a monoclinic crystal system with P2(1)/n space group and cell dimensions of a = 12.2029(8) Å, b = 11.4010(7) Å, c = 14.4052(9) Å and β = 102.414(2)°. The compound was further characterized by mass spectrometry, CHN elemental analysis, infrared and UV-visible spectroscopy and the results concurred with the x-ray structure. The presence of d-d transition at 671 nm (ε = 116 dm{sup 3} mol{sup −1} cm{sup −1}) supports the presence of Cu(II) centres.« less

Genistein Binding to Copper(II)-Solvent Dependence and Effects on Radical Scavenging.

PubMed

Yang, Jing; Xu, Yi; Liu, Hao-Yu; Han, Rui-Min; Zhang, Jian-Ping; Skibsted, Leif H

2017-10-18

Genistein, but not daidzein, binds to copper(II) with a 1:2 stoichiometry in ethanol and with a 1:1 stoichiometry in methanol, indicating chelation by the 5-phenol and the 4-keto group of the isoflavonoid as demonstrated by the Jobs method and UV-visible absorption spectroscopy. In ethanol, the stability constants had the value 1.12 × 10 11 L²∙mol -2 for the 1:2 complex and in methanol 6.0 × 10⁵ L∙mol -1 for the 1:1 complex at 25 °C. Binding was not detected in water, as confirmed by an upper limit for the 1:1 stability constant of K = 5 mol -1 L as calculated from the difference in solvation free energy of copper(II) between methanol and the more polar water. Solvent molecules compete with genistein as demonstrated in methanol where binding stoichiometry changes from 1:2 to 1:1 compared to ethanol and methanol/chloroform (7/3, v / v ). Genistein binding to copper(II) increases the scavenging rate of the stable, neutral 2,2-diphenyl-1-picrylhydrazyl radical by more than a factor of four, while only small effects were seen for the short-lived but more oxidizing β -carotene radical cation using laser flash photolysis. The increased efficiency of coordinated genistein is concluded to depend on kinetic rather than on thermodynamic factors, as confirmed by the small change in reduction potential of -0.016 V detected by cyclic voltammetry upon binding of genistein to copper(II) in methanol/chloroform solutions.

Synthesis, crystal structure and DFT studies of a Zinc(II) complex of 1,3-diaminopropane (Dap), [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]n. The additional stabilizing role of S⋯π chalcogen bond

NASA Astrophysics Data System (ADS)

Alotaibi, Mshari A.; Alharthi, Abdulrahman I.; Zierkiewicz, Wiktor; Akhtar, Muhammad; Tahir, Muhammad Nawaz; Mazhar, Muhammad; Isab, Anvarhusein A.; Ahmad, Saeed

2017-04-01

A zinc(II) complex of 1,3-diaminopropane (Dap), [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]n (1) has been prepared and characterized by elemental analysis, IR, 1H &13C NMR spectroscopy, and its crystal structure was determined by X-ray crystallography. The crystal structure of 1 consists of two types of molecules, a discrete monomer and a polymeric one. In the monomeric unit, the zinc atom is bound to one terminal Dap molecule and to two N-bound thiocyanate ions, while in the polymeric unit, Dap acts as a bridging ligand forming a linear chain. The Zn(II) ions in both assume a slightly distorted tetrahedral geometry. The structures of two systems: the [Zn(Dap)(NCS)2][Zn(Dap)(NCS)2]3 complex as a model of 1 and [Zn(Dap)(NCS)2]4 as a simple polymeric structure were optimized with the B3LYP-D3 method. The DFT results support that the experimentally determined structure (1) is more stable in comparison to a simple polymeric structure, [Zn(Dap)(NCS)2]n (2). The interaction energies (ΔE) for NCS anions obtained by B3LYP-D3 method are about -145 kcal mol-1, while the calculated ΔE values for neutral organic ligands are about twice smaller. The X-ray structure of 1 shows that the complex is stabilized mainly by hydrogen bonds. We also found that weak chalcogen bonds play an additional role in stabilization of compound 1. Some of the intermolecular S⋯N distances are smaller than the sum of the van der Waals radii of the corresponding atoms. To the best of our knowledge, this is the first study that shows the structure where the trivalent sulfur is involved in formation of a S⋯π chalcogen bond. The NBO and NCI analyses confirm the existence of this kind of interactions.

Hydrothermal syntheses, characterizations and crystal structures of a new lead(II) carboxylate-phosphonate with a double layer structure and a new nickel(II) carboxylate-phosphonate containing a hydrogen-bonded 2D layer with intercalation of ethylenediamines

NASA Astrophysics Data System (ADS)

Song, Jun-Ling; Mao, Jiang-Gao; Sun, Yan-Qiong; Zeng, Hui-Yi; Kremer, Reinhard K.; Clearfield, Abraham

2004-03-01

Hydrothermal reactions of N, N-bis(phosphonomethyl)aminoacetic acid (HO 2CCH 2N(CH 2PO 3H 2) 2) with metal(II) salts afforded two new metal carboxylate-phosphonates, namely, Pb 2[O 2CCH 2N(CH 2PO 3)(CH 2PO 3H)]·H 2O ( 1) and {NH 3CH 2CH 2NH 3}{Ni[O 2CCH 2N(CH 2PO 3H) 2](H 2O) 2} 2 ( 2). Among two unique lead(II) ions in the asymmetric unit of complex 1, one is five coordinated by five phosphonate oxygen atoms from 5 ligands, whereas the other one is five-coordinated by a tridentate chelating ligand (1 N and 2 phosphonate O atoms) and two phosphonate oxygen atoms from two other ligands. The carboxylate group of the ligand remains non-coordinated. The bridging of above two types of lead(II) ions through phosphonate groups resulted in a <002> double layer with the carboxylate group of the ligand as a pendant group. These double layers are further interlinked via hydrogen bonds between the carboxylate groups into a 3D network. The nickel(II) ion in complex 2 is octahedrally coordinated by a tetradentate chelating ligand (two phosphonate oxygen atoms, one nitrogen and one carboxylate oxygen atoms) and two aqua ligands. These {Ni[O 2CCH 2N(CH 2PO 3H) 2][H 2O] 2} - anions are further interlinked via hydrogen bonds between non-coordinated phosphonate oxygen atoms to form a <800> hydrogen bonded 2D layer. The 2H-protonated ethylenediamine cations are intercalated between two layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Results of magnetic measurements for complex 2 indicate that there is weak Curie-Weiss behavior with θ=-4.4 K indicating predominant antiferromagnetic interaction between the Ni(II) ions. Indication for magnetic low-dimension magnetism could not be detected.

Synthesis, crystal structure and investigation of mononuclear copper(II) and zinc(II) complexes of a new carboxylate rich tripodal ligand and their interaction with carbohydrates in alkaline aqueous solution

PubMed Central

Stewart, Christopher D.; Pedraza, Mayra; Arman, Hadi; Fan, Hua-Jun; Schilling, Eduardo Luiz; Szpoganicz, Bruno; Musie, Ghezai T.

2016-01-01

A new carboxylate rich asymmetric tripodal ligand, N-[2-carboxybenzomethyl]-N-[carboxymethyl]-β-alanine (H3camb), and its di-copper(II), (NH4)2[1]2, and di-zinc(II), ((CH3)4 N)2[2]2, complexes have been synthesized as carbohydrate binding models in aqueous solutions. The ligand and complexes have been fully characterized using several techniques, including single crystal X-ray diffraction. The interactions of (NH4)2[1]2 and ((CH3)4 N)2[2]2 with D-glucose, D-mannose, D-xylose and xylitol in aqueous alkaline media were investigated using UV–Vis and 13C-NMR spectroscopic techniques, respectively. The molar conductance, NMR and ESI–MS studies indicate that the complexes dissociate in solution to produce the respective complex anions, 1− and 2−. Complexes 1− and 2− showed chelating ability towards the naturally abundant and biologically relevant sugars, D-glucose, D-mannose, D-xylose, and xylitol. The complex ions bind to one molar equivalent of the sugars, even in the presence of stoichiometric excess of the substrates, in solution. Experimentally obtained spectroscopic data and computational results suggest that the substrates bind to the metal center in a bidentate fashion. Apparent binding constant values, pKapp, between the complexes and the substrates were determined and a specific mode of substrate binding is proposed. The pKapp and relativistic density functional theory (DFT) calculated Gibbs free energy values indicate that D-mannose displayed the strongest interaction with the complexes. Syntheses, characterizations, detailed substrate binding studies using spectroscopic techniques, single crystal X-ray diffraction and geometry optimizations of the complex-substrates with DFT calculations are also reported. PMID:25969174

Discovery and development of microporous metal carboxylates.

PubMed

Mori, Wasuke; Sato, Tomohiko; Kato, Chika Nozaki; Takei, Tohru; Ohmura, Tetsushi

2005-01-01

We have found a form of copper(II) terephthalate that occluded an enormous amount of gases such as N2, Ar, O2, and Xe. Copper(II) terephthalate is the first metal complex found capable of adsorbing gases. This complex has opened a new field of adsorbent chemistry and is recognized as a leader in the construction of microporous metal complexes. In extending the route for the synthesis of microporous complexes, we obtained many new porous materials that are widely recognized as useful materials for applications in areas such as gas storage, molecular sieves, catalysis, inclusion complexes, and surface science. 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Novel water soluble morpholine substituted Zn(II) phthalocyanine: Synthesis, characterization, DNA/BSA binding, DNA photocleavage and topoisomerase I inhibition.

PubMed

Barut, Burak; Demirbaş, Ümit; Özel, Arzu; Kantekin, Halit

2017-12-01

In this study, novel peripherally tetra 3-morpholinophenol substituted zinc(II) phthalocyanine (4) and its water soluble form quaternized zinc(II) phthalocyanine (ZnQ) were synthesized for the first time. These novel compounds were characterized by a combination of different spectroscopic techniques such as FT-IR, 1 H NMR, 13 C NMR, UV-vis and mass. The DNA binding of ZnQ was investigated using UV-vis absorption titration, competitive ethidium bromide, thermal denaturation and viscosity experiments that the ZnQ bound to CT-DNA via intercalation mode. ZnQ indicated photocleavage activity on supercoiled pBR322 plasmid DNA via formation of singlet oxygen under irradiation at 700nm. Besides, the topoisomerase I inhibitory effect experiments showed that ZnQ inhibited topoisomerase I enzyme in a concentration-dependent manner. The bovine serum albumin (BSA) binding experiments indicated that ZnQ bound to proteins through a static quenching mechanism. All of these results claim that ZnQ has potential agent for photodynamic therapy owing to its nucleic acid interactions and photobiological or photochemical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Fluorescent mixed ligand copper(II) complexes of anthracene-appended Schiff bases: studies on DNA binding, nuclease activity and cytotoxicity.

PubMed

Jaividhya, Paramasivam; Ganeshpandian, Mani; Dhivya, Rajkumar; Akbarsha, Mohammad Abdulkadher; Palaniandavar, Mallayan

2015-07-14

A series of mixed ligand copper(ii) complexes of the type [Cu(L)(phen)(ACN)](ClO4)21-5, where L is a bidentate Schiff base ligand (N(1)-(anthracen-10-ylmethylene)-N(2)-methylethane-1,2-diamine (L1), N(1)-(anthracen-10-ylmethylene)-N(2),N(2)-dimethylethane-1,2-diamine (L2), N(1)-(anthracen-10-yl-methylene)-N(2)-ethylethane-1,2-diamine (L3), N(1)-(anthracen-10-ylmethylene)-N(2),N(2)-diethylethane-1,2-diamine (L4) and N(1)-(anthracen-10-ylmethylene)-N(3)-methylpropane-1,3-diamine (L5)) and phen is 1,10-phenanthroline, have been synthesized and characterized by spectral and analytical methods. The X-ray crystal structure of 5 reveals that the coordination geometry around Cu(ii) is square pyramidal distorted trigonal bipyramidal (τ, 0.76). The corners of the trigonal plane of the geometry are occupied by the N2 nitrogen atom of phen, the N4 nitrogen atom of L5 and the N5 nitrogen of acetonitrile while the N1 nitrogen of phen and the N3 nitrogen of L5 occupy the axial positions with an N1-Cu1-N3 bond angle of 176.0(3)°. All the complexes display a ligand field band (600-705 nm) and three less intense anthracene-based bands (345-395 nm) in solution. The Kb values calculated from absorption spectral titration of the complexes (π→π*, 250-265 nm) with Calf Thymus (CT) DNA vary in the order 5 > 4 > 3 > 2 > 1. The fluorescence intensity of the complexes (520-525 nm) decreases upon incremental addition of CT DNA, which reveals the involvement of phen rather than the appended anthracene ring in partial DNA intercalation with the DNA base stack. The extent of quenching is in agreement with the DNA binding affinities and the relative increase in the viscosity of DNA upon binding to the complexes as well. Thus 5 interacts with DNA more strongly than 4 on account of the stronger involvement in hydrophobic DNA interaction of the anthracenyl moiety, which is facilitated by the propylene ligand backbone with chair conformation. The ability of complexes (100 μM) to cleave DNA (p

Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone

NASA Astrophysics Data System (ADS)

Chumakov, Yu. M.; Tsapkov, V. I.; Jeanneau, E.; Bairac, N. N.; Bocelli, G.; Poirier, D.; Roy, J.; Gulea, A. P.

2008-09-01

The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate ( I), bromo-(2-formylpyridinethiosemicarbazono)copper ( II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate ( III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I III at a concentration of 10-5 mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

Catalytic and inhibiting effect of amino acids on the porphyrin metallation reactions

NASA Astrophysics Data System (ADS)

Mamardashvili, Galina M.; Zhdanova, Daria Yu.; Mamardashvili, Nugzar Zh.; Koifman, Oskar I.; Dehaen, Wim

In the present work, using the interaction of tetra-(4-sulfophenyl)porphyrin with copper(II) chloride as an example, it has been shown how different amino acid additives (glycine, valine, leucine and tryptophan) catalyze or inhibit the formation of Cu-porphyrin as a function of the chemical environment (borate buffer (pH7.4), DMSO) and the concentration of the additive. It has been demonstrated that the type of amino acid affects the complexation reaction rate. Possible mechanisms of metalloporphyrin formation and the ways of their acceleration are discussed. Ways in which different amino acid additives catalyze or inhibit the interaction of tetra-(4-sulfophenyl)porphyrin with copper(II) chloride are examined.

Functionalized CdS quantum dots-based luminescence probe for detection of heavy and transition metal ions in aqueous solution.

PubMed

Chen, Jinlong; Zheng, Aifang; Gao, Yingchun; He, Chiyang; Wu, Genhua; Chen, Youcun; Kai, Xiaoming; Zhu, Changqing

2008-03-01

Strong luminescence CdS quantum dots (QDs) have been prepared and modified with l-cysteine by a facile seeds-assistant technique in water. They are water-soluble and highly stable in aqueous solution. CdS QDs evaluated as a luminescence probe for heavy and transition metal (HTM) ions in aqueous solution was systematically studied. Five HTM ions such as silver(I) ion, copper(II) ion, mercury(II) ion, cobalt(II) ion, and nickel(II) ion significantly influence the photophysics of the emission from the functionalized CdS QDs. Experiment results showed that the fluorescence emission from CdS QDs was enhanced significantly by silver ion without any spectral shift, while several other bivalent HTM ions, such as Hg(2+), Cu(2+), Co(2+), and Ni(2+), exhibited effective optical quenching effect on QDs. Moreover, an obvious red-shift of emission band was observed in the quenching of CdS QDs for Hg(2+) and Cu(2+) ions. Under the optimal conditions, the response was linearly proportional to the concentration of Ag(+) ion ranging from 1.25 x 10(-7) to 5.0 x 10(-6)molL(-1) with a detection limit of 2.0 x 10(-8)molL(-1). The concentration dependence of the quenching effect on functionalized QDs for the other four HTM ions could be well described by typical Stern-Volmer equation, with the linear response of CdS QDs emission proportional to the concentration ranging from 1.50 x 10(-8) to 7.50 x 10(-7)molL(-1) for Hg(2+) ion, 3.0 x 10(-7) to 1.0 x 10(-5)molL(-1) for Ni(2+) ion, 4.59 x 10(-8) to 2.295 x 10(-6)molL(-1) for Cu(2+) ion, and 1.20 x 10(-7) to 6.0 x 10(-6)molL(-1) Co(2+) ion, respectively. Based on the distinct optical properties of CdS QDs system with the five HTM ions, and the relatively wide linear range and rapid response to HTM ions, CdS QDs can be developed as a potential identified luminescence probe for familiar HTM ions detection in aqueous solution.

Cu(II) and Cu(I) complexes with 1,2-dithiosquarate as a ligand; from molecular compounds to supramolecular network structures

NASA Astrophysics Data System (ADS)

Calatayud, M. Luisa; Castro, Isabel; Julve, Miguel; Sletten, Jorunn

2008-03-01

Four new complexes of copper(II) and/or copper(I) with 1,2-dtsq as a ligand have been synthesized and characterized by single crystal X-ray diffraction methods, [Cu II(terpy)(1,2-dtsq)] ( 1), [Cu II(dmen)(1,2-dtsq)] n ( 2), {[Cu II(dmen) 2][Cu I(1,2-dtsq)] 2} n·2nH 2O( 3) and {[Cu II(men) 2][Cu I (1,2-dtsq)] 2} n·nH 2O ( 4) (1,2-dtsq = 1,2-dithiosquarate, dianion of 3,4-dimercapto-1-cyclobutene-1,2-dione; dmen = N, N-dimethylethylenediamine; men = N-methylethylenediamine, terpy = 2,2':6,2″-terpyridine). Compound 1 consists of neutral [Cu II(terpy)(1,2-dtsq)] mononuclear units which are held together by O⋯H-C and van der Waals interactions. Compound 2 is built of neutral [Cu II(dmen)(1,2-dtsq)] entities which are connected through weak Cu-S (pairs) and Cu-O (single) interactions into a layer structure. The structures of 3 and 4 feature polynuclear [Cu(1,2-dtsq)]nn- chains, in which dtsq groups are linking copper(I) ions in the μ-1,1, μ-1,1,1 and μ-1,2 bridging modes. The dtsq groups in these chains connect to the copper(II) ions of the [Cu IIL 2] 2+ cations [L being the bidentate dmen ( 3) and men ( 4) ligands], but in different manners in the two structures. The connections in compound 3 are unsymmetrical, so that columns of {[Cu II(dmen) 2][Cu I(1,2-dtsq)] 2} n where the copper(II) ions bind to 1,2-dtsq oxygen atoms with relatively strong axial bonds may be identified. These columns are further connected to each other through weak axial Cu II⋯S interactions, creating a three-dimensional (3D) network with channels containing the solvent water. In compound 4, on the other hand, the two crystallographically independent cations each forms a symmetrical link between the anionic chains through, respectively, O-Cu II-O and S-Cu II-S axial bonds, again creating a 3D structure with channels running parallel to the chain axis. The reduction of copper(II) to copper(I) by 1,2-dtsq is precluded when the coordination sphere of the copper(II) ion is partially

Modeling adsorption of copper(II), cobalt(II) and nickel(II) metal ions from aqueous solution onto a new carboxylated sugarcane bagasse. Part II: Optimization of monocomponent fixed-bed column adsorption.

PubMed

Xavier, Amália Luísa Pedrosa; Adarme, Oscar Fernando Herrera; Furtado, Laís Milagres; Ferreira, Gabriel Max Dias; da Silva, Luis Henrique Mendes; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius Alves

2018-04-15

In the second part of this series of studies, the monocomponent adsorption of Cu 2+ , Co 2+ and Ni 2+ onto STA adsorbent in a fixed-bed column was investigated and optimized using a 2 2 central composite design. The process variables studied were: initial metal ion concentration and spatial time, and the optimized responses were: adsorption capacity of the bed (Q max ), efficiency of the adsorption process (EAP), and effective use of the bed (H). The higher Q max for Cu 2+ , Co 2+ and Ni 2+ were 1.060, 0.800 and 1.029 mmol/g, respectively. The breakthrough curves were modeled by the original Thomas and Bohart-Adams models. The changes in enthalpy (Δ ads H°) of adsorption of the metal ions onto STA were determined by isothermal titration calorimetry (ITC). The values of Δ ads H° were in the range of 3.0-6.8 kJ/mol, suggesting that the adsorption process involved physisorption. Desorption (E des ) and re-adsorption (E re-ads ) of metal ions from the STA adsorbent were also investigated in batch mode, and the optimum conditions were applied for three cycles of adsorption/desorption in a fixed bed column. For these cycles, the lowest values of E des and E re-ads were 95 and 92.3%, respectively, showing that STA is a promising candidate for real applications on a large scale. Copyright © 2018 Elsevier Inc. All rights reserved.

Nickel(II) biosorption by Rhodotorula glutinis.

PubMed

Suazo-Madrid, Alicia; Morales-Barrera, Liliana; Aranda-García, Erick; Cristiani-Urbina, Eliseo

2011-01-01

The present study reports the feasibility of using Rhodotorula glutinis biomass as an alternative low-cost biosorbent to remove Ni(II) ions from aqueous solutions. Acetone-pretreated R. glutinis cells showed higher Ni(II) biosorption capacity than untreated cells at pH values ranging from 3 to 7.5, with an optimum pH of 7.5. The effects of other relevant environmental parameters, such as initial Ni(II) concentration, shaking contact time and temperature, on Ni(II) biosorption onto acetone-pretreated R. glutinis were evaluated. Significant enhancement of Ni(II) biosorption capacity was observed by increasing initial metal concentration and temperature. Kinetic studies showed that the kinetic data were best described by a pseudo-second-order kinetic model. Among the two-, three-, and four-parameter isotherm models tested, the Fritz-Schluender model exhibited the best fit to experimental data. Thermodynamic parameters (activation energy, and changes in activation enthalpy, activation entropy, and free energy of activation) revealed that the biosorption of Ni(II) ions onto acetone-pretreated R. glutinis biomass is an endothermic and non-spontaneous process, involving chemical sorption with weak interactions between the biosorbent and Ni(II) ions. The high sorption capacity (44.45 mg g(-1) at 25°C, and 63.53 mg g(-1) at 70°C) exhibited by acetone-pretreated R. glutinis biomass places this biosorbent among the best adsorbents currently available for removal of Ni(II) ions from aqueous effluents.

Combining sorption experiments and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) to study the adsorption of propranolol onto environmental solid matrices - Influence of copper(II).

PubMed

Smith, Rose-Michelle; Sayen, Stéphanie; Nuns, Nicolas; Berrier, Elise; Guillon, Emmanuel

2018-05-23

The bioavailability of pharmaceuticals is governed by their sorption in soils/sediments, as the retention processes determine their concentration in surface- and ground-water. The adsorption of these contaminants can involve various solid components such as organic matter, clays and metallic oxides, and their distribution among these solid components depends on contaminant and solid properties. In this paper we studied the adsorption of the pharmaceutical propranolol - a beta-blocker - on eight different solids (six soils, one sediment and one kaolinite-based sample) by batch experiments. The influence of contact time, propranolol concentration and pH was considered, as well as the presence of copper(II). The investigated solids displayed a wide variability in terms of CEC (cationic exchange capacity) and organic carbon and carbonates contents. The influence of pH was negligible in the pH range from 5.5 to 8.6. The adsorbed amounts were greatly dependent on the solid and two groups of solids were evidenced: three soils of high CEC and organic carbon contents which retained high amounts of propranolol, and three soils, the sediment and the kaolinite-based sample (low CEC and organic carbon content) displaying a low adsorption capacity for the beta-blocker. A linear model enabling the determination of the sorption parameters K d and K oc was pertinent to describe the adsorption isotherms but the K oc values showed a great variability. It was shown that organic carbon content alone could not explain propranolol adsorption. The CEC value was identified as influent parameter and a simple empirical model was proposed to describe propranolol adsorption. At microscopic and molecular scales, ToF-SIMS experiments indicated (i) a decrease of potassium on the surface upon propranolol adsorption with a distribution of the beta-blocker similarly to alumino-silicates, iron and organic carbon on the surface confirming a cation exchange mechanism and (ii) the absence of degradation

Evaluation of the Intramolecular Charge-Transfer Properties in Solvatochromic and Electrochromic Zinc Octa(carbazolyl)phthalocyanines.

PubMed

Majeed, Shereen A; Ghazal, Basma; Nevonen, Dustin E; Goff, Philip C; Blank, David A; Nemykin, Victor N; Makhseed, Saad

2017-10-02

2,3,9,10,16,17,23·24-Octakis-(9H-carbazol-9-yl) phthalocyaninato zinc(II) (3) and 2,3,9,10,16,17,23·24-octakis-(3,6-di-tert-butyl-9H-carbazole) phthalocyaninato zinc(II) (4) complexes were prepared and characterized by NMR and UV-vis spectroscopies, magnetic circular dichroism (MCD), matrix-assisted laser desorption ionization mass spectrometry, and X-ray crystallography. UV-vis and MCD data are indicative of the interligand charge-transfer nature of the broad band observed in 450-500 nm range for 3 and 4. The redox properties of 3 and 4 were probed by electrochemical and spectro-electrochemical methods, which are suggestive of phthalocyanine-centered first oxidation and reduction processes. Photophysics of 3 and 4 were investigated by steady-state fluorescence and time-resolved transient absorption spectroscopy demonstrating the influence of the carbazole substituents on deactivation from the first excited state in 3 and 4. Protonation of the meso-nitrogen atoms in 3 results in much faster deactivation kinetics from the first excited state. Spectroscopic data were correlated with density functional theory (DFT) and time-dependent DFT calculations on 3 and 4.

Ultrasound-assisted synthesis of nano-structured Zinc(II)-based metal-organic frameworks as precursors for the synthesis of ZnO nano-structures.

PubMed

Bigdeli, Fahime; Ghasempour, Hosein; Azhdari Tehrani, Alireza; Morsali, Ali; Hosseini-Monfared, Hassan

2017-07-01

A 3D, porous Zn(II)-based metal-organic framework {[Zn 2 (oba) 2 (4-bpmn)]·(DMF) 1.5 } n (TMU-21), (4-bpmn=N,N'-Bis-pyridin-4-ylmethylene-naphtalene-1,5-diamine, H 2 oba=4,4'-oxybis(benzoic acid)) with nano-rods morphology under ultrasonic irradiation at ambient temperature and atmospheric pressure was prepared and characterized by scanning electron microscopy. Sonication time and concentration of initial reagents effects on the size and morphology of nano-structured MOFs were studied. Also {[Zn 2 (oba) 2 (4-bpmn)] (TMU-21) and {[Zn 2 (oba) 2 (4-bpmb)] (TMU-6), 4-bpmb=N,N'-(1,4-phenylene)bis(1-(pyridin-4-yl)methanimine) were easily prepared by mechanochemical synthesis. Nanostructures of Zinc(II) oxide were obtained by calcination of these compounds and their de-solvated analogue as activated MOFs, at 550°C under air atmosphere. As a result of that, different Nanostructures of Zinc(II) oxide were obtained. The ZnO nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and FT-IR spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

Site-Specific Biomolecule Labeling with Gold Clusters

PubMed Central

Ackerson, Christopher J.; Powell, Richard D.; Hainfeld, James F.

2013-01-01

Site-specific labeling of biomolecules in vitro with gold clusters can enhance the information content of electron cryomicroscopy experiments. This chapter provides a practical overview of well-established techniques for forming biomolecule/gold cluster conjugates. Three bioconjugation chemistries are covered: Linker-mediated bioconjugation, direct gold–biomolecule bonding, and coordination-mediated bonding of nickel(II) nitrilotriacetic acid (NTA)-derivatized gold clusters to polyhistidine (His)-tagged proteins. PMID:20887859

Novel copper(II) complexes as new promising antitumour agents. A crystal structure of [Cu(1,10-phenanthroline-5,6-dione)2(OH2)(OClO3)](ClO4).

PubMed

Pivetta, Tiziana; Trudu, Federica; Valletta, Elisa; Isaia, Francesco; Castellano, Carlo; Demartin, Francesco; Tuveri, Rossana; Vascellari, Sarah; Pani, Alessandra

2014-12-01

The cytotoxic properties of copper(II) complexes with 1,10-phenanthroline (phen) can be modified by substitution in the phen backbone. For this purpose, Cu(II) complexes with phen, 1,10-phenanthrolin-5,6-dione (phendione) and 1,10-phenanthrolin-5,6-diol (phendiol) have been synthesised and characterised. The crystal structure of [Cu(phendione)2(OH2)(OClO3)](ClO4) is discussed. The complex formation equilibria between Cu(II) and phen or phendione were studied by potentiometric measurements at 25 and 37°C in 0.1 M ionic strength (NaCl). The antitumour activity of the compounds has been tested in vitro against a panel of tumour (DU-145, HEP-G2, SK-MES-1, CCRF-CEM, CCRF-SB) and normal (CRL-7065) human cell lines. The studied compounds generally present an antiproliferative effect greater than that of cisplatin. The phen and phendione ligands present a similar antiproliferative effect against all the tested cells. Phendiol presents an antiproliferative effect 1.3 to 18 times greater than that of phen or phendione for leukemic, lung, prostatic and fibroblast cells, while it presents less activity towards hepatic cells. Complexes with two ligands are more cytotoxic towards all the tested cell lines than complexes with one ligand and are generally more cytotoxic than the ligand alone. Complexes [Cu(phendiol)2(OH2)](ClO4)2 and [Cu(phendione)2(OH2)(OClO3)](ClO4) appear to be the most active compounds for the treatment of SK-MES-1 and HEP-G2 cells, respectively, being at least 18 times more cytotoxic than cisplatin. The studied Cu(II) complexes are characterised by a strong DNA affinity and were found to interact with DNA mainly by groove binding or electrostatic interactions. The complexes appear to act on cells with a mechanism different from that of cisplatin. Copyright © 2014 Elsevier Inc. All rights reserved.

Newer mixed ligand Schiff base complexes from aquo-N-(2‧-hydroxy acetophenone) glycinatocopper(II) as synthon: DFT, antimicrobial activity and molecular docking study

NASA Astrophysics Data System (ADS)

Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

2014-02-01

Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2‧-hydroxy acetophenone) glycinate, X = imidazole (im) 2, benzimidazole (benz) 3, pyridine (py) 4, hydrazine (hz) 5,8-hydroxyquinoline (8-hq) 6, pyrrolidine (pyrr) 7, piperidine (pip) 8, and nicotinamide (nic) 9) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H2O)]·H2O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H2O)]·H2O, L = N-(2‧-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2‧ hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

Synthesis, characterization, crystal structure and antimicrobial studies of a novel Cu(II) complex based on itaconic acid and nicotinamide

NASA Astrophysics Data System (ADS)

Tella, Adedibu C.; Owalude, Samson O.; Ajibade, Peter A.; Simon, Nzikahyel; Olatunji, Sunday J.; Abdelbaky, Mohammed S. M.; Garcia-Granda, Santiago

2016-12-01

A novel complex was synthesized from Cu(II), nicotinamide and itaconic acid and is formulated as [Cu(C5H4O4)2(C6H6N2O)2(H2O)2·2(H2O)] (1). The compound was characterized by elemental analysis, FTIR spectroscopy, UV-Vis and single crystal X-ray diffraction. The complex crystallizes in the triclinic P-1 space group, with a = 7.5111(2) Å, b = 9.8529(3) Å, c = 10.5118(4) Å, α = 116.244(3)°, β = 90.291(3)°, γ = 103.335(3)°, V = 673.81(4) Å3, Z = 1.The octahedral geometry around the copper(II) ion is of the form CuN2O4 consisting of two molecules of nicotinamide acting as monodentate ligand through the nitrogen atoms, two molecules itaconate ligand and two coordinated water molecules each coordinating through the oxygen atoms. The structure of 1 showed infinite chains build up linking the molecules together via strong Osbnd H⋯O and Nsbnd H⋯O intermolecular hydrogen bonds generating a two dimensional network sheet along c axis. The antimicrobial study of the synthesized complex 1 was investigated and showed higher antibacterial activity against all the organisms comparing with Copper(II) nicotinamide 2 and Copper(II) itaconate 3.

Effects of selected herbicides and fungicides on growth, sporulation and conidial germination of entomopathogenic fungus Beauveria bassiana.

PubMed

Celar, Franci A; Kos, Katarina

2016-11-01

The in vitro fungicidal effects of six commonly used fungicides, namely fluazinam, propineb, copper(II) hydroxide, metiram, chlorothalonil and mancozeb, and herbicides, namely isoxaflutole, fluazifop-P-butyl, flurochloridone, foramsulfuron, pendimethalin and prosulfocarb, on mycelial growth, sporulation and conidial germination of entomopathogenic fungus Beauveria bassiana (ATCC 74040) were investigated. Mycelial growth rates and sporulation at 15 and 25 °C were evaluated on PDA plates containing 100, 75, 50, 25, 12.5, 6.25 and 0% of the recommended application rate of each pesticide. The tested pesticides were classified in four scoring categories based on reduction in mycelial growth and sporulation. All pesticides, herbicides and fungicides tested had fungistatic effects of varying intensity, depending on their rate in the medium, on B. bassiana. The most inhibitory herbicides were flurochloridone and prosulfocarb, and fluazinam and copper(II) hydroxide were most inhibitory among the fungicides, while the least inhibitory were isoxaflutole and chlorothalonil. Sporulation and conidial germination of B. bassiana were significantly inhibited by all tested pesticides compared with the control treatment. Flurochloridone, foramsulfuron, prosulfocarb and copper(II) hydroxide inhibited sporulation entirely at 100% rate (99-100% inhibition), and the lowest inhibition was shown by fluazifop-P-butyl (22%) and metiram (33%). At 100% dosage, all herbicides in the test showed a high inhibitory effect on conidial germination. Conidial germination inhibition ranged from 82% with isoxaflutole to 100% with fluorochloridone, pendimethalin and prosulfocarb. At 200% dosage, inhibition rates even increased (96-100%). All 12 pesticides tested had a fungistatic effect on B. bassiana of varying intensity, depending on the pesticide and its concentration. B. bassiana is highly affected by some herbicides and fungicides even at very low rates. Flurochloridone, foramsulfuron

Combination of a Copper-Ion Selective Electrode and Fluorometric Titration for the Determination of Copper(II) Ion Conditional Stability Constants of Humic Substances.

PubMed

Chen, Juan; Chen, Hao; Zhang, Xing-wen; Lei, Kun; Kenny, Jonathan E

2015-11-01

A fluorescence quenching model using copper(II) ion (Cu(2+)) ion selective electrode (Cu-ISE) is developed. It uses parallel factor analysis (PARAFAC) to model fluorescence excitation-emission matrices (EEMs) of humic acid (HA) samples titrated with Cu(2+) to resolve fluorescence response of fluorescent components to Cu(2+) titration. Meanwhile, Cu-ISE is employed to monitor free Cu(2+) concentration ([Cu]) at each titration step. The fluorescence response of each component is fit individually to a nonlinear function of [Cu] to find the Cu(2+) conditional stability constant for that component. This approach differs from other fluorescence quenching models, including the most up-to-date multi-response model that has a problematic assumption on Cu(2+) speciation, i.e., an assumption that total Cu(2+) present in samples is a sum of [Cu] and those bound by fluorescent components without taking into consideration the contribution of non-fluorescent organic ligands and inorganic ligands to speciation of Cu(2+). This paper employs the new approach to investigate Cu(2+) binding by Pahokee peat HA (PPHA) at pH values of 6.0, 7.0, and 8.0 buffered by phosphate or without buffer. Two fluorescent components (C1 and C2) were identified by PARAFAC. For the new quenching model, the conditional stability constants (logK1 and logK2) of the two components all increased with increasing pH. In buffered solutions, the new quenching model reported logK1 = 7.11, 7.89, 8.04 for C1 and logK2 = 7.04, 7.64, 8.11 for C2 at pH 6.0, 7.0, and 8.0, respectively, nearly two log units higher than the results of the multi-response model. Without buffer, logK1 and logK2 decreased but were still high (>7) at pH 8.0 (logK1 = 7.54, logK2 = 7.95), and all the values were at least 0.5 log unit higher than those (4.83 ~ 5.55) of the multi-response model. These observations indicate that the new quenching model is more intrinsically sensitive than the multi-response model in revealing strong fluorescent

Structural Modifications and Photophysical Studies of Fluorescent Conjugated Polymers for Solid State Sensor Development

NASA Astrophysics Data System (ADS)

Chen, Anting

Fluorescent conjugated polymers (FCPs) represent an exciting area of research in chemosensors and biosensors. Previously, the polymer tmeda-PPETE, N,N,N'-trimethylethylenediamino (tmeda) receptors on a poly[2,5-thiophenediyl-1,2-ethynediyl-1,4-phenylenediyl-1,2-ethynediyl] (PPETE) backbone, showed significant quenching when copper(II) was added. Tmeda-PPETE polymer preloaded with copper(II) was found to be a fluorescent "turn-on" sensor for iron cations. Additional investigation of this metallopolymer revealed a selective sensory system toward carbonate and phosphorus anions through a competitive binding of copper(II) between the polymer tmeda-PPETE and the anions. Fluorescent turn-on response under systematically varied pH was affected by the equilibrium shift of the ionization of polyprotic ions. A sterically hindered pentiptycene group was introduced to the PPETE polymer backbone aiming to reduce aggregation and self-quenching in the solid state. A new FCP, tmeda-PPpETE (poly[(pentiptycene ethynylene)-alt-(thienylene ethynylene)] with tmeda receptors, has been designed and synthesized via Sonogashira cross-coupling reaction. Absorption and emission spectra of tmeda-PPpETE showed blue shifting from tmeda-PPETE, suggesting increased rigidity of polymer backbone. Tmeda-PPpETE showed a high selectivity towards copper(II) with improved sensitivity compared to tmeda-PPETE. The fluorescent quenching response is over 120-fold at emission maximum, and the detection limit is 1.04 ppb, significantly lower than the EPA action level of 1.3 ppm for copper(II). A small turn-off fluorescent response of tmeda-PPpETE was also observed upon addition of iron cations. To further investigate the interaction between pentiptycene containing polymers and iron cations, tmpda-PPpETE containing N,N,N'-trimethylpropylenediamino (tmpda) receptors was designed and synthesized. The absorption and emission spectra for tmpda-PPpETE were analogous to those of tmeda-PPpETE, with a higher quantum

Metals in Metal Salts: A Copper Mirror Demonstration

ERIC Educational Resources Information Center

Pike, Robert D.

2010-01-01

A simple lecture demonstration is described to show the latent presence of metal atoms in a metal salt. Copper(II) formate tetrahydrate is heated in a round-bottom flask forming a high-quality copper mirror.

Synthesis and characterization of heterobimetallic molybdenum and nickel complexes derived from polyfunctional disalicylaldehyde oxaloyldihydrazone

NASA Astrophysics Data System (ADS)

Kumar, Arvind; Borthakur, Rosmita; Koch, Angira; Chanu, Oinam B.; Choudhury, Sanjesh; Lemtur, Aka; Lal, Ram A.

2011-07-01

Heterobimetallic nickel and molybdenum complexes of the composition [Ni(L)MoO 2(A) 4]· nH 2O (A = H 2O (1), py (2), 2-pic (3), 3-pic (4), and 4-pic (5); n = 0, 2) and [Ni(L)(MoO 2)(BB) 2](BB = bpy (6) and (phen (7)) have been synthesized from the multidentate ligand disalicylaldehyde oxaloyldihydrazone (H 4L) in methanol. The composition of the complexes has been established based on data obtained from elemental analyses, thermoanalytical, mass spectral and molecular weight studies. The probable structures of the complexes have been discussed in the light of molar conductance, magnetic moment data and electronic, EPR and infrared spectral studies. In all of the complexes, the dihydrazone is present in enol form and coordinates to the metal centre as a tetrabasic hexadentate ligand. All of the complexes are normal paramagnetic to the extent of two unpaired electrons per nickel atom. The μeff values for the complexes lying in the region 2.87-3.07 B.M. are consistent with the octahedral stereochemistry of nickel(II) in the heterobimetallic complexes. The EPR and electronic spectral data also support the distorted octahedral stereochemistry of the nickel(II) centre. Both nickel and molybdenum have octahedral geometry in the complexes.

Indole synthesis by conjugate addition of anilines to activated acetylenes and an unusual ligand-free copper(II)-mediated intramolecular cross-coupling.

PubMed

Gao, Detian; Back, Thomas G

2012-11-12

A versatile new synthesis of indoles was achieved by the conjugate addition of N-formyl-2-haloanilines to acetylenic sulfones, ketones, and esters followed by a copper-catalyzed intramolecular C-arylation. The conjugate addition step was conducted under exceptionally mild conditions at room temperature in basic, aqueous DMF. Surprisingly, the C-arylation was performed most effectively by employing copper(II) acetate as the catalyst in the absence of external ligands, without the need for protection from air or water. An unusual feature of this process, for the case of acetylenic ketones, is the ability of the initial conjugate-addition product to serve as a ligand for the catalyst, which enables it to participate in the catalysis of its further transformation to the final indole product. Mechanistic studies, including EPR experiments, indicated that copper(II) is reduced to the active copper(I) species by the formate ion that is produced by the base-catalyzed hydrolysis of DMF. This process also served to recycle any copper(II) that was produced by the adventitious oxidation of copper(I), thereby preventing deactivation of the catalyst. Several examples of reactions involving acetylenic sulfones attached to a modified Merrifield resin demonstrated the feasibility of solid-phase synthesis of indoles by using this protocol, and tricyclic products were obtained in one pot by employing acetylenic sulfones that contain chloroalkyl substituents. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and spectral characterization of Zn(II) microsphere series for antimicrobial application

NASA Astrophysics Data System (ADS)

Singh, Ajay K.; Pandey, Sarvesh K.; Pandey, O. P.; Sengupta, S. K.

2014-09-01

Microsphere series have been synthesized by reacting zinc(II) acetate dihydrate with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole/oxadiazole/triazole with salicylaldehyde. Elemental analysis suggests that the complexes have 1:2 and 1:1 stoichiometry of the type [Zn(L)2(H2O)2] and [Zn(L‧)(H2O)2]; LH = Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thia/oxadiazole with salicylaldehyde; L‧H2 = Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1,2,4-triazole and salicylaldehyde and were characterized by elemental analyses, IR, 1H NMR and 13C NMR spectral data. Scanning electron microscopy (SEM) showed that synthesized materials have microsphere like structure and there EDX analysis comparably matches with elemental analysis. For the antimicrobial application Schiff bases and their zinc(II) complexes were screened for four bacteria e.g. Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Streptococcus pyogenes and four fungi e.g. Cyrtomium falcatum, Aspergillus niger, Fusarium oxysporium and Curvularia pallescence by the reported method. Schiff base and Zn(II) compounds showed significant antimicrobial activities. However, activities increase upon chelation. Thermal analysis (TGA) data of compound (10) showed its stability up to 300 °C.

Assemblies of Boron Dipyrromethene/Porphyrin, Phthalocyanine, and C60 Moieties as Artificial Models of Photosynthesis: Synthesis, Supramolecular Interactions, and Photophysical Studies.

PubMed

Chen, Xiao-Fei; El-Khouly, Mohamed E; Ohkubo, Kei; Fukuzumi, Shunichi; Ng, Dennis K P

2018-03-12

A series of light-harvesting conjugates based on a zinc(II) phthalocyanine core with either two or four boron dipyrromethene (BODIPY) or porphyrin units have been synthesized and characterized. The conjugation of BODIPY/porphyrin units can extend the absorptions of the phthalocyanine core to cover most of the visible region. Upon addition of an imidazole-substituted C 60 (C 60 Im), it can axially bind to the zinc(II) center of the phthalocyanine core through metal-ligand interactions. The resulting complexes form photosynthetic antenna-reaction center mimics in which the BODIPY/porphyrin units serve as the antennas to capture the light and transfer the energy to the phthalocyanine core by efficient excitation energy transfer. The excited phthalocyanine is then quenched by the axially bound C 60 Im moiety by electron transfer, which has been supported by computational studies. The photoinduced processes of the assemblies have been studied in detail by various steady-state and time-resolved spectroscopic methods. By femtosecond transient absorption spectroscopic studies, the lifetimes of the charge-separated state of the bis(BODIPY) and bis(porphyrin) systems have been determined to be 3.2 and 4.0 ns, respectively. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum-chemical, NMR, FT IR, and ESI MS studies of complexes of colchicine with Zn(II).

PubMed

Jankowski, Wojciech; Kurek, Joanna; Barczyński, Piotr; Hoffmann, Marcin

2017-04-01

Colchicine is a tropolone alkaloid from Colchicinum autumnale. It shows antifibrotic, antimitotic, and anti-inflammatory activities, and is used to treat gout and Mediterranean fever. In this work, complexes of colchicine with zinc(II) nitrate were synthesized and investigated using DFT, 1 H and 13 C NMR, FT IR, and ESI MS. The counterpoise-corrected and uncorrected interaction energies of these complexes were calculated. We also calculated their 1 H, 13 C NMR, and IR spectra and compared them with the corresponding experimentally obtained data. According to the ESI MS mass spectra, colchicine forms stable complexes with zinc(II) nitrate that have various stoichiometries: 2:1, 1:1:1, and 2:1:1 with respect to colchichine, Zn(II), and nitrate ion. All of the complexes were investigated using the quantum theory of atoms in molecules (QTAIM). The calculated and the measured spectra showed differences before and after the complexation process. Calculated electron densities and bond critical points indicated the presence of bonds between the ligands and the central cation in the investigated complexes that satisfied the quantum theory of atoms in molecules. Graphical Abstract DFT, NMR, FT IR, ESI MS, QTAIM and puckering studies of complexes of colchicine with Zn(II).

Effect of acetate and nitrate anions on the molecular structure of 3-(hydroxyimino)-2-butanone-2-(1H-benzimidazol-2-yl)hydrazone

NASA Astrophysics Data System (ADS)

Kamat, Vinayak; Naik, Krishna; Revankar, Vidyanand K.

2017-04-01

A novel Schiff base ligand 3-(hydroxyimino)-2-butanone-2-(1H-benzimidazol-2-yl)hydrazone has been synthesized by the condensation reaction of 2-Hydrazinobenzimidazole with diacetyl monoxime in presence of acetic acid catalyst. The ligand has crystallized as its acetate salt, due to the charge-assisted hydrogen bonding between protonated benzimidazole ring and acetate anion. Efforts to synthesize the zinc(II) complex of the title compound, has resulted in the formation of a nitrate salt of the ligand, instead of coordination complex of zinc(II). Acetate salt has crystallized in monoclinic P 21/n, while the nitrate salt has crystallized in a triclinic crystal system with P -1 space group. Hirshfeld surface analysis is presented for both of the crystal structures. Structures of synthesized molecules are even computationally optimized using DFT. A comparative structural approach between the synthesized molecules and DFT optimized structure of bare ligand without any counterions is analyzed in terms of bond parameters. Hydrogen bonding is explained keeping the anions as the central dogma. Mass fragmentation pattern of the organic molecule and comparative account of IR, 1H and 13C NMR chemical shifts are also presented. Compounds are screened for their antibacterial and antifungal potencies against few pathogenic microorganisms. The organic motif is found be an excellent antifungal agent.

Site-specific biomolecule labeling with gold clusters.

PubMed

Ackerson, Christopher J; Powell, Richard D; Hainfeld, James F

2010-01-01

Site-specific labeling of biomolecules in vitro with gold clusters can enhance the information content of electron cryomicroscopy experiments. This chapter provides a practical overview of well-established techniques for forming biomolecule/gold cluster conjugates. Three bioconjugation chemistries are covered: linker-mediated bioconjugation, direct gold-biomolecule bonding, and coordination-mediated bonding of nickel(II) nitrilotriacetic acid (NTA)-derivatized gold clusters to polyhistidine (His)-tagged proteins. Copyright © 2010 Elsevier Inc. All rights reserved.

A Solution-Processed Transparent NiO Hole-Extraction Layer for High-Performance Inverted Perovskite Solar Cells.

PubMed

Tang, Li Juan; Chen, Xiao; Wen, Tian Yu; Yang, Shuang; Zhao, Jun Jie; Qiao, Hong Wei; Hou, Yu; Yang, Hua Gui

2018-02-26

A highly transparent NiO layer was prepared by a solution processing method with nickel(II) 2-ethylhexanoate in non-polar solvent and utilized as HTM in perovskite solar cells. Excellent optical transmittance and the matched energy level lead to the enhanced power conversion efficiency (PCE, 18.15 %) than that of conventional sol-gel-processed NiO-based device (12.98 %). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spectrophotometric Determination of Metoprolol Tartrate in Pharmaceutical Dosage Forms on Complex Formation with Cu(II)

PubMed Central

Cesme, Mustafa; Tarinc, Derya; Golcu, Aysegul

2011-01-01

A new, simple, sensitive and accurate spectrophotometric method has been developed for the assay of metoprolol tartrate (MPT), which is based on the complexation of drug with copper(II) [Cu(II)] at pH 6.0, using Britton-Robinson buffer solution, to produce a blue adduct. The latter has a maximum absorbance at 675 nm and obeys Beer's law within the concentration range 8.5-70 μg/mL. Regression analysis of the calibration data showed a good correlation coefficient (r = 0.998) with a limit of detection of 5.56 μg/mL. The proposed procedure has been successfully applied to the determination of this drug in its tablets. In addition, the spectral data and stability constant for the binuclear copper(II) complex of MPT (Cu2MPT2Cl2) have been reported.

Copper(II) and zinc(II) as metal-carboxylate coordination complexes based on (1-methyl-1H-benzo[d]imidazol-2-yl) methanol derivative: Synthesis, crystal structure, spectroscopy, DFT calculations and antioxidant activity

NASA Astrophysics Data System (ADS)

Benhassine, Anfel; Boulebd, Houssem; Anak, Barkahem; Bouraiou, Abdelmalek; Bouacida, Sofiane; Bencharif, Mustapha; Belfaitah, Ali

2018-05-01

This work presents a combined experimental and theoretical study of two new metal-carboxylate coordination compounds. These complexes were prepared from (1-methyl-1H-benzimidazol-2-yl)methanol under mild conditions. The structures of the prepared compounds were characterized by single-crystal X-ray analysis, FTIR and UV-Vis spectroscopy. In the Cupper complex, the Cu(II) ion is coordinated by two ligands, which act as bidentate chelator through the non-substituted N and O atoms, and two carboxylicg oxygen atoms, displaying a hexa-coordinated compound in a distorted octahedral geometry, while in the Zinc complex the ligand is ligated to the Zn(II) ion in monodentate fashion through the N atom, and the metal ion is also bonded to carboxylic oxygen atoms. The tetra-coordinated compound displays a distorted tetrahedral shape. The density functional theory calculations are carried out for the determination of the optimized structures. The electronic transitions and fundamental vibrational wave numbers are calculated and are in good agreement with experimental. In addition, the ligand and its Cu(II) and Zn(II) complexes were screened and evaluated for their potential as DPPH radical scavenger.

Tested Demonstrations.

ERIC Educational Resources Information Center

Gilbert, George L., Ed.

1985-01-01

Background information, procedures, and typical results obtained are provided for two demonstrations. The first involves the colorful complexes of copper(II). The second involves reverse-phase separation of Food, Drug, and Cosmetic (FD & C) dyes using a solvent gradient. (JN)

Dinuclear metallacycles with single M-O(H)-M bridges [M = Fe(II), Co(II), Ni(II), Cu(II)]: effects of large bridging angles on structure and antiferromagnetic superexchange interactions.

PubMed

Reger, Daniel L; Pascui, Andrea E; Foley, Elizabeth A; Smith, Mark D; Jezierska, Julia; Ozarowski, Andrew

2014-02-17

The reactions of M(ClO4)2·xH2O and the ditopic ligands m-bis[bis(1-pyrazolyl)methyl]benzene (Lm) or m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*) in the presence of triethylamine lead to the formation of monohydroxide-bridged, dinuclear metallacycles of the formula [M2(μ-OH)(μ-Lm)2](ClO4)3 (M = Fe(II), Co(II), Cu(II)) or [M2(μ-OH)(μ-Lm*)2](ClO4)3 (M = Co(II), Ni(II), Cu(II)). With the exception of the complexes where the ligand is Lm and the metal is copper(II), all of these complexes have distorted trigonal bipyramidal geometry around the metal centers and unusual linear (Lm*) or nearly linear (Lm) M-O-M angles. For the two solvates of [Cu2(μ-OH)(μ-Lm)2](ClO4)3, the Cu-O-Cu angles are significantly bent and the geometry about the metal is distorted square pyramidal. All of the copper(II) complexes have structural distortions expected for the pseudo-Jahn-Teller effect. The two cobalt(II) complexes show moderate antiferromagnetic coupling, -J = 48-56 cm(-1), whereas the copper(II) complexes show very strong antiferromagnetic coupling, -J = 555-808 cm(-1). The largest coupling is observed for [Cu2(μ-OH)(μ-Lm*)2](ClO4)3, the complex with a Cu-O-Cu angle of 180°, such that the exchange interaction is transmitted through the dz(2) and the oxygen s and px orbitals. The interaction decreases, but it is still significant, as the Cu-O-Cu angle decreases and the character of the metal orbital becomes increasingly d(x(2)-y(2)). These intermediate geometries and magnetic interactions lead to spin Hamiltonian parameters for the copper(II) complexes in the EPR spectra that have large E/D ratios and one g matrix component very close to 2. Density functional theory calculations were performed using the hybrid B3LYP functional in association with the TZVPP basis set, resulting in reasonable agreement with the experiments.

Diffraction efficiency study of holographic gratings in dichromated poly(vinyl alcohol) NiCl II•6H IIO doped

NASA Astrophysics Data System (ADS)

Fontanilla-Urdaneta, R. C.; Hernández-Garay, M. P.; Olivares-Pérez, A.; Páez-Trujillo, G.; Fuentes-Tapia, I.

2008-02-01

Experimental results to the saturation and diffraction efficiency from holographic gratings are presented in this investigation. The experiments were carried out during real time holographic gratings formation. Dichromated poly(vinyl alcohol) was doped with nickel(II) chloride hexahydrate and it is used like optical material. The influence of the hologram parameters to get the maximum diffraction efficiency is studied at room conditions. This study contributes to get more information about the behavior of this material for holographic gratings recording.

Polarization analysis of holographic gratings recorded in organic conductive material

NASA Astrophysics Data System (ADS)

Fontanilla-Urdaneta, R.; Hernández-Garay, M. P.; Olivares-Pérez, A.; Páez-Trujillo, G.; Fuentes-Tapia, I.

2007-09-01

This work presents experimental results of intensity changes by polarization conditions at the resultant diffraction patters. The substrate used as retarder plate was a commercial transparency film for use with plain paper copier (3M-PP2900 TM). The conductive material composition was introduce to dichromated poly(vinyl alcohol) by adding a metallic salt as nickel(II) chloride hexahydrate. Some electro-optical characteristics of organic conductive material that are used in the holographic gratings storage specifically when applied voltage.

Does Cu(acac)2 Quench Benzene Fluorescence? A Physical Chemistry Experiment.

ERIC Educational Resources Information Center

Marciniak, Bronislaw

1986-01-01

Describes a laboratory experiment in which benzene fluorescence is quenched by bis(acetylacetonato) copper(II). Discusses how this experiment can demonstrate a special technique used in the field of photochemistry. Provides an outline of the experimental procedure and discusses its results. (TW)

Removal of Cu(II) from leachate using natural zeolite as a landfill liner material.

PubMed

Turan, N Gamze; Ergun, Osman Nuri

2009-08-15

All hazardous waste disposal facilities require composite liner systems to act as a barrier against migration of contaminated leachate into the subsurface environment. Removal of copper(II) from leachate was studied using natural zeolite. A serial of laboratory systems on bentonite added natural zeolite was conducted and copper flotation waste was used as hazardous waste. The adsorption capacities and sorption efficiencies were determined. The sorption efficiencies increased with increasing natural zeolite ratio. The pseudo-first-order, the pseudo-second-order, Elovich and the intra-particle diffusion kinetic models were used to describe the kinetic data to estimate the rate constants. The second-order model best described adsorption kinetic data. The results indicated that natural zeolite showed excellent adsorptive characteristics for the removal of copper(II) from leachate and could be used as very good liner materials due to its high uptake capacity and the abundance in availability.

Metal Fluorides, Metal Chlorides and Halogenated Metal Oxides as Lewis Acidic Heterogeneous Catalysts. Providing Some Context for Nanostructured Metal Fluorides.

PubMed

Lennon, David; Winfield, John M

2017-01-28

Aspects of the chemistry of selected metal fluorides, which are pertinent to their real or potential use as Lewis acidic, heterogeneous catalysts, are reviewed. Particular attention is paid to β-aluminum trifluoride, aluminum chlorofluoride and aluminas γ and η, whose surfaces become partially fluorinated or chlorinated, through pre-treatment with halogenating reagents or during a catalytic reaction. In these cases, direct comparisons with nanostructured metal fluorides are possible. In the second part of the review, attention is directed to iron(III) and copper(II) metal chlorides, whose Lewis acidity and potential redox function have had important catalytic implications in large-scale chlorohydrocarbons chemistry. Recent work, which highlights the complexity of reactions that can occur in the presence of supported copper(II) chloride as an oxychlorination catalyst, is featured. Although direct comparisons with nanostructured fluorides are not currently possible, the work could be relevant to possible future catalytic developments in nanostructured materials.

The Analysis of Cyanide and Its Breakdown Products in Biological Samples

DTIC Science & Technology

2010-01-01

simultaneous GC-mass spectrometric (MS) analysis of cyanide and thiocyanate, and Funazo et al. (53) quantita- tively methylated cyanide and thiocyanate for...selective membrane electrode for thiocyanate ion based on a bis-taurine- salicylic binuclear copper(II) complex as ionophore. Chinese Journal of Chemistry

Stereoselective Synthesis of Morpholines Via Copper-Promoted Oxyamination of Alkenes

PubMed Central

Sequeira, Fatima C.

2012-01-01

A new copper(II) 2-ethylhexanoate promoted addition of an alcohol and an amine across an alkene (oxyamination) is reported. The alcohol addition is intramolecular while coupling with the amine occurs intermolecularly. Several 2-aminomethyl morpholines were synthesized in good to excellent yields and diastereoselectivities. PMID:22894680

A new copper(II) chelate complex with tridentate ligand: Synthesis, crystal and molecular electronic structure of aqua-(diethylenetriamine-N, N‧, N‧‧)-copper(II) sulfate monohydrate and its fire retardant properties

NASA Astrophysics Data System (ADS)

Lavrenyuk, H.; Mykhalichko, O.; Zarychta, B.; Olijnyk, V.; Mykhalichko, B.

2015-09-01

The crystals of a new aqua-(diethylenetriamine-N, N‧, N‧‧)-copper(II) sulfate monohydrate have been synthesized by direct interaction of solid copper(II) sulfate pentahydrate with diethylenetriamine (deta). The crystal structure of [Cu(deta)H2O]SO4ṡH2O (1) has been determined by X-ray diffraction methods at 100 K and characterized using X-ray powder diffraction pattern: space group P 1 bar, a = 7.2819(4), b = 8.4669(4), c = 8.7020(3) Å, α = 83.590(3), β = 89.620(4), γ = 84.946(4)°, Z = 2. The environment of the Cu(II) atom is a distorted, elongated square pyramid which consists of three nitrogen atoms of the deta molecule and oxygen atom of the water molecule in the basal plane of the square pyramid (the average lengths of the in-plane Cu-N and Cu-O bonds are 2.00 Å). The apical position of the coordination polyhedron is occupied by complementary oxygen atom of the sulfate anion (the length of the axial Cu-O bond is 2.421(1) Å). The crystal packing is governed by strong hydrogen bonds of O-H⋯O and N-H⋯O types. The ab initio quantum-chemical calculations have been performed by the restricted Hartree-Fock method with a basis set 6-31∗G using the structural data of [Cu(deta)H2O]SO4ṡH2O. It has been ascertained that the degenerate d-orbitals of the Cu2+ ion split under the co-action of both the square-pyramidal coordination and the chelation. It is significant that visually observed crystals color (blue-violet) of the [Cu(deta)H2O]SO4ṡH2O complex is in good agreement with the calculated value of wavelength of visible light (λ = 5735 Å) which is closely related to the energy of the absorbed photon (Δ = 2.161 eV). Furthermore, the stereo-chemical aspect of influence of the CuSO4 upon combustibility of modified epoxy-amine polymers has been scrutinized.

Heptacopper(II) and dicopper(II)-adenine complexes: synthesis, structural characterization, and magnetic properties

DOE PAGES

Leite Ferreira, B. J. M.; Brandão, Paula; Dos Santos, A. M.; ...

2015-07-13

The syntheses, crystal structures, and magnetic properties of two new copper(II) complexes with molecular formulas [Cu 7(μ 2-OH 2) 6(μ 3-O) 6(adenine) 6(NO 3) 26H 2O (1) and [Cu 2(μ 2-H 2O) 2(adenine) 2(H 2O) 4](NO 3) 42H 2O (2) are reported. We composed the heptanuclear compound of a central octahedral CuO 6 core sharing edges with six adjacent copper octahedra. In 2, the copper octahedra shares one equatorial edge. In both compounds, these basic copper cluster units are further linked by water bridges and bridging adenine ligands through N3 and N9 donors. All copper(II) centers exhibit Jahn-Teller distorted octahedralmore » coordination characteristic of a d 9 center. Our study of the magnetic properties of the heptacopper complex revealed a dominant ferromagnetic intra-cluster interaction, while the dicopper complex exhibits antiferromagnetic intra-dimer interactions with weakly ferromagnetic inter-dimer interaction.« less

Synthesis and Electric Properties of a Two-Dimensional Metal-Organic Framework Based on Phthalocyanine.

PubMed

Nagatomi, Hisanori; Yanai, Nobuhiro; Yamada, Teppei; Shiraishi, Kanji; Kimizuka, Nobuo

2018-02-06

Complexation of copper(II) 2,3,9,10,16,17,23,24-octahydroxy-29H,31H-phthalocyanine (CuPcOH) with copper(II) ions gives a two-dimensional (2D) metal-organic framework (MOF). This is the first report of a phthalocyanine-based MOF. This 2D MOF was obtained as a black powder and showed an electrical conductivity of 1.6×10 -6  S cm -1 at 80 °C. When this MOF is used as a cathode of lithium ion battery (LIB), large charge/discharge capacities of 151/128 mAh g -1 were obtained. In addition, it showed a good stability during 200 charge/discharge cycles. The obtained LIB performance mainly originates from the electrically conductive and redox-active framework of the phthalocyanine-based 2D MOF and its hierarchical microporous/mesoporous structure. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Covalent modifications of the amyloid beta peptide by hydroxynonenal: Effects on metal ion binding by monomers and insights into the fibril topology.

PubMed

Grasso, G; Komatsu, H; Axelsen, P H

2017-09-01

Amyloid β peptides (Aβ) and metal ions are associated with oxidative stress in Alzheimer's disease (AD). Oxidative stress, acting on ω-6 polyunsaturated fatty acyl chains, produces diverse products, including 4-hydroxy-2-nonenal (HNE), which can covalently modify the Aβ that helped to produce it. To examine possible feedback mechanisms involving Aβ, metal ions and HNE production, the effects of HNE modification and fibril formation on metal ion binding was investigated. Results indicate that copper(II) generally inhibits the modification of His side chains in Aβ by HNE, but that once modified, copper(II) still binds to Aβ with high affinity. Fibril formation protects only one of the three His residues in Aβ from HNE modification, and this protection is consistent with proposed models of fibril structure. These results provide insight into a network of biochemical reactions that may be operating as a consequence of oxidative stress in AD, or as part of the pathogenic process. Copyright © 2016. Published by Elsevier Inc.

Zinc(II) binds to the neuroprotective peptide humanin.

PubMed

Armas, Ambar; Sonois, Vanessa; Mothes, Emmanuelle; Mazarguil, Honoré; Faller, Peter

2006-10-01

The abnormal accumulation of the peptide amyloid-beta in the form of senile (or amyloid) plaques is one of the hallmarks of Alzheimer's disease (AD). Zinc ions have been implicated in AD and plaques formation. Recently, the peptide humanin has been discovered. Humanin showed neuroprotective activity against amyloid-beta insults. Here the question investigated is if humanin could interact directly with Zn(II). It is shown that Zn(II) and its substitutes Cd(II)/Co(II) bind to humanin via a thiolate bond from the side chain of the single cysteine at position 8. The low intensity of the d-d bands of Co(II)-humanin indicated an octahedral coordination geometry. Titration experiments suggest that Zn(II) binds to humanin with an apparent affinity in the low muM range. This apparent Zn-binding affinity is in the same order as for amyloid-beta and glutathione and could thus be of physiological relevance.

Dissociation constants, neutralization enthalpies and reactions of 3-styryl-2-mercaptopropenoic and 3-(1-naphthyl)-2-mercaptopropenoic acids.

PubMed

Izquierdo, A; Bosch, E; Beltran, J L

1984-06-01

Dissociation constants (pK(a1) and pK(a2) in water-ethanol medium for 3-styryl-2-mercaptopropenoic and 3-(1-naphthyl)-2-mercaptopropenoic acid have been determined potentiometrically, and pK(a2) for both in aqueous medium, spectrophotometrically. Neutralization enthalpies in water-ethanol medium have been determined by thermometric titration. The reactions with metal ions have been studied, and the main reactions are described. The most sensitive reactions are with titanium(IV) (pD = 7.00) and nickel(II) (pD = 6.50).

Elaboration and use of nickel planar macrocyclic complex-based sensors for the direct electrochemical measurement of nitric oxide in biological media.

PubMed

Bedioui, F; Trevin, S; Devynck, J; Lantoine, F; Brunet, A; Devynck, M A

1997-01-01

We describe here the electrochemical detection of nitric oxide, NO, in biological systems by using chemically modified ultramicro carbon electrodes. In the first part of the paper, the different steps involved in the electrochemical preparation and characterization of the nickel-based sensor are described. This is illustrated by the use of nickel(II) tetrasulfonated phthalocyanine complex. The second part of the paper describes two examples of the direct electrochemical measurement of NO production in human blood platelets and endothelial cells from umbilical cord vein.

Using Modern Solid-State Analytical Tools for Investigations of an Advanced Carbon Capture Material: Experiments for the Inorganic Chemistry Laboratory

ERIC Educational Resources Information Center

Wriedt, Mario; Sculley, Julian P.; Aulakh, Darpandeep; Zhou, Hong-Cai

2016-01-01

A simple and straightforward synthesis of an ultrastable porous metal-organic framework (MOF) based on copper(II) and a mixed N donor ligand system is described as a laboratory experiment for chemistry undergraduate students. These experiments and the resulting analysis are designed to teach students basic research tools and procedures while…

ANALYSIS OF ANIONIC METALLIZED AZO AND FORMAZAN DYES BY CAPILLARY ELECTROPHORESIS/MASS SPECTROMETRY

EPA Science Inventory

Capillary electrophoresis-mass spectrometry was applied to the separation of several anionic dyes containing copper(II), chromium(III), or cobalt(III) as part of the dye molecule. The dyes were separated using a 110 cmX50 mu m uncoated fused-silica capillary and a 5 mM ammonium a...

Exhaustive oxidation of a nickel dithiolate complex: some mechanistic insights en route to sulfate formation.

PubMed

Hosler, Erik R; Herbst, Robert W; Maroney, Michael J; Chohan, Balwant S

2012-01-21

A study of the step-wise oxidation of a Ni(II) diaminodithiolate complex through the formation of sulfate, the ultimate sulfur oxygenate, is reported. Controlled oxygenations or peroxidations of a neutral, planar, tetracoordinate, low-spin Ni(II) complex of a N(2)S(2)-donor ligand, (N,N'-dimethyl-N-N'-bis(2-mecaptoethyl)-1,3-propanediaminato) nickel(ii) (1), led to a series of sulfur oxygenates that have been isolated and characterized by ESI-MS and single-crystal X-ray diffraction. A monosulfenate complex (2) was detected by ESI-MS as a product of oxidation with one equivalent of H(2)O(2). However, this complex proved too unstable to isolate. Reaction of the dithiolate (1) with two equivalents of H(2)O(2) or one O(2) molecule leads to the formation of a monosulfinate complex (3), which was isolated and fully characterized by crystallography. The oxidation product of the monosulfinate (3) produced with either O(2) or H(2)O(2) is an interesting dimeric complex containing both sulfonate and thiolate ligands (4), this complex was fully characterized by crystallography, details of which were reported earlier by us. A disulfonate complex (7) is produced by reaction of 1 in the presence of O(2) or by reaction with exactly six equivalents of H(2)O(2). This complex was isolated and also fully characterized by crystallography. Possible intermediates in the conversion of the monosulfinate complex (3) to the disulfonate complex (7) include complexes with mixed sulfonate/sulfenate (5) or sulfonate/sulfinate (6) ligands. Complex 5, a four-oxygen adduct of 1, was not detected, but the sulfonate/sulfinate complex (6) was isolated and characterized. The oxidation chemistry of 1 is very different from that reported for other planar cis-N(2)S(2) Ni(ii) complexes including N,N'-dimethyl-N-N'-bis(2-mecaptoethyl)-1,3-ethylenediaminato) nickel(II), (8), and N,N'-bis(mercaptoethyl)-1,5-diazacyclooctane nickel(II). To address the structural aspects of the reactivity differences, the

Chitosan-bound pyridinedicarboxylate Ni(II) and Fe(III) complex biopolymer films as waste water decyanidation agents.

PubMed

Adewuyi, Sheriff; Jacob, Julianah Modupe; Olaleye, Oluwatoyin Omolola; Abdulraheem, Taofiq Olanrewaju; Tayo, Jubril Ayopo; Oladoyinbo, Fatai Oladipupo

2016-10-20

Chitosan is a biopolymer with immense structural advantage for chemical and mechanical modifications to generate novel properties, functions and applications. This work depicts new pyridinedicarboxylicacid (PDC) crosslinked chitosan-metal ion films as veritable material for cyanide ion removal from aqueous solution. The PDC-crosslinked chitosan-metal films (PDC-Chit-Ni(II) and PDC-Chit-Fe(III)) were formed by complexing PDC-crosslinked chitosan film with anhydrous nickel(II) and iron(III) chloride salts respectively. The PDC-Chit and its metal films were characterized employing various analytical and spectroscopic techniques. The FT-IR, UV-vis and the XRD results confirm the presence of the metal ions in the metal coordinated PDC-crosslinked chitosan film. The surface morphological difference of PDC-Chit-Ni(II) film before and after decyanidation was explored with scanning electron microscopy. Furthermore, the quantitative amount of nickel(II) and iron(III) present in the complex were determined using Atomic Absorption Spectrophotometer as 32.3 and 37.2μg/g respectively which portends the biopolymer film as a good complexing agent. Removal of cyanide from aqueous solution with PDC-Chit, PDC-Chit-Ni(II) and PDC-Chit-Fe(III) films was studied with batch equilibrium experiments. At equilibrium, decyanidation capacity (DC) followed the order PDC-Chit-Ni (II)≈PDC-Chit-Fe(III)>PDC-Chit. PDC-Chit-Ni(II) film gave 100% CN(-) removal within 40min decyanidation owing to favorable coordination geometry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and characterization of Ni(II) complex with 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium bromide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yusoff, Latifah M.; Yusoff, Siti Fairus M.; Ismail, Wafiuddin

Nickel(II) complex have been synthesized by treating a 14-membered ring tetraaza macrocyclic compound, 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium, bromide (Me{sub 6}N{sub 4}H{sub 4})Br{sub 2} with nickel acetate in metanol. The complex was characterized using elemental analysis, Fourier Transform Infrared (FTIR), Ultraviolet-Visible (UV-Vis), and single crystal diffraction (X-ray). The nickel atom coordinates through four nitrogen atoms in the ligand. Square planar geometry has been proposed for this complex.

Magnetic anisotropy in nickel complexes as determined by combined magnetic susceptibility/magnetization/theoretical studies

NASA Astrophysics Data System (ADS)

Mašlejová, Anna; Boča, Roman; Dlháň, L.'ubor; Herchel, Radovan

2004-05-01

The zero-field splitting in nickel(II) complexes was modeled by considering all relevant operators (electron repulsion, crystal-field, spin-orbit coupling, orbital-Zeeman, and spin-Zeeman) in the complete basis set spanned by d n-atomic terms. D-values between weak and strong crystal field limits were evaluated from the crystal-field multiplets as well as using the spin Hamiltonian formalism. Importance of the anisotropic orbital reduction factors is discussed and exemplified by D/hc=-22 cm-1 as subtracted from magnetic data for [Ni(imidazole) 4(acetate) 2] complex.

Post-synthetic modifications of cadmium-based knots and links.

PubMed

Prakasam, Thirumurugan; Bilbeisi, Rana A; Lusi, Matteo; Olsen, John-Carl; Platas-Iglesias, Carlos; Trabolsi, Ali

2016-05-31

Three topologically non-trivial cadmium(ii)-based complexes-Cd-[2]C, Cd-TK and Cd-SL-were simultaneously self-assembled in a dynamic library, individually isolated and fully characterized using solid-state, gas-phase and solution-phase techniques. Post-synthetic modifications, including reduction and transmetalation, were subsequently achieved. Imine bond reduction followed by demetallation led to the isolation of the corresponding organic molecules [2]C, TK and SL. Transmetalation of Cd-TK and Cd-SL with the zinc(ii) cation resulted in isolation of the corresponding zinc(ii)-containing complexes Zn-TK and Zn-SL.

Electrochemical Water Oxidation and Stereoselective Oxygen Atom Transfer Mediated by a Copper Complex.

PubMed

Kafentzi, Maria-Chrysanthi; Papadakis, Raffaello; Gennarini, Federica; Kochem, Amélie; Iranzo, Olga; Le Mest, Yves; Le Poul, Nicolas; Tron, Thierry; Faure, Bruno; Simaan, A Jalila; Réglier, Marius

2018-04-06

Water oxidation by copper-based complexes to form dioxygen has attracted attention in recent years, with the aim of developing efficient and cheap catalysts for chemical energy storage. In addition, high-valent metal-oxo species produced by the oxidation of metal complexes in the presence of water can be used to achieve substrate oxygenation with the use of H 2 O as an oxygen source. To date, this strategy has not been reported for copper complexes. Herein, a copper(II) complex, [(RPY2)Cu(OTf) 2 ] (RPY2=N-substituted bis[2-pyridyl(ethylamine)] ligands; R=indane; OTf=triflate), is used. This complex, which contains an oxidizable substrate moiety (indane), is used as a tool to monitor an intramolecular oxygen atom transfer reaction. Electrochemical properties were investigated and, upon electrolysis at 1.30 V versus a normal hydrogen electrode (NHE), both dioxygen production and oxygenation of the indane moiety were observed. The ligand was oxidized in a highly diastereoselective manner, which indicated that the observed reactivity was mediated by metal-centered reactive species. The pH dependence of the reactivity was monitored and correlated with speciation deduced from different techniques, ranging from potentiometric titrations to spectroscopic studies and DFT calculations. Water oxidation for dioxygen production occurs at neutral pH and is probably mediated by the oxidation of a mononuclear copper(II) precursor. It is achieved with a rather low overpotential (280 mV at pH 7), although with limited efficiency. On the other hand, oxygenation is maximum at pH 8-8.5 and is probably mediated by the electrochemical oxidation of an antiferromagnetically coupled dinuclear bis(μ-hydroxo) copper(II) precursor. This constitutes the first example of copper-centered oxidative water activation for a selective oxygenation reaction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of a potential generator-produced PET tracer for cerebral perfusion imaging: Single-pass cerebral extraction measurements and imaging with radiolabeled Cu-PTSM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathias, C.J.; Welch, M.J.; Raichle, M.E.

1990-03-01

Copper(II) pyruvaldehyde bis(N4-methylthiosemicarbazone) (Cu-PTSM), copper(II) pyruvaldehyde bis(N4-dimethylthiosemicarbazone) (Cu-PTSM2), and copper(II) ethylglyoxal bis(N4-methylthiosemicarbazone) (Cu-ETSM), have been proposed as PET tracers for cerebral blood flow (CBF) when labeled with generator-produced 62Cu (t1/2 = 9.7 min). To evaluate the potential of Cu-PTSM for CBF PET studies, baboon single-pass cerebral extraction measurements and PET imaging were carried out with the use of 67Cu (t1/2 = 2.6 days) and 64Cu (t1/2 = 12.7 hr), respectively. All three chelates were extracted into the brain with high efficiency. There was some clearance of all chelates in the 10-50-sec time frame and Cu-PTSM2 continued to clear. Cu-PTSM andmore » Cu-ETSM have high residual brain activity. PET imaging of baboon brain was carried out with the use of (64Cu)-Cu-PTSM. For comparison with the 64Cu brain image, a CBF (15O-labeled water) image (40 sec) was first obtained. Qualitatively, the H2(15)O and (64Cu)-Cu-PTSM images were very similar; for example, a comparison of gray to white matter uptake resulted in ratios of 2.42 for H2(15)O and 2.67 for Cu-PTSM. No redistribution of 64Cu was observed in 2 hr of imaging, as was predicted from the single-pass study results. Quantitative determination of blood flow using Cu-PTSM showed good agreement with blood flow determined with H2(15)O. This data suggests that (62Cu)-Cu-PTSM may be a useful generator-produced radiopharmaceutical for blood flow studies with PET.« less

Simple Potentiometric Determination of Reducing Sugars

ERIC Educational Resources Information Center

Moresco, Henry; Sanson, Pedro; Seoane, Gustavo

2008-01-01

In this article a potentiometric method for reducing sugar quantification is described. Copper(II) ion reacts with the reducing sugar (glucose, fructose, and others), and the excess is quantified using a copper wire indicator electrode. In order to accelerate the kinetics of the reaction, working conditions such as pH and temperature must be…

Characterization of Cu(II)-reconstituted ACC Oxidase using experimental and theoretical approaches.

PubMed

El Bakkali-Tahéri, Nadia; Tachon, Sybille; Orio, Maylis; Bertaina, Sylvain; Martinho, Marlène; Robert, Viviane; Réglier, Marius; Tron, Thierry; Dorlet, Pierre; Simaan, A Jalila

2017-06-01

1-Aminocyclopropane-1-carboxylic acid oxidase (ACCO) is a non heme iron(II) containing enzyme that catalyzes the final step of the ethylene biosynthesis in plants. The iron(II) ion is bound in a facial triad composed of two histidines and one aspartate (H177, D179 and H234). Several active site variants were generated to provide alternate binding motifs and the enzymes were reconstituted with copper(II). Continuous wave (cw) and pulsed Electron Paramagnetic Resonance (EPR) spectroscopies as well as Density Functional Theory (DFT) calculations were performed and models for the copper(II) binding sites were deduced. In all investigated enzymes, the copper ion is equatorially coordinated by the two histidine residues (H177 and H234) and probably two water molecules. The copper-containing enzymes are inactive, even when hydrogen peroxide is used in peroxide shunt approach. EPR experiments and DFT calculations were undertaken to investigate substrate's (ACC) binding on the copper ion and the results were used to rationalize the lack of copper-mediated activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Precursor Ion Scan Mode-Based Strategy for Fast Screening of Polyether Ionophores by Copper-Induced Gas-Phase Radical Fragmentation Reactions.

PubMed

Crevelin, Eduardo J; Possato, Bruna; Lopes, João L C; Lopes, Norberto P; Crotti, Antônio E M

2017-04-04

The potential of copper(II) to induce gas-phase fragmentation reactions in macrotetrolides, a class of polyether ionophores produced by Streptomyces species, was investigated by accurate-mass electrospray tandem mass spectrometry (ESI-MS/MS). Copper(II)/copper(I) transition directly induced production of diagnostic acylium ions with m/z 199, 185, 181, and 167 from α-cleavages of [macrotetrolides + Cu] 2+ . A UPLC-ESI-MS/MS methodology based on the precursor ion scan of these acylium ions was developed and successfully used to identify isodinactin (1), trinactin (2), and tetranactin (3) in a crude extract of Streptomyces sp. AMC 23 in the precursor ion scan mode. In addition, copper(II) was also used to induce radical fragmentation reactions in the carboxylic acid polyether ionophore nigericin. The resulting product ions with m/z 755 and 585 helped to identify nigericin in a crude extract of Streptomyces sp. Eucal-26 by means of precursor ion scan experiments, demonstrating that copper-induced fragmentation reactions can potentially identify different classes of polyether ionophores rapidly and selectively.

Adduct simplification in the analysis of cyanobacterial toxins by matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Howard, Karen L; Boyer, Gregory L

2007-01-01

A novel method for simplifying adduct patterns to improve the detection and identification of peptide toxins using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry is presented. Addition of 200 microM zinc sulfate heptahydrate (ZnSO(4) . 7H(2)O) to samples prior to spotting on the target enhances detection of the protonated molecule while suppressing competing adducts. This produces a highly simplified spectrum with the potential to enhance quantitative analysis, particularly for complex samples. The resulting improvement in total signal strength and reduction in the coefficient of variation (from 31.1% to 5.2% for microcystin-LR) further enhance the potential for sensitive and accurate quantitation. Other potential additives tested, including 18-crown-6 ether, alkali metal salts (lithium chloride, sodium chloride, potassium chloride), and other transition metal salts (silver chloride, silver nitrate, copper(II) nitrate, copper(II) sulfate, zinc acetate), were unable to achieve comparable results. Application of this technique to the analysis of several microcystins, potent peptide hepatotoxins from cyanobacteria, is illustrated. Copyright (c) 2007 John Wiley & Sons, Ltd.

The Unusual Colour of Copper Deposited on a Graphite Electrode in an Aqueous Solution of CuSO[subscript 4

ERIC Educational Resources Information Center

Petrusevski, Vladimir M.; Stojanovska, Marina

2010-01-01

The colour of the copper layer deposited on a graphite electrode during electrolysis of an aqueous solution of copper(II) sulfate looks whitish-grey when inspected in situ. Taking the electrode out of the solution reveals the familiar orange-red colour of deposited copper. The explanation is found in terms of the almost ideal complementary colours…

Copper-promoted sulfenylation of sp2 C-H bonds.

PubMed

Tran, Ly Dieu; Popov, Ilya; Daugulis, Olafs

2012-11-07

An auxiliary-assisted, copper catalyzed or promoted sulfenylation of benzoic acid derivative β-C-H bonds and benzylamine derivative γ-C-H bonds has been developed. The method employs disulfide reagents, copper(II) acetate, and DMSO solvent at 90-130 °C. Application of this methodology to the direct trifluoromethylsulfenylation of C-H bonds was demonstrated.

Reduction of Iodine by Phosphorus(I): Integration of the Rate Equation

ERIC Educational Resources Information Center

Kustin, Kenneth; Ross, Edward W.

2005-01-01

A. D. Mitchell's work on the phosphorus(I) reduction of the halogens and of mercury(II) and copper(II) chlorides is examined. A review of some salient characteristics of the Mitchell mechanism is presented, together with a discussion on how a student might benefit from a case study of the phosphorus(I) reduction of iodine or the similarly behaving…

Some More Microscale Gas Experiments

ERIC Educational Resources Information Center

Worley, Bob

2011-01-01

In 1984, a teacher was successfully prosecuted by the Health and Safety Executive. The case centred around chemically prepared hydrogen that was dried by bubbling it through concentrated sulfuric(VI) acid and then passed over hot copper(II) oxide. The procedure was often carried out quantitatively to find the mass of copper in a sample of…

Effect of Cu(II) coordination compounds on the activity of antioxidant enzymes catalase and superoxide dismutase in patients with colorectal cancer.

PubMed

Kubiak, Katarzyna; Malinowska, Katarzyna; Langer, Ewa; Dziki, Łukasz; Dziki, Adam; Majsterek, Ireneusz

2011-03-01

Colorectal cancer (CRC) is a serious medical and economical problem of our times. It is the most common gastrointestinal cancer in the world. In Poland, the treatment and detection of CRC are poorly developed and the pathogenesis is still unclear. One hypothesis suggests a role of reactive oxygen species (ROS) in the pathogenesis of CRC. Experimental studies in recent years confirm the participation of ROS in the initiation and promotion of CRC. The aim of the study was to examine the effect of the following coordination compounds coordination compounds: dinitrate (V) tetra(3,4,5-trimethyl-N1-pyrazole-κN2) copper(II), dichloro di(3,4,5-trimethyl-N1-pyrazole-κN2) copper(II), dinitrate (V) di(1,4,5-trimethyl-N1-pyrazole-κN2) copper(II), dichloro di(1,3,4,5-tetramethyl-N1-pyrazole-κN2) copper(II) on the activity of antioxidant enzymes superoxide dismutase (SOD, ZnCu-SOD) and catalase (CAT) in a group of patients with colorectal cancer (CRC) and in the control group consisting of patients with minor gastrointestinal complaints. The study was conducted in 20 patients diagnosed with colorectal cancer at the age of 66.5±10.2 years (10 men and 10 women) versus the control group of 20 people (10 men and 10 women) aged 57.89±17.10 years without cancer lesions in the biological material - hemolysate prepared in a proportion of 1ml of water per 1 ml of blood. CAT activity was measured by the Beers method (1952), while SOD activity was measured by the Misra and Fridovich method (1972). We found that patients with CRC showed a statistically significant decrease of SOD and CAT activity (CAT - 12,75±1.97 U/g Hb, SOD - 1111.52±155.52 U/g Hb) in comparison with the control group (CAT - 19.65±2,17 U/g Hb, SOD - 2046.26±507.22 U/g Hb). Simultaneously, we observed that the investigated coordination compounds of Cu(II) significantly increased the antioxidant activity of CAT and SOD in patients with CRC (mean: CAT 25.23±4.86 U/g Hb, SOD - 3075.96±940.20 U/g Hb). Patients with

Synthesis, characterization, structural and biological aspects of copper(II) dithiocarbamate complexes - Part II, [Cu{S2CN(Me)(R1)}2], [Cu{S2CN(Me)(R2)}2] and [Cu{S2CN(R3)(R4)}2] {R1 = CH2CH(OMe)2, R2 = 2-methyl-1,3-dioxolane, R3 = CH2(CH2)2NCHPhOCH2Ph and R4 = CH2CH2OH}

NASA Astrophysics Data System (ADS)

Ferreira, Isabella P.; de Lima, Geraldo M.; Paniago, Eucler B.; Takahashi, Jacqueline A.; Krambrock, Klaus; Pinheiro, Carlos B.; Wardell, James L.; Visentin, Lorenzo C.

2013-09-01

Three new copper(II) dithiocarbamates (DTC), [Cu{S2CN(Me)(R1)}2] (1), [Cu{S2CN(Me)(R2)}2] (2) and [Cu{S2CN(R3)(R4)}2] (3) with R1 = CH2CH(OMe)2, R2 = 2-methyl-1,3-dioxolane, R3 = CH2(CH2)2NCHPhOCH2Ph and R4 = CH2CH2OH, have been synthesized and characterized by different spectroscopic techniques. Complexes (1) and (2) display typical EPR spectra for separated Cu(II) centers, and the spectrum of (3) is characteristic of two magnetically coupled Cu(II) ions with S = 1. The X-ray crystallographic determination has shown that complexes (1) and (2) crystallise in the triclinic and monoclinic systems. In addition both complexes are monomers in which the geometry at each Cu(II) is square planar. The in vitro antimicrobial activity of the sodium salts of ligands, and of the Cu(II)-DTC complexes have been screened against Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus, Penicillium citrinum and Curvularia senegalensis, as well as Gram positive and Gram negative bacteria. Finally, the toxic effects of complexes (1)-(3) were performed using Chlorella vulgaris.

Dinuclear complexes containing linear M-F-M [M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)] bridges: trends in structures, antiferromagnetic superexchange interactions, and spectroscopic properties.

PubMed

Reger, Daniel L; Pascui, Andrea E; Smith, Mark D; Jezierska, Julia; Ozarowski, Andrew

2012-11-05

The reaction of M(BF(4))(2)·xH(2)O, where M is Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), with the new ditopic ligand m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (L(m)*) leads to the formation of monofluoride-bridged dinuclear metallacycles of the formula [M(2)(μ-F)(μ-L(m)*)(2)](BF(4))(3). The analogous manganese(II) species, [Mn(2)(μ-F)(μ-L(m)*)(2)](ClO(4))(3), was isolated starting with Mn(ClO(4))(2)·6H(2)O using NaBF(4) as the source of the bridging fluoride. In all of these complexes, the geometry around the metal centers is trigonal bipyramidal, and the fluoride bridges are linear. The (1)H, (13)C, and (19)F NMR spectra of the zinc(II) and cadmium(II) compounds and the (113)Cd NMR of the cadmium(II) compound indicate that the metallacycles retain their structure in acetonitrile and acetone solution. The compounds with M = Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) are antiferromagnetically coupled, although the magnitude of the coupling increases dramatically with the metal as one moves to the right across the periodic table: Mn(II) (-6.7 cm(-1)) < Fe(II) (-16.3 cm(-1)) < Co(II) (-24.1 cm(-1)) < Ni(II) (-39.0 cm(-1)) ≪ Cu(II) (-322 cm(-1)). High-field EPR spectra of the copper(II) complexes were interpreted using the coupled-spin Hamiltonian with g(x) = 2.150, g(y) = 2.329, g(z) = 2.010, D = 0.173 cm(-1), and E = 0.089 cm(-1). Interpretation of the EPR spectra of the iron(II) and manganese(II) complexes required the spin Hamiltonian using the noncoupled spin operators of two metal ions. The values g(x) = 2.26, g(y) = 2.29, g(z) = 1.99, J = -16.0 cm(-1), D(1) = -9.89 cm(-1), and D(12) = -0.065 cm(-1) were obtained for the iron(II) complex and g(x) = g(y) = g(z) = 2.00, D(1) = -0.3254 cm(-1), E(1) = -0.0153, J = -6.7 cm(-1), and D(12) = 0.0302 cm(-1) were found for the manganese(II) complex. Density functional theory (DFT) calculations of the exchange integrals and the zero-field splitting on manganese(II) and iron(II) ions were performed

Amphiphilic zinc phthalocyanine photosensitizers: synthesis, photophysicochemical properties and in vitro studies for photodynamic therapy.

PubMed

Çakır, Dilek; Göksel, Meltem; Çakır, Volkan; Durmuş, Mahmut; Biyiklioglu, Zekeriya; Kantekin, Halit

2015-05-28

Peripherally and non-peripherally tetra-substituted zinc(ii) phthalocyanines bearing 2-(2-{2-[3-(dimethylamino)phenoxy]ethoxy}ethoxy)ethoxy and 2-(2-{2-[3-(diethylamino)phenoxy]ethoxy}ethoxy)ethoxy groups (, , and ) were synthesized by cyclotetramerization of the corresponding phthalonitriles (, , and ). Their quaternized ionic derivatives (, , and ) were also synthesized by the reaction of them with methyl iodide. The novel compounds were characterized by using standard spectroscopic techniques such as FT-IR, (1)H NMR, (13)C NMR, UV-vis, mass and elemental analyses. The obtained quaternized phthalocyanines (, , and ) showed amphiphilic behaviour with excellent solubility in both organic and aqueous solutions, which makes them potential photosensitizers for use in photodynamic therapy (PDT) of cancer. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yields) properties of these novel phthalocyanines were studied in DMSO for both non-ionic and ionic quaternized derivatives. However, these properties were examined in both DMSO and phosphate buffer solution (PBS) for quaternized ionic phthalocyanines. The effects of the positions of substituents (peripheral or non-peripheral) and the quaternization of the nitrogen atoms on the substituents about their photophysical and photochemical properties were also compared in this study. The bovine serum albumin (BSA) binding behaviours of the studied quaternized ionic zinc(ii) phthalocyanines were also described in PBS solutions. The quaternized phthalocyanines (, , and ) successfully displayed light-dependent photodamage in HeLa and HuH-7 cancer cells in photodynamic therapy treatment. The photosensitivity and the intensity of damage were found directly related to the concentration of the photosensitizers.

Amino Acid Profiling of Zinc Resistant Prostate Cancer Cell Lines: Associations With Cancer Progression.

PubMed

Kratochvilova, Monika; Raudenska, Martina; Heger, Zbynek; Richtera, Lukas; Cernei, Natalia; Adam, Vojtech; Babula, Petr; Novakova, Marie; Masarik, Michal; Gumulec, Jaromir

2017-05-01

Failure in intracellular zinc accumulation is a key process in prostate carcinogenesis. Nevertheless, epidemiological studies of zinc administration have provided contradicting results. In order to examine the impact of the artificial intracellular increase of zinc(II) ions on prostate cancer metabolism, PNT1A, 22Rv1, and PC-3 prostatic cell lines-depicting different stages of cancer progression-and their zinc-resistant counterparts were used. To determine "benign" and "malignant" metabolic profiles, amino acid patterns, gene expression, and antioxidant capacity of these cell lines were assessed. Amino acid profiles were examined using an ion-exchange liquid chromatography. Intracellular zinc content was measured by atomic absorption spectrometry. Metallothionein was quantified using differential pulse voltammetry. The content of reduced glutathione was determined using high performance liquid chromatography coupled with an electrochemical detector. Cellular antioxidant capacity was determined by the ABTS test and gene expression analysis was performed by qRT-PCR. Long-term zinc treatment was shown to reroute cell metabolism from benign to more malignant type. Long-term application of high concentration of zinc(II) significantly enhanced cisplatin resistance, invasiveness, cellular antioxidant capacity, synthesis of glutathione, and expression of treatment resistance- and stemness-associated genes (SOX2, POU5F1, BIRC5). Tumorous cell lines universally displayed high accumulation of aspartate and sarcosine and depletion of essential amino acids. Increased aspartate/threonine, aspartate/methionine, and sarcosine/serine ratios were associated with cancer phenotype with high levels of sensitivity and specificity. Prostate 77: 604-616, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Towards a better understanding of honeycomb alternating magnetic networks.

PubMed

Marino, Nadia; Armentano, Donatella; De Munno, Giovanni; Lloret, Francesc; Cano, Joan; Julve, Miguel

2015-06-28

Two new two-dimensional homometallic compounds {[M2(bpm)(ox)2]n·5nH2O} with M = Co(II) (1) and Zn(II) (2) and the mononuclear nickel(II) complex [Ni(bpm)2(ox)]·2H2O (3) [bpm = 2,2'-bipyrimidine and ox = oxalate] have been prepared and structurally characterized. 1 and 2 are isostructural compounds whose structures are made up of oxalate-bridged M(II) cations cross-linked by bis-bidentate bpm molecules to afford a honeycomb layered network extending in the crystallographic ab plane. The layers are eclipsed along the crystallographic c axis and show graphitic-like interactions between the bpm rings. The three-dimensional supramolecular network deriving from such interactions is characterized by hexagonal-shaped channels extending in the same direction. Each M(II) ion in 1 and 2 is tris-chelated with four oxygen atoms from two oxalate groups and two bpm-nitrogen atoms building a distorted octahedral surrounding. The reduced values of the angles subtended by the bis-chelating bpm [77.69(8) (1) and 76.59(8)° (2)] and oxalate [79.69(6) (1) and 80.01(5)° (2)] are the main factors accounting for this distortion. The values of the metal-metal separation through bridging bpm are 5.6956(7) (1) and 5.7572(9) Å (2), whereas those across the bis-bidentate oxalate are 5.4306(4) (1) and 5.4058(5) Å (2). 3 is a neutral mononuclear nickel(II) complex where each metal ion is six-coordinate with four nitrogen atoms from two bpm ligands in a cis arrangement and two oxalate-oxygen atoms building a somewhat distorted octahedral surrounding. The values of the angles subtended at the nickel(II) ion by bpm and oxalate are 78.14(4) and 80.95(5)°, respectively. The magnetic properties of 1 have been investigated in the temperature range 1.9-295 K. They are typical of an overall antiferromagnetic coupling with a maximum of the magnetic susceptibility at 22.0 K. The analysis of the susceptibility data of 1 through an effective spin Hamiltonian allowed a satisfactory simulation in the

Synthesis, Spray Deposition, and Hot-Press Transfer of Copper Nanowires for Flexible Transparent Electrodes.

PubMed

Deshmukh, Rupali; Calvo, Micha; Schreck, Murielle; Tervoort, Elena; Sologubenko, Alla S; Niederberger, Markus

2018-06-20

We report a solution-phase approach to the synthesis of crystalline copper nanowires (Cu NWs) with an aspect ratio >1000 via a new catalytic mechanism comprising copper ions. The synthesis involves the reaction between copper(II) chloride and copper(II) acetylacetonate in a mixture of oleylamine and octadecene. Reaction parameters such as the molar ratio of precursors as well as the volume ratio of solvents offer the possibility to tune the morphology of the final product. A simple low-cost spray deposition method was used to fabricate Cu NW films on a glass substrate. Post-treatment under reducing gas (5% H 2 + 95% N 2 ) atmosphere resulted in Cu NW films with a low sheet resistance of 24.5 Ω/sq, a transmittance of T = 71% at 550 nm (including the glass substrate), and a high oxidation resistance. Moreover, the conducting Cu NW networks on a glass substrate can easily be transferred onto a polycarbonate substrate using a simple hot-press transfer method without compromising on the electrical performance. The resulting flexible transparent electrodes show excellent flexibility ( R/ R o < 1.28) upon bending to curvatures of 1 mm radius.

Catalytic determination of molybdenum(VI) by means of an iodide ion-selective electrode and a landolt-type hydrogen peroxide-iodide reaction.

PubMed

Kataoka, M; Nishimura, K; Kambara, T

1983-12-01

A trace amount of molybdenum(VI) can be determined by using its catalytic effect on the oxidation of iodide to iodine by hydrogen peroxide in acidic medium. Addition of ascorbic acid added to the reaction mixture produces the Landolt effect, i.e., the iodine produced by the indicator reaction is reduced immediately by the ascorbic add. Hence the concentration of iodide begins to decrease once all the ascorbic acid has been consumed. The induction period is measured by monitoring the concentration of iodide ion with an iodide ion-selective electrode. The reciprocal of the induction period varies linearly with the concentration of molybdenum(VI). The most suitable pH and concentrations of hydrogen peroxide and potassium iodide are found to be 1.5, 5 and 10mM, respectively. An appropriate amount of ascorbic acid is added to the reaction mixture according to the concentration of molybdenum(VI) in the sample solution. A calibration graph with good proportionality is obtained for the molybdenum(VI) concentration range from 0.1 to 160 muM. Iron(III), vanadium(IV), zirconium(IV), tungsten(VI), copper(II) and chromium(VI) interfere, but iron(III) and copper(II) can be masked with EDTA.

Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole.

PubMed

Kalanithi, M; Rajarajan, M; Tharmaraj, P; Sheela, C D

2012-02-15

Tridentate chelate complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the chalcone based ligands 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-(phenylallyl)]phenol(HL(1)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol(HL(2)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol(HL(3)). Microanalytical data, UV-vis spectrophotometric method, magnetic susceptibility measurements, IR, 1H NMR, Mass, and EPR techniques were used to characterize the structure of chelates. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted square planar geometry for the copper(II) ion. The other metal complexes show distorted tetrahedral geometry. The coordination of the ligands with metal(II) ions was further confirmed by solution fluorescence spectrum. The antimicrobial activity of the ligands and metal(II) complexes against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger has been carried out and compared. The electrochemical behavior of copper(II) complex is studied by cyclic voltammetry. Copyright © 2011 Elsevier B.V. All rights reserved.

External anion effect on the synthesis of new MOFs based on formate and a twisted divergent ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lago, Ana Belén, E-mail: ablago@uvigo.es; Carballo, Rosa; Lezama, Luis

2015-11-15

New copper(II) metal–organic compounds with the formulae [Cu{sub 3}Cl(HCO{sub 2}){sub 5}(SCS){sub 3}(H{sub 2}O){sub 2}]·8H{sub 2}O·EtOH (1) and [Cu{sub 3}(HCO{sub 2}){sub 4}(SCS){sub 4}(H{sub 2}O){sub 2}](NO{sub 3}){sub 2}·9H{sub 2}O (2) (SCS=bis(4-pyridylthio)methane) have been synthesized after a careful study of the reaction of the SCS ligand with copper(II) formate. The compounds were obtained in the presence of sodium chloride and nitrate salts under microwave irradiation. The influence of the anion at different metal/anion ratios on the final architecture has been studied. The new chloride-MOF 1 has been characterized by electron paramagnetic resonance (EPR), magnetic properties and single crystal X-ray diffraction studies. The thermalmore » stability and topological analysis have also been investigated. - Highlights: • Microwave synthesis of coordination polymers. • Anion-derived structural changes. • Influence of anions at different metal/anion ratios on the final architectures. • EPR and magnetic characterization of a MOF compound.« less

Biosorption of Cu(II) by powdered anaerobic granular sludge from aqueous medium.

PubMed

Zhou, Xu; Chen, Chuan; Wang, Aijie; Jiang, Guangming; Liu, Lihong; Xu, Xijun; Yuan, Ye; Lee, Duu-Jung; Ren, Nanqi

2013-01-01

Copper(II) biosorption processes by two pre-treated powdered anaerobic granular sludges (PAGS) (original sludges were methanogenic anaerobic granules and denitrifying sulfide removal (DSR) anaerobic granules) were investigated through batch tests. Factors affecting the biosorption process, such as pH, temperature and initial copper concentrations, were examined. Also, the physico-chemical characteristics of the anaerobic sludge were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy image, surface area and elemental analysis. A second-order kinetic model was applied to describe the biosorption process, and the model could fit the biosorption process. The Freundlich model was used for describing the adsorption equilibrium data and could fit the equilibrium data well. It was found that the methanogenic PAGS was more effective in Copper(II) biosorption process than the DSR PAGS, whose maximum biosorption capacity was 39.6% lower. The mechanisms of the biosorption capacities for different PAGS were discussed, and the conclusion suggested that the environment and biochemical reactions during the growth of biomass may have affected the structure of the PAGS. The methanogenic PAGS had larger specific surface area and more biosorption capacity than the DSR PAGS.

A Study on the Copper Effect on gold leaching in copper-ethanediamine-thiosulphate solutions

NASA Astrophysics Data System (ADS)

Liu, Qiong; Xiang, Pengzhi; Huang, Yao

2018-01-01

A simple, fast and sensitive square-wave voltammetry (SWV), cyclic voltammetry(CV) and tafel method for the determination of various factors of gold in thiosulphate solution in this paper. We present our study on the effect of copper(II) on the leaching of gold in thiosulphate solutions. The current study aims to establish the interaction of copper in the leaching process by electrochemical method.

Liquid-crystalline dendrimer Cu(II) complexes and Cu(0) nanoclusters based on the Cu(II) complexes: An electron paramagnetic resonance investigation

NASA Astrophysics Data System (ADS)

Domracheva, N. E.; Mirea, A.; Schwoerer, M.; Torre-Lorente, L.; Lattermann, G.

2007-07-01

New nanostructured materials, namely, the liquid-crystalline copper(II) complexes that contain poly(propylene imine) dendrimer ligands of the first (ligand 1) and second (ligand 2) generations and which have a columnar mesophase and different copper contents (x = Cu/L), are investigated by EPR spectroscopy. The influence of water molecules and nitrate counterions on the magnetic properties of complex 2 (x = 7.3) is studied. It is demonstrated that water molecules can extract some of the copper ions from dendrimer complexes and form hexaaqua copper complexes with free ions. The dimer spectra of fully hydrated complex 2 (x = 7.3) are observed at temperatures T < 10 K. For this complex, the structure is identified and the distance between the copper ions is determined. It is shown that the nitrate counterion plays the role of a bridge between the hexaaqua copper(II) complex and the dendrimer copper(II) complex. The temperature-induced valence tautomerism attended by electron transport is revealed for the first time in blue dendrimer complexes 1 (x = 1.9) with a dimer structure. The activation energy for electron transport is estimated to be 0.35 meV. The coordination of the copper ion site (NO4) and the structural arrangement of green complexes 1 (x = 1.9) in the columnar mesophase are determined. Complexes of this type form linear chains in which nitrate counterions serve as bridges between copper centers. It is revealed that green complexes 1 (x = 1.9) dissolved in isotropic inert solvents can be oriented in the magnetic field (B 0 = 8000 G). The degree of orientation of these complexes is rather high (S z = 0.76) and close to that of systems with a complete ordering (S z = 1) in the magnetic field. Copper(0) nanoclusters prepared by reduction of complex 2 (x = 7.3) in two reducing agents (NaBH4, N2H4 · H2O) are examined. A model is proposed for a possible location of Cu(0) nanoclusters in a dendrimer matrix.

Structure of the Ni(II) complex of Escherichia coli peptide deformylase and suggestions on deformylase activities depending on different metal(II) centres.

PubMed

Yen, Ngo Thi Hai; Bogdanović, Xenia; Palm, Gottfried J; Kühl, Olaf; Hinrichs, Winfried

2010-02-01

Crystal structures of polypeptide deformylase (PDF) of Escherichia coli with nickel(II) replacing the native iron(II) have been solved with chloride and formate as metal ligands. The chloro complex is a model for the correct protonation state of the hydrolytic hydroxo ligand and the protonated status of the Glu133 side chain as part of the hydrolytic mechanism. The ambiguity that recently some PDFs have been identified with Zn(2+) ion as the active-site centre whereas others are only active with Fe(2+) (or Co(2+), Ni(2+) is discussed with respect to Lewis acid criteria of the metal ion and substrate activation by the CD loop.

Concentration dependences of the density, viscosity, and refraction index of Cu(NO3)2 · 3H2O solutions in DMSO at 298 K

NASA Astrophysics Data System (ADS)

Mamyrbekova, A. K.

2013-03-01

Physicochemical properties (density, dynamic viscosity, refraction index) of the DMSO-Cu(NO3)2 · 3H2O system are studied in the concentration range of 0.01-2 M at 298 K. The refraction index of a solution of copper(II) nitrate in dimethylsulfoxide (DMSO) is measured at 288-318 K. The excess and partial molar volumes of the solvent and dissolved substance are calculated analytically.

Ligand- and base-free copper(II)-catalyzed C-N bond formation: cross-coupling reactions of organoboron compounds with aliphatic amines and anilines.

PubMed

Quach, Tan D; Batey, Robert A

2003-11-13

[reaction: see text] A ligandless and base-free Cu-catalyzed protocol for the cross-coupling of arylboronic acids and potassium aryltrifluoroborate salts with primary and secondary aliphatic amines and anilines is described. The process utilizes catalytic copper(II) acetate monohydrate and 4 A molecular sieves in dichloromethane at slightly elevated temperatures under an atmosphere of oxygen. A broad range of functional groups are tolerated on both of the cross-coupling partners.

Synthesis Characterization and DNA Interaction Studies of a New Zn(II) Complex Containing Different Dinitrogen Aromatic Ligands

PubMed Central

Shahabadi, Nahid; Mohammadi, Somaye

2012-01-01

A mononuclear complex of Zn(II), [Zn(DIP)2 (DMP)] (NO3)2 ·2H2O in which DIP is 4,7-diphenyl-1,10-phenanthroline and DMP is 4,4′-dimethyl-2,2′-bipyridine has been prepared and characterized by 1HNMR spectroscopy, FT-IR, UV-Vis and elemental analysis techniques. DNA-binding properties of the complex were studied using UV-vis spectra, circular dichroism (CD) spectra, fluorescence, cyclic voltammetry (CV), and viscosity measurements. The results indicate that this zinc(II) complex can intercalate into the stacked base pairs of DNA and compete with the strong intercalator ethidium bromide for the intercalative binding sites. PMID:22956919

Zinc(II) complexation by some biologically relevant pH buffers.

PubMed

Wyrzykowski, D; Tesmar, A; Jacewicz, D; Pranczk, J; Chmurzyński, L

2014-12-01

The isothermal titration calorimetry (ITC) technique supported by potentiometric titration data was used to study the interaction of zinc ions with pH buffer substances, namely 2-(N-morpholino)ethanesulfonic acid (Mes), piperazine-N,N'-bis(2-ethanesulfonic acid) (Pipes), and dimethylarsenic acid (Caco). The displacement ITC titration method with nitrilotriacetic acid as a strong, competitive ligand was applied to determine conditional-independent thermodynamic parameters for the binding of Zn(II) to Mes, Pipes, and Caco. Furthermore, the relationship between the proposed coordination mode of the buffers and the binding enthalpy has been discussed. Copyright © 2014 John Wiley & Sons, Ltd.

Impact of metal ions in porphyrin-based applied materials for visible-light photocatalysis: key information from ultrafast electronic spectroscopy.

PubMed

Kar, Prasenjit; Sardar, Samim; Alarousu, Erkki; Sun, Jingya; Seddigi, Zaki S; Ahmed, Saleh A; Danish, Ekram Y; Mohammed, Omar F; Pal, Samir Kumar

2014-08-11

Protoporphyrin IX-zinc oxide (PP-ZnO) nanohybrids have been synthesized for applications in photocatalytic devices. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and steady-state infrared, absorption, and emission spectroscopies have been used to analyze the structural details and optical properties of these nanohybrids. Time-resolved fluorescence and transient absorption techniques have been applied to study the ultrafast dynamic events that are key to photocatalytic activities. The photocatalytic efficiency under visible-light irradiation in the presence of naturally abundant iron(III) and copper(II) ions has been found to be significantly retarded in the former case, but enhanced in the latter case. More importantly, femtosecond (fs) transient absorption data have clearly demonstrated that the residence of photoexcited electrons from the sensitizer PP in the centrally located iron moiety hinders ground-state bleach recovery of the sensitizer, affecting the overall photocatalytic rate of the nanohybrid. The presence of copper(II) ions, on the other hand, offers additional stability against photobleaching and eventually enhances the efficiency of photocatalysis. In addition, we have also explored the role of UV light in the efficiency of photocatalysis and have rationalized our observations from femtosecond- to picosecond-resolved studies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Uncovering the Terahertz Spectrum of Copper Sulfate Pentahydrate.

PubMed

Ruggiero, Michael T; Korter, Timothy M

2016-01-21

Terahertz vibrational spectroscopy has evolved into a powerful tool for the detection and characterization of transition metal sulfate compounds, specifically for its ability to differentiate between various hydrated forms with high specificity. Copper(II) sulfate is one such system where multiple crystalline hydrates have had their terahertz spectra fully assigned, and the unique spectral fingerprints of the forms allows for characterization of multicomponent systems with relative ease. Yet the most commonly occurring form, copper(II) sulfate pentahydrate (CuSO4·5H2O), has proven elusive due to the presence of a broad absorption across much of the terahertz region, making the unambiguous identification of its spectral signature difficult. Here, it is shown that the sub-100 cm(-1) spectrum of CuSO4·5H2O is obscured by absorption from adsorbed water and that controlled drying reveals sharp underlying features. The crystalline composition of the samples was monitored in parallel by X-ray diffraction as a function of drying time, supporting the spectroscopic results. Finally, the terahertz spectrum of CuSO4·5H2O was fully assigned using solid-state density functional theory simulations, helping attribute the additional absorptions that appear after excessive drying to formation of CuSO4·3H2O.

Redox chemistry of a binary transition metal oxide (AB2O4): a study of the Cu(2+)/Cu(0) and Fe(3+)/Fe(0) interconversions observed upon lithiation in a CuFe2O4 battery using X-ray absorption spectroscopy.

PubMed

Cama, Christina A; Pelliccione, Christopher J; Brady, Alexander B; Li, Jing; Stach, Eric A; Wang, Jiajun; Wang, Jun; Takeuchi, Esther S; Takeuchi, Kenneth J; Marschilok, Amy C

2016-06-22

Copper ferrite, CuFe2O4, is a promising candidate for application as a high energy electrode material in lithium based batteries. Mechanistic insight on the electrochemical reduction and oxidation processes was gained through the first X-ray absorption spectroscopic study of lithiation and delithiation of CuFe2O4. A phase pure tetragonal CuFe2O4 material was prepared and characterized using laboratory and synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Ex situ X-ray absorption spectroscopy (XAS) measurements were used to study the battery redox processes at the Fe and Cu K-edges, using X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and transmission X-ray microscopy (TXM) spectroscopies. EXAFS analysis showed upon discharge, an initial conversion of 50% of the copper(ii) to copper metal positioned outside of the spinel structure, followed by a migration of tetrahedral iron(iii) cations to octahedral positions previously occupied by copper(ii). Upon charging to 3.5 V, the copper metal remained in the metallic state, while iron metal oxidation to iron(iii) was achieved. The results provide new mechanistic insight regarding the evolution of the local coordination environments at the iron and copper centers upon discharging and charging.

Understanding the fate of the oxyallyl cation following Nazarov electrocyclization: sequential Wagner-Meerwein migrations and the synthesis of spirocyclic cyclopentenones

PubMed Central

Huang, Jie; Lebœuf, David; Frontier, Alison J.

2011-01-01

A general reaction sequence is described that involves Nazarov cyclization followed by two sequential Wagner Meerwein migrations, to afford spirocyclic compounds from divinyl ketones in the presence of one equivalent of copper(II) complexes. A detailed investigation of this sequence is described including a study of substrate scope and limitations. It was found that after 4π electrocyclization, two different pathways are available to the oxyallyl cation intermediate: elimination of a proton can give the usual Nazarov cycloadduct, or ring contraction can give an alternative tertiary carbocation. After ring contraction, either [1,2]-hydride or carbon migration can occur, depending upon the substitution pattern of the substrate, to furnish spirocyclic products. The rearrangement pathway is favored over the elimination pathway when catalyst loading was high and the copper(II) counterion is noncoordinating. Several ligands were found to be effective for the reaction. Thus, the reaction sequence can be controlled by judicious choice of reaction conditions to allow selective generation of richly functionalized spirocycles. The three steps of the sequence are stereospecific: electrocyclization followed by two [1,2]-suprafacial Wagner-Meerwein shifts: the ring contraction and then an hydride, alkenyl or aryl shift. The method allows stereospecific installation of adjacent stereocenters or adjacent quaternary centers arrayed around a cyclopentenone ring. PMID:21466152

Composition and particle size of electrolytic copper powders prepared in water-containing dimethyl sulfoxide electrolytes

NASA Astrophysics Data System (ADS)

Mamyrbekova, Aigul'; Abzhalov, B. S.; Mamyrbekova, Aizhan

2017-07-01

The possibility of the electroprecipitation of copper powder via the cathodic reduction of an electrolyte solution containing copper(II) nitrate trihydrate and dimethyl sulfoxide (DMSO) is shown. The effect electrolysis conditions (current density, concentration and temperature of electrolyte) have on the dimensional characteristics of copper powder is studied. The size and shape of the particles of the powders were determined by means of electron microscopy; the qualitative composition of the powders, with X-ray diffraction.

Discovery of a potent and highly specific β2 proteasome inhibitor from a library of copper complexes.

PubMed

Zhou, Tongliang; Cai, Yuanbo; Liang, Lei; Yang, Lingfei; Xu, Fengrong; Niu, Yan; Wang, Chao; Zhang, Jun-Long; Xu, Ping

2016-12-01

We reported the synthesis, characterization and biological activity of several copper(II) Schiff base complexes, which exhibit high proteasome inhibitory activities with particular selectivity of β 2 subunit. Structure-activity relationships information obtained from complex Na 2 [Cu(a4s1)] demonstrated that distinct bonding modes in β 2 and β 5 subunits determines its selectivity and potent inhibition for β 2 subunit. Copyright © 2016 Elsevier Ltd. All rights reserved.

Crystal structure of tin(II) perchlorate trihydrate

PubMed Central

Hennings, Erik; Schmidt, Horst; Köhler, Martin; Voigt, Wolfgang

2014-01-01

The title compound, [Sn(H2O)3](ClO4)2, was synthesized by the redox reaction of copper(II) perchlorate hexa­hydrate and metallic tin in perchloric acid. Both the trigonal–pyramidal [Sn(H2O)3]2+ cations and tetra­hedral perchlorate anions lie on crystallographic threefold axes. In the crystal, the cations are linked to the anions by O—H⋯O hydrogen bonds, generating (001) sheets. PMID:25552969

Nickel(II) biosorption from aqueous solutions by shrimp head biomass.

PubMed

Hernández-Estévez, Alejandro; Cristiani-Urbina, Eliseo

2014-11-01

The present study evaluates the capacity of shrimp (Farfantepenaeus aztecus) head to remove toxic Ni(II) ions from aqueous solutions. Relevant parameters that could affect the biosorption process, such as shrimp head pretreatment, solution pH level, contact time and initial Ni(II) concentration, were studied in batch systems. An increase in Ni(II) biosorption capacity and a reduction in the time required to reach Ni(II) biosorption equilibrium was manifested by shrimp head biomass pretreated by boiling in 0.5 N NaOH for 15 min; this biomass was thereafter denominated APSH. The optimum biosorption level of Ni(II) ions onto APSH was observed at pH 7.0. Biosorption increased significantly with rising initial Ni(II) concentration. In terms of biosorption dynamics, the pseudo-second-order kinetic model described Ni(II) biosorption onto APSH best. The equilibrium data adequately fitted the Langmuir isotherm model within the studied Ni(II) ion concentration range. According to this isotherm model, the maximum Ni(II) biosorption capacity of APSH was 104.22 mg/g. Results indicate that APSH could be used as a low-cost, environmentally friendly, and promising biosorbent with high biosorption capacity to remove Ni(II) from aqueous solutions.

Syntheses, solid state and solution structures of the palladium(II) complexes of malonamide-derived open-chain and macrocyclic ligands.

PubMed

Gavrish, Sergey P; Lampeka, Yaroslaw D; Pritzkow, Hans; Lightfoot, Philip

2010-09-07

The crystal structures of the palladium(II) complexes of the open-chain and macrocyclic ligands PdL(1).3H(2)O, PdL(2).6H(2)O and PdL(3).5H(2)O have been determined (H(2)L(1) = 1,4,8,11-tetraazaundecane-5,7-dione, H(2)L(2) = 1,4,8,11-tetraazacyclotetradecane-5,7-dione, H(2)L(3) = 1,4,8,11-tetraazacyclotridecane-5,7-dione). The coordination polyhedra of the palladium(II) ions in all complexes are formed by two deprotonated amide and two amine donors with Pd-N distances being similar in PdL(1) and PdL(2) and substantially shorter in PdL(3). A detailed analysis of the (1)H NMR spectra of the macrocyclic complexes supports the formation in aqueous solution of only N-meso isomers of both compounds in agreement with the X-ray data. The spectra of the palladium(II) macrocyclic complexes are shifted downfield as a whole as compared to those of the nickel(II) analogues with the shifts being essentially non-uniform. The latter feature can be related to the differences in magnetic anisotropy of the M-N bonds. The maxima of d-d absorption bands of the palladium(II) complexes demonstrate weaker dependence on the macrocycle size as compared to those of the nickel(II) analogues. Both macrocyclic compounds PdL(2).6H(2)O and PdL(3).5H(2)O are characterized by lamellar crystal structures consisting of interleaved layers formed by macrocyclic units and by water molecules with similar metal complex layers and different 2D water sheets. A columnar crystal structure is inherent for PdL(1).3H(2)O with the water molecules present as discrete (H(2)O)(3) clusters.

N-(2,2-Dimethyl-1-(quinolin-2-yl)propylidene) arylaminonickel Complexes and Their Ethylene Oligomerization.

PubMed

Suo, Hongyi; Zhao, Tong; Wang, Yiqing; Ban, Qing; Sun, Wen-Hua

2017-04-13

A series of N -(2,2-dimethyl-1-(quinolin-2-yl)propylidene) arylamines was sophisticatedly synthesized and reacted with nickel(II) bromine for the formation of the corresponding nickel complexes. All the organic compounds were characterized by IR, NMR spectra and elemental analysis, while all the nickel complexes were characterized by IR spectra and elemental analysis. On activation with ethylaluminium sesquichloride (EASC) and modified methylaluminoxane (MMAO), all nickel precatalysts exhibited good activities toward ethylene oligomerization, indicating the positive efficiency of gem-dimethyl substitutents; in which major hexenes were obtained with MMAO. The catalytic parameters were verified, and the steric and electronic influences of substituents with ligands were observed, with a slight change of activities under different ethylene pressures.

Synthesis of C-functionalized TE1PA and comparison with its analogues. An example of bioconjugation on 9E7.4 mAb for multiple myeloma 64Cu-PET imaging.

PubMed

Le Bihan, Thomas; Navarro, Anne-Sophie; Le Bris, Nathalie; Le Saëc, Patricia; Gouard, Sébastien; Haddad, Ferid; Gestin, Jean-François; Chérel, Michel; Faivre-Chauvet, Alain; Tripier, Raphaël

2018-04-27

In view of the excellent copper(ii) and 64-copper(ii) complexation of a TE1PA ligand, a monopicolinate cyclam, in both aqueous medium and in vivo, we looked for a way to make it bifunctional, while maintaining its chelating properties. Overcoming the already known drawback of grafting via its carboxyl group, which is essential to the overall properties of the ligand, a TE1PA bifunctional derivative bearing an additional isothiocyanate coupling function on a carbon atom of the macrocyclic ring was synthesized. This led to an architecture that is comparable to that of other commercially available bifunctional copper(ii) chelators such as p-SCN-Bn-DOTA already used in clinical trials for 64Cu-immuno-PET imaging. The C-functionalization of TE1PA on one carbon atom in the β-N position of the cyclam backbone was successfully achieved by adapting our patented methodology to the huge challenge, allowing the regiospecific mono-N-functionalization of the unsymmetrical ligand. The obtained ligand p-SCN-Bn-TE1PA was coupled to a 9E7.4 murine antibody (mAb), an IgG2a anti CD-138 for multiple myeloma (MM) targeting. The conjugation efficiency was assessed by looking at the 64Cu radiolabeling and the radiopharmaceutical 64Cu-9E7.4-p-SCN-Bn-TE1PA immunoreactivity, and in particular by comparing with 9E7.4-p-SCN-Bn-NOTA and 9E7.4-p-SCN-Bn-DOTA obtained from commercial and presumably highly efficient chelators NOTA and DOTA, respectively. The results are quite clear, showing that p-SCN-Bn-TE1PA has a coupling rate 5 times higher and an immunoreactivity 1.5 to 2 times greater than those of its two competitors. p-SCN-Bn-TE1PA also outperforms TE1PA conjugated via its carboxylic function on the same antibody. The first 64Cu-immuno-PET preclinical study in a syngeneic model of MM was performed, confirming the good in vivo properties of 64Cu-9E7.4-p-SCN-Bn-TE1PA for PET imaging, considering the high clearance even after 24 h and the particularly important tumor-to-liver ratio that was

In situ study of binding of copper by fulvic acid: comparison of differential absorbance data and model predictions.

PubMed

Yan, Mingquan; Dryer, Deborah; Korshin, Gregory V; Benedetti, Marc F

2013-02-01

This study examined the binding of copper(II) by Suwannee River fulvic acid (SRFA) using the method of differential absorbance that was used at environmentally-relevant concentrations of copper and SRFA. The pH- and metal-differential spectra were processed via numeric deconvolution to establish commonalities seen in the changes of absorbance caused by deprotonation of SRFA and its interactions with copper(II) ions. Six Gaussian bands were determined to be present in both the pH- and Cu-differential spectra. Their maxima were located, in the order of increasing wavelengths at 208 nm, 242 nm, 276 nm, 314 nm, 378 nm and 551 nm. The bands with these maxima were denoted as A0, A1, A2, A3, A4 and A5, respectively. Properties of these bands were compared with those existing in the spectra of model compounds such as sulfosalicylic acid (SSA), tannic acid (TA), and polystyrenesulfonic acid-co-maleic acid (PSMA). While none of the features observed in differential spectra of the model compound were identical to those present in the case of SRFA, Gaussian bands A1, A3 and possibly A2 were concluded to be largely attributable to a combination of responses of salicylic- and polyhydroxyphenolic groups. In contrast, bands A4 and A5 were detected in the differential spectra of SRFA only. Their nature remains to be elucidated. To examine correlations between the amount of copper(II) bound by SRFA and changes of its absorbance, differential absorbances measured at indicative wavelengths 250 nm and 400 nm were compared with the total amount of SRFA-bound copper estimated based on Visual MINTEQ calculations. This examination showed that the differential absorbances of SRFA in a wide range of pH values and copper concentrations were strongly correlated with the concentration of SRFA-bound copper. The approach presented in this study can be used to generate in situ information concerning the nature of functional groups in humic substances engaged in interactions with metals ions. This