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1

Coordination chemistry, thermodynamics and DFT calculations of copper(II) NNOS Schiff base complexes.  

PubMed

Synthesis, magnetic and spectroscopy techniques are described for five copper(II) containing tetradentate Schiff bases are synthesized from methyl-2-(N-2'-aminoethane), (1-methyl-2'-aminoethane), (3-aminopropylamino)cyclopentenedithiocarboxylate. Molar conductance and infrared spectral evidences indicate that the complexes are four-coordinate in which the Schiff bases are coordinated as NNOS ligands. Room temperature ?eff values for the complexes are 1.71-1.80B.M. corresponding to one unpaired electron respectively. The formation constants and free energies were measured spectrophotometrically, at constant ionic strength 0.1M (NaClO4), at 25?C in DMF solvent. Also, the DFT calculations were carried out to determine the structural and the geometrical properties of the complexes. The DFT results are further supported by the experimental formation constants of these complexes. PMID:24992917

Esmaielzadeh, Sheida; Azimian, Leila; Shekoohi, Khadijeh; Mohammadi, Khosro

2014-12-10

2

Coordination chemistry, thermodynamics and DFT calculations of copper(II) NNOS Schiff base complexes  

NASA Astrophysics Data System (ADS)

Synthesis, magnetic and spectroscopy techniques are described for five copper(II) containing tetradentate Schiff bases are synthesized from methyl-2-(N-2";-aminoethane), (1-methyl-2";-aminoethane), (3-aminopropylamino)cyclopentenedithiocarboxylate. Molar conductance and infrared spectral evidences indicate that the complexes are four-coordinate in which the Schiff bases are coordinated as NNOS ligands. Room temperature ?eff values for the complexes are 1.71-1.80 B.M. corresponding to one unpaired electron respectively. The formation constants and free energies were measured spectrophotometrically, at constant ionic strength 0.1 M (NaClO4), at 25?C in DMF solvent. Also, the DFT calculations were carried out to determine the structural and the geometrical properties of the complexes. The DFT results are further supported by the experimental formation constants of these complexes.

Esmaielzadeh, Sheida; Azimian, Leila; Shekoohi, Khadijeh; Mohammadi, Khosro

2014-12-01

3

Synthesis, crystal structure and nuclease activity of a Schiff base copper(II) complex.  

PubMed

A new Schiff base copper(II) complex, Cu(o-VANAHE)(2) (o-VANAHE = 2-(o-vanillinamino)-1-hydroxyethane), has been synthesized and characterized. Single crystal X-ray diffraction results suggest that this complex structure belongs to triclinic crystal system, space group P1 with the following crystallographic parameters: a = 8.819(4) angstroms, b = 10.794(5) angstroms, c = 11.350(5) angstroms, alpha = 70.262(6) degrees, beta = 70.816(6) degrees, gamma = 78.360(6) degrees, V = 955.4(7) angstroms3, Z = 2, D(c) = 1.571 Mg x m(-3), and the final R1 = 0.0393, wR2 = 0.0994 for the observed reflections 2620(I > 2sigma(I)). The molecular geometry is almost coplanar. Viscosity, fluorescence spectroscopy and cyclic voltammetry have been conducted to assess their interaction between this complex and DNA. Results showed that the copper(II) complex can increase DNA's relative viscosity and quench the fluorescence intensity of EB bound to DNA. The adding of DNA to the solution of Cu(o-VANAHE)2 causes a slight decrease in the voltammetric current, as well as a slight shift in the E(1/2) to less negative potential. The interaction between the complex and DNA has also been investigated by submarine gel electrophoresis, interestingly, we found that the copper(II) complex can cleave circular plasmid pBR322 DNA to nicked and linear forms. PMID:15833330

Li, Lian-Zhi; Zhao, Chao; Xu, Tao; Ji, Hai-Wei; Yu, Yan-Hong; Guo, Guang-Qiang; Chao, Hui

2005-05-01

4

Efficient in situ three-component formation of chiral oxazoline-Schiff base copper(II) complexes: towards combinatorial library of chiral catalysts for asymmetric Henry reaction.  

PubMed

A combinatorial in situ three-component chiral oxazoline-Schiff base copper(II) complex catalyst formation method was developed. This simple combinatorial chiral catalyst approach provided a modular library of chiral oxazoline-Schiff base copper(II) complex catalysts. The catalytic activity of these in situ generated catalysts can be rapidly and conveniently evaluated in the asymmetric Henry reaction. Moderate to good yields and enantioselectivities (up to 92% ee) were obtained under the optimized condition. The combination of modular three-component catalyst formation and in situ asymmetric reaction provides a new technology in asymmetric catalysis. PMID:20458398

Yang, Wen; Liu, Han; Du, Da-Ming

2010-06-28

5

A new copper(II) Schiff base complex containing asymmetrical tetradentate N2O2 Schiff base ligand: Synthesis, characterization, crystal structure and DFT study  

NASA Astrophysics Data System (ADS)

A new copper (II) Schiff base complex, CuL1, was prepared from the reaction of asymmetrical Schiff base ligand of L1 and Cu(OAC)2 (L1 = salicylidene imino-ethylimino-pentan-2-one). The Schiff base ligand, L1, and its copper (II) complex, CuL1, have been characterized by elemental analysis (CHN) and FT-IR and UV-vis spectroscopy. In addition, 1H NMR was employed for characterization of the ligand. Thermogrametric analysis of the CuL1 reveals its thermal stability and its decomposition pattern shows that it is finally decomposed to the copper oxide (CuO). The crystal structure of CuL1 was determined by the single crystal X-ray analysis. The CuL1 complex crystallizes in the monoclinic system, with space group P21/n and distorted square planar coordination around the metal ion. The Schiff base ligand of L1 acts as a chelating ligand and coordinates via two nitrogen and two oxygen atoms to the copper (II) ion with C1 symmetry. The structure of the CuL1 complex was also studied theoretically at different levels of DFT and basis sets. According to calculated results the Csbnd O bond length of the salicylate fragment is slightly higher than that in the acetylacetonate fragment of ligand, which could be interpreted by resonance increasing between phenyl and chelated rings in ligand in relative to the acetylacetonate fragment.

Grivani, Gholamhossein; Baghan, Sara Husseinzadeh; Vakili, Mohammad; Khalaji, Aliakbar Dehno; Tahmasebi, Vida; Eigner, Vclav; Duek, Michal

2015-02-01

6

DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds  

PubMed Central

Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO4] and [Cu. L. A] where L is Schiff bases, namely 2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-bromophenol (DMIIMBP)/2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-chlorophenol (DMIIMCP), and A is heterocyclic compound, such as 1,10-phenanthroline (phen)/2,21-bipyridyl (bipy)/8-hydroxyquinoline (oxine)/5-chloro-8-hydroxyquinoline (5-Cl-oxine), have been synthesized. These complexes have been characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, TG, and DTA. On the basis of spectral studies and analytical data, five-coordinated square pyramidal/four-coordinated square planar geometry is assigned to all complexes. The ligands and their ternary complexes with Cu(II) have been screened for antimicrobial activity against bacteria and fungi by paper disc method. The antimicrobial studies of Schiff bases and their metal complexes showed significant activity and further it is observed that the metal complexes showed more activity than corresponding Schiff bases. In vitro antitumor activity of Cu(II) complexes was assayed against human cervical carcinoma (HeLa) cancer cells and it was observed that few complexes exhibit good antitumor activity on HeLa cell lines. The DNA cleavage studies have also been carried out on pBR 322 and it is observed that these Cu(II) complexes are capable of cleaving supercoiled plasmid DNA in the presence of H2O2 and UV light. PMID:24895493

Chityala, Vijay Kumar; Sathish Kumar, K.; Macha, Ramesh; Tigulla, Parthasarathy; Shivaraj

2014-01-01

7

DNA binding, cytotoxicity and apoptosis induction activity of a mixed-ligand copper(II) complex with taurine Schiff base and imidazole  

NASA Astrophysics Data System (ADS)

A novel binuclear copper(II) complex (complex 1) with taurine Schiff base and imidazole has been synthesized and structurally characterized by single crystal X-ray diffraction, elemental analysis, ESI-MS spectrometry, UV-vis and IR spectroscopy. Single-crystal analysis revealed that 1 displays the sulfonate-bridged dinuclear copper(II) centers. Both copper atoms are five-coordinated and exhibit slightly distorted square pyramidal geometries. Each of copper atom is surrounded by three oxygen atoms and one nitrogen atom from different taurine Schiff base ligands, and one nitrogen atom from one imidazole ligand. The interaction between 1 and calf thymus DNA (CT-DNA) was investigated by UV-vis, fluorescence, circular dichroism (CD) spectra and agarose gel electrophoresis. The experimental results indicated that 1 could bind to CT-DNA via an intercalative mode and show efficient cleavage activity. In addition, 1 showed an antitumor effect on cell cycle and apoptosis. Flow cytometric analysis revealed that MGC-803 cells were arrested in the S phase after treatment with 1. Fluorescence microscopic observation indicated that 1 could induce apoptosis of MGC-803 cells.

Li, Mei; kong, Lin Lin; Gou, Yi; Yang, Feng; Liang, Hong

2014-07-01

8

Oxidation of phenyl propyne catalyzed by copper(II) complexes of a benzimidazolyl schiff base ligand: Effect of acid/base, oxidant, surfactant and morphology  

NASA Astrophysics Data System (ADS)

Copper(II) complexes with a new N-Substituted benzimidazolyl schiff base ligand are used as catalyst for the oxidation of 1-phenyl propyne. The oxidation is carried out under mild conditions using stoichiometric amounts of oxidant and catalytic amounts of Cu(II) complex as catalyst. Effect of acid/base, oxidant, morphology and surfactant has been studied. Two major products of phenyl propyne oxidation are the ?-diketonic product and a terminal aldehyde. Diketone is the major product under acidic conditions while aldehyde formation is highest under basic conditions. The maximum conversion is found with the NO3- bound complex. GC-MS is used to find the percentage yields of products. SEM and PXRD of the reused complexes as catalyst suggest that morphology affects the catalytic efficiency.

Kumar, Ravinder; Mathur, Pavan

2015-02-01

9

A novel dinuclear Schiff-base copper(II) complex modified electrode for ascorbic acid catalytic oxidation and determination.  

PubMed

A new dinuclear copper salicylaldehyde-glycine Schiff-base complex [Cu(2)(Sal-Gly)(2)(H(2)O)(2)] was synthesized and structurally characterized. [Cu(2)(Sal-Gly)(2)(H(2)O)(2)] crystallized in the monoclinic system in the P2(1)/c space group. The molecule is a dinuclear complex, formed by two [Cu(Sal-Gly)(H(2)O)] units. The electropolymerization properties of the copper complex on a glass carbon electrode were studied at different potential ranges. The electropolymerization occurred when the high scan potential reached 1.4 V. The modified electrode exhibited good electrocatalytic oxidation properties to ascorbic acid and showed a sensitivity of 22.9 nA ?M(-1) (r(2) = 0.9998) and detection limit of 0.39 ?M (S/N = 3) in the amperometric determination of ascorbic acid. The designed determination method can be used to analyze vitamin C tablets. PMID:22124199

Zhang, Zhijun; Li, Xi; Wang, Chenggang; Zhang, Chaocan; Liu, Peng; Fang, Tingting; Xiong, Yan; Xu, Wenjing

2012-01-28

10

The interaction of taurine-salicylaldehyde Schiff base copper(II) complex with DNA and the determination of DNA using the complex as a fluorescence probe  

NASA Astrophysics Data System (ADS)

The interaction of taurine-salicylaldehyde Schiff base copper(II) (Cu(TSSB) 22+) complex with DNA was explored by using UV-vis, fluorescence spectrophotometry, and voltammetry. In pH 7.4 Tris-HCl buffer solution, the binding constant of the Cu(TSSB) 22+ complex interaction with DNA was 3.49 10 4 L mol -1. Moreover, due to the fluorescence enhancing of Cu(TSSB) 22+ complex in the presence of DNA, a method for determination of DNA with Cu(TSSB) 22+ complex as a fluorescence probe was developed. The fluorescence spectra indicated that the maximum excitation and emission wavelength were 389 nm and 512 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range of 0.03-9.03 ?g mL -1 for calf thymus DNA (CT-DNA), 0.10-36 ?g mL -1 for yeast DNA and 0.01-10.01 ?g mL -1 for salmon DNA (SM-DNA), respectively. The corresponding detection limits are 7 ng mL -1 for CT-DNA, 3 ng mL -1 for yeast DNA and 3 ng mL -1 for SM-DNA. Using this method, DNA in synthetic samples was determined with satisfactory results.

Zhang, Xiaoyan; Wang, Yong; Zhang, Qianru; Yang, Zhousheng

2010-09-01

11

Field-induced ferromagnetism and multiferroic behavior in end-on pseudohalide-bridged dinuclear copper(II) complexes with tridentate Schiff base blocking ligands.  

PubMed

Four new end-on pseudohalide-bridged dinuclear copper(II) complexes, [Cu2(L(1))2(N3)2]DMF (1), [Cu2(L(2))2(N3)2] (2), [Cu2(L(3))2(NCS)2] (3), and [Cu2(L(4))2(N3)2] (4) {where HL(1), HL(2), HL(3), and HL(4) are tridentate N2O donor Schiff bases}, are synthesized and characterized. Complexes 1, 2, and 3 possess ?? stacking interactions, while in addition hydrogen-bonding interactions are present in 1 and 3. However, by contrast, complex 4 contains neither type of interaction. Field-induced long-range ferromagnetic ordering beyond 0.9 T is observed in complexes 1 and 2 due to ?? stacking interactions, while ferroelectric ordering is observed in complexes 1 and 3 due to hydrogen-bonding interactions. Most interestingly, complex 1, which contains both ?? stacking and hydrogen-bonding interactions, shows multiferroic behavior as a result of coupling between the dielectric and magnetic fields with 8% change in the magneto-dielectric effect at room temperature. We believe that from this study will emerge a new class of multiferroic materials. PMID:25083947

Jana, Subrata; Shaw, Bikash Kumar; Bhowmik, Prasanta; Harms, Klaus; Drew, Michael G B; Chattopadhyay, Shouvik; Saha, Shyamal Kumar

2014-08-18

12

Influence of inductive effects and steric encumbrance on the catecholase activities of copper(II) complexes of reduced Schiff base ligands.  

PubMed

A series of copper(ii) complexes derived from reduced Schiff base ligands has been synthesized and characterized by single-crystal X-ray diffraction and spectroscopic analyses. With the exception of [Cu(Ala5NO2)(H2O)] (), which crystallized as a mononuclear repeating unit, [Cu2L2(H2O)x(DMSO)y]solvent (L = Ala5H (), Ala5OMe (), Ala5Cl (), Ala5Br (), Gly5Br (), Val5Br () and Leu5Br (), x = 1 or 2, y = 0 or 1, solvent = MeOH or DMSO and H2O) crystallized as phenoxo-bridged dinuclear building units containing Cu2O2 cores. In , , , and , the axial positions are occupied by solvent ligands and carboxylate oxygen atoms from adjacent dimers, resulting in the formation of 1D helical coordination polymers. In , a 2D network is constructed by utilizing weak CuO interactions (?2.7 ) with carboxylate groups. All complexes have been investigated for their catecholase activities with 3,5-DTBC, and they show significant catalytic activities except for . The catalytic activities are also observed to increase with increasing +I effects, as well as increase with increasing steric bulkiness on the ?-carbon of the carboxylate group. PMID:24435550

Thio, Yude; Yang, Xiandong; Vittal, Jagadese J

2014-03-01

13

Synthesis, characterization, and tyrosinase biomimetic catalytic activity of copper(II) complexes with schiff base ligands derived from ?-diketones with 2-methyl-3-amino-(3 H)-quinazolin-4-one  

NASA Astrophysics Data System (ADS)

A template condensation of ?-diketones (biacetyl, benzile and 2,3-pentanedione) with 2-methyl-3-amino-(3 H)-quinazolin-4-one (AMQ) in the presence of CuX 2 (X = Cl -, Br -, NO3- or ClO4-) resulted in the formation of tetradentate Schiff base copper(II) complexes of the type [CuLX]X and [CuL]X 2. Structural characterization of the complex species was achieved by several physicochemical methods, namely elemental analysis, electronic spectra, IR, ESR, molar conductivity, thermal analysis (TAG & DTG), and magnetic moment measurements. The stereochemistry, the nature of the metal chelates, and the catalytic reactivity are markedly dependent upon the type of counter anions and the ligand substituent within the carbonyl moiety. A square planar monomeric structure is proposed for the perchlorate, nitrate, and bromide complexes, in which the counter anions are loosely bonded to copper(II) ion. For the chloride complexes, the molar conductivities and the spectral data indicated that they have square-pyramidal environments around copper(II) center. The reported copper(II) complexes exhibit promising tyrosinase catalytic activity towards the hydroxylation of phenol followed by the aerobic oxidation of the resulting catechol. A linear correlation almost exists between the catalytic reactivity and the Lewis-acidity of the central copper(II) ion created by the donating properties of the parent ligand. The steric considerations could be accounted to clarify the difference in the catalytic activity of these functional models.

Ramadan, Abd El-Motaleb M.; Ibrahim, Mohamed M.; Shaban, Shaban Y.

2011-12-01

14

Copper(II) complexes of asymmetrical and symmetrical acyclic pentadentate (N 5 ) mono-Schiff-base ligands. The X-ray structure of [Cu(ppe-py)](ClO 4 ) 2  

Microsoft Academic Search

In the presence of copper(II) ion, two asymmetrical tripodal tetraamine ligands N{(CH2)3NH2}{(CH2)2NH2}2 (pee), N{(CH2)3NH2}2{(CH2)2NH2} (ppe) and one symmetrical ligand, N{(CH2)3NH2}3 (tpt), were condensed with 2-acetylpyridine. In EtOHH2O solutions the reaction stops after the first condensation stage, and complexes of acyclic pentadentate(N5) mono-Schiff-base ligands were obtained. With asymmetrical tetraamines there are two possible condensation sites: the primary amine of the propylene,

Hassan Keypour; Sadegh Salehzadeh; Robin G. Pritchard; Richard V. Parish

2002-01-01

15

Synthesis and characterization of a copper(II) complex of a ONN donor Schiff base ligand derived from pyridoxal and 2-(pyrid-2-yl)ethylamine - A novel pyridoxal based fluorescent probe  

NASA Astrophysics Data System (ADS)

The title complex, Cu(LH)Cl2 is the first copper(II) complex with a Schiff base derived from pyridoxal and 2-(pyrid-2-yl)ethylamine. The central metal lies in a distorted square pyramidal environment with basal plane occupied by the tridentate ONN donor ligand and a Cl atom. The apical position is occupied by another Cl atom. The existence of two different kinds of H-bonds stabilize the network that propagates as parallel layers along crystallographic b axis. The compound exhibits an irreversible CuII/CuI couple in DMF. As pyridoxal containing moieties are fluorescent in nature, its potential as a fluorescent probe is cultivated. Copper(II) ion effectively quenches the fluorescence of HL and the association constant for Cu(II) was estimated to be 10.8 104 M-1 in methanol by the linear Benesi-Hildebrand equation.

Mandal, Senjuti; Modak, Ritwik; Goswami, Sanchita

2013-04-01

16

Synthesis, characterization and X-ray crystal structures of Vanadium(IV), Cobalt(III), Copper(II) and Zinc(II) complexes derived from an asymmetric bidentate Schiff-base ligand at ambient temperature  

NASA Astrophysics Data System (ADS)

An asymmetric bidentate Schiff-base ligand (HL: 2-((allylimino)methyl)phenol) was prepared from reaction of salicylaldehyde and Allylamine. Vanadium(IV), Cobalt(III), Copper(II) and Zinc(II) complexes, VOL2, CoL3, CuL2 and ZnL2 were synthesized from the reaction of VO(acac)2, CoCl26H2O, CuCl22H2O and Zn(NO3)26H2O with the bidentate Schiff base ligand (HL: 2-allyliminomethyl-phenol) in methanol at ambient temperature. The ligand and its metal complexes were characterized by elemental analysis (CHN), FT-IR spectroscopy. In addition, 1H and 13C NMR techniques were employed for characterization of the ligand (HL) and diamagnetic complex ZnL2. The molecular structures of all complexes were determined by single crystal X-ray diffraction technique. In the ZnL2 and CuL2 complexes, the metal ion is coordinated by two nitrogen and two oxygen atoms from two Schiff base ligands in an approximately square planar trans-[MN2O2] coordination geometry. In the Vanadium(IV) complex, VOL2, the vanadium center in this structure has a distorted tetragonal pyramidal N2O3 coordination sphere and for Cobalt(III) complex, CoL3, the CoIII ion is six coordinated by three bidentate Schiff base ligands in a distorted octahedral environment.

Khorshidifard, Mahsa; Amiri Rudbari, Hadi; Kazemi-Delikani, Zahra; Mirkhani, Valiollah; Azadbakht, Reza

2015-02-01

17

Highly polarizable metallic complexes for nonlinear optics copper(II) and nickel(II) complexes of bis(salicylaldiminato) Schiff base  

NASA Astrophysics Data System (ADS)

In this study highly polarizable metallic complexes of Cu2+, Ni2+, and Cr3+ of Bis(salicylaldiminato) Schiff base have been synthesized. These nonlinear optical materials showed second harmonic generation (SHG) when they were pumped 1.06 micrometers Nd:YAG laser. The intensity of the SH signal varied between the metal complexes, being strongest for Ni-salen complex. An extensive study for these materials has been done to characterize their optical quality and chemical stability. We report here the synthesis, nonlinear optical characterization, electron paramagnetic resonance, FTIR, thermogravimetric measurements and the second order nonlinear response of thermally robust series of donor- acceptor substituted Bis(salicylaldiminato) Ni2+, Cu2+, and Cr3+ complexes.

Darwish, Abdalla M.; Copeland, Robert R.; Sliz, R.; Venkateswarlu, Putcha; Aggarwal, Mohan D.; Williams, Alton; Bhat, Kamala N.; Thompson, James M.; Laxmeshwar, N. B.

1996-11-01

18

Synthesis and characterization of copper(II) and cobalt(II) complexes with two new potentially hexadentate Schiff base ligands. X-ray crystal structure determination of one copper(II) complex  

Microsoft Academic Search

Two new potentially hexadentate N2O4 Schiff base ligands 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy) phenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H2L1] and 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy)-5-tert-butylphenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H2L2] were prepared from the reaction of 3,5-di-tert-butyl-2-hydroxy benzaldehyde with 1,2-bis(2?-aminophenoxy)benzene or 1,2-bis(2?-aminophenoxy)-4-t-butylbenzene, respectively. From the direct reaction of ligands [H2L1] and [H2L2] with copper(II) and cobalt(II) salts in methanolic solution and in the presence of N(Et)3 the neutral [CuL1], [CuL2],

Hassan Keypour; Maryam Shayesteh; Abdolhossein Sharifi-Rad; Sadegh Salehzadeh; Hamidreza Khavasi; Laura Valencia

2008-01-01

19

Spectra and DNA-binding affinities of Copper(II), Nickel(II) complexes with a novel glycine Schiff base derived from chromone  

NASA Astrophysics Data System (ADS)

New [CuL(H 2O) 3]NO 3H 2O and [NiLH 2O]NO 32H 2O complexes with Schiff base (LNa) derived from 6-hydroxy-3-carbaldehyde chromone (CDC) and glycine are reported. Two complexes have been characterized by elemental analysis, IR data, TG/DTA and molar conductivity. The binding of these two complexes to calf thymus DNA (CT-DNA) has been investigated, respectively, with UV-vis spectroscopy, fluorescence spectroscopy and viscosity measurements. The experiment results indicate that the two complexes may bind to CT-DNA through an intercalative mode and [CuL(H 2O) 3]NO 3H 2O intercalates into DNA more deeply than [NiLH 2O]NO 32H 2O. Their intrinsic binding constants ( K) with DNA are 6.08 10 5 and 2.76 10 5 M -1.

Qin, Dong-dong; Yang, Zheng-yin; Wang, Bao-dui

2007-11-01

20

Variation in DNA binding constants with a change in geometry of ternary copper(II) complexes with N2O donor Schiff base and cyanate or dicyanamide  

NASA Astrophysics Data System (ADS)

Two new copper(II) complexes, [Cu(L)(OCN)] (1) and [CuL(dca)]n (2), where HL = 2-(-(2-(diethylamino)ethylimino)methyl)naphthalen-1-ol, dca = N(CN)2-, have been synthesized and characterized by elemental analysis, IR, UV-VIS spectroscopy and single crystal X-ray diffraction studies. Complex 1 has square planar and complex 2 square pyramidal geometries in solid state around metal centre. Interactions of the complexes with calf thymus DNA (CT DNA) were studied by UV-VIS spectroscopy. Binding constant and site size of interaction were determined. Binding site size and intrinsic binding constant K revealed complex 1 interacted with calf thymus DNA better than complex 2.

Jana, Subrata; Santra, Ramesh Chandra; Das, Saurabh; Chattopadhyay, Shouvik

2014-09-01

21

Binuclear cobalt(II), nickel(II), copper(II) and palladium(II) complexes of a new Schiff-base as ligand: Synthesis, structural characterization, and antibacterial activity  

NASA Astrophysics Data System (ADS)

A binucleating new Schiff-base ligand with a phenylene spacer, afforded by the condensation of glycyl-glycine and o-phthalaldehyde has been served as an octadentate N 4O 4 ligand in designing some binuclear complexes of cobalt(II), nickel(II), copper(II), and palladium(II). The binding manner of the ligand to the metal and the composition and geometry of the metal complexes were examined by elemental analysis, conductivity measurements, magnetic moments, IR, 1H, 13C NMR, ESR and electronic spectroscopies, and TGA measurements. There are two different coordination/chelation environments present around two metal centers of each binuclear complex. The composition of the complexes in the coordination sphere was found to be [M 2(L)(H 2O) 4] (where M = Co(II) and Ni(II)) and [M 2(L)] (where M = Cu(II) and Pd(II)). In the case of Cu(II) complexes, ESR spectra provided further information to confirm the binuclear structure and the presence of magnetic interactions. All the above metal complexes have shown moderate to good antibacterial activity against Gram-positive and Gram-negative bacteria.

Geeta, B.; Shravankumar, K.; Reddy, P. Muralidhar; Ravikrishna, E.; Sarangapani, M.; Reddy, K. Krishna; Ravinder, V.

2010-11-01

22

Binuclear cobalt(II), nickel(II), copper(II) and palladium(II) complexes of a new Schiff-base as ligand: synthesis, structural characterization, and antibacterial activity.  

PubMed

A binucleating new Schiff-base ligand with a phenylene spacer, afforded by the condensation of glycyl-glycine and o-phthalaldehyde has been served as an octadentate N?O? ligand in designing some binuclear complexes of cobalt(II), nickel(II), copper(II), and palladium(II). The binding manner of the ligand to the metal and the composition and geometry of the metal complexes were examined by elemental analysis, conductivity measurements, magnetic moments, IR, H, C NMR, ESR and electronic spectroscopies, and TGA measurements. There are two different coordination/chelation environments present around two metal centers of each binuclear complex. The composition of the complexes in the coordination sphere was found to be [M?(L)(H(2)O)?] (where M=Co(II) and Ni(II)) and [M?(L)] (where M=Cu(II) and Pd(II)). In the case of Cu(II) complexes, ESR spectra provided further information to confirm the binuclear structure and the presence of magnetic interactions. All the above metal complexes have shown moderate to good antibacterial activity against Gram-positive and Gram-negative bacteria. PMID:20801709

Geeta, B; Shravankumar, K; Reddy, P Muralidhar; Ravikrishna, E; Sarangapani, M; Reddy, K Krishna; Ravinder, V

2010-11-01

23

Formation of a novel ferromagnetic end-to-end cyanate bridged homochiral helical copper(ii) Schiff base complex via spontaneous symmetry breaking.  

PubMed

A homochiral helical coordination polymer of copper(ii) has been synthesized using achiral precursors via spontaneous symmetry breaking and has been confirmed by single crystal X-ray diffraction and solid-state CD spectroscopy. The variable temperature magnetic measurements indicate the presence of weak ferromagnetic exchange interactions mediated by end-to-end cyanate bridges (J = +0.12 cm(-1)). PMID:25427985

Bhattacharyya, Anik; Ghosh, Biswa Nath; Herrero, Santiago; Rissanen, Kari; Jimnez-Aparicio, Reyes; Chattopadhyay, Shouvik

2014-12-01

24

Syntheses, crystal structure and biological evaluation of Schiff bases and copper complexes derived from 4-formylpyrazolone  

NASA Astrophysics Data System (ADS)

Two new pyrazolone based Schiff base ligands 4-((2,4-dimethylphenylimino)methyl)-4,5-dihydro-3-methyl-1-p-tolyl-1H-pyrazol-5-ol [PTPMP-ME] and 4-((3,4-difluorophenylimino)methyl)-4,5-dihydro-3-methyl-1-p-tolyl-1H-pyrazol-5-ol [PTPMP-F] were synthesized. Using these Schiff base ligands two new Copper(II) complexes, [Cu(PTPMP-ME)2] (1) and [Cu(PTPMP-F)2] (2) were synthesized. The ligands and their copper complexes were characterized by IR, 1H NMR, mass, UV-Visible spectroscopy, molar conductivity and magnetic measurement. The molecular geometry of Schiff base ligand PTPMP-ME and copper complexes were determined by single-crystal X-ray analysis. On the basis of single crystal X-ray analysis and spectroscopic techniques, square planar geometry of the complexes was proposed. The Schiff base ligands and their metal complexes were tested for antimicrobial activity against Gram-positive bacteria; Staphylococcus aureus and Bacillus subtilis and Gram-negative bacteria; Escherichia coli and Pseudomonas aeruginosa.

Joseph, V. A.; Pandya, J. H.; Jadeja, R. N.

2015-02-01

25

Synthesis, characterization and antibacterial activity of a tridentate Schiff base derived from cephalothin and sulfadiazine, and its transition metal complexes.  

PubMed

Metal(II) coordination compounds of a cephalothin Schiff base (H2L) derived from the condensation of cephalothin antibiotic with sulfadiazine were synthesized. The Schiff base ligand, mononuclear [ML(H2O)3] (M(II)=Mn,Co,Ni,Zn) complexes and magnetically diluted dinuclear copper(II) complex [CuL(H2O)3]2 were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The cephalothin Schiff base ligand H2L behaves as a dianionic tridentate NOO chelating agent. The biological applications of complexes have been studied on two bacteria strains (Escherichia coli and Staphylococcus aureus) by agar diffusion disc method. PMID:25194315

Anacona, J R; Noriega, Natiana; Camus, Juan

2015-02-25

26

Synthesis, characterization and antibacterial activity of a Schiff base derived from cephalexin and sulphathiazole and its transition metal complexes.  

PubMed

Metal(II) coordination compounds of a cephalexin Schiff base (HL) derived from the condensation of cephalexin antibiotic with sulphathiazole were synthesized. The Schiff base ligand, mononuclear [ML(OAc)(H2O)2] (M(II)=Mn, Co, Ni, Zn) complexes and magnetically diluted trinuclear copper(II) complex [Cu3L(OH)5] were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The analytical and molar conductance values indicated that the acetate ions coordinate to the metal ions. The Schiff base ligand HL behaves as a monoanionic tridentate NNO and tetradentate NNOO chelating agent in the mono and trinuclear complexes respectively. PMID:24727167

Anacona, J R; Rodriguez, Juan Luis; Camus, Juan

2014-08-14

27

Synthesis, characterization and antibacterial activity of a tridentate Schiff base derived from cephalothin and sulfadiazine, and its transition metal complexes  

NASA Astrophysics Data System (ADS)

Metal(II) coordination compounds of a cephalothin Schiff base (H2L) derived from the condensation of cephalothin antibiotic with sulfadiazine were synthesized. The Schiff base ligand, mononuclear [ML(H2O)3] (M(II) = Mn, Co, Ni, Zn) complexes and magnetically diluted dinuclear copper(II) complex [CuL(H2O)3]2 were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and 1H NMR spectral studies. The cephalothin Schiff base ligand H2L behaves as a dianionic tridentate NOO chelating agent. The biological applications of complexes have been studied on two bacteria strains (Escherichia coli and Staphylococcus aureus) by agar diffusion disc method.

Anacona, J. R.; Noriega, Natiana; Camus, Juan

2015-02-01

28

Synthesis, characterization and antibacterial activity of a Schiff base derived from cephalexin and sulphathiazole and its transition metal complexes  

NASA Astrophysics Data System (ADS)

Metal(II) coordination compounds of a cephalexin Schiff base (HL) derived from the condensation of cephalexin antibiotic with sulphathiazole were synthesized. The Schiff base ligand, mononuclear [ML(OAc)(H2O)2] (M(II) = Mn, Co, Ni, Zn) complexes and magnetically diluted trinuclear copper(II) complex [Cu3L(OH)5] were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and 1H NMR spectral studies. The analytical and molar conductance values indicated that the acetate ions coordinate to the metal ions. The Schiff base ligand HL behaves as a monoanionic tridentate NNO and tetradentate NNOO chelating agent in the mono and trinuclear complexes respectively.

Anacona, J. R.; Rodriguez, Juan Luis; Camus, Juan

2014-08-01

29

Synthesis and Spectral Characterization of 14- and 16-membered tetraazamacrocyclic Schiff base ligands and their transition metal complexes and a comparative study of interaction of calf thymus DNA with copper(II) complexes  

NASA Astrophysics Data System (ADS)

14 and 16 membered Schiff base macrocyclic ligands, 7,14-dimethyl-5,12-di(N-amino)-2-methylphenyl-1,4,8,11-tetraaza-cyclotetradecane-4,7,11,14-tetraene (L 1) and 8,16-dimethyl-6,14-di(N-amino)-2-methylphenyl-1,5,9,13-tetraaza-cyclohexadecane-5,8,13,16-tetraene (L 2) were synthesized by condensation reaction between 2'-methyleacetoacetanilide and aliphatic diamines. The metal complexes of the types, [ML 1](NO 3) 2 and [ML 2(NO 3) 2] [M = Co(II), Ni(II), Cu(II) and Zn(II)] were prepared by interaction of ligands, L 1 or L 2 with hydrated metal(II) nitrates. The ligands and their complexes were characterized by elemental analysis, IR, 1H and 13C NMR, EPR, UV-Vis spectroscopy, magnetic susceptibility, conductivity measurements and ESI-mass spectral studies. The results of elemental analyses, ESI-mass and conductivity measurements confirmed the stoichiometry of ligands and their complexes while the characteristic absorption bands and resonance peaks in IR and NMR spectra confirmed the formation of ligand frameworks around the metal ions. The square planar geometry for complexes derived from ligand L 1 and octahedral environment for complexes derived from ligand L 2 with distortion in Cu(II) complex have been confirmed on the basis of results of electronic and electron spin resonance spectral studies and magnetic moment measurements. Absorption and fluorescence spectral studies revealed different binding mode for complex, [CuL 1](NO 3) 2 as compared with [CuL 2(NO 3) 2] on interaction with calf thymus DNA.

Khan, Tahir Ali; Naseem, Sultana; Khan, Shahper N.; Khan, Asad U.; Shakir, Mohammad

2009-08-01

30

A novel copper(II)-Schiff base complex containing pyrrole ring: Synthesis, characterization and its modified electrodes applied in oxidation of aliphatic alcohols  

E-print Network

1 A novel copper(II)-Schiff base complex containing pyrrole ring: Synthesis, characterization 35042 Rennes Cedex, France. Abstract A new copper(II) complex Cu(II)-L containing N2O2 donor atoms has of copper acetate monohydrate. It was characterized by spectroscopic methods such as FT-IR, UV­vis, mass

Boyer, Edmond

31

Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds: synthesis, characterization and biological evolution.  

PubMed

Present work reviews that, the synthesis of (E)-N'-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M(2+)L]X2, where M(2+)=Mn, Co, Ni, Cu, Sr and Cd, L=(7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X=Cl(-). Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective ?-glucosidase inhibitory activity than free Schiff base ligand. PMID:24858195

Kumar Naik, K H; Selvaraj, S; Naik, Nagaraja

2014-10-15

32

Oxidative peptide /and amide/ formation from Schiff base complexes  

NASA Technical Reports Server (NTRS)

One hypothesis of the origin of pre-modern forms of life is that the original replicating molecules were specific polypeptides which acted as templates for the assembly of poly-Schiff bases complementary to the template, and that these polymers were then oxidized to peptide linkages, probably by photo-produced oxidants. A double cycle of such anti-parallel complementary replication would yield the original peptide polymer. If this model were valid, the Schiff base between an N-acyl alpha mino aldehyde and an amino acid should yield a dipeptide in aqueous solution in the presence of an appropriate oxidant. In the present study it is shown that the substituted dipeptide, N-acetyl-tyrosyl-tyrosine, is produced in high yield in aqueous solution at pH 9 through the action of H2O2 on the Schiff-base complex between N-acetyl-tyrosinal and tyrosine and that a great variety of N-acyl amino acids are formed from amino acids and aliphatic aldehydes under similar conditions.

Strehler, B. L.; Li, M. P.; Martin, K.; Fliss, H.; Schmid, P.

1982-01-01

33

Remarkable photocytotoxicity in hypoxic HeLa cells by a dipyridophenazine copper(II) Schiff base thiolate.  

PubMed

Copper(II) complexes [Cu(satp)(L)] (1-3) of a Schiff base thiolate (salicylidene-2-aminothiophenol, H2satp) and phenanthroline bases (L), viz. 1,10-phenanthroline (phen in 1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 2) and dipyrido[3,2-a:2',3'-c]phenazine (dppz in 3), were prepared, characterized and their anaerobic DNA photocleavage activity and hypoxic photocytotoxicity studied. The redox active complexes show the Cu(II)-Cu(I) couple near -0.5 V for 1 and near 0.0 V vs. SCE (saturated calomel electrode) for 2 and 3. The one-electron paramagnetic complexes (~1.85 ?B) are avid DNA binders giving Kb values within 1.010(5)-8.010(5) M(-1). Thermal melting and viscosity data along with molecular docking calculations suggest DNA groove and/or partial intercalative binding of the complexes. The complexes show anaerobic DNA cleavage activity in red light under argon via type-I pathway, while DNA photocleavage in air proceeds via hydroxyl radical pathway. The DFT (density functional theory) calculations reveal a thyil radical pathway for the anaerobic DNA photocleavage activity and suggest the possibility of generation of a transient copper(I) species due to bond breakage between the copper and sulfur to generate the thyil radical. An oxidation of the copper(I) species is likely by oxygen in an aerobic medium or by the buffer medium in an anaerobic condition. Complex 3 exhibits significant photocytotoxicity in HeLa cells (IC50=8.3(1.0) ?M) in visible light, while showing lower dark toxicity (IC50=17.2(1.0) ?M). A significant reduction in the dark toxicity is observed under hypoxic cellular conditions (IC50=30.0(1.0) ?M in dark), while retaining its photocytotoxicity (IC50=8.0(1.0) ?M). PMID:21726772

Lahiri, Debojyoti; Majumdar, Ritankar; Mallick, Dibyendu; Goswami, Tridib K; Dighe, Rajan R; Chakravarty, Akhil R

2011-08-01

34

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)

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.

Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

2014-02-01

35

Chromotropism Behavior and Biological Activity of some Schiff Base-Mixed Ligand Transition Metal Complexes  

Microsoft Academic Search

We report about a series of mono-nuclear and bi-nuclear complexes with acyclic as well as macro-cyclic ligands, which have been synthesized with Schiff base ligands in tri- tetra and pentadentate forms. The bonding sites on complex formation are mainly the azomethine groups and\\/or imide nitrogen, ketonic oxygen or sulphur atoms. Complexes of two series of Schiff base ligands, H2La and

Azza A. A. Abou-Hussen; Wolfgang Linert

2009-01-01

36

Dicopper(II) complexes of a new pyrazolate-containing Schiff-base macrocycle and related acyclic ligand.  

PubMed

Dicopper(II) complexes of two new 3,5-disubstituted-pyrazole-based ligands, bis(quadridentate) macrocyclic ligand (L1)(2-) and bis(terdentate) acyclic ligand (L2)(-), were synthesised by Schiff base condensation of 3,5-diformylpyrazole and either one equivalent of 1,3-diaminopropane or two equivalents of 2-(2-aminoethyl)pyridine in the presence of one or two equivalents of copper(II) ions, respectively. Copper(II) acetate monohydrate was employed in the synthesis of [Cu(2)(L1)(OAc)(2)], [Cu(2)(L2)(H(2)O)(2)(OAc)(3)] and [Cu(II)(2)(L1)(NCS)(2)]; in the last of these one equivalent of NaNCS per copper(II) ion was also added. The fourth complex, [Cu(2)(L2)(NCS)(2)(DMF)]BF(4), was prepared using copper(II) tetrafluoroborate hexahydrate, along with two equivalents of NaOH and six of NaSCN. All four of these dimetallic complexes have been characterised by single crystal X-ray diffraction: the two macrocyclic complexes are the first such Schiff base complexes to be so characterised. A feature common to all four of the structures is bridging of the two copper(II) centres by the pyrazolate moiety/moieties. The structure determinations show that the coordination mode of the acetate groups in both [Cu(2)(L1)(OAc)(2)].2MeOH.H(2)O and [Cu(2)(L2)(H(2)O)(2)(OAc)(3)] is unidentate as had been tentatively predicted by analysis of the infrared spectra (DeltaOCO of 199 and 208 cm(-1), respectively). The magnetochemical studies of the macrocyclic complexes, over the temperature range 4-300 K, revealed strong antiferromagnetic coupling with J = -169 and -213 cm(-1) for [Cu(2)(L1)(OAc)(2)].2H(2)O and [Cu(II)(2)(L1)(NCS)(2)].DMF respectively. The J values have been discussed in relation to a published correlation involving the CuN(pyrazolate)N(pyrazolate) angles. PMID:17213932

de Geest, Duncan J; Noble, Andy; Moubaraki, Boujemaa; Murray, Keith S; Larsen, David S; Brooker, Sally

2007-01-28

37

Infrared and DNA-binding on ultraviolet and fluorescence spectra of new copper and zinc complexes with a naringenin Schiff-base ligand  

NASA Astrophysics Data System (ADS)

A naringenin Schiff-base ligand (H 3L) and its copper(II) and zinc(II) complexes have been synthesized and characterized by elemental analyses, molar conductivities, 1H NMR, IR spectra, UV spectra and thermal analyses. The DNA-binding properties of the Cu(II) and Zn(II) complexes have been investigated by fluorescence spectroscopy, ultraviolet spectroscopy and by viscosity measurements. The results indicate that complexes and ligand may bind to DNA by intercalation modes, but the binding affinity of the complexes is much higher than that of the ligand.

Li, Yan-hua; Wang, Bao-dui; Yang, Zheng-yin

2007-06-01

38

Synthesis, X-ray crystallography, thermal studies, spectroscopic and electrochemistry investigations of uranyl Schiff base complexes.  

PubMed

Some tetradentate salen type Schiff bases and their uranyl complexes were synthesized and characterized by UV-Vis, NMR, IR, TG, C.H.N. and X-ray crystallographic studies. From these investigations it is confirmed that a solvent molecule occupied the fifth position of the equatorial plane of the distorted pentagonal bipyramidal structure. Also, the kinetics of complex decomposition by using thermo gravimetric methods (TG) was studied. The thermal decomposition reactions are first order for the studied complexes. To examine the properties of uranyl complexes according to the substitutional groups, we have carried out the electrochemical studies. The electrochemical reactions of uranyl Schiff base complexes in acetonitrile were reversible. PMID:23321220

Asadi, Zahra; Shorkaei, Mohammad Ranjkesh

2013-03-15

39

Mononuclear Ru(III) Schiff base complexes: Synthesis, spectral, redox, catalytic and biological activity studies  

NASA Astrophysics Data System (ADS)

An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh 3)(L)] (where, X = Cl/Br; E = As/P; L = dianion of the Schiff bases derived from acetoacetanilide with o-phenylenediamine and salicylaldehyde/ o-hydroxyacetophenone/ o-vanillin/2-hydroxy-1-naphthaldehyde) have been synthesized from the reactions of equimolar reactions of [RuX 3(EPh 3) 3] and Schiff bases in benzene. The new Ru(III) Schiff base complexes have been characterized by elemental analyses, FT-IR, electronic, 1H NMR and 13C NMR spectra, EPR spectral studies, powder X-ray diffraction (XRD) and electrochemical studies. The new complexes were found to be effective catalysts for aryl-aryl coupling and the oxidation of alcohols into their corresponding carbonyl compounds, respectively, using molecular oxygen atmosphere at ambient temperature. Further, the new Ru(III) Schiff base complexes were screened for their antibacterial activity against Pseudomonas aeruginosa, Vibrio cholera, Salomonella typhi and Staphylococcus aureaus.

Priya, N. Padma; Arunachalam, S.; Manimaran, A.; Muthupriya, D.; Jayabalakrishnan, C.

2009-04-01

40

Synthesis, characterization and electrochemical study of synthesis of a new Schiff base (H?cddi(t)butsalen) ligand and their two asymmetric Schiff base complexes of Ni(II) and Cu(II) with NN'OS coordination spheres.  

PubMed

A novel Schiff base (H(2)cddi(t)butsalen) ligand was prepared via condensation of Methyl-2-{N-(2'-aminoethane)}-amino-1-cyclopentenedithiocarboxylate(Hcden) and 3,5-di-tert-butyl-2-hydroxybenzaldehyde. The ligand and Ni(II) and Cu(II) complexes were characterized based on elemental analysis, IR, (1)H NMR, (13)C NMR, UV-Vis spectrometry and cyclic voltammetry. The structure of copper{methyl-2-{N-[2-(3,5-di-tert-butyl-2-hydroxyphenyl)methylidynenitrilo]ethyl}amino-1-cyclopentedithiocarboxylate has been determined by X-ray crystallography. The X-ray results confirm that the geometry of the complex is slightly distorted square-planar structure. The copper(II) ion coordinates to two nitrogen atoms from the imine moiety of the ligand, a sulfur atom the methyl dithiocarboxylate moiety and phenolic oxygen atom. PMID:22925979

Menati, Saeid; Azadbakht, Azadeh; Taeb, Abbas; Kakanejadifard, Ali; Khavasi, Hamid Reza

2012-11-01

41

Ruthenium(II) hydrazone Schiff base complexes: Synthesis, spectral study and catalytic applications  

NASA Astrophysics Data System (ADS)

Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B = PPh 3, AsPh 3 or Py; L = hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh 3) 2(B)] (where E = P or As; B = PPh 3, AsPh 3 or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, 1H, 13C and 31P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol.

Manikandan, R.; Viswanathamurthi, P.; Muthukumar, M.

2011-12-01

42

Studies on synthesis, characterization, DNA interaction and cytotoxicity of ruthenium(II) Schiff base complexes.  

PubMed

The synthesis and characterization of three hexa-coordinated ruthenium(II) Schiff base complexes of the type [RuCl(CO)(B)L] (B=PPh(3)/AsPh(3)/py and L=monobasic tridentate Schiff base ligand derived by the condensation of salicylaldehyde with 4-aminoantipyrine) are reported. IR, electronic, NMR and mass spectral data of the complexes are discussed. An octahedral geometry has been tentatively proposed for all the complexes. DNA binding properties of the ligand and its ruthenium(II) complexes have been investigated by electronic absorption spectroscopy. Two of the complexes were tested for DNA cleavage property. Finally, in vitro study of the cytotoxicity of the ligand and the complex [RuCl(CO)(PPh(3))L] on HeLa were tested. The IC(50) value for the ligand and the complex were 52.3 and 31.6?m respectively. PMID:22522297

Raja, Gunasekaran; Butcher, Ray J; Jayabalakrishnan, Chinnasamy

2012-08-01

43

[Photochromic properties of complexes of curcumin aniline schiff base with rare earth].  

PubMed

Using Ce, La, Nd (III) nitrate and a curcumin aniline schiff base and a curcumin bis (4-methyl aniline) schiff base as raw materials, six complexes were synthesized. Through the molar conductance, IR, TG-DTA and element analysis motheds, the structures of complexes were characterized. Moreover, the properties of UV-Visible spectra and photochromic properties of the complex, and the solvatechromic performance in organic solvents were explored. The experiments showed that the complexes have good photochromic and solvate-chromic properties. The fluorescence intensity and UV-Visible spectra intensity were reduced under exposure,and the color of the complex solution became light. The complexes have different UV-Visible spectra in difference organic solvents. The relationship between photochromic properties and time was also studied. PMID:24611370

Song, Yu-Min; Yang, Mei-Ling; Ma, Jun-Huai; Zhang, Yu-Mei

2013-12-01

44

Effect of the Schiff base complex diaqua-(N-salicylidene-l-glutamato)copper(II) monohydrate on human tumor cells.  

PubMed

The aim of our study was to estimate cytostatic/cytotoxic activity of the copper(II) Schiff base complex of the composition [Cu(N-salicylidene-l-glutamato)(H2O)2]H2O, further Cu(SG-L)H2O, against human colon carcinoma cell line HT-29, as well as to determine type of cell death and to find out the molecular mechanism of apoptosis induced by this complex. Two highest concentrations (50, 100 mol/l) of the complex showed a strong cytotoxic activity against human colon carcinoma cells HT-29 after 72 h of influence. Other concentrations had a cytostatic activity. Unchelated copper(II) ions and free ligands had no effect on the cell growth. Cu(SG-L)H2O preferentially reduced cancer cell viability compared to healthy cells (NIH-3T3). Cu(SG-L)H2O induced apoptosis of cells HT-29 at all concentrations used (1-100 mol/l) after 48 h of influence. Apoptosis was carried out by the mitochondrial pathway with active caspases 3 and 9. By the spin-trapping technique combined with electron paramagnetic resonance we found that our complex is photochemically stable in aqueous systems and does not exhibit radical-scavenging activity when 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) cation radical was used as an oxidant. The complex exhibits a strong prooxidant property in the initial stages of thermal decomposition of K2S2O8 in water solutions leading to the massive production of ()OH radicals. Therefore, this complex could strongly participate in anticancer action via a free radical mechanism. PMID:24113525

Konarikova, Katarina; Andrezalova, Lucia; Rapta, Peter; Slovakova, Marianna; Durackova, Zdenka; Laubertova, Lucia; Gbelcova, Helena; Danisovic, Lubomir; Bohmer, Daniel; Ruml, Tomas; Sveda, Martin; Zitnanova, Ingrid

2013-12-01

45

Docking of ethanamine Schiff base imines & metal (II) complexes, cytotoxicity & DNA interaction studies  

NASA Astrophysics Data System (ADS)

The present study deals with a series of biologically and stereo chemically important novel transition metal (II) Schiff base chelates. The Cu (II), Co (II), Mn (II) and Ni (II) ions containing complexes were synthesized by using diphenylethanamine and 2-hydroxy/2, 4-dihydroxy/2-hydroxy-4-methoxybenzaldehydes. The synthesized complexes were characterized using micro analytical, IR, NMR, ESI-Mass, UV-Visible, cyclic voltammetry and the EPR spectroscopic techniques. The spectral data evidenced the action of ligands as a neutral bidentate Schiff bases, coordinating through azomethine nitrogen and oxygen atom of hydroxyl group. The interaction studies revealed the groove binding nature of complexes with CT-DNA. The ligand and synthesized metal complexes showed cytotoxicity against cancerous cells. The strong binding affinity of the imine and metal complexes was also confirmed by molecular docking studies.

Sujarani, S.; Ramu, A.

2015-01-01

46

Synthesis and spectral characterization of ternary mixed-vanadyl ?-diketonate complexes with Schiff bases.  

PubMed

A new method to synthesize some mononuclear ternary oxovanadium(IV) complexes of the general formula [VO(?-dike)(SB)] (where H?-dike=acetylacetone; benzoylacetone or dibenzoylmethane, HSB=Schiff bases) has been explored by stepwise substitutions of acetylacetonate ion of VO(acac)(2) with Schiff bases. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. The complexes were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, (1)H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of ?-diketones and Schiff base anions in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with (51)V nucleus (I=7/2). Cyclic voltammograms of all the complexes displayed two-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Transmission electron microscopy (TEM) indicated spherical particles of ?200 nm diameter. The synthesized complexes are mixed-ligand complexes showing a considerable hydrolytic stability in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes. PMID:22387685

Baranwal, Balram Prasad; Tripathi, Kiran; Singh, Alok Kumar; Tripathi, Saurabh

2012-06-01

47

Transition Metal(II) Complexes with Cefotaxime-Derived Schiff Base: Synthesis, Characterization, and Antimicrobial Studies  

PubMed Central

New [ML2(H2O)2] complexes, where M?=?Co(II), Ni(II), Cu(II), and Zn(II) while L corresponds to the Schiff base ligand, were synthesized by condensation of cefotaxime with salicylaldehyde in situ in the presence of divalent metal salts in ethanolic medium. The complexes were characterized by elemental analyses, conductance, and magnetic measurements, as well as by IR and UV-Vis spectroscopy. The low values of the molar conductance indicate nonelectrolyte type of complexes. Based on spectral data and magnetic moments, an octahedral geometry may be proposed for Co(II), Ni(II), and Zn(II) complexes while a tetragonal geometry for Cu(II) complex. Molecular structure of the Schiff base ligand and its complexes were studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. All the synthesized complexes were tested for in vitro antibacterial activity against some pathogenic bacterial strains, namely Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The MIC values shown by the complexes against these bacterial strains revealed that the metal complexes possess superior antibacterial activity than the Schiff base. PMID:24688454

Amzoiu, Emilia; Spnu, Cezar Ionu?

2014-01-01

48

Synthesis, spectrochemical characterisation and catalytic activity of transition metal complexes derived from Schiff base modified chitosan  

NASA Astrophysics Data System (ADS)

Three novel quadridentate Schiff base complexes, [Cu(OIAC)Cl2], [Co(OIAC)Cl2] and [Ni(OIAC)Cl2] [OIAC, a Schiff base ligand: (([2-oxo-1H-indol-3-ylidene]amino)chitosan)] have been synthesized. The molecular structure of the complexes has been characterised by elemental analyses, magnetic measurements, molar conductance studies, vibrational (FT-IR), electronic (UV-Vis) and 1H NMR spectroscopic techniques. Thermal properties of the complexes have been investigated with TG-DTG analyses. The surface morphological difference of ligand and the complexes has been explored with scanning electron microscopy. The crystallinity of the compounds was analysed by powder X-ray diffraction technique and it was found to be less for the Schiff base (OIAC) and the complexes as compared to the chitosan. The catalytic activities of the complexes have been studied in the oxidation of cyclohexane, using environmental friendly oxidant, hydrogen peroxide. Complex with rough surface has shown higher catalytic activity compared to the other complexes.

Antony, R.; Theodore David, S.; Saravanan, K.; Karuppasamy, K.; Balakumar, S.

2013-02-01

49

A dinuclear cadmium(II) Schiff base thiocyanato complex: crystal structure and fluorescence.  

PubMed

A new dinuclear cadmium(II) complex, [Cd(L)(NCS)]2 (1) has been synthesized using a potentially tetradentate Schiff base ligand HL, 2-((E)-(2-(diethylamino)ethylimino)methyl)-6-methoxyphenol, obtained by the condensation of 2-diethylaminoethylamine and o-vanillin, and characterized by different physicochemical techniques. Crystal structure of the title complex was unambiguously established by single crystal X-ray diffraction which reveals that metal centers are connected by bridging phenolato and chelating methoxy oxygen atoms of the coordinating Schiff bases and embedded in severely distorted octahedral geometries. Fluorescence properties of the ligand and its complex, studied at room temperature indicate that later may serve as strong fluorescent emitter. PMID:24664327

Shit, Shyamapada; Sankolli, Ravish; Guru Row, Tayur N

2014-01-01

50

Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties  

NASA Astrophysics Data System (ADS)

New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV-Vis, TG-DTA and 1H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH).

Selvi, Canan; Nartop, Dilek

2012-09-01

51

Ruthenium(II) hydrazone Schiff base complexes: synthesis, spectral study and catalytic applications.  

PubMed

Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B=PPh(3), AsPh(3) or Py; L=hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh(3))(2)(B)] (where E=P or As; B=PPh(3), AsPh(3) or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, (1)H, (13)C and (31)P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol. PMID:21924947

Manikandan, R; Viswanathamurthi, P; Muthukumar, M

2011-12-01

52

Oxidation of benzoin catalyzed by oxovanadium(IV) schiff base complexes  

PubMed Central

Background The oxidative transformation of benzoin to benzil has been accomplished by the use of a wide variety of reagents or catalysts and different reaction procedures. The conventional oxidizing agents yielded mainly benzaldehyde or/and benzoic acid and only a trace amount of benzil. The limits of practical utilization of these reagents involves the use of stoichiometric amounts of corrosive acids or toxic metallic reagents, which in turn produce undesirable waste materials and required high reaction temperatures. In recent years, vanadium complexes have attracted much attention for their potential utility as catalysts for various types of reactions. Results Active and selective catalytic systems of new unsymmetrical oxovanadium(IV) Schiff base complexes for the oxidation of benzoin is reported. The Schiff base ligands are derived between 2-aminoethanol and 2-hydroxy-1-naphthaldehyde (H2L1) or 3-ethoxy salicylaldehyde (H2L3); and 2-aminophenol and 3-ethoxysalicylaldehyde (H2L2) or 2-hydroxy-1-naphthaldehyde (H2L4). The unsymmetrical Schiff bases behave as tridentate dibasic ONO donor ligands. Reaction of these Schiff base ligands with oxovanadyl sulphate afforded the mononuclear oxovanadium(IV) complexes (VIVOLx.H2O), which are characterized by various physico-chemical techniques. The catalytic oxidation activities of these complexes for benzoin were evaluated using H2O2 as an oxidant. The best reaction conditions are obtained by considering the effect of solvent, reaction time and temperature. Under the optimized reaction conditions, VOL4 catalyst showed high conversion (>99%) with excellent selectivity to benzil (~100%) in a shorter reaction time compared to the other catalysts considered. Conclusion Four tridentate ONO type Schiff base ligands were synthesized. Complexation of these ligands with vanadyl(IV) sulphate leads to the formation of new oxovanadium(IV) complexes of type VIVOL.H2O. Elemental analyses and spectral data of the free ligands and their oxovanadium(IV) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. Oxovanadium complexes were screened for the oxidation of benzoin to benzil using H2O2 as oxidant. The effect of time, solvent and temperature were optimized to obtain maximum yield. The catalytic activity results demonstrate that these catalytic systems are both highly active and selective for the oxidation of benzoin under mild reaction conditions. PMID:23294561

2013-01-01

53

Synthesis, Dioxygen Affinities and Biomimetic Catalytic Oxidation Performance of Crown Ether-tethered Schiff Base Transition-Metal Complexes  

Microsoft Academic Search

Mono-Schiff bases containing crown ether ring (HL1, HL2, HL3 and HL4) and their transition-metal complexes were synthesized and characterized by 1H NMR, IR, MS spectra and elemental analysis. The crystal structures of HL1, HL3 and CoL21 were determined from X-ray diffraction data. The oxygenation constants (Ko2) of Schiff-base Co (II) complexes were measured over a range of ?5C to 25C,

Wei Zeng; Zhihua Mao; Xingyao Wei; Jianzhang Li; Zhou Hong; Shengying Qin

2002-01-01

54

Synthesis and characterization of Ni(II), Cu(II) and Zn(II) complexes with new macrocyclic Schiff base ligands containing piperazine moiety  

NASA Astrophysics Data System (ADS)

Two new macrocyclic Schiff base ligands L 1 and L 2 from [1 + 1] and [2 + 2] condensation reaction, respectively, have been obtained in a one-pot synthesis starting from 1,4-bis(2-formylphenyl)piperazine and 2,2-dimethyl-propylendiamine. Unfortunately, because of the low solubility of two products, we were unable to separate them effectively. Macrocyclic Schiff base complexes [NiL 1](ClO 4) 2, [CuL 1](ClO 4) 2 and [ZnL 1](ClO 4) 2 were prepared from the reaction of a mixture of L 1 and L 2 in the presence of nickel(II), copper(II) and zinc(II) metal ions, respectively. In all cases, only [1 + 1] condensation products were obtained and no metal complexes were isolated with the L 2 macrocycle. All of complexes have been characterized by elemental analysis, IR spectra, FAB-MS, conductivity measurements and in the case of Zn(II) complex by 1H and 13C NMR spectroscopy. Crystal structures of [NiL 1](ClO 4) 2 and [NiL 1'](ClO 4) 2 complexes have been also determined. The Ni(II) is coordinated to the ligand L 1 and L 1' by two nitrogen atoms of piperazine group and two nitrogen atoms of the imine groups, in a slightly distorted square-planar geometry.

Keypour, Hassan; Arzhangi, Parisa; Rahpeyma, Nasibeh; Rezaeivala, Majid; Elerman, Yalcin; Bykgngr, Orhan; Valencia, Laura; Khavasi, Hamid Reza

2010-08-01

55

Synthesis and characterization of copper complexes of Schiff base derived from isatin and salicylic hydrazide  

NASA Astrophysics Data System (ADS)

A series of novel metal complexes of Schiff base have been prepared by the interaction of Cu(II) with isatin salicylic hydrazide. All the new compounds were characterized by elemental analysis, conductance measurement, magnetic moment determination, IR, UV, NMR, Mass and EPR spectral studies, thermal studies and microbial activities. The results indicate that the ligand acts as a tridentate chelating ligand coordinating through nitrogen and oxygen atoms. The ligand and complexes show inactive against Escherichia coli and active against Staphylococcus aureus and B.substilis. By analyzing the results of spectral, thermal and elemental analysis square planar geometry is proposed for all the complexes.

Lekshmy, R. K.; Thara, G. S.

2014-10-01

56

Schiff base ligands and their transition metal complexes in the mixtures of ionic liquid + organic solvent: a thermodynamic study.  

PubMed

Schiff bases and their metal complexes in the mixtures of ionic liquid (IL) + organic solvent have shown great potential in attractive oxidation catalytic processes. The efficiency of such a process is strongly dependent on the various molecular interactions occurring between components. Thermodynamic properties of these systems can provide valuable information about structural interactions. Therefore, in this work, the interactions of the IL 1-hexyl-3-methylimidazolium chloride ([HMIm]Cl) with Schiff bases in organic solvents were studied through the measurements of density, viscosity, and electrical conductivity. The effect of solvent on the interactions was examined by the solutions of IL + BPIC Schiff base + solvent (C2H6O-C3H8O-C4H10O). Moreover, the influence of Schiff base ligand and Schiff base complex structures was probed by the solutions of IL + DMA + ligand (salcn/salpr/salen) and IL + DMA + complex (VO(3-OMe-salen)/VO(salophen)/VO(salen)), respectively. Using the experimental data, some important thermodynamic properties, such as standard partial molar volume (V), experimental slope (Sv), viscosity B-coefficient, solvation number (B/V), and limiting molar conductivity (?0) were calculated and discussed in terms of solute-solvent (IL-DMF/alcohol) and solute-cosolute (IL-Schiff base) interactions. PMID:25482659

Shekaari, Hemayat; Kazempour, Amir; Khoshalhan, Maryam

2015-01-21

57

Synthesis and characterization of chromium(III) Schiff base complexes: Antimicrobial activity and its electrocatalytic sensing ability of catechol.  

PubMed

A series of acyclic Schiff base chromium(III) complexes were synthesized with the aid of microwave irradiation method. The complexes were characterized on the basis of elemental analysis, spectral analysis such as UV-Visible, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) spectroscopies and electrospray ionization (ESI) mass spectrometry. Electrochemical analysis of the complexes indicates the presence of chromium ion in +3 oxidation state. Cr (III) ion is stabilized by the tetradentate Schiff base ligand through its nitrogen and phenolic oxygen. From the spectral studies it is understood that the synthesized chromium(III) complexes exhibits octahedral geometry. Antimicrobial activity of chromium complexes was investigated towards the Gram positive and Gram negative bacteria. In the present work, an attempt was made to fabricate a new kind of modified electrode based on chromium Schiff base complexes for the detection of catechol at nanomolar level. PMID:25576940

Praveen Kumar, S; Suresh, R; Giribabu, K; Manigandan, R; Munusamy, S; Muthamizh, S; Narayanan, V

2015-03-15

58

Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases.  

PubMed

A new series of three biologically active triazole derived Schiff base ligands L(1)-L(3) have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination. PMID:23277183

Hanif, Muhammad; Chohan, Zahid H

2013-03-01

59

New 3,4-diaminobenzoic acid Schiff base compounds and their complexes: synthesis, characterization and thermodynamics.  

PubMed

Some new tetradentate Schiff base ligands (H3L) were prepared via condensation of 3,4-diaminobenzoic acid with 2-hydroxybenzaldehyde derivatives, such as 3,4-bis((E)-2,4-dihydroxybenzylideneamino)benzoic acid (H3L(1)), 3,4-bis((E)-2-hydroxy-3-methoxybenzylideneamino)benzoic acid (H3L(2)) and 3,4-bis((E)-5-bromo-2-hydroxybenzylideneamino)benzoic acid (H3L(4)). Additionally, a tetradentate Schiff base ligand 3,4-bis((E)-2-hydroxybenzylideneamino)benzoic acid (H3L(3)) and its complexes were synthesized. Their metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) were prepared in good yields from the reaction of the ligands with the corresponding metal acetate. They were characterized based on IR, (1)H NMR, Mass spectroscopy and UV-Vis spectroscopy. Also, the formation constants of the complexes were measured by UV-Vis spectroscopic titration at constant ionic strength 0.1M (NaClO4), at 25 C in dimethylformamide (DMF) as a solvent. PMID:24309180

Mohammadi, Khosro; Niad, Mahmood; Jafari, Tahereh

2014-03-25

60

Crystal structures of transition metal complexes with an asymmetrical tridentate Schiff-base ligand  

NASA Astrophysics Data System (ADS)

The asymmetrical tridentate Schiff base ( H 2L = (E)-N'-(2-hydroxybenzylidene)-4-hydroxybenzohydrazide) has been designed and synthesized. The four transition metal complexes with this ligand [Cu(HL)(NO 3)](H 2O) ( 1), [Zn 2(HL) 2(bipy)(H 2O) 2](NO 3) 2 ( 2), [Cu(HL)(H 2O)] 2(NO 3) 2 ( 3) and [Cu(HL)(Me 2NCO)] 2 ( 4) have been studied. The unsaturated coordination site of metal ion in complexes 1 and 2 is occupied by secondary ligand of nitrate and 4,4'-bipyridine. The crystal structure of complex 1 exhibits supramolecular framework with homochirality. Complexes 3 and 4 are dinuclear complexes bridged by the phenol oxygen atoms and the fifth coordination is occupied by H 2O molecular and DMF anion respectively. Hydrogen bonding and ?-? stacking exist in all four complexes to construct supramolecular architecture.

Tang, Bei-bei; Sun, Xiao-ping; Liu, Gui-lei; Li, Hui

2010-12-01

61

Magnetic properties and structure of a Cu IIDy III heterodinuclear Schiff base complex  

NASA Astrophysics Data System (ADS)

The crystal structure of a new heterodinuclear lanthanide complex, L 2Cu(Me 2CO)Dy(NO 3) 3 (L 2= N, N'-bis(2-hydroxy-3-methoxy-benzylidene)-ethylenediamine) has determined and the magnetic properties of the complex investigated. (C 18H 18N 2O 4)Cu(C 3H 6O)Dy(NO 3) 3, monoclinic, space group P2 1/ c, with a=9.875(2), b=18.870(7), c=15.675(8) , ?=95.45(3), V=2908(2) 3, Z=4. The structure consists of ordered dinuclear units with Cu II and Dy III ions bridged by two phenolato oxygen atoms of the Schiff base ligand. The Cu II ion has a square-pyramidal geometry involving the basal N 2O 2 donor atoms of the Schiff base ligands and one oxygen atom of the acetone molecule at the apex position. The Dy III ion is decacoordinated by the four oxygen atoms of L 2 and six oxygen atoms from the three bidentate nitrate ions. The Cu⋯Dy separation is 3.461(2) . The ?T versus T plots, ? being the molar magnetic susceptibility per Cu IIDy III unit and T the temperature, has been measured in the 4.5-300 K temperature range. The magnetic properties of the compound are dominated by the crystal field effect on the Dy III site, masking the magnetic interaction between the paramagnetic centers.

Elmali, A.; Elerman, Y.

2005-02-01

62

Coordination properties of hydralazine Schiff base. Synthesis and equilibrium studies of some metal ion complexes  

NASA Astrophysics Data System (ADS)

In the present study, a new ligand is prepared by condensation of hydralazine (1-Hydralazinophthalazine) with 2-butanon-3-oxime. The acid-base equilibria of the schiff-base and the complex formation equilibria with the metal ions as Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Zn(II) are investigated potentiometrically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The effect of metal ion properties as atomic number, ionic radius, electronegativity and ionization potential are investigated. The isolated solid complexes are characterized by conventional chemical and physical methods. The potential coordination sites are assigned using the i.r. and 1H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies.

Shoukry, Azza A.; Shoukry, Mohamed M.

2008-08-01

63

Optical chemosensors based on transmetalation of salen-based Schiff base complexes.  

PubMed

We report our systematic studies of novel, simple, selective, and sensitive optical (both colorimetric and fluorescent) chemosensors for detecting Al(3+) based on transmetalation reactions (metal displacement or exchange reactions) of a series of K(I), Ca(II), Zn(II), Cu(II), and Pt(II) complexes containing different ligands of salen-based Schiff bases. Both the chemical structure of the salen ligand and the identity of the central metal ion have a tremendous impact on the sensing performance, which is mainly determined by the stability constant of the complex. Moreover, the selectivities of the salen-complex-based chemosensors are much better than those of the corresponding free salen ligands because of the shielding function of the filled-in metal ion in the complex. Therefore, the present work potentially provides a new and simple way to design optical probes via complex-based transmetalation reactions. PMID:24559169

Cheng, Jinghui; Ma, Xiaofeng; Zhang, Yuhui; Liu, Jiaoyan; Zhou, Xiangge; Xiang, Haifeng

2014-03-17

64

Spectroscopic and electrochemical characterization of some Schiff base metal complexes containing benzoin moiety  

NASA Astrophysics Data System (ADS)

The ligation behavior of bis-benzoin ethylenediamine (B2ED) and benzoin thiosemicarbazone (BTS) Schiff bases towards Ru3+, Rh3+, Pd2+, Ni2+ and Cu2+ were determined. The bond length of M-N and spectrochemical parameters (10Dq, ?, B and LFSE) of the complexes were evaluated. The redox characteristics of selected complexes were explored by cyclic voltammetry (CV) at Pt working electrode in non aqueous solvents. Au mesh (100 w/in.) optically transparent thin layer electrode (OTTLE) was also used for recording thin layer CV for selected Ru complex. Oxidation of some complexes occurs in a consecutive chemical reaction of an EC type mechanism. The characteristics of electron transfer process of the couples M2+/M3+ and M3+/M4+ (M = Ru3+, Rh3+) and the stability of the complexes towards oxidation and/or reduction were assigned. The nature of the electroactive species and reduction mechanism of selected electrode couples were assigned.

El-Shahawi, M. S.; Al-Jahdali, M. S.; Bashammakh, A. S.; Al-Sibaai, A. A.; Nassef, H. M.

2013-09-01

65

Towards dipyrrins: oxidation and metalation of acyclic and macrocyclic Schiff-base dipyrromethanes.  

PubMed

Oxidation of acyclic Schiff-base dipyrromethanes cleanly results in dipyrrins, whereas the macrocyclic 'Pacman' analogues either decompose or form new dinuclear copper(ii) complexes that are inert to ligand oxidation; the unhindered hydrogen substituent at the meso-carbon allows new structural motifs to form. PMID:25563854

Pankhurst, James R; Cadenbach, Thomas; Betz, Daniel; Finn, Colin; Love, Jason B

2015-01-20

66

The NMR and X-ray study of L-arginine derived Schiff bases and its cadmium complexes  

NASA Astrophysics Data System (ADS)

The structure study of five Schiff bases derived from L-arginine (L-Arg) and 2-hydroxy carbonyl compounds were performed in both solution and solid state using NMR and X-ray methods. Both analytical methods applied to the solid state sample of two Schiff bases showed a significant difference in molecular structures of unsubstituted and 7-CH3 substituted compounds. This effect was explained as a steric interaction of methyl group. Additionally the structure of two Cd2+ complexes with some Schiff bases were determined by NMR methods in DMSO solution and in the solid state. On the base of heteronuclear NMR measurement (13C, 15N and 113Cd) it was possible to define the complexation site on nitrogen atom. The large set of spectral parameters: chemical shifts, homo- and heteronuclear coupling constants, were used in structure study.

Ko?odziej, B.; Grech, E.; Schilf, W.; Kamie?ski, B.; Pazio, A.; Wo?niak, K.

2014-04-01

67

Synthesis, characterization and the interaction of some new water-soluble metal Schiff base complexes with human serum albumin.  

PubMed

Some new water-soluble Schiff base complexes of Na2[M(L)(H2O)n]; (M=Zn, Cu, Ni, Mn) with a new water-soluble Schiff base ligand where L denotes an asymmetric N2O2 Schiff base ligands; N,N'-bis(5-sulfosalicyliden)-3,4-diaminobenzophenone (5-SO3-3,4-salbenz) were synthesized and characterized. The formation constants of the water soluble Schiff base complexes were calculated by Ketelaar's equation. The theoretical molecular structure for the complexes was computed by using the HF method and the 6-311G basis set. The mechanism of binding of Na2[M(L)(H2O)n] with human serum albumin (HSA) was studied by fluorescence spectroscopic technique. The results of fluorescence titration showed that the intrinsic fluorescence of HSA was quenched by the complexes; which was rationalized in terms of the dynamic quenching mechanism. The values of Stern-Volmer constants, quenching rate constants, binding constants, binding sites and average aggregation number of HSA have been determined. The thermodynamic parameters, were calculated by van't Hoff equation, indicate that the binding is entropy driven and enthalpically disfavored. Based on the Frster theory of non-radiation energy transfer, the efficiency of energy transfer and the distance between the donor (Trp residues) and the acceptor (complex) were obtained. Finally, the growth inhibitory effects of the complexes toward the K562 cancer cell line were measured. PMID:24299984

Asadi, Mozaffar; Asadi, Zahra; Sadi, Somaye Barzegar; Zarei, Leila; Baigi, Fatemeh Moosavi; Amirghofran, Zahra

2014-03-25

68

Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands  

PubMed Central

Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultravioletvisible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms. PMID:24070648

Abou-Hussein, Azza A.; Linert, Wolfgang

2014-01-01

69

Self-assembly of a 15-nickel metallamacrocyclic complex derived from the L-glutamic acid Schiff base ligand.  

PubMed

An intriguing 15-nickel metallamacrocyclic complex, [Ni15(EVan)10(H2O)20], (EVan = Schiff base formed between l-glutamic acid and o-vanillin), has been synthesized and characterized by single-crystal X-ray diffraction and spectroscopic analyses. adopts a Ni-O-Ni-O-Ni-O configuration and can be divided into five discrete trinuclear units. PMID:24615170

Thio, Yude; Toh, Shi Wei; Xue, Feng; Vittal, Jagadese J

2014-04-28

70

Synthesis, spectroscopic, antimicrobial, DNA binding and cleavage studies of some metal complexes involving symmetrical bidentate N, N donor Schiff base ligand.  

PubMed

The Schiff base ligand, N,N'-bis-(4-isopropylbenzaldimine)-1,2-diaminoethane (L), obtained by the condensation of 4-isopropylbenzaldehyde and 1,2-diaminoethane, has been used to synthesize the complexes of the type [ML(2)X(2)] [M = Co(II), Ni(II) and Zn(II); X = Cl and OAc]. The newly synthesized ligand (L) and its complexes have been characterized on the basis of elemental analyses, mass, (1)H and (13)C-NMR, molar conductance, IR, UV-vis, magnetic moment, CV and thermal analyses, powder XRD and SEM. IR spectral data show that the ligand is coordinated to the metal ions in a bidentate manner. The geometrical structures of these complexes are found to be octahedral. Interestingly, reaction with Cu(II) ion with this ligand undergoes hydrolytic cleavage to form ethylenediamine copper(II) complex and the corresponding aldehyde. The antimicrobial results indicate that the chloro complexes exhibit more activity than the acetato complexes. The complexes bind to CT-DNA by intercalation modes. Novel chloroform soluble ZnL(2)Cl(2) complex exhibits tremendous antimicrobial, DNA binding and cleaving properties. PMID:21855399

Arish, D; Nair, M Sivasankaran

2011-11-01

71

A novel 1D chain of azido bridged copper(II) with a salen-type di-Schiff base ligand  

NASA Astrophysics Data System (ADS)

One new complex of Cu(II), [(CuL)2Cu3(N3)6]n (1) has been synthesized by reacting the "ligand complex", [CuL] with copper acetate and sodium azide (NaN3) in methanol-water where the di-Schiff base ligand H2L = N,N'-bis(?-methylsalicylidene)-1,3-propanediamine. The X-ray single crystal structural analysis shows that complex 1 consists of an incomplete face-sharing double cube of four Cu(II) ions with the formula of [(CuL)2Cu2(N3)2]2+ which are connected by [Cu(N3)4]2- unit to form a novel 1D chain.

Biswas, Saptarshi; Ghosh, Ashutosh

2012-07-01

72

Modulation of amyloid-? aggregation by histidine-coordinating Cobalt(III) Schiff base complexes.  

PubMed

Oligomers of the A?42 peptide are significant neurotoxins linked to Alzheimer's disease (AD). Histidine (His) residues present at the N terminus of A?42 are believed to influence toxicity by either serving as metal-ion binding sites (which promote oligomerization and oxidative damage) or facilitating synaptic binding. Transition metal complexes that bind to these residues and modulate A? toxicity have emerged as therapeutic candidates. Cobalt(III) Schiff base complexes (Co-sb) were evaluated for their ability to interact with A? peptides. HPLC-MS, NMR, fluorescence, and DFT studies demonstrated that Co-sb complexes could interact with the His residues in a truncated A?16 peptide representing the A?42 N terminus. Coordination of Co-sb complexes altered the structure of A?42 peptides and promoted the formation of large soluble oligomers. Interestingly, this structural perturbation of A? correlated to reduced synaptic binding to hippocampal neurons. These results demonstrate the promise of Co-sb complexes in anti-AD therapeutic approaches. PMID:24961930

Heffern, Marie C; Velasco, Pauline T; Matosziuk, Lauren M; Coomes, Joseph L; Karras, Constantine; Ratner, Mark A; Klein, William L; Eckermann, Amanda L; Meade, Thomas J

2014-07-21

73

Synthesis, molecular structure, and properties of a neutral Schiff base phenolic complex of magnesium  

SciTech Connect

Multidrug resistance (MDR) in cancer mediated by the MDR1 P-glycoprotein (Pgp), a 140--180 kDa plasma membrane protein, renders chemotherapeutic treatment ineffective by pumping a variety of natural product cytotoxic agents and xenobiotic compounds out of cancer cells. Pgp has been a major target for synthesis and development of both therapeutic antagonists that block its transport function and diagnostic radiopharmaceuticals that are transported by the protein for use in functional imaging of Pgp transport activity in tumors in vivo. Most, but not all, compounds that interact with Pgp are hydrophobic and cationic at physiological pH. To further understand the Pgp targeting properties, the authors sought to directly evaluate the effect of charge of the complex on Pgp interactions. This could be done by comparing the cytotoxicity profile of a neutral complex to that of an identical, but positively charged, complex in both drug-sensitive and multidrug-resistant cancer cells. Thus, a neutral analogue of the Ga(III) and Fe(III) complexes was desired. Herein the authors describe the synthesis and structure of a novel neutral Schiff base Mg complex and evaluate its cytotoxic potency in human drug-sensitive KB-3-1 and multi-drug-resistant KB-8-5 tumor cells.

Polyakov, V.R.; Sharma, V.; Crankshaw, C.L.; Piwnica-Worms, D. [Washington University Medical School, St. Louis, MO (United States)] [Washington University Medical School, St. Louis, MO (United States)

1998-09-07

74

Syntheses, characterization, biological activities and photophysical properties of lanthanides complexes with a tetradentate Schiff base ligand  

NASA Astrophysics Data System (ADS)

A tetradentate Schiff base ligand L (N,N'-bis(1-naphthaldimine)-o-phenylenediamine) was prepared from the condensation of 2-hydroxy-1-naphthaldehyde with o-phenylenediamine in a molar ratio of 2:1. New eight lanthanide metal complexes [Ln L(NO 3) 2(H 2O) x](NO 3) {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, x = 0 for Nd, Sm, 1 for La, Gd, Pr, Nd, Dy, and 2 for Tb} were prepared. The characterization and nature of bonding of these complexes were elucidated by elemental analysis, spectral analysis ( 1H NMR, FT-IR, UV-vis), molar conductivity measurements, luminescence spectra and thermogravimetric studies. Analytical and spectral data revealed that the ligand L coordinates to the central Ln(III) ions by its two imine nitrogen atoms and two phenolic oxygen atoms with 1:1 stoichiometry. Under the excitation with 329 nm at room temperature, Tb and Dy complexes exhibited characteristic luminescence of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of Ln(III) complexes found to exhibit antibacterial activities against a number of pathogenic bacteria. We found that the antioxident activity of Ln(III) complexes on DPPH rad is concentration dependent and higher than that of the free ligand L.

Taha, Ziyad A.; Ajlouni, Abdulaziz M.; Al Momani, Waleed; Al-Ghzawi, Abeer A.

2011-10-01

75

Syntheses, characterization, biological activities and photophysical properties of lanthanides complexes with a tetradentate Schiff base ligand.  

PubMed

A tetradentate Schiff base ligand L (N,N'-bis(1-naphthaldimine)-o-phenylenediamine) was prepared from the condensation of 2-hydroxy-1-naphthaldehyde with o-phenylenediamine in a molar ratio of 2:1. New eight lanthanide metal complexes [LnL(NO(3))(2)(H(2)O)(x)](NO(3)) {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, x = 0 for Nd, Sm, 1 for La, Gd, Pr, Nd, Dy, and 2 for Tb} were prepared. The characterization and nature of bonding of these complexes were elucidated by elemental analysis, spectral analysis ((1)H NMR, FT-IR, UV-vis), molar conductivity measurements, luminescence spectra and thermogravimetric studies. Analytical and spectral data revealed that the ligand L coordinates to the central Ln(III) ions by its two imine nitrogen atoms and two phenolic oxygen atoms with 1:1 stoichiometry. Under the excitation with 329 nm at room temperature, Tb and Dy complexes exhibited characteristic luminescence of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of Ln(III) complexes found to exhibit antibacterial activities against a number of pathogenic bacteria. We found that the antioxident activity of Ln(III) complexes on DPPH() is concentration dependent and higher than that of the free ligand L. PMID:21764359

Taha, Ziyad A; Ajlouni, Abdulaziz M; Al Momani, Waleed; Al-Ghzawi, Abeer A

2011-10-15

76

Exploring DNA binding and nucleolytic activity of few 4-aminoantipyrine based amino acid Schiff base complexes: a comparative approach.  

PubMed

A series of novel Co(II), Cu(II), Ni(II) and Zn(II) complexes were synthesized from Schiff base(s), obtained by the condensation of 4-aminoantipyrine with furfural and amino acid (glycine(L1)/alanine(L2)/valine(L3)) and respective metal(II) chloride. Their structural features and other properties were explored from the analytical and spectral methods. The binding behaviors of the complexes to calf thymus DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The intrinsic binding constants for the above synthesized complexes are found to be in the order of 10(2) to 10(5) indicating that most of the synthesized complexes are good intercalators. The binding constant values (Kb) clearly indicate that valine Schiff-base complexes have more intercalating ability than alanine and glycine Schiff-base complexes. The results indicate that the complexes bind to DNA through intercalation and act as efficient cleaving agents. The in vitro antibacterial and antifungal assay indicates that these complexes are good antimicrobial agents against various pathogens. The IC50 values of [Ni(L1)2] and [Zn(L1)2] complexes imply that these complexes have preferable ability to scavenge hydroxyl radical. PMID:24566120

Raman, N; Sakthivel, A; Pravin, N

2014-05-01

77

Metal (II) Complexes Derived from Naphthofuran-2-carbohydrazide and Diacetylmonoxime Schiff Base: Synthesis, Spectroscopic, Electrochemical, and Biological Investigation  

PubMed Central

A new Schiff base and a new series of Co(II), Ni(II), Cu(II), Cd(II), and Hg(II) complexes were synthesized by the condensation of naphthofuran-2-carbohydrazide and diacetylmonoxime. Metal complexes of the Schiff base were prepared from their chloride salts of Co(II), Ni(II), Cu(II), Cd(II), and Hg(II) in ethanol. The ligand along with its metal complexes have been characterized on the basis of analytical data, IR, electronic, mass, 1HNMR, ESR spectral data, thermal studies, magnetic susceptibility, and molar conductance measurements. The nonelectrolytic behaviour of the complexes was assessed from the measured low conductance data. The elemental analysis of the complexes confirm the stoichiometry of the type CuL2Cl2 and MLCl2 where M = Ni(II), Co(II), Cd(II), and Hg(II) and L = Schiff base. The redox property of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. In the light of these results, Co(II), Ni(II), and Cu(II) complexes are assigned octahedral geometry, Cd(II), and Hg(II) complexes tetrahedral geometry. In order to evaluate the effect of metal ions upon chelation, both the ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleaving capacity of all the complexes was analysed by agarose gel electrophoresis method. PMID:24592203

Sumathi, R. B.; Halli, M. B.

2014-01-01

78

Mixed (phthalocyaninato)(Schiff-base) di-dysprosium sandwich complexes. Effect of magnetic coupling on the SMM behavior.  

PubMed

Reaction between Schiff-base ligand and half-sandwich complex M(Pc)(acac) led to the isolation of new sandwich-type mixed (phthalocyaninato)(Schiff-base) di-lanthanide compounds M2(Pc)2(L)H2O (M = Dy, Gd) (1, 2) [H2Pc = metal free phthalocyanine, Hacac = acetylacetone, H2L = N,N'-bis(3-methyloxysalicylidene)benzene-1,2-diamine] with the triple-decker molecular structure clearly revealed by single crystal X-ray diffraction analysis. For the comparative studies, sandwich triple-decker analogues with pure Schiff-base ligand M2(L)3H2O (M = Dy, Gd) (3, 4) were also prepared. Dynamic magnetic measurement result reveals the single-molecule magnet (SMM) nature of the di-dysprosium derivative 1, while the static magnetic investigation over both pure and the diamagnetic diluted samples of this compound discloses the interionic ferromagnetic coupling between the two dysprosium ions, which in turn effectively suppresses the QTM and enhances the energy barrier of this SMM. Nevertheless, comparative studies over the static magnetic properties of the di-dysprosium triple-decker complexes 1 and 3 indicate the stronger magnetic coupling between the two lanthanide ions in mixed (phthalocyaninato)(Schiff-base) species than in the pure Schiff-base triple-decker analogue, suggesting the special coordination sphere around the dysprosium ions in the former compound over the latter one on the more intense inter-ionic ferromagnetic coupling. As a very small step towards understanding the structure-property relationship, the present result will be surely helpful for the design and synthesis of the multinuclear lanthanide-based SMMs with good properties. PMID:24005576

Wang, Hailong; Liu, Chenxi; Liu, Tao; Zeng, Suyuan; Cao, Wei; Ma, Qi; Duan, Chunying; Dou, Jianmin; Jiang, Jianzhuang

2013-11-21

79

Mononuclear and tetranuclear Fe(III) complexes with two different types of N, O donor Schiff base ligands  

NASA Astrophysics Data System (ADS)

A mononuclear Fe(III) complex of a tetradentate N2O2 donor Schiff base ligand derived from 3-ethoxysalicaldehyde and ethylenediamine has been reported. In addition two tetranuclear Fe(III) complexes with discrete Fe4III(?4-O) cores have been synthesized and characterized using two Schiff base ligands (H2L1-2) derived from two different aromatic acid hydrazides and diacetyl monoxime. The mononuclear Fe(III) and one of the tetranuclear Fe(III) complexes have been structurally characterized by single-crystal X-ray crystallography. The mononuclear complex has a highly distorted octahedral geometry. The tetranuclear Fe(III) complexes are found to be rare examples with discrete neutral alkoxido-oxido clusters with Fe4III(?4-O) cores.

Sutradhar, Manas; Roy Barman, Tannistha; Drew, Michael G. B.; Rentschler, Eva

2013-06-01

80

Synthesis, Spectral, and In Vitro Antibacterial Studies of Organosilicon(IV) Complexes with Schiff Bases Derived from Amino Acids  

PubMed Central

The present work stems from our interest in the synthesis, characterization, and antibacterial evaluation of organosilicon(IV) complexes of a class of amino-acid-based Schiff base which have been prepared by the interaction of ethoxytrimethylsilane with the Schiff bases (N OH) in 1?:?1 molar ratio. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including electronic IR and NMR (1H, 13C, and 29Si) spectroscopy. The analytical and spectral data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Bacillus cereus, Nocardia spp., E. aerogenes, Escherichia coli, Klebsiella spp., and Staphylococcus spp.). The complexes were found to be more potent as compared to the ligands. PMID:23983671

Singh, Har Lal; Singh, Jangbhadur; Mukherjee, A.

2013-01-01

81

Self-assembled nanostructures of specially designed Schiff-bases and their zinc complexes: Preparation, characterization and photoluminescence property  

NASA Astrophysics Data System (ADS)

Four specially designed Schiff bases 2-formyl-4-R-6-(3N-4-hydroxybenzoicacid)-iminomethyl-phenolato (where R = methyl/tert-butyl/chloro for L1, L2, L3 respectively) and 2-(3N-4-hydroxybenzoicacid)-iminomethyl-phenolato (L4) having ability to form hydrogen bonding and their zinc complexes (1-4) have been synthesized and characterized. These complexes gave various types of nano-sized materials via self-assembly in solid state. FE-SEM was employed to investigate their morphology. Using a variety of analytical techniques such as elemental analysis, infrared spectroscopy (FT-IR), ESI-MS and 1H NMR spectroscopy, a consistent picture of structures of these complexes are obtained. All the Schiff-bases and their zinc complexes exhibit photoluminescence property. Density functional theory calculation has been performed to rationalize the origin of the spectral bands of the ligands as well as the complexes.

Guha, Averi; Sanyal, Ria; Chattopadhyay, Tanmay; Han, YounGyu; Mondal, Tapan Kumar; Das, Debasis

2013-06-01

82

Coordination geometry around copper in a Schiff-base trinuclear copper complex using EXAFS spectroscopy  

NASA Astrophysics Data System (ADS)

In the present investigation, we have studied extended X-ray absorption fine structure (EXAFS) spectra of a trinuclear Schiff-base copper complex tetraaqua-di-?3-(N-salicylidene-DL-glutamato)-tricopper(II)heptahydrate, [Cu3(C12H10NO5)2 (H2O)4]. 7H2O, in which three metal sites are present. One metal site is square-pyramidal (4+1) and other two similar metal sites are tetragonally distorted octahedral (4+2). EXAFS has been recorded at the K-edge of copper in the complex at the dispersive EXAFS beamline at 2 GeV Indus-2 synchrotron source at RRCAT, Indore, India. The analysis of EXAFS spectra of multinuclear metal complexes pose some problems due to the presence of many absorbing atoms, even when the absorbing atoms may be of the same element. Hence, using the available crystal structure of the complex, theoretical models have been generated for the different copper sites separately, which are then fitted to the experimental EXAFS data. The two coordination geometries around the copper sites have been determined. The contributions of the different copper sites to the experimental spectrum have been estimated. The structural parameters, which include bond-lengths, coordination numbers and thermal disorders, for the two types of copper sites have been reported. Further, copper has been found to be in +2 oxidation state at these metal sites.

Gaur, Abhijeet; Shrivastava, B. D.; Gaur, D. C.; Prasad, J.; Srivastava, K.; Jha, S. N.; Bhattacharyya, D.; Poswal, A.

2012-05-01

83

Synthesis, characterization, biological and catalytic applications of transition metal complexes derived from Schiff base.  

PubMed

A novel series of Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) complexes have been synthesized from the Schiff base. Structural features were determined by analytical and spectral techniques like IR, (1)H NMR, UV-vis, elemental analysis, molar electric conductibility, magnetic susceptibility and thermal studies. The complexes are found to be soluble in dimethylformamide and dimethylsulfoxide. Molar conductance values in dimethylformamide indicate the non-electrolytic nature of the complexes. Binding of synthesized complexes with calf thymus DNA (CT DNA) was studied. There is significant binding of DNA in lanes 2, 3, and 5. Lanes 4 and 6 are showing more florescence when compared to the control indicating that these molecules are strongly bound to the DNA by inserting themselves between the two stacked base pairs and exhibiting their original property of fluorescence. Angiogenesis study has revealed that the compounds B-2, B-4 and B-5 have potent antitumor efficacy and activation of antiangiogenesis could be one of the possible underlying mechanisms of tumor inhibition. PMID:24915881

Bushra Begum, A; Rekha, N D; Vasantha Kumar, B C; Lakshmi Ranganatha, V; Khanum, Shaukath Ara

2014-08-01

84

Tetradentate Schiff base ligands and their complexes: Synthesis, structural characterization, thermal, electrochemical and alkane oxidation  

NASA Astrophysics Data System (ADS)

Three Schiff base ligands (H2L1-H2L3) with N2O2 donor sites were synthesized by condensation of 1,5-diaminonapthalene with benzaldehyde derivatives. A series of Cu(II), Co(II), Ni(II), Mn(II) and Cr(III) complexes were prepared and characterized by spectroscopic and analytical methods. Thermal, electrochemical and alkane oxidation reactions of the ligands and their metal complexes were investigated. Extensive application of 1D (1H, 13C NMR) and 2D (COSY, HETCOR, HMBC and TOSCY) NMR techniques were used to characterize the structures of the ligands and establish the 1H and 13C resonance assignments of the three ligands. Ligands H2L1 and H2L3 were obtained as single crystals from THF solution and characterized by X-ray diffraction. Both molecules are centrosymmetric and asymmetric unit contains one half of the molecule. Catalytic alkane oxidation reactions with the transition metal complexes investigated using cyclohexane and cyclooctane as substrates. The Cu(II) and Cr(III) complexes showed good catalytic activity in the oxidation of cyclohexane and cyclooctane to desired oxidized products. Electrochemical and thermal properties of the compounds were also investigated.

Ceyhan, Gkhan; Kse, Muhammet; McKee, Vickie; Uru?, Serhan; Glc, Ay?egl; Tmer, Mehmet

85

Two new heterodinuclear Schiff base complexes: Synthesis, crystal structure and thermal studies  

NASA Astrophysics Data System (ADS)

Two new heterodinuclear Schiff base complexes, [Hg(L)NiCl2(DMF)2] 1, and [Zn(L)NiCl2(DMF)2] 2, where H2L = N,N?-bis(salicylidene)-1,3-diaminopropane and DMF = dimethylformamide have been synthesized and characterized using elemental analysis, IR spectroscopy, thermal analysis and X-ray diffraction. Structural studies on 1 and 2 reveal the presence of a heterodinuclear [NiIIHgII] unit and [ZnIINiII] in which the central metal ions are connected to each other by two phenolate oxygen bridges. For complex 1 the Ni(II) ion adopts an elongated octahedral geometry (NiN2O4) while the Hg(II) ion assumes a distorted tetrahedral arrangement (HgO2Cl2) whereas for complex 2 the Zn(II) ion adopts an elongated octahedral geometry (ZnN2O4) while the Ni(II) ion assumes a distorted tetrahedral arrangement (NiO2Cl2). There are intermolecular Csbnd HClsbnd M interactions among the dinuclear complexes which are interconnected for 1 and 2. These intermolecular interactions result in the formation of a three dimensional structure for 1 and one dimensional zig-zag chains for 2.

Yardan, Alper; Hopa, Cigdem; Yahsi, Yasemin; Karahan, Ahmet; Kara, Hulya; Kurtaran, Raif

2015-02-01

86

Synthesis, characterization and antimicrobial activities of mixed ligand transition metal complexes with isatin monohydrazone Schiff base ligands and heterocyclic nitrogen base  

NASA Astrophysics Data System (ADS)

Mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with various uninegative tridentate ligands derived from isatin monohydrazone with 2-hydroxynapthaldehyde/substituted salicylaldehyde and heterocyclic nitrogen base 8-hydroxyquinoline have been synthesized and characterized by elemental analysis, conductometric studies, magnetic susceptibility and spectroscopic techniques (IR, UV-VIS, NMR, mass and ESR). On the basis of these characterizations, it was revealed that Schiff base ligands existed as monobasic tridentate ONO bonded to metal ion through oxygen of carbonyl group, azomethine nitrogen and deprotonated hydroxyl oxygen and heterocyclic nitrogen base 8-hydroxyquinoline existed as monobasic bidentate ON bonded through oxygen of hydroxyl group and nitrogen of quinoline ring with octahedral or distorted octahedral geometry around metal ion. All the compounds have been tested in vitro against various pathogenic Gram positive bacteria, Gram negative bacteria and fungi using different concentrations (25, 50, 100, 200 ?g/mL) of ligands and their complexes. Comparative study of antimicrobial activity of ligands, and their mixed complexes indicated that complexes exhibit enhanced activity as compared to free ligands and copper(II) Cu(LIV)(Q)?H2O complex was found to be most potent antimicrobial agent.

Devi, Jai; Batra, Nisha

2015-01-01

87

Synthesis, characterization and experimental, theoretical, electrochemical, antioxidant and antibacterial study of a new Schiff base and its complexes.  

PubMed

A new Schiff base ligand was synthesized by reaction of salicylaldehyde with 1,6-bis(4-chloro-2-aminophenoxy)hexane. Then the Schiff base complexes were synthesized by metal salts and the Schiff base. The metal to ligand ratio of metal complexes was found to be 1:1. The Cu(II) complex is proposed to be square planar and the Co(II), Ni(II), Mn(II) and Zn(II) complexes are proposed to be tetrahedral geometry. The Ti(III) and V(III) complexes are proposed to be a capped octahedron in which a seventh ligand has been added to triangular face. The complexes are non-electrolytes as shown by their molar conductivities (?M). The structure of metal complexes is proposed from elemental analysis, FT-IR, UV-vis, magnetic susceptibility measurements, molar conductivity measurements, Mass Spectra and thermal gravimetric analysis. In addition antimicrobial and antioxidant studies, cyclic voltammetry of the complexes, theoretical 1H NMR and HOMO-LUMO energy calculations of the new di-functional ligand were done. PMID:24792202

Baykara, Haci; Ilhan, Salih; Levent, Abdulkadir; Salih Seyitoglu, M; zdemir, Sadin; Okumu?, Veysi; ztomsuk, Abdussamet; Cornejo, Mauricio

2014-09-15

88

Unsymmetrical Schiff base (ON) ligand on complexation with some transition metal ions: Synthesis, spectral characterization, antibacterial, fluorescence and thermal studies  

NASA Astrophysics Data System (ADS)

A series of eight metal Schiff base complexes were synthesized by the thermal reaction of Cu(II), Ni(II), Fe(III), Co(II), Zn(II), Hg(II), La(III) or Sm(III) with a Schiff base "L" produced by the condensation of furfuraldehyde and 1,2-diaminobenzene. These compounds were characterized by elemental analysis, UV-Vis, FT-IR, molar conductance, mass spectrometry, thermal and fluorescence studies. The studies suggested the coordination of the ligand L to metal through azomethine imine nitrogen and furan oxygen atoms of Schiff base moiety. Thermogravimetric (TG/DTG) analyses data were studied and indicated high stability for all complexes and suggested the presence of lattice and/or coordinated water molecules in the complexes. Coats-Redfern method has been used to calculate the kinetic and thermodynamic parameters of the metal complexes. The spectral and thermal analysis reveal that all complexes have octahedral geometry except Cu(II) and Ni(II) complexes which can attain a square planner arrangements. The ligand and its complexes exhibited intraligand (?-??) fluorescence and can potentially serve as photoactive materials. Both the ligand and its complexes have been screened for antibacterial activities.

Ali, Omyma A. M.; El-Medani, Samir M.; Abu Serea, Maha R.; Sayed, Abeer S. S.

2015-02-01

89

DNA interaction with octahedral and square planar Ni(II) complexes of aspartic-acid Schiff-bases  

NASA Astrophysics Data System (ADS)

Ni(II) complexes of (S,E)-2-(2-OHbenzilydene)aspartic acid; (S,E)-2-(2,3-diOHbenzilydene)aspartic acid-; (S,E)-2-(2,4-diOH-benzilydene)aspartic acid; (S,E)-2-(2,5-diOHbenzilydene)aspartic acid and (S,E)-2-((2-OHnaphthalene-1-yl)methylene)aspartic acid Schiff-bases have been synthesized by template method in ethanol or ammonia media. They were characterized by elemental analyses, conductivity measurements, magnetic moment, UV, IR and 1H nmr spectra as well as thermal analysis (TG, DTG, DTA). The Schiff-bases are dibasic tridentate or tetradentate donors and the complexes have square planar and octahedral structures. The complexes decompose in two or three steps where kinetic and thermodynamic parameters of the decomposition steps were computed. The interactions of the formed complexes with FM-DNA were monitored by UV and fluorescence spectroscopy.

Sallam, S. A.; Orabi, A. S.; Abbas, A. M.

2011-12-01

90

Synthesis, characterization and crystal structure of some bidentate heterocyclic Schiff base ligands of 4-toluoyl pyrazolones and its mononuclear Cu(II) complexes  

NASA Astrophysics Data System (ADS)

We depict the synthesis of a new set of six bidentate heterocyclic Schiff base ligands, formed by the condensation of three different 4-toluoyl pyrazolones with various aromatic amines in ethanolic medium. All of these ligands have been characterized on the basis of elemental analysis, IR, 1H NMR, 13C NMR and Mass spectral data. The molecular geometries of three of these ligands have been determined by single crystal X-ray study. It reveals that these ligands exist in amine-one tautomeric form in the solid state. The reaction of these ligands with copper(II) resulted in the formation of mononuclear complexes having the general composition [CuL 2(H 2O) 2] with two water molecules at axial positions. These complexes have been characterized on the basis of elemental analysis, Cu-estimation, molar conductivity, magnetic measurements, IR, UV-Visible, FAB-Mass, TG-DTA-DSC data, cyclic voltametric measurements and ESR spectral studies. ESR spectra and magnetic susceptibility measurements indicates distorted octahedral stereochemistry of Cu(II) complexes, while non-electrolytic behaviour of complexes indicates the absence of counter ion.

Vyas, Komal M.; Jadeja, R. N.; Gupta, Vivek K.; Surati, K. R.

2011-03-01

91

Selective Anion Binding by a Cofacial Binuclear Zinc Complex of a Schiff-Base Pyrrole Macrocycle  

PubMed Central

The synthesis of the new cofacial binuclear zinc complex [Zn2(L)] of a Schiff-base pyrrole macrocycle is reported. It was discovered that the binuclear microenvironment between the two metals of [Zn2(L)] is suited for the encapsulation of anions, leading to the formation of [K(THF)6][Zn2(?-Cl)(L)].2THF and [Bun4N][Zn2(?-OH)(L)] which were characterized by X-ray crystallography. Unusually obtuse Zn-X-Zn angles (X=Cl: 150.54(9) and OH: 157.4(3)) illustrate the weak character of these interactions and the importance of the cleft pre-organization to stabilize the host. In the absence of added anion, aggregation of [Zn2(L)] was inferred and investigated by successive dilutions and by the addition of coordinating solvents to [Zn2(L)] solutions using NMR spectroscopy as well as isothermal microcalorimetry (ITC). On anion addition, evidence for de-aggregation of [Zn2(L)], combined with the formation of the 1:1 host-guest complex, was observed by NMR spectroscopy and ITC titrations. Furthermore, [Zn2(L)] binds to Cl? selectively in THF as deduced from the ITC analyses, while other halides induce only de-aggregation. These conclusions were reinforced by DFT calculations, which indicated that the binding energies of OH? and Cl? were significantly greater than for the other halides. PMID:21391550

Devoille, Aline M. J.; Richardson, Patricia; Bill, Nathan; Sessler, Jonathan L.; Love, Jason B.

2011-01-01

92

Antioxidant, electrochemical, thermal, antimicrobial and alkane oxidation properties of tridentate Schiff base ligands and their metal complexes  

NASA Astrophysics Data System (ADS)

In this study, two Schiff base ligands (HL 1 and HL 2) and their Cu(II), Co(II), Ni(II), Pd(II) and Ru(III) metal complexes were synthesized and characterized by the analytical and spectroscopic methods. Alkane oxidation activities of the metal complexes were studied on cyclohexane as substrate. The ligands and their metal complexes were evaluated for their antimicrobial activity against Corynebacterium xerosis, Bacillus brevis, Bacillus megaterium, Bacillus cereus, Mycobacterium smegmatis, Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis (as Gram-positive bacteria) and Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Yersinia enterocolitica, Klebsiella fragilis, Saccharomyces cerevisiae, and Candida albicans (as Gram-negative bacteria). The antioxidant properties of the Schiff base ligands were evaluated in a series of in vitro tests: 1,1-diphenyl-2-picrylhydrazyl (DPPH rad ) free radical scavenging and reducing power activity of superoxide anion radical generated non-enzymatic systems. Electrochemical and thermal properties of the compounds were investigated.

Ceyhan, Gkhan; elik, Cumali; Uru?, Serhan; Demirta?, ?brahim; Elmasta?, Mahfuz; Tmer, Mehmet

2011-10-01

93

Synthesis and characterization of Schiff base octaazamacrocyclic complexes and their biological studies.  

PubMed

A condensation reaction between 1,2-diphenylethane-1,2-dione dihydrazone (DPEDDH) and dimethyl or diethyloxalate in methanol resulted in a novel Schiff base octaazamacrocyclic ligand, (L): (6,7,14,15-tetraoxa-2,3,10,11-tetraphenyl-1,4,5,8,9,12,13,16-octaazacyclohexadecane-1,3,9,11-tetraene). Subsequently metal complexes of the type [MLX2] and [CuL]X2; (M=Mn(II), Co(II), Ni(II) and Zn(II); X=Cl or NO3) were synthesized by the reaction of the free macrocyclic ligand (L) with the corresponding metal salts in 1:1 molar ratio. These complexes were characterized on the basis of analytical data, molar conductivity and magnetic susceptibility measurements, ESI-mass, IR, NMR ((1)H and (13)C), EPR and electronic spectral studies. The thermal stability of the complexes was also studied by TGA and DTA analyses. These studies show that all the complexes have octahedral arrangement around the metal ions except copper complexes which are square planar. The ligand and its complexes were screened for their antibacterial activity in vitro against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and were also studied for their anticancer activity against the human cancer cells lines: HeLa (Human cervical carcinoma), MCF7 (Human breast adenocarcinoma) and Hep3B (Human Hepatocellular carcinoma). The recorded IC50 values for the tested compounds show moderate to good cytotoxicity against these cancer cell lines. The copper complex, [CuL]Cl2, showed excellent antimicrobial activity against tested microorganisms which is almost equivalent to the standard drug ciprofloxacin. PMID:25490374

Zafar, Hina; Kareem, Abdul; Sherwani, Asif; Mohammad, Owais; Ansari, Mohammad Azam; Khan, Haris M; Khan, Tahir Ali

2014-10-24

94

Spectroscopic, thermal analysis and DFT computational studies of salen-type Schiff base complexes.  

PubMed

A new series of metal(II) complexes of Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) have been synthesized from a salen-type Schiff base ligand derived from o-vanillin and 4-methyl-1,2-phenylenediamine and characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR, (13)C NMR and EI-mass), molar conductance measurements and thermal analysis techniques. Coats-Redfern method has been utilized to calculate the kinetic and thermodynamic parameters of the metal complexes. The molecular geometry, Mulliken atomic charges of the studied compounds were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The theoretical (13)C chemical shift results of the studied compounds have been calculated at the B3LYP, PBEPBE and PW91PW91 methods and standard 6-311+G(d,p) basis set starting from optimized geometry. The comparison of the results indicates that B3LYP/6-311+G(d,p) yields good agreement with the observed chemical shifts. The measured low molar conductance values in DMF indicate that the metal complexes are non-electrolytes. The spectral and thermal analysis reveals that all complexes have octahedral geometry except Cu(II) complex which can attain the square planner arrangement. The presence of lattice and coordinated water molecules are indicated by thermograms of the complexes. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps. PMID:24021948

Ebrahimi, Hossein Pasha; Hadi, Jabbar S; Abdulnabi, Zuhair A; Bolandnazar, Zeinab

2014-01-01

95

Spectroscopic, thermal analysis and DFT computational studies of salen-type Schiff base complexes  

NASA Astrophysics Data System (ADS)

A new series of metal(II) complexes of Co(II), Ni(II), Cu(II), Zn(II), and Pb(II) have been synthesized from a salen-type Schiff base ligand derived from o-vanillin and 4-methyl-1,2-phenylenediamine and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, 13C NMR and EI-mass), molar conductance measurements and thermal analysis techniques. Coats-Redfern method has been utilized to calculate the kinetic and thermodynamic parameters of the metal complexes. The molecular geometry, Mulliken atomic charges of the studied compounds were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The theoretical 13C chemical shift results of the studied compounds have been calculated at the B3LYP, PBEPBE and PW91PW91 methods and standard 6-311+G(d,p) basis set starting from optimized geometry. The comparison of the results indicates that B3LYP/6-311+G(d,p) yields good agreement with the observed chemical shifts. The measured low molar conductance values in DMF indicate that the metal complexes are non-electrolytes. The spectral and thermal analysis reveals that all complexes have octahedral geometry except Cu(II) complex which can attain the square planner arrangement. The presence of lattice and coordinated water molecules are indicated by thermograms of the complexes. The thermogravimetric (TG/DTG) analyses confirm high stability for all complexes followed by thermal decomposition in different steps.

Ebrahimi, Hossein Pasha; Hadi, Jabbar S.; Abdulnabi, Zuhair A.; Bolandnazar, Zeinab

2014-01-01

96

Synthesis and characterization of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of chromone based azo-linked Schiff base ligand  

NASA Astrophysics Data System (ADS)

Azo-Schiff-base complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized and characterized by elemental analysis, IR, UV-Vis, 1H NMR, mass spectra, molar conductance, magnetic susceptibility measurement, electron spin resonance (EPR), CV, fluorescence, NLO and SEM. The conductance data indicate the nonelectrolytic nature of the complexes, except VO(II) complex which is electrolytic in nature. On the basis of electronic spectra and magnetic susceptibility octahedral geometry has been proposed for the complexes. The EPR spectra of copper and oxovanadium complexes in DMSO at 300 and 77 K were recorded and its salient features are reported. The redox behavior of the copper(II) complex was studied using cyclic voltammetry. The in vitro antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella enterica typhi, Bacillus subtilis and Candida strains was studied and compared with that of free ligand by well-diffusion technique. The azo Schiff base exhibited fluorescence properties originating from intraligand (?-??) transitions and metal-mediated enhancement is observed on complexation and so the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. On the basis of the optimized structures, the second-order nonlinear optical properties (NLO) are calculated by using second-harmonic generation (SHG) and also the surface morphology of the complexes was studied by SEM.

Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Johnson Raja, S.

2012-12-01

97

Synthesis, Spectroscopic, Molecular Structure, and Antibacterial Studies of Dibutyltin(IV) Schiff Base Complexes Derived from Phenylalanine, Isoleucine, and Glycine  

PubMed Central

New series of organotin(IV) complexes and Schiff bases derived from amino acids have been designed and synthesized from condensation of 1H-indole-2,3-dione, 5-chloro-1H-indole-2,3-dione, and ?-amino acids (phenylalanine, isoleucine, and glycine). All compounds are characterized by elemental analyses, molar conductance measurements, and molecular weight determinations. Bonding of these complexes is discussed in terms of their UV-visible, infrared, and nuclear magnetic resonance (1H, 13C, and 119Sn NMR) spectral studies. The results suggest that Schiff bases behave as monobasic bidentate ligands and coordinate with dibutyltin(IV) in octahedral geometry according to the general formula [Bu2Sn(L)2]. Elemental analyses and NMR spectral data of the ligands with their dibutyltin(IV) complexes agree with their proposed distorted octahedral structures. Few representative compounds are tested for their in vitro antibacterial activity against Gram-positive (B. cereus, Staphylococcus spp.) and Gram-negative (E. coli, Klebsiella spp.) bacteria. The results show that the dibutyltin complexes are more reactive with respect to their corresponding Schiff base ligands. PMID:25525422

Singh, Har Lal; Singh, Jangbhadur

2014-01-01

98

Synthesis, characterization of complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 12-membered Schiff base tetraazamacrocyclic ligand and the study of their antimicrobial and reducing power  

NASA Astrophysics Data System (ADS)

Schiff base tetraazamacrocyclic ligand, L (C 40H 28N 4) and its complexes of types, [MLX 2] and [CuL]X 2 (M = Co(II), Ni(II), Zn(II); X = Cl -, NO 3-) were synthesized and characterized by elemental analyses, mass, 1H NMR, IR, UV-vis, magnetic susceptibility and molar conductance data. An octahedral geometry has been proposed for all the complexes except the copper(II) complexes which have a square planar environment. The reducing power of the Co(II) and Cu(II) complexes have been checked and compared. The ligand (L) and its complexes have also been screened against different fungi and bacteria in vitro.

Shakir, Mohammad; Azim, Yasser; Chishti, Hamida-Tun-Nisa; Parveen, Shama

2006-10-01

99

Synthesis, structural characterization and magnetic properties of new tripeptide Schiff base heterotrinuclear Cu(II) M(II) Cu(II) (M=Ni and Mn) complexes  

NASA Astrophysics Data System (ADS)

Two novel heterotrinuclear Cu(II)-M(II)-Cu(II) (M=Ni and Mn) complexes, [Ni(H 2O) 4(CuL) 2]7H 2O ( 1), [Mn(H 2O) 4(CuL) 2]8H 2O ( 2), have been obtained by the self-assembly of the mononuclear tripeptide Schiff base complexes [CuL] - with bivalent metal ion M 2+, where H 3L= N-salicylideneglycylglycylglycine. Single crystal X-ray diffraction experiments indicate that the structures both 1 and 2, are made up of centrosymmetric trinuclear units with the M atom lying on an inversion center, formed the 1D supramolecular chain structures via hydrogen bondings and M⋯O weak interactions. The magnetic susceptibility data (2-300 K) revealed antiferromagnetic interactions between copper(II) ions and the central metal. The magnetic susceptibility data were quantitatively analyzed using the theoretical expressions deduced from the spin Hamiltonian for a symmetrical three-spin system H=-2JS(S+S) to give the coupling parameters JCuNi=-0.46 cm -1 and JCuMn=-0.15 cm -1.

Liu, Wen-Long; Zou, Yang; Ni, Chun-Lin; Li, Yi-Zhi; Meng, Qing-Jin

2005-09-01

100

Recent advances in cooperative bimetallic asymmetric catalysis: dinuclear Schiff base complexes.  

PubMed

Cooperative catalysis has proven to be a powerful strategy for realizing high reactivity and selectivity in asymmetric transformations. A variety of cooperative asymmetric catalysts have been developed over the last two decades. In this feature article, recent advances from our research on cooperative asymmetric catalysis, focusing on dinuclear Schiff base catalysis, are described. Design of dinuclear Schiff base catalysts and their applications in several asymmetric C-C and C-N bond-forming reactions under simple proton transfer conditions with perfect atom-economy are discussed in detail. PMID:24281133

Matsunaga, Shigeki; Shibasaki, Masakatsu

2014-02-01

101

Adherence to Brgi-Dunitz stereochemical principles requires significant structural rearrangements in Schiff-base formation: insights from transaldolase complexes.  

PubMed

The Brgi-Dunitz angle (?BD) describes the trajectory of approach of a nucleophile to an electrophile. The adoption of a stereoelectronically favorable ?BD can necessitate significant reactive-group repositioning over the course of bond formation. In the context of enzyme catalysis, interactions with the protein constrain substrate rotation, which could necessitate structural transformations during bond formation. To probe this theoretical framework vis--vis biocatalysis, Schiff-base formation was analysed in Francisella tularensis transaldolase (TAL). Crystal structures of wild-type and Lys?Met mutant TAL in covalent and noncovalent complexes with fructose 6-phosphate and sedoheptulose 7-phosphate clarify the mechanism of catalysis and reveal that substrate keto moieties undergo significant conformational changes during Schiff-base formation. Structural changes compelled by the trajectory considerations discussed here bear relevance to bond formation in a variety of constrained enzymic/engineered systems and can inform the design of covalent therapeutics. PMID:24531488

Light, Samuel H; Minasov, George; Duban, Mark-Eugene; Anderson, Wayne F

2014-02-01

102

Spectral, magnetic, biocidal screening, DNA binding and photocleavage studies of mononuclear Cu(II) and Zn(II) metal complexes of tricoordinate heterocyclic Schiff base ligands of pyrazolone and semicarbazide/thiosemicarbazide based derivatives  

NASA Astrophysics Data System (ADS)

We depict the synthesis and characterization of copper(II) and zinc(II) coordination compounds of 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-semicarbazone ( 1a), 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone ( 1b), 4-(3'-hydroxy-4'-nitrobenzaldehydene)2-3-dimeth yl-1-phenyl-3-pyrazolin-5-semicarbazone ( 1c) and 4-(3'-hydroxy-4'-nitrobenzal dehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone ( 1d). All the remote compounds have the general composition [ML 2] (M = Cu(II) and Zn(II)); L = Schiff base ( 1a- 1d). All the complexes were characterized by elemental analysis, molar conductivity, IR, 1H NMR, UV-vis, ESI-Mass, magnetic susceptibility measurements, cyclic voltammetric measurements, and EPR spectral studies. It has been originated that the Schiff bases with Cu(II) and Zn(II) ions form mononuclear complexes on 1:2 (metal:ligand) stoichiometry. Distorted octahedral environment is suggested for the metal complexes. The conductivity data confirm the non-electrolytic nature of the complexes. The interaction of CuL 21a- 1d complexes with CT DNA was investigated by spectroscopic, electrochemical and viscosity measurements. Results suggest that the copper complexes bind to DNA via an intercalative mode. Moreover, the complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. The Schiff bases and their metal complexes were screened for their antifungal and antibacterial activities against different species of pathogenic fungi and bacteria and their biopotency has been discussed.

Raman, N.; Selvan, A.; Manisankar, P.

2010-07-01

103

Reactivity of rhenium(V) oxo Schiff base complexes with phosphine ligands: rearrangement and reduction reactions.  

PubMed

The symmetric rhenium(V) oxo Schiff base complexes trans-[ReO(OH2)(acac2en)]Cl and trans-[ReOCl(acac2pn)], where acac2en and acac2pn are the tetradentate Schiff base ligands N,N'-ethylenebis(acetylacetone) diimine and N,N'-propylenebis(acetylacetone) diimine, respectively, were reacted with monodentate phosphine ligands to yield one of two unique cationic phosphine complexes depending on the ligand backbone length (en vs pn) and the identity of the phosphine ligand. Reduction of the Re(V) oxo core to Re(III) resulted on reaction of trans-[ReO(OH2)(acac2en)]Cl with triphenylphosphine or diethylphenylphosphine to yield a single reduced, disubstituted product of the general type trans-[Re(III)(PR3)2(acac2en)]+. Rather unexpectedly, a similar reaction with the stronger reducing agent triethylphosphine yielded the intramolecularly rearranged, asymmetric cis-[Re(V)O(PEt3)(acac2en)]+ complex. Reactions of trans-[Re(V)O(acac2pn)Cl] with the same phosphine ligands yielded only the rearranged asymmetric cis-[Re(V)O(PR3)(acac2pn)]+ complexes in quantitative yield. The compounds were characterized using standard spectroscopic methods, elemental analyses, cyclic voltammetry, and single-crystal X-ray diffraction. The crystallographic data for the structures reported are as follows: trans-[Re(III)(PPh3)2(acac2en)]PF6 (H48C48N2O2P2Re.PF6), 1, triclinic (P), a = 18.8261(12) A, b = 16.2517(10) A, c = 15.4556(10) A, alpha = 95.522(1) degrees , beta = 97.130(1) degrees , gamma = 91.350(1) degrees , V = 4667.4(5) A(3), Z = 4; trans-[Re(III)(PEt2Ph)2(acac2en)]PF6 (H48C32N2O2P2Re.PF6), 2, orthorhombic (Pccn), a = 10.4753(6) A, b =18.4315(10) A, c = 18.9245(11) A, V = 3653.9(4) A3, Z = 4; cis-[Re(V)O(PEt3)(acac2en)]PF6 (H33C18N2O3PRe.1.25PF6, 3, monoclinic (C2/c), a = 39.8194(15) A, b = 13.6187(5) A, c = 20.1777(8) A, beta = 107.7730(10) degrees , V = 10419.9(7) A3, Z = 16; cis-[Re(V)O(PPh3)(acac2pn)]PF6 (H35C31N2O3PRe.PF6), 4, triclinic (P), a = 10.3094(10) A, b =12.1196(12) A, c = 14.8146(15) A, alpha = 105.939(2) degrees , beta = 105.383(2) degrees , gamma = 93.525(2) degrees , V = 1698.0(3) A3, Z = 2; cis-[Re(V)O(PEt2Ph)(acac2pn)]PF6 (H35C23N2O3PRe.PF6), 5, monoclinic (P2(1)/n), a = 18.1183(18) A, b = 11.580(1) A, c = 28.519(3) A, beta = 101.861(2) degrees , V = 5855.9(10) A(3), Z = 4. PMID:15792474

Benny, Paul D; Green, Jenny L; Engelbrecht, Hendrik P; Barnes, Charles L; Jurisson, Silvia S

2005-04-01

104

Surfactant-copper(II) Schiff base complexes: synthesis, structural investigation, DNA interaction, docking studies, and cytotoxic activity.  

PubMed

A series of surfactant-copper(II) Schiff base complexes (1-6) of the general formula, [Cu(sal-R2)2] and [Cu(5-OMe-sal-R2)2], {where, sal?=?salicylaldehyde, 5-OMe-sal?=?5-methoxy- salicylaldehyde, and R2?=?dodecylamine (DA), tetradecylamine (TA), or cetylamine (CA)} have been synthesized and characterized by spectroscopic, ESI-MS, and elemental analysis methods. For a special reason, the structure of one of the complexes (2) was resolved by single crystal X-ray diffraction analysis and it indicates the presence of a distorted square-planar geometry in the complex. Analysis of the binding of these complexes with DNA has been carried out adapting UV-visible-, fluorescence-, as well as circular dichroism spectroscopic methods and viscosity experiments. The results indicate that the complexes bind via minor groove mode involving the hydrophobic surfactant chain. Increase in the length of the aliphatic chain of the ligands facilitates the binding. Further, molecular docking calculations have been performed to understand the nature as well as order of binding of these complexes with DNA. This docking analysis also suggested that the complexes interact with DNA through the alkyl chain present in the Schiff base ligands via the minor groove. In addition, the cytotoxic property of the surfactant-copper(II) Schiff base complexes have been studied against a breast cancer cell line. All six complexes reduced the visibility of the cells but complexes 2, 3, 5, and 6 brought about this effect at fairly low concentrations. Analyzed further, but a small percentage of cells succumbed to necrosis. Of these complexes (6) proved to be the most efficient aptotoxic agent. PMID:24854148

Lakshmipraba, Jagadeesan; Arunachalam, Sankaralingam; Solomon, Rajadurai Vijay; Venuvanalingam, Ponnambalam; Riyasdeen, Anvarbatcha; Dhivya, Rajakumar; Akbarsha, Mohammad Abdulkader

2015-04-01

105

Selective coordination ability of sulfamethazine Schiff-base ligand towards copper(II): molecular structures, spectral and SAR study.  

PubMed

In the present work, a combined experimental and theoretical study of the N-(4,6-Dimethyl-pyrimidin-2-yl)-4-[(2-hydroxy-benzylidene)amino]benzenesulfonamide ligand (H2L) and its mononuclear and magnetically diluted binuclear Cu(II) complexes has been performed using IR, TG/DTA, magnetic, EPR, and conductivity measurements. Calculated g-tensor values showed best agreement with experimental values from EPR when carried out using the MPW1PW91 functional. Coordination of H2L to a Cu(II) center, regardless of the binding site and Cu:L stoichiometry, leads to a significant decrease in the antibacterial activity compared to the free ligand as well as reference drugs in the case of Staphylococcus aureus. Structural-activity relationship suggests that ELUMO, ?E, dipole moment, polarizability and electrophilicity index were the most significant descriptors for the correlation with the antibacterial activity. PMID:24398469

Mansour, Ahmed M

2014-04-01

106

Cadmium(II) complexes of fully condensed Schiff-base ligands derived from two different symmetrical and asymmetrical tripodal tetraamines and 2-acetylpyridine; the novel observations for heptadentate mono-capped trigonal antiprismatic Schiff-base complexes  

Microsoft Academic Search

In the presence of cadmium(II), 2-acetylpyridine condenses with tris(3-aminopropyl)amine, tpt, and bis(3-aminopropyl)(2-aminoethyl)amine, ppe, in absolute methanol to produce two fully condensed potentially heptadentate Schiff-base complexes, [Cd(py3tpt)](ClO4)2 and [Cd(py3ppe)](ClO4)2. X-ray structure analysis of the former complex shows mono-capped distorted trigonal antiprism geometry wherein the Cd?unique nitrogen distance is 2.486 . In comparison with the weighted mean of other Cd?N distances, 2.425

Hassan Keypour; Sadegh Salehzadeh; Robin G. Pritchard; R. V. Parish

2000-01-01

107

NH-type of chiral Ni(II) complexes of glycine Schiff base: design, structural evaluation, reactivity and synthetic applications.  

PubMed

The work being reported here deals with the design of a new type of "N-H" Ni(II) complexes of glycine Schiff bases and study general aspects of their reactivity. It was confirmed that the presence of NH function in these Ni(II) complexes does not interfere with the homologation of the glycine residue, rendering these derivatives of high synthetic value for the general synthesis of ?-amino acids. In particular, the practical application of these NH-type complexes was demonstrated by asymmetric synthesis of various ?-substituted pyroglutamic acids via Michael addition reactions with chiral Michael acceptors. PMID:24424805

Bergagnini, Mackenzie; Fukushi, Kazunobu; Han, Jianlin; Shibata, Norio; Roussel, Christian; Ellis, Trevor K; Acea, Jos Luis; Soloshonok, Vadim A

2014-02-28

108

Structurally diverse copper complexes bearing NNO-tridentate Schiff-base derivatives as efficient catalysts for copolymerization of carbon dioxide and cyclohexene oxide.  

PubMed

Structurally diverse copper acetate complexes based on NNO-tridentate Schiff-base ligands were synthesized and characterized as mono-, di-, and trinuclear complexes with respect to varied ancillary ligands. Treatment of the ligand precursors (L(1)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-4-methylphenol, L(2)-H = 4-chloro-2-(1-((2-(dimethylamino)ethyl)imino)ethyl)phenol, and L(3)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methylphenol) with Cu(OAc)2H2O (1 equiv) in refluxing ethanol afforded five-coordinate mono- or bimetallic copper complexes ([(L(1))Cu(OAc)(H2O)] (1); [(L(2))Cu(OAc)(H2O)] (2); [(L(3))2Cu2(OAc)2] (3)) in high yields. Dinuclear copper acetate analogue [(L(1))2Cu2(OAc)2] (4) resulted from treatment of L(1)-H as the ligand precursor in refluxing anhydrous MeOH with equimolar proportions of metal acetate salt under a dry nitrogen atmosphere. However, a trinuclear complex, [(L(4))2Cu3(OAc)4] (5), was obtained on utilizing 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methoxyphenol (L(4)-H) as the proligand under the same synthetic route of 1-3; this complex was also synthesized in the reaction of L(4)-H and copper(II) acetate monohydrate in the ratio of 2:3, giving a quantitative yield. All complexes are active catalysts for copolymerization of cyclohexene oxide (CHO) and CO2 without cocatalysts. In particular, dinuclear Cu complex 3 performed satisfactorily to produce polycarbonates with controllable molecular weights and high carbonate linkages. These copper complexes are the first examples that are effective for both CO2/CHO copolymerization and formation of polymers in a controlled fashion. PMID:24802071

Tsai, Chen-Yen; Huang, Bor-Hunn; Hsiao, Mon-Wei; Lin, Chu-Chieh; Ko, Bao-Tsan

2014-05-19

109

Immobilization of cobalt(III) Schiff base complexes onto Montmorillonite-K10: Synthesis, experimental and theoretical structural determination  

NASA Astrophysics Data System (ADS)

The [Co(naphophen)(PPh3)(OH2)]ClO4 and [Co(naphophen)(PBu3)(OH2)]BF4 (where naphophen = bis(naphthaldehyde)1,2-phenylenediimine) complexes were synthesized and chracterized by FT-IR, UV-Vis, 1H NMR, 13C NMR spectroscopy and elemental analysis techniques. The coordination geometry of the synthesized complexes were determined by X-ray crystallography. Cobalt (III) complexes have six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base forms the equatorial plane. These complexes showed a dimeric structure via hydrogen bonding between the phenolate oxygen and the hydrogens of the coordinated H2O molecule. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The synthesized complexes were incorporated onto the Montmorillonite-K10 nanoclay via simple ion-exchange reaction. The structure and morphology of the obtained nanohybrids were identified by FT-IR, XRD, TGA/DTA, SEM and TEM techniques. Based on the XRD results of the new nanohybrid materials, the Schiff base complexes were intercalated in the interlayer spaces of clay. SEM and TEM micrographs of the clay/complex shows that the resulting hybrid nanomaterials has layer structures.

Kianfar, Ali Hossein; Kamil Mahmood, Wan Ahmad; Dinari, Mohammad; Farrokhpour, Hossein; Enteshari, Majid; Azarian, Mohammad Hossein

2015-02-01

110

Crystal Structures of Type I Dehydroquinate Dehydratase in Complex with Quinate and Shikimate Suggest a Novel Mechanism of Schiff Base Formation  

PubMed Central

A component of the shikimate biosynthetic pathway, dehydroquinate dehydratase (DHQD) catalyzes the dehydration of 3-dehydroquniate (DHQ) to 3-dehydroshikimate. In the type I DHQD reaction mechanism a lysine forms a Schiff base intermediate with DHQ. The Schiff base acts as an electron sink to facilitate the catalytic dehydration. To address the mechanism of Schiff base formation, we determined structures of the Salmonella enterica wild-type DHQD in complex with the substrate analogue quinate and the product analogue shikimate. In addition, we determined the structure of the K170M mutant (Lys170 being the Schiff base forming residue) in complex with quinate. Combined with nuclear magnetic resonance and isothermal titration calorimetry data that revealed altered binding of the analogue to the K170M mutant, these structures suggest a model of Schiff base formation characterized by the dynamic interplay of opposing forces acting on either side of the substrate. On the side distant from the substrate 3-carbonyl group, closure of the enzymes ?8??8 loop is proposed to guide DHQ into the proximity of the Schiff base-forming Lys170. On the 3-carbonyl side of the substrate, Lys170 sterically alters the position of DHQs reactive ketone, aligning it at an angle conducive for nucleophilic attack. This study of a type I DHQD reveals the interplay between the enzyme and substrate required for the correct orientation of a functional group constrained within a cyclic substrate. PMID:24437575

2015-01-01

111

Crystal structures of type I dehydroquinate dehydratase in complex with quinate and shikimate suggest a novel mechanism of Schiff base formation.  

PubMed

A component of the shikimate biosynthetic pathway, dehydroquinate dehydratase (DHQD) catalyzes the dehydration of 3-dehydroquniate (DHQ) to 3-dehydroshikimate. In the type I DHQD reaction mechanism a lysine forms a Schiff base intermediate with DHQ. The Schiff base acts as an electron sink to facilitate the catalytic dehydration. To address the mechanism of Schiff base formation, we determined structures of the Salmonella enterica wild-type DHQD in complex with the substrate analogue quinate and the product analogue shikimate. In addition, we determined the structure of the K170M mutant (Lys170 being the Schiff base forming residue) in complex with quinate. Combined with nuclear magnetic resonance and isothermal titration calorimetry data that revealed altered binding of the analogue to the K170M mutant, these structures suggest a model of Schiff base formation characterized by the dynamic interplay of opposing forces acting on either side of the substrate. On the side distant from the substrate 3-carbonyl group, closure of the enzyme's ?8-?8 loop is proposed to guide DHQ into the proximity of the Schiff base-forming Lys170. On the 3-carbonyl side of the substrate, Lys170 sterically alters the position of DHQ's reactive ketone, aligning it at an angle conducive for nucleophilic attack. This study of a type I DHQD reveals the interplay between the enzyme and substrate required for the correct orientation of a functional group constrained within a cyclic substrate. PMID:24437575

Light, Samuel H; Antanasijevic, Aleksandar; Krishna, Sankar N; Caffrey, Michael; Anderson, Wayne F; Lavie, Arnon

2014-02-11

112

Synthesis, characterization, and antibacterial activity of new rare-earth ion complexes with unsymmetrical Schiff base ligand  

Microsoft Academic Search

A new unsymmetrical Schiff base ligand (H2LLi) was synthesized using L-lysine, salicylaldehyde, and 2-hydroxy-1-naphthaldehyde. Three rare-earth ion complexes of this\\u000a ligand, [REE(H2L)(NO3)]NO3 ? 2H2O (REE = La, Sm, Ho), have been prepared and characterized by elemental analyses, IR spectra, UV spectra, TG-DTG, and molar conductance. The antibacterial activity of the ligand and its complexes are also studied. The antibacterial experiments

Y. H. Fan; X. T. He; C. F. Bi; F. Guo; Y. Bao; R. Chen

2007-01-01

113

Synthesis, characterization, cytotoxic activities, and DNA-binding properties of the La(III) complex with Naringenin Schiff-base  

Microsoft Academic Search

A new Naringenin Schiff-base ligand (H3L) and its complex, [La(H2L)2(NO3)3H2O], have been synthesized and characterized on the basis of elemental analyses, molar conductivities, mass spectra, 1H NMR, thermogravimetry\\/differential thermal analysis (TGDTA), UV spectra, and IR spectra. Spectrometric titrations, ethidium bromide displacement experiments, and viscosity measurements indicate that the two compounds, especially the La(III) complex, strongly bind with calf-thymus DNA, presumably

Bao-dui Wang; Zheng-Yin Yang; Qin Wang; Ti-kuan Cai; Patrick Crewdson

2006-01-01

114

Affinity to bovine serum albumin and anticancer activity of some new water-soluble metal Schiff base complexes  

NASA Astrophysics Data System (ADS)

Metal Schiff-base complexes show biological activity but they are usually insoluble in water so four new water-soluble metal Schiff base complexes of Na2[M(5-SO3-1,2-salben]; (5-SO3-1,2-salben denoted N,N";-bis(5-sulphosalicyliden)-1,2-diaminobenzylamine and M = Mg, Mn, Cu, Zn) were synthesized and characterized. The formation constants of the metal complexes were determined by UV-Vis absorption spectroscopy. The interaction of these complexes with bovine serum albumin (BSA) was studied by fluorescence spectroscopy. Type of quenching, binding constants, number of binding sites and binding stoichiometries were determined by fluorescence quenching method. The results showed that the mentioned complexes strongly bound to BSA. Thermodynamic parameters indicated that hydrophobic association was the major binding force and that the interaction was entropy driven and enthalpically disfavoured. The displacement experiment showed that these complexes could bind to the subdomain IIA (site I) of albumin. Furthermore the synchronous fluorescence spectra showed that the microenvironment of the tryptophan residues was not apparently changed. Based on the Frster theory of non-radiation energy transfer, the distance between the donor (Trp residues) and the acceptor metal complexes was obtained. The growth inhibitory effect of complexes toward the K562 cancer cell line was measured.

Asadi, Mozaffar; Asadi, Zahra; Zarei, Leila; Sadi, Somaye Barzegar; Amirghofran, Zahra

2014-12-01

115

Spectrophotometric study on the binding of two water soluble Schiff base complexes of Mn(III) with ct-DNA.  

PubMed

In this work, binding of two water soluble Schiff base complexes: Bis sodium (5-sulfosalicylaldehyde) o-phenylendiiminato) Manganese (III) acetate (Salophen complex) and Bis sodium (5-sulfosalicylaldehyde) 1, 2 ethylendiiminato) Manganese (III) acetate (Salen complex) with calf thymus (ct) DNA were investigated by using different spectroscopic and electrometric techniques including UV-vis, Circular dichroism (CD) and fluorescence spectroscopy, viscommetry and cyclic voltammetry (CV). Both complexes have shown a hyperchromic and a small bathochromic shift in the visible region spectra. A competitive binding study showed that the enhanced emission intensity of ethidium bromide (EB) in the presence of DNA was quenched by the addition of the two Schiff base complexes indicating that they displace EB from its binding site in DNA. Moreover structural changes in the CD spectra and an increase in the CV spectra with addition of DNA were observed. The results show that both complexes bind to DNA. The binding constants have been calculated using fluorescence data for two complexes also K(b) was calculated with fluorescence Scatchard plot for Salophen. Ultimately, the experimental results show that the dominant interactions are electrostatic while binding mode is surface binding then followed by hydrophobic interactions in grooves in high concentration of complexes. PMID:21365249

Dehkordi, Maryam Nejat; Bordbar, Abdol-Khlegh; Mehrgardi, Masood Ayatolahi; Mirkhani, Valiolah

2011-07-01

116

Chloroform-soluble schiff-base Zn(II) or Cd(II) complexes from a dynamic combinatorial library.  

PubMed

A dynamic combinatorial library of metal ion Schiff-base complexes have been studied for the extraction of Zn(II) or Cd(II) from aqueous solution into chloroform. Library components consist of different aminophenols and 2-pyridinecarboxaldehyde. Extraction of both Zn(II) and Cd(II) into chloroform was observed from aqueous solutions containing 0.0500 mM M(NO3)2, 0.100 M aminophenol, 0.100 M 2-pyridinecarboxaldehyde, 0.100 M NaCl, and 5.00 mM buffer at pH 8.5. Extraction was dependent on pH but not on counterions including Cl-, Br-, or NO3-. Studies showed that equilibrium was attained between the Schiff-base complexes across the two-phase chloroform-water system after 24 h of stirring. Analysis of the extracted species by use of 1H NMR spectroscopy and mass spectrometry as well as solubility studies on characterized complexes suggested that the major extracted species is the neutral bis-Schiff-base metal ion complex. In libraries containing mixtures of two different aminophenols and 2-pyridinecarboxaldehyde, an enhanced extent of extraction of Zn(II) into chloroform is observed. Studies suggest that a Zn(II) complex, which is likely the mixed Schiff-base complex, has superior extraction properties compared to simple libraries with a single aminophenol component. The structures of two bis-Schiff-base complexes of Zn(II) and one of Cd(II) have been determined by X-ray crystallography. The geometries of the two Zn(II) complexes, which differ only by a methyl substituent on the Schiff-base ligand, are markedly different, supporting the use of combinatorial methods in coordination chemistry. Zn(SB14)2 crystallized as the sesquihydrate (C24H18N4O2Zn.1.5 H2O) in the space group C2/c, with cell dimensions a = 23.219(15) A, b = 11.299(7) A, c = 16.822(11) A, beta = 102.91(5) degrees, V = 4302(5) A3, and Z = 8. Zn(SB15)2 crystallized as a 1:1 methanol solvate (C26H22N4O2Zn.CH3OH) in the space group P2(1)/c with cell dimensions a = 13.981(5) A, b = 7.978(3) A, c = 22.568(8) A, beta = 104.53(3) degrees, V = 2436.8(15) A3, and Z = 4. Cd(SB14)2 crystallized as a 1:1 ethanol solvate (C24H18N4O2Cd.CH3CH2OH) in the space group R3 with unit cell dimensions of a = 36.423(2) A, c = 9.2930(10) A, V = 10678(2) A3, and Z = 18. PMID:11261969

Epstein, D M; Choudhary, S; Churchill, M R; Keil, K M; Eliseev, A V; Morrow, J R

2001-03-26

117

Spectral characterization, electrochemical and anticancer studies on some metal(II) complexes containing tridentate quinoxaline Schiff base.  

PubMed

Co(II), Ni(II), Cu(II) and Zn(II) complexes of a tridentate ONO donor Schiff base ligand derived from 3-(2-aminoethylamino)quinoxalin-2(1H)-one were synthesized. The ligand and its metal complexes were characterized using elemental analysis, molar conductance, IR, (1)H NMR, mass, magnetic susceptibility, electronic spectra and ESR spectral studies. Electrochemical behavior of the synthesized compounds was studied using cyclic voltammetry. The grain size of the synthesized compounds was determined by powder XRD. The Schiff base and its complexes have been screened for their antimicrobial activities against the bacterial species E. coli, K. pneumoniae, P. aeruginosa and S. aureus; fungal species include, A. niger, and C. albicans by disc diffusion method. The results show that the complexes have higher activity than the free ligand. The interaction of the complexes with calf thymus DNA (CT DNA) has been investigated by electronic absorption method. Furthermore, the DNA cleavage activity of the complexes was studied using agarose gel electrophoresis. In vitro anticancer studies of the ligand and its complexes using MTT assay was also done. PMID:24637276

Chellaian, Justin Dhanaraj; Johnson, Jijo

2014-06-01

118

Spectral characterization, electrochemical and anticancer studies on some metal(II) complexes containing tridentate quinoxaline Schiff base  

NASA Astrophysics Data System (ADS)

Co(II), Ni(II), Cu(II) and Zn(II) complexes of a tridentate ONO donor Schiff base ligand derived from 3-(2-aminoethylamino)quinoxalin-2(1H)-one were synthesized. The ligand and its metal complexes were characterized using elemental analysis, molar conductance, IR, 1H NMR, mass, magnetic susceptibility, electronic spectra and ESR spectral studies. Electrochemical behavior of the synthesized compounds was studied using cyclic voltammetry. The grain size of the synthesized compounds was determined by powder XRD. The Schiff base and its complexes have been screened for their antimicrobial activities against the bacterial species E. coli, K. pneumoniae, P. aeruginosa and S. aureus; fungal species include, A. niger, and C. albicans by disc diffusion method. The results show that the complexes have higher activity than the free ligand. The interaction of the complexes with calf thymus DNA (CT DNA) has been investigated by electronic absorption method. Furthermore, the DNA cleavage activity of the complexes was studied using agarose gel electrophoresis. In vitro anticancer studies of the ligand and its complexes using MTT assay was also done.

Chellaian, Justin Dhanaraj; Johnson, Jijo

2014-06-01

119

Preparation and Characterization of Di-, Tri-, and Tetranuclear Schiff Base Complexes Derived from Diamines and 3,4-Dihydroxybenzaldehyde  

PubMed Central

A series of new di-, tri-, and tetranuclear Co(II) and Cu(II) complexes of three new diSchiff base ligands were synthesized by two different methods. The first method involved the synthesis of the three ligands from condensation reaction of 3,4-dihydroxybenzaldehyde (L?H2) with ethylenediamine (en), o-phenylenediamine (o-PD), or 4,5-dimethyl-1,2-phenylendiamine (DMPD) in a mole ratio of 2?:?1 followed by the reaction of the resulting Schiff bases ligands with Cu(II) or Co(II) ions in the presence of 2,2?-bipyridyl (L) to form the di- and trinuclear metal complexes. The second method involved the condensation of the copper complex LCu(II)L? (L = 2,2?-bipyridyl, L? = 4-formylbenzene-1,2-bis(olate)) with en, o-PD, or DMPD in a mole ratio of 2?:?1, respectively, followed by reaction with CuCl2 or Cu(ClO4)2 to form di-, tri-, and tetranuclear copper (II) complexes, respectively. The structures of the ligands and metal complexes were characterized by elemental analyses, NMR, and FTIR spectra. The geometries of metal complexes were suggested according to elemental analysis, electronic spectra, thermal analyses, atomic absorption, and magnetic moments and conductivity measurements. PMID:24453995

Abdulghani, Ahlam Jameel; Khaleel, Asmaa Mohammed Noori

2013-01-01

120

Co(II) and Cd(II) Complexes Derived from Heterocyclic Schiff-Bases: Synthesis, Structural Characterisation, and Biological Activity  

PubMed Central

New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N?-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L1) and N?-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L2) are reported. Schiff-base ligands L1 and L2 were derived from condensation of 3-hydroxy-4-methoxybenzaldehyde (iso-vanillin) with furan-2-carboxylic acid hydrazide and thiophene-2-carboxylic acid hydrazide, respectively. Complexes of the general formula [M(L)2]Cl2 (where M = Co(II) or Cd(II), L?=?L1 or L2) have been obtained from the reaction of the corresponding metal chloride with the ligands. The ligands and their metal complexes were characterised by spectroscopic methods (FTIR, UV-Vis, 1H, and 13C NMR spectra), elemental analysis, metal content, magnetic measurement, and conductance. These studies revealed the formation of four-coordinate complexes in which the geometry about metal ion is tetrahedral. Biological activity of the ligands and their metal complexes against gram positive bacterial strain Bacillus (G+) and gram negative bacteria Pseudomonas (G?) revealed that the metal complexes become less resistive to the microbial activities as compared to the free ligands. PMID:24027449

Ahmed, Riyadh M.; Yousif, Enaam I.; Al-Jeboori, Mohamad J.

2013-01-01

121

Synthesis, structure, DNA binding and cleavage properties of ternary amino acid Schiff base-phen/bipy Cu(II) complexes.  

PubMed

Ternary Cu(II) complexes [Cu(II)(saltrp)(B)] (1,2), (saltrp=salicylidene tryptophan, B=1,10 phenathroline (1) or 2,2' bipyridine (2)) were synthesized and characterized. Complex 2 was structurally characterized by single crystal X-ray crystallography. The molecular structure shows a distorted square pyramidal coordination geometry (CuN(3)O(2)) in which the ONO donor Schiff base is bonded to the Cu(II) in the basal plane. The N,N donor heterocyclic base displays an axial-equatorial binding mode. CT-DNA binding studies revealed that the complexes show good binding propensity (Intrinsic binding constant, K(b)=3.3210(5) M(-1) for 1 and K(b)=3.1010(5) M(-1) for 2). The catalytic role of these complexes in the oxidative and hydrolytic cleavage of DNA was studied in detail. Complex 1 binds and cleaves DNA more efficiently as compared to 2. From the kinetic experiments, rate constants for the hydrolysis of phosphodiester bond of DNA backbone were determined as 1.94 h(-1) and 1.05 h(-1) for 1 and 2 respectively. It amounts to (2.93-5.41)10(7) fold rate enhancement compared to uncatalyzed double stranded DNA, which is impressive as compared to related Cu(II) Schiff base complexes. PMID:22071085

Reddy, Pulimamidi Rabindra; Shilpa, Addla; Raju, Nomula; Raghavaiah, Pallepogu

2011-12-01

122

A theoretical investigation into the luminescent properties of d8-transition-metal complexes with tetradentate Schiff base ligands.  

PubMed

A theoretical investigation on the luminescence efficiency of a series of d(8) transition-metal Schiff base complexes was undertaken. The aim was to understand the different photophysics of [M-salen](n) complexes (salen = N,N'-bis(salicylidene)ethylenediamine; M = Pt, Pd (n = 0); Au (n = +1)) in acetonitrile solutions at room temperature: [Pt-salen] is phosphorescent and [Au-salen](+) is fluorescent, but [Pd-salen] is nonemissive. Based on the calculation results, it was proposed that incorporation of electron-withdrawing groups at the 4-position of the Schiff base ligand should widen the (3)MLCT-(3)MC gap (MLCT = metal-to-ligand charge transfer and MC = metal centered, that is, the dd excited state); thus permitting phosphorescence of the corresponding Pd(II) Schiff base complex. Although it is experimentally proven that [Pd-salph-4E] (salph = N,N'-bis(salicylidene)-1,2-phenylenediamine; 4E means an electron-withdrawing substituent at the 4-position of the salicylidene) displays triplet emission, its quantum yield is low at room temperature. The corresponding Pt(II) Schiff base complex, [Pt-salph-4E], is also much less emissive than the unsubstituted analogue, [Pt-salph]. Thus, a detailed theoretical analysis of how the substituent and central metal affected the photophysics of [M-salph-X] (X is a substituent on the salph ligand, M = Pt or Pd) was performed. Temperature effects were also investigated. The simple energy gap law underestimated the nonradiative decay rates and was insufficient to account for the temperature dependence of the nonradiative decay rates of the complexes studied herein. On the other hand, the present analysis demonstrates that inclusions of low-frequency modes and the associated frequency shifts are decisive in providing better quantitative estimates of the nonradiative decay rates and the experimentally observed temperature effects. Moreover, spin-orbit coupling, which is often considered only in the context of radiative decay rate, has a significant role in determining the nonradiative rate as well. PMID:24715418

Tong, Glenna So Ming; Chow, Pui Keong; To, Wai-Pong; Kwok, Wai-Ming; Che, Chi-Ming

2014-05-19

123

Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: spectral, thermal, XRD and antimicrobial studies.  

PubMed

Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, (1)H NMR, (13)C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base. PMID:24820326

Sundararajan, M L; Jeyakumar, T; Anandakumaran, J; Karpanai Selvan, B

2014-10-15

124

Modern spectroscopic technique in the characterization of biosensitive macrocyclic Schiff base ligand and its complexes: inhibitory activity against plantpathogenic fungi.  

PubMed

Complexes of the type [M(L)Cl2], where M = Co(II), Ni(II) and Cu(II) have been synthesized with a macrocyclic Schiff base ligand (1,4,5,7,10,11,12,15-octaaza,5,11,16,18-tetraphenyl, 3,4,12,13-tetramethyl cyclo-octadecane) derived from Schiff base (obtained by the condensation of 4-aminoantipyrine and dibenzoyl methane) and ethylenediamine. The ligand was characterized on the basis of elemental analysis, IR, (1)H NMR, EI Mass and molecular modeling studies while the complexes were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, IR, electronic and EPR spectral studies. All the complexes are non-electrolyte in nature. The covalency factor (?) and coefficient factor (?) suggest the covalent nature of the complexes. The ligand and its metal complexes have shown antifungal activity with their LD50 values determined by probit analysis against two economically important fungal plant pathogens i.e. Macrophomina phaseolina and Fusarium solani. PMID:24161868

Tyagi, Monika; Chandra, Sulekh; Akhtar, Jameel; Chand, Dinesh

2014-01-24

125

Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: Spectral, thermal, XRD and antimicrobial studies  

NASA Astrophysics Data System (ADS)

Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, 1H NMR, 13C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, 1H NMR, 13C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base.

Sundararajan, M. L.; Jeyakumar, T.; Anandakumaran, J.; Karpanai Selvan, B.

2014-10-01

126

Synthesis, characterization, spectroscopic and thermodynamic studies of charge transfer interaction of a new water-soluble cobalt(II) Schiff base complex with imidazole derivatives  

NASA Astrophysics Data System (ADS)

The water-soluble cobalt(II) tetradentate Schiff base complex [Co(II)L](ClO 4) 2, L: ( N, N'-bis{5-[(triphenylphosphonium)-methyl]salicylidine}- o-phenylenediamineperchlorate has been synthesized and characterized. This complex forms charge transfer (CT) complexes with imidazole and 1-methylimidazole. The formation constant, molar absorptivity ( ?'), and thermodynamic parameters for charge transfer complexes formation of cobalt(II) Schiff base complexes with imidazole derivatives were determined by using UV-vis spectrophotometric method in aqueous solutions at constant ionic strength ( I = 0.2 mol dm -3 KNO 3) at pH 6.0 and various temperatures between 292 and 315 K.

Boghaei, Davar M.; Askarizadeh, Elham; Bezaatpour, Abolfazl

2008-02-01

127

Co(II), Ni(II) and Cu(II) complexes with coumarin-8-yl Schiff-bases: Spectroscopic, in vitro antimicrobial, DNA cleavage and fluorescence studies  

NASA Astrophysics Data System (ADS)

A new series of Co(II), Ni(II) and Cu(II) complexes of the type ML2H 2O of Schiff-bases derived from m-substituted thiosemicarbazides and 8-acetyl-7-hydroxy-4-methylcoumarin have been synthesized and characterized by spectroscopic studies. Schiff-bases exhibit thiol-thione tautomerism wherein sulphur plays an important role in the coordination. The coordination possibility of the Schiff-bases towards metal ions have been proposed in the light of elemental analyses, spectral (IR, UV-vis, FAB-mass, ESR and fluorescence), magnetic and thermal studies. The low molar conductance values in DMF indicate that, the metal complexes are non-electrolytes. The cyclic voltammetric studies suggested that, the Cu(II) and Ni(II) complexes are of single electron transfer quasi-reversible nature. The Schiff-bases and its metal complexes have been evaluated for their in vitro antibacterial ( Escherichia coli, Staphilococcus aureus, Bascillus subtilis and Salmonella typhi) and antifungal activities ( Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The Schiff-base I and its metal complexes exhibited DNA cleavage activity on isolated DNA of A. niger.

Patil, Sangamesh A.; Unki, Shrishila N.; Kulkarni, Ajaykumar D.; Naik, Vinod H.; Badami, Prema S.

2011-09-01

128

pH-metric and spectroscopic properties of new 4-hydroxysalicylidene-2-aminopyrimidine Schiff-base transition metal complexes  

NASA Astrophysics Data System (ADS)

The new complexes, cis-[WO 2(Hsap) 2], [Ru(PPh 3) 2(Hsap) 2], [Pd(Hsap)Cl(H 2O)], [Pd(PPh 3) 2(Hsap)]Cl, [Ag(Hsap)(H 2O) 2], [Ni(Hsap)(AcO)(H 2O) 2], [Ni(Hsap) 2] and [Cu(Hsap)Cl(H 2O)] are reported, where H 2sap is 4-hydroxysalicylidene-2-amino pyrimidine Schiff-base. The complexes were characterized by elemental analyses, spectroscopic (IR, NMR, UV-vis, ESR and mass) and physical techniques (conductivity, magnetic and thermal measurements). The Schiff-base H 2sap behaves as a bidentate chelate with the deprotonated 2-hydroxy and azomethine nitrogen centers with the pendant pyrimidine cyclic nitrogen functionality playing no role in coordination. The dissociation constants of H 2sap and the stability constants of the metal complexes have been determined pH-metrically at various temperatures, and the thermodynamic activation parameters (? S*, ? G*, ? H*) calculated.

Ouf, Abd El-Fatah; Ali, Mayada S.; Saad, Eman M.; Mostafa, Sahar I.

2010-06-01

129

Synthesis, spectral, electrochemical and catalytic properties of Ru(III) Schiff base complexes containing N, O donors  

NASA Astrophysics Data System (ADS)

A series of new hexa coordinated ruthenium(III) complexes of the type [RuY2(EPh3)2(X-DPMP)] (where Y = Br or Cl; E = P or As; DPMP = 2-[(2,6-Diisopropyl-phenylimino)-methyl]-phenol, X = H, Br, Cl, I and Ph) have been synthesized by equimolar [RuY3(EPh3)3] and the Schiff base ligands in benzene. The bidentate Schiff base ligands (X-DPMP) have been derived from condensation of 2,6-diisopropylaniline with mono and multisubstituted salicylaldehyde derivatives. The complexes have been characterized by elemental analysis, magnetic susceptibility, UV-Vis., IR and EPR spectral and electrochemical measurements. All the ruthenium(III) complexes are found to be stable, paramagnetic, low spin, redox active and display either quasi reversible or irreversible redox couples based on metal centre. They have exhibited catalytic activity for the oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant.

Raja, K. Kanmani; Indra Gandhi, N.; Lekha, L.; Easwaramoorthy, D.; Rajagopal, G.

2014-02-01

130

Synthesis, characterization and biological activity of transition metal complexes with Schiff bases derived from 2-nitrobenzaldehyde with glycine and methionine  

NASA Astrophysics Data System (ADS)

Schiff bases derived from 2-nitrobenzaldehyde with amino acids (glycine, methionine) and their Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized by various physico-chemical techniques. From spectral studies, it has been concluded that the ligands acts as bidentate molecule, coordinates metal through azomethine nitrogen and carboxylate oxygen. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML2 complexes. X-ray powder diffraction helps to determine the cell parameters of the complexes. Molecular structure of the complexes has been optimized by MM2 calculations and suggests a square planar geometry. The ligands and their metal complexes have been tested in vitro against Streptococcus, Staph, Staphylococcus aureus and Escherchia coli bacteria in order to assess their antibacterial potential. The results indicate that the biological activity increases on complexation.

Singh, Bibhesh K.; Rajour, Hemant K.; Prakash, Anant

131

Synthesis and biodistribution of six novel 99mTc complexes of 2-hydroxybenzaldehyde-amino acid Schiff bases.  

PubMed

For the purpose of developing novel diagnostic pharmaceuticals of 99mTc-labeled small-size complexes, six novel complexes of 99mTc-2-hydroxybenzaldehyde-amino acid Schiff bases were designed and synthesized, and their biodistributions in mice were investigated. All the compounds were obtained in radiochemical yields higher than 90% at optimal conditions, and poor uptakes in muscle, brain, heart and tumor were commonly observed with rapid blood clearance. Potentiality was revealed of good kidney imaging by 2-hydroxybenzaldehyde-alanine (L2) complex within 40 min post-injection. Good bone uptake of 2-hydroxybenzaldehyde-histidine (L4) and 2-hydroxybenzaldehyde-aspartic acid (L5) complexes, high spleen accumulation of 2-hydroxybenzaldehyde-glycine (L1) and 2-hydroxybenzaldehyde-cysteine (L3) complexes, and non-specific biodistribution of 2-hydroxybenzaldehyde-glutamic acid (L6) complex were demonstrated. PMID:16309915

Wang, Mingzhao; Meng, Zhaoxing; Fu, Jisheng

2006-02-01

132

Synthesis, Spectral Characterization, and Biological Evaluation of Transition Metal Complexes of Bidentate N, O Donor Schiff Bases  

PubMed Central

New series of three bidentate N, O donor type Schiff bases (L1)(L3) were prepared by using ethylene-1,2-diamine with 5-methyl furfural, 2-anisaldehyde, and 2-hydroxybenzaldehyde in an equimolar ratio. These ligands were further complexed with Co(II), Cu(II), Ni(II), and Zn(II) metals to produce their new metal complexes having an octahedral geometry. These compounds were characterized on the basis of their physical, spectral, and analytical data. Elemental analysis and spectral data of the uncomplexed ligands and their metal(II) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. All ligands and their metal complexes were screened for antimicrobial activity. The results of antimicrobial activity indicated that metal complexes have significantly higher activity than corresponding ligands. This higher activity might be due to chelation process which reduces the polarity of metal ion by coordinating with ligands. PMID:25147493

Sumrra, Sajjad Hussain; Ambreen, Sabahat; Imran, Muhammad; Danish, Muhammad; Rehmani, Fouzia Sultana

2014-01-01

133

Synthesis, characterization and biological activity of ferrocene-based Schiff base ligands and their metal (II) complexes  

NASA Astrophysics Data System (ADS)

Metal (II) complexes derived from S-benzyl-N-(1-ferrocenyl-3-(4-methylbenzene)acrylketone) dithiocarbazate; HL1, S-benzyl-N-(1-ferrocenyl-3-(4-chlorobenzene)acrylketone)dithiocarbazate; HL2, all the compounds were characterized using various spectroscopic techniques. The molar conductance data revealed that the chelates were non-electrolytes. IR spectra showed that the Schiff bases were coordinated to the metal ions in a bidentate manner with N, S donor sites. The ligands and their metal complexes have been screened for in vitro antibacterial, antifungal properties. The result of these studies have revealed that zinc (II) complexes 6 and 13 of both the ligands and copper (II) complexes 9 of the HL2 were observed to be the most active against all bacterial strains, antifungal activity was overall enhanced after complexation of the ligands.

Liu, Yu-Ting; Lian, Gui-Dan; Yin, Da-Wei; Su, Bao-Jun

134

Homo dinuclear lanthanide(III) complexes of a mesogenic Schiff-base, N, N'-di-(4-decyloxysalicylidene)-1',6'-diaminohexane: Synthesis and characterization  

NASA Astrophysics Data System (ADS)

A mesogenic Schiff-base, N, N'-di-(4-decyloxysalicylidene)-1',6'-diaminohexane, H 2ddsdh (abbreviated as H 2L 2) that exhibits smectic-B ( SmB) mesophase, was synthesized and its structure studied by elemental analysis, mass spectrometry, NMR & IR spectral techniques. The Schiff-base, H 2L 2, upon condensation with hydrated lanthanide(III) nitrates, yields Ln III complexes of the general composition [Ln 2(L 2H 2) 3(NO 3) 4](NO 3) 2, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. IR and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as L 2H 2) to the Ln III ions through two phenolate oxygens. The POM and DSC studies reveal that none of the Ln III complexes exhibits mesomorphism. Fluorescence studies show that the Tb III complex displays characteristic metal-centered fluorescence (solution state).

Shakya, Pawan Raj; Singh, Angad Kumar; Rao, T. R.

2011-09-01

135

A novel Schiff base bearing dopamine groups with tripodal structure. Synthesis and its salen/salophen-bridged Fe/Cr(III) capped complexes  

NASA Astrophysics Data System (ADS)

This work presents the synthesis of a novel Schiff base and its complexation properties with Fe(III) and Cr(III). A Schiff base bearing dopamine (TRDPA) was synthesized using dopamine hydrochloride and 1,3,5-tris (formylphenoxymethyl)benzene in methanol media. The prepared TRDPA was then reacted with four new trinuclear Fe(III) and Cr(III) complexes involving tetradenta Schiff bases N,N-bis(salicylidene)ethylenediamine-(salenH2) or bis(salicylidene)-o-phenylenediamine-(salophenH2). The structures of these compounds were characterized through 1H NMR, 13C NMR, FT-IR, thermal analysis (TG), elemental analysis, and magnetic susceptibility measurements. The complexes were also characterized as low-spin distorted octahedral Fe(III) and Cr(III) bridged by a catechol group.

Kocyigit, Ozcan

2013-02-01

136

Immobilization of cobalt(III) Schiff base complexes onto Montmorillonite-K10: Synthesis, experimental and theoretical structural determination.  

PubMed

The [Co(naphophen)(PPh3)(OH2)]ClO4 and [Co(naphophen)(PBu3)(OH2)]BF4 (where naphophen=bis(naphthaldehyde)1,2-phenylenediimine) complexes were synthesized and chracterized by FT-IR, UV-Vis, (1)H NMR, (13)C NMR spectroscopy and elemental analysis techniques. The coordination geometry of the synthesized complexes were determined by X-ray crystallography. Cobalt (III) complexes have six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base forms the equatorial plane. These complexes showed a dimeric structure via hydrogen bonding between the phenolate oxygen and the hydrogens of the coordinated H2O molecule. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The synthesized complexes were incorporated onto the Montmorillonite-K10 nanoclay via simple ion-exchange reaction. The structure and morphology of the obtained nanohybrids were identified by FT-IR, XRD, TGA/DTA, SEM and TEM techniques. Based on the XRD results of the new nanohybrid materials, the Schiff base complexes were intercalated in the interlayer spaces of clay. SEM and TEM micrographs of the clay/complex shows that the resulting hybrid nanomaterials has layer structures. PMID:25459719

Kianfar, Ali Hossein; Kamil Mahmood, Wan Ahmad; Dinari, Mohammad; Farrokhpour, Hossein; Enteshari, Majid; Azarian, Mohammad Hossein

2014-11-01

137

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

PubMed

A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1M 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 2:1M 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, (1)H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction. PMID:24681321

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

2014-07-15

138

Synthesis of copper/nickel nanoparticles using newly synthesized Schiff-base metals complexes and their cytotoxicity/catalytic activities.  

PubMed

Transition metal complexes compounds with Schiff bases ligand representing an important class of compounds that could be used to develop new metal-based anticancer agents and as precursors of metal NPs. Herein, 2,3-bis-[(3-ethoxy-2-hydroxybenzylidene)amino]but-2-enedinitrile Schiff base ligand and its corresponding copper/nickel complexes were synthesized. Also, we reported a facile and rapid method for synthesis nickel/copper nanoparticles based on thermal reduction of their complexes. Free ligand, its metal complexes and metals nanoparticles have been characterized based on elemental analysis, transmission electron microscopy, powder X-ray diffraction, magnetic measurements and by various spectroscopic (UV-vis, FT-IR, (1)H NMR, GC-MS) techniques. Additionally, the in vitro cytotoxic activity of free ligand and its complexes compounds were assessed against two cancer cell lines (HeLa and MCF-7 cells)and one healthy cell line (HEK293 cell). The copper complex was found to be active against these cancer cell lines at very low LD50 than the free ligand, while nickel complex did not show any anticancer activity against these cell lines. Also, the antibacterial activity of as-prepared copper nanoparticles were screened against Escherichia coli, which demonstrated minimum inhibitory concentration and minimum bactericidal concentration values lower than those values of the commercial Cu NPs as well as the previous reported values. Moreover, the synthesized nickel nanoparticles demonstrated remarkable catalytic performance toward hydrogenation of nitrobenzene that producing clean aniline with high selectivity (98%). This reactivity could be attributed to the high degree of dispersion of Ni nanoparticles. PMID:25159596

Aazam, Elham S; El-Said, Waleed Ahmed

2014-12-01

139

Structural investigation of oxovanadium(IV) Schiff base complexes: X-ray crystallography, electrochemistry and kinetic of thermal decomposition.  

PubMed

A series of new VO(IV) complexes of tetradentate N2O2 Schiff base ligands (L(1)-L(4)), were synthesized and characterized by FT-IR, UV-vis and elemental analysis. The structure of the complex VOL(1)?DMF was also investigated by X-ray crystallography which revealed a vanadyl center with distorted octahedral coordination where the 2-aza and 2-oxo coordinating sites of the ligand were perpendicular to the "-yl" oxygen. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeOcomplexes and kinetic aspects of their thermal decomposition. The formation constants with various substituents on the aldehyde ring follow the trend 5-OMe>5-H>5-Br>5-Cl. Furthermore, the kinetic parameters of thermal decomposition were calculated by using the Coats-Redfern equation. According to the Coats-Redfern plots the kinetics of thermal decomposition of studied complexes is of the first-order in all stages, the free energy of activation for each following stage is larger than the previous one and the complexes have good thermal stability. The preparation of VOL(1)?DMF yielded also another compound, one kind of vanadium oxide [VO]X, with different habitus of crystals, (platelet instead of prisma) and without L(1) ligand, consisting of a V10O28 cage, diaminium moiety and dimethylamonium as a counter ions. Because its crystal structure was also new, we reported it along with the targeted complex. PMID:25448962

Asadi, Mozaffar; Asadi, Zahra; Savaripoor, Nooshin; Dusek, Michal; Eigner, Vaclav; Shorkaei, Mohammad Ranjkesh; Sedaghat, Moslem

2015-02-01

140

Structural investigation of oxovanadium(IV) Schiff base complexes: X-ray crystallography, electrochemistry and kinetic of thermal decomposition  

NASA Astrophysics Data System (ADS)

A series of new VO(IV) complexes of tetradentate N2O2 Schiff base ligands (L1-L4), were synthesized and characterized by FT-IR, UV-vis and elemental analysis. The structure of the complex VOL1?DMF was also investigated by X-ray crystallography which revealed a vanadyl center with distorted octahedral coordination where the 2-aza and 2-oxo coordinating sites of the ligand were perpendicular to the '-yl' oxygen. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO < H < Br < Cl. We also studied the thermodynamics of formation of the complexes and kinetic aspects of their thermal decomposition. The formation constants with various substituents on the aldehyde ring follow the trend 5-OMe > 5-H > 5-Br > 5-Cl. Furthermore, the kinetic parameters of thermal decomposition were calculated by using the Coats-Redfern equation. According to the Coats-Redfern plots the kinetics of thermal decomposition of studied complexes is of the first-order in all stages, the free energy of activation for each following stage is larger than the previous one and the complexes have good thermal stability. The preparation of VOL1?DMF yielded also another compound, one kind of vanadium oxide [VO]X, with different habitus of crystals, (platelet instead of prisma) and without L1 ligand, consisting of a V10O28 cage, diaminium moiety and dimethylamonium as a counter ions. Because its crystal structure was also new, we reported it along with the targeted complex.

Asadi, Mozaffar; Asadi, Zahra; Savaripoor, Nooshin; Dusek, Michal; Eigner, Vaclav; Shorkaei, Mohammad Ranjkesh; Sedaghat, Moslem

2015-02-01

141

Enhanced catalytic activity of zeolite encapsulated Fe(III)-Schiff-base complexes for oxidative coupling of 2-napthol.  

PubMed

Iron(III) Schiff-base complexes of general formula [Fe(L)(2)Cl]2H(2)O, where L = N,?-bis(salicylidene)ethylenediamine and N,N?-disalicylidene-1,2-phenylenediamine have been encapsulated within various alkali exchanged zeolites viz. LiY, NaY, and KY by flexible ligand method. The encapsulated complexes are characterized by EDX, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), FT-IR, UV-vis, diffuse reflectance spectroscopy (DRS), electron spin resonance spectroscopy (ESR) and cyclic voltammetry studies. The diffuse reflectance UV-vis spectra of encapsulated complexes show a dramatic red shift of the charge transfer band with increasing electropositivity of the exchangeable cations. The electrochemical analysis predicts the shifting of the reduction potential toward negative values with increasing size of the alkali exchanged cations. The zeolite encapsulated Schiff-base complexes of iron are found to be catalytically active toward the oxidative coupling of 2-napthol. Metal complexes incorporated in potassium exchanged zeolite-Y are found to be more effective for catalytic conversion of 2-naphthol to binaphthol and induces higher selectivity toward the R-conformation. The catalytic conversion of 2-napthol to BINOL is found to depend on the reduction potential of the catalyst, with a more negative reduction potential being better for the catalytic conversion. Density functional calculation is being carried out on both the neat Fe-Salen and Fe-Salophen complexes and those encapsulated in NaY zeolite to investigate change in structural parameters, energies of the HOMO and LUMO, and global hardness and softness. Fukui functions, as local descriptors, are used to analyze the hard-hard interaction at a particular site of the complexes. PMID:22256783

Bania, Kusum K; Bharali, Dipsikha; Viswanathan, B; Deka, Ramesh C

2012-02-01

142

Synthesis and characterization of metal complexes of Schiff base ligand derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine.  

PubMed

The Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine were synthesized. These compounds were characterized by elemental analysis, IR, mass, (1)H NMR, electronic spectra, magnetic moment, molar conductance, thermal analysis, powder XRD and SEM. The analytical data show that the metal to ligand ratio is 1:1. The IR results show that the ligand acts as a bidentate donor coordinating through the azomethine nitrogen and imidazole nitrogen atoms. From the electronic spectra and magnetic moment value predicts the geometry of the complexes. The surface morphology of the compounds was studied by SEM. The compounds were screened for their antibacterial activity and antifungal activity using Kirby Bayer disc diffusion method. The DNA cleavage and superoxide dismutase activities of the compounds were investigated. The anticancer activities of the complexes have been carried out towards HeLa and HCT116 cancer cells. PMID:24934973

Selwin Joseyphus, R; Shiju, C; Joseph, J; Justin Dhanaraj, C; Arish, D

2014-12-10

143

Synthesis and characterization of metal complexes of Schiff base ligand derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine  

NASA Astrophysics Data System (ADS)

The Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine were synthesized. These compounds were characterized by elemental analysis, IR, mass, 1H NMR, electronic spectra, magnetic moment, molar conductance, thermal analysis, powder XRD and SEM. The analytical data show that the metal to ligand ratio is 1:1. The IR results show that the ligand acts as a bidentate donor coordinating through the azomethine nitrogen and imidazole nitrogen atoms. From the electronic spectra and magnetic moment value predicts the geometry of the complexes. The surface morphology of the compounds was studied by SEM. The compounds were screened for their antibacterial activity and antifungal activity using Kirby Bayer disc diffusion method. The DNA cleavage and superoxide dismutase activities of the compounds were investigated. The anticancer activities of the complexes have been carried out towards HeLa and HCT116 cancer cells.

Selwin Joseyphus, R.; Shiju, C.; Joseph, J.; Justin Dhanaraj, C.; Arish, D.

2014-12-01

144

Binuclear ruthenium(III) Schiff base complexes bearing N 4O 4 donors and their catalytic oxidation of alcohols  

NASA Astrophysics Data System (ADS)

An interesting series of binuclear ruthenium(III) Schiff base complexes bearing bis-salophen/bis-naphophen units of the general composition [(EPh 3)(X)Ru-L-Ru(X)(EPh 3)] (where E = P or As; X = Cl or Br; L = binucleating dianionic tetradentate ligands) have been synthesized and characterized by analytical (elemental analysis, magnetic susceptibility measurements), spectral (FT-IR, UV-vis and EPR) and electrochemical methods. These ruthenium(III) complexes have two N 2O 2 metal binding sites, which are linked to each other with a biphenyl bridge and acts as potential catalyst for oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine- N-oxide (NMO). The formation of high-valent Ru V = O species as a catalytic active intermediate is proposed for the catalytic processes.

Venkatachalam, G.; Raja, N.; Pandiarajan, D.; Ramesh, R.

2008-12-01

145

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde.  

PubMed

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 ?m. PMID:22728967

Anitha, C; Sheela, C D; Tharmaraj, P; Sumathi, S

2012-10-01

146

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde  

NASA Astrophysics Data System (ADS)

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 ?m.

Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Sumathi, S.

2012-10-01

147

Synthesis, characterization, and thermodynamics of some new unsymmetrical Schiff bases of salicylaldehyde with 3,4-diaminopyridine and their cobalt(III) complexes.  

PubMed

Some new Schiff bases derived from 3,4-diaminopyridine (3,4-DAP) and their new unsymmetrical Co(III) five coordinate complexes described as [Co(Chel)(L)]ClO4?H2O where (Chel) is the deprotonated form of a series of unsymmetric ligands containing 3,4-diaminopyridine (3,4-DAP) and substituted salicylaldehyde moieties and a new Co(III) six coordinate Co(III) complex, were synthesized and characterized by (1)H NMR, IR, UV-Vis, and elemental analysis. For the new synthesized five coordinate complexes, the formation constants of the interaction of the Co(III) Schiff bases with various donors were measured spectrophotometrically. The trend of the formation constants of the five coordinate Co(III) Schiff base complexes toward a given phosphine is as follow: 5-H>5-Br and the formation constants trend of these donors are as follow: PBu3>PPh2Me. Furthermore the adduct formation of the five coordinate [Co(3,4-Salpyr)(PBu3)] ClO4?H2O, with aromatic amines shows the following binding trend: Im>2-MeIm>2-EtIm>BzIm. The trend of the formation constants of Co(III) Schiff base complexes toward a given donor according to the phosphine axial ligand is as follow: PBu3>PPh2Me. PMID:24342295

Asadi, Mozaffar; Torabi, Susan; Mohammadi, Khosro

2014-03-25

148

Synthesis, spectral characterization and biological activity of zinc(II) complexes with 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole Schiff bases  

NASA Astrophysics Data System (ADS)

New Zn(II) complexes have been synthesized by the reactions of zinc(II) acetate with Schiff bases derived from 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde, 2-hydroxyacetophenone or indoline-2,3-dione. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non-electrolytes. Elemental analyses suggest that the complexes have 1:1 stoichiometry of the type [ZnL(H 2O) 2], [ZnL'(OAc) 2(H 2O) 2] (L = dianionic Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and 2-hydroxyacetophenone or indoline-2,3-dione; L' = neutral Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde) and they were characterized by FT-IR, 1H NMR, 13C NMR and FAB mass. All these Schiff bases and their complexes have also been screened for their antibacterial activities against Bacillus subtilis, Escherichia coli and antifungal activities against Colletotrichum falcatum, Aspergillus niger, Fusarium oxysporium and Carvularia pallescence by petriplates methods.

Singh, A. K.; Pandey, O. P.; Sengupta, S. K.

149

Synthesis, structural characterization, fluorescence, antimicrobial, antioxidant and DNA cleavage studies of Cu(II) complexes of formyl chromone Schiff bases  

NASA Astrophysics Data System (ADS)

Cu(II) complexes have been synthesized from different Schiff bases, such as 3-((2-hydroxy phenylimino)methyl)-4H-chromen-4-one (HL1), 2-((4-oxo-4H-chromen-3-yl)methylneamino) benzoicacid (HL2), 3-((3-hydroxypyridin-2-ylimino)methyl)-4H-chromen-4-one (HL3) and 3-((2-mercaptophenylimino)methyl)-4H-chromen-4-one (HL4). The complexes were characterized by analytical, molar conductance, IR, electronic, magnetic, ESR, thermal, powder XRD and SEM studies. The analytical data reveal that metal to ligand molar ratio is 1:2 in all the complexes. Molar conductivity data indicates that all the Cu(II) complexes are neutral. On the basis of magnetic and electronic spectral data, distorted octahedral geometry is proposed for all the Cu(II) complexes. Thermal behaviour of the synthesized complexes illustrates the presence of lattice water molecules in the complexes. X-ray diffraction studies reveal that all the ligands and their Cu(II) complexes have triclinic system with different unit cell parameters. Antimicrobial, antioxidant and DNA cleavage activities indicate that metal complexes exhibited greater activity as compared with ligands.

Kavitha, P.; Saritha, M.; Laxma Reddy, K.

2013-02-01

150

Antimicrobial efficacy of phenanthrenequinone based Schiff base complexes incorporating methionine amino acid: structural elucidation and in vitro bio assay.  

PubMed

This work focuses the synthesis and characterization of few novel mixed ligand Schiff base metal complexes and their biological activities. For deriving the structural aspects, spectral techniques such as FT-IR, UV-Vis., (1)H NMR, Raman, EPR and the physicochemical characterizations including elemental analysis, molar conductance and magnetic susceptibility method have been involved. All the complexes adopt square planar geometry. DNA binding ability of these complexes has been explored using diverse techniques viz. UV-Vis. absorption, fluorescence spectroscopy, viscometry and cyclic voltammetry. These studies prove that CT-DNA binding of the complexes follows the intercalation mode. Comparative DNA oxidative cleavage ability of the complexes has been done under ultraviolet photo radiation on pUC19 DNA. In addition, the biocidal action of the complexes has been investigated against few pathogenic bacteria and fungi by disc diffusion method. Importantly, the amylase inhibition activity of Cu(II) complex has been explored. The amylase inhibition property has been found to be increased upon increasing the complex concentration. PMID:24632238

Arun, Thesingu Rajan; Raman, Natarajan

2014-06-01

151

Synthesis, spectroscopic (electronic, IR, NMR and ESR) and theoretical studies of transition metal complexes with some unsymmetrical Schiff bases  

NASA Astrophysics Data System (ADS)

Two unsymmetrical Schiff bases, glyoxal salicylaldehyde oxalic acid dihydrazone (gsodh) and glyoxal salicylaldehyde malonic acid dihydrazone (gsmdh) and their Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized. The structures of metal complexes are elucidated on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, electronic, ESR, IR and NMR (1H and 13C) spectral studies. Both ligands show monobasic tetra-dentate behaviour, bonding through CO, two CN and a phenolate group. The electronic spectral studies in solid state indicate a square planar geometry for Ni(II) and Cu(II) complexes and a tetrahedral geometry for Co(II) complexes. However, Co(II) and Cu(II) complexes adopt octahedral geometry in DMSO solution. The ESR spectra of Cu(II) complexes in DMSO solution at 77 K predict an elongated tetragonal distorted octahedral geometry around metal ion and presence of unpaired electron in d orbital. Further, the structures of ligands and their Ni(II) complexes have been satisfactorily modelled by calculations based on density functional theory (DFT). The electronic spectra of Ni(II) complexes are also analyzed in depth with the help of time dependent-DFT (TD-DFT). The theoretical analyses of electronic structure and molecular orbitals have demonstrated that the high-energy absorption bands are M ? L charge transfer and low energy transitions are d-d transitions.

Singh, Vinod P.; Singh, Shweta; Singh, Divya P.; Tiwari, K.; Mishra, Monika

2014-01-01

152

Antimicrobial efficacy of phenanthrenequinone based Schiff base complexes incorporating methionine amino acid: Structural elucidation and in vitro bio assay  

NASA Astrophysics Data System (ADS)

This work focuses the synthesis and characterization of few novel mixed ligand Schiff base metal complexes and their biological activities. For deriving the structural aspects, spectral techniques such as FT-IR, UV-Vis., 1H NMR, Raman, EPR and the physicochemical characterizations including elemental analysis, molar conductance and magnetic susceptibility method have been involved. All the complexes adopt square planar geometry. DNA binding ability of these complexes has been explored using diverse techniques viz. UV-Vis. absorption, fluorescence spectroscopy, viscometry and cyclic voltammetry. These studies prove that CT-DNA binding of the complexes follows the intercalation mode. Comparative DNA oxidative cleavage ability of the complexes has been done under ultraviolet photo radiation on pUC19 DNA. In addition, the biocidal action of the complexes has been investigated against few pathogenic bacteria and fungi by disc diffusion method. Importantly, the amylase inhibition activity of Cu(II) complex has been explored. The amylase inhibition property has been found to be increased upon increasing the complex concentration.

Arun, Thesingu Rajan; Raman, Natarajan

2014-06-01

153

Emissive bis-salicylaldiminato Schiff base ligands and their zinc(II) complexes: Synthesis, photophysical properties, mesomorphism and DFT studies  

NASA Astrophysics Data System (ADS)

Bis-salicylaldiminato Schiff base ligands and their Zn(II) complexes derived from 2,3-Diaminomaleonitrile (DAMN) were synthesized. Their molecular structures, photophysical properties and mesogenic behaviors were investigated. The ligands and their Zn(II) complexes were characterized by using elemental analysis, FT-IR, 1H NMR and molar conductivity measurements. Photophysical properties of ligands and their Zn(II) complexes were investigated in different polar solvents by using UV-visible and fluorescence spectroscopic studies. Ligands emit green light whereas complexes emit orange light upon irradiation with UV-visible light. The liquid crystalline phases of ligands and their Zn(II) complexes were characterized by polarizing optical microscopy and differential scanning calorimetry. The ligand having longer 4-n-octadecyloxy chain (n = 18) displays columnar phase whereas the lower homologues (n = 16, 12) did not show mesophase. The Zn(II) complexes having 4-n-octadecyloxy end chain display smectic B like phase whereas other lower homologues are non mesogenic in nature. The thermal stability of the compounds were studied by using thermo gravimetric analysis. The density functional theory was carried out to obtain the stable molecular conformation, dipole moment, molecular orbitals and polarizability of the ligands and their Zn(II) complexes.

Paul, Manoj Kr.; Dilipkumar Singh, Y.; Bedamani Singh, N.; Sarkar, Utpal

2015-02-01

154

Synthesis, spectral, antitumor and antimicrobial studies on Cu(II) complexes of purine and triazole Schiff base derivatives  

NASA Astrophysics Data System (ADS)

A series of copper (II) complexes of Schiff bases derived from 7H-2,6-diaminopurine and 4H-3,5-diamino-1,2,4-triazole with 2-pyridinecarbaldehyde, salicylaldehyde, 2,4-dihydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde have been prepared. The donor atoms and the possible geometry of the complexes were investigated by means of elemental and thermal analyses, molar conductance, magnetic moment, UV-Vis, IR, ESR and mass spectra. The ligands behaved as tetradentate, coordinating through the nitrogen atom of the azomethine group and the nearest nitrogen atom to it or oxygen atom of ?-hydroxyl group. The results of simultaneous DTA & TGA analyses of the complexes showed the final degradation product for these complexes is CuO. The spectral studies confirmed a four coordinate environment around the metal ion. The obtained results were supported by 3D molecular modeling of complexes using molecular mechanics (MM+) and semiempirical molecular orbital calculations (PM3). These complexes were also tested for their in vitro antimicrobial activities against some bacterial and fungal strains. Complex 2 was investigated for its cyctotoxic effect against human breast cancer (MCF7), liver carcinoma (HEPG2) and colon carcinoma cell lines (HCT116). This compound exhibited a moderate activity against the tested cell lines with IC50 of 10.3, 9.8 and 8.7 ?g/ml against MCF7, HCT116 and HEPG2, respectively.

Amer, Said; El-Wakiel, Nadia; El-Ghamry, Hoda

2013-10-01

155

Synthesis, Characterization, DNA Interaction, and Antitumor Activities of La (III) Complex with Schiff Base Ligand Derived from Kaempferol and Diethylenetriamine  

PubMed Central

A novel La (III) complex, [LaL(H2O)3]NO33H2O, with Schiff base ligand L derived from kaempferol and diethylenetriamine, has been synthesized and characterized by elemental analysis, IR, UV-visible, 1H NMR, thermogravimetric analysis, and molar conductance measurements. The fluorescence spectra, circular dichroism spectra, and viscosity measurements and gel electrophoresis experiments indicated that the ligand L and La (III) complex could bind to CT-DNA presumably via intercalative mode and the La (III) complex showed a stronger ability to bind and cleave DNA than the ligand L alone. The binding constants (Kb) were evaluated from fluorescence data and the values ranged from 0.454 to 0.659 105 L mol?1 and 1.71 to 17.3 105 L mol?1 for the ligand L and La (III) complex, respectively, in the temperature range of 298310?K. It was also found that the fluorescence quenching mechanism of EB-DNA by ligand L and La (III) complex was a static quenching process. In comparison to free ligand L, La (III) complex exhibited enhanced cytotoxic activities against tested tumor cell lines HL-60 and HepG-2, which may correlate with the enhanced DNA binding and cleaving abilities of the La (III) complex. PMID:25371657

Wang, Qin; Huang, Yu; Zhang, Jin-Sheng; Yang, Xin-Bin

2014-01-01

156

Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes  

NASA Astrophysics Data System (ADS)

In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride ions coordinate to the metal ions. The complexes have the general formulae [M(L)(Cl) 2] (M: Cu(II), Co(II) and Ni(II) metal ions). Electrochemical properties were investigated as ligand and metal centres in the different solvents and at the scan rates, respectively. The thermal properties of the metal complexes were studied in the N 2 atmosphere. We investigated the improved catalytic activity of the Cu(II), Co(II) and Ni(II) complexes on the cyclohexane as a substrate. Obtained data showed that the best catalyst is the Cu(II) complex. The single crystal of the ligand (L) was obtained from CH 3CN solution. There is a C-HN H-bond linking the molecules into chains (C6)N(2) 3.4415(18) under symmetry operation ( x + 1, y, z) as well as ?-? stacking on the outside of the "V" shape - nothing on the inside.

Dolaz, Mustafa; McKee, Vickie; Uru?, Serhan; Demir, Necmettin; Sabik, Ali E.; Glc, Ay?egl; Tmer, Mehmet

2010-07-01

157

Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes.  

PubMed

In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride ions coordinate to the metal ions. The complexes have the general formulae [M(L)(Cl)(2)] (M: Cu(II), Co(II) and Ni(II) metal ions). Electrochemical properties were investigated as ligand and metal centres in the different solvents and at the scan rates, respectively. The thermal properties of the metal complexes were studied in the N(2) atmosphere. We investigated the improved catalytic activity of the Cu(II), Co(II) and Ni(II) complexes on the cyclohexane as a substrate. Obtained data showed that the best catalyst is the Cu(II) complex. The single crystal of the ligand (L) was obtained from CH(3)CN solution. There is a C-H...N H-bond linking the molecules into chains (C6)...N(2) 3.4415(18)A under symmetry operation (x+1,y,z) as well as pi-pi stacking on the outside of the "V" shape--nothing on the inside. PMID:20409747

Dolaz, Mustafa; McKee, Vickie; Uru?, Serhan; Demir, Necmettin; Sabik, Ali E; Glc, Ay?egl; Tmer, Mehmet

2010-07-01

158

Studies on DNA binding behaviour of biologically active transition metal complexes of new tetradentate N2O2 donor Schiff bases: Inhibitory activity against bacteria  

NASA Astrophysics Data System (ADS)

A series of Cu(II), Ni(II) and Zn(II) complexes of the type ML have been synthesized with Schiff bases derived from o-acetoacetotoluidide, 2-hydroxybenzaldehyde and o-phenylenediamine/1,4-diaminobutane. 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 six 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 bases are found to act as tetradentate ligands using N2O2 donor set of atoms leading to a square-planar geometry for the complexes around all the metal ions. The binding properties of metal complexes with DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. Detailed analysis reveals that the metal complexes intercalate into the DNA base stack as intercalators. All the metal complexes cleave the pUC19 DNA in presence of H2O2. The Schiff bases and their complexes have been screened for their antibacterial activity against five bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae) by disk diffusion method. All the metal complexes have potent biocidal activity than the free ligands.

Sobha, S.; Mahalakshmi, R.; Raman, N.

159

New ruthenium(II) carbonyl complexes bearing disulfide Schiff base ligands and their applications as catalyst for some organic transformations.  

PubMed

Schiff base disulfide ligands (H2L(1-6)) were synthesized from the condensation of cystamine with salicylaldehyde(H2L(1)), 5-chlorosalicylaldehyde(H2L(2)), o-vanillin(H2L(3)), 2-hydroxyacetophenone(H2L(4)), 3-methyl-2-hydroxyacetophenone(H2L(5)), and 2-hydroxy-1-naphthaldehyde(H2L(6)). H2L(1-6) reacts with the ruthenium precursor complex [RuHCl(CO)(PPh3)3] in benzene giving rise to six new ruthenium(II) complexes of general formula [Ru(CO)L(1-6)]. Characterization of the new complexes was carried out by using elemental and spectral (IR, UV-Vis, NMR ((1)H and (13)C) and Mass) techniques. An octahedral geometry was assigned for all the complexes based on the spectral data obtained. The catalytic efficiency of the new complexes in aldehyde to amide conversion in the presence of NaHCO3, N-alkylation of aniline in the presence of t-BuOK, and transfer hydrogenation of ketones in the presence of iPrOH/KOH reactions were studied. Furthermore, the effect of solvents and catalyst/substrate ratio on the catalytic aldehyde to amide conversion were also discussed. PMID:24747860

Prakash, Govindan; Viswanathamurthi, Periasamy

2014-08-14

160

Enhancing the copper(II) complexes cytotoxicity to cancer cells through bound to human serum albumin.  

PubMed

We use Schiff-base salicylaldehyde benzoylhydrazone (HL) as the ligand for copper(II), resulting in the complexes [CuCl(L)]H2O (C1), [CuNO3(L)]H2O (C2) and [CuBr(L)]2 (C3). We characterize the Cu(II) compounds' interactions with human serum albumin (HSA) using fluorescence spectroscopy and molecular docking. These studies revealed that Cu(II) compounds propensity bound to IIA subdomain of HSA possible by hydrophobic interactions and hydrogen bond. Cu(II) compounds produce intracellular reactive oxygen species (ROS) in cancer cells. Complexes of HSA and copper(II) compounds enhance about 2-fold cytotoxicity in cancer cells but do not raise cytotoxicity levels in normal cells in vitro. Compared with C3 alone, HSA-C3 complex promotes HepG2 cell apoptosis and has a stronger capacity to promote cell cycle arrest at the G2/M phase of HepG2. PMID:25573806

Gou, Yi; Zhang, Yao; Qi, Jinxu; Zhou, Zuping; Yang, Feng; Liang, Hong

2015-03-01

161

Environmental Dependence of Artifact CD Peaks of Chiral Schiff Base 3d-4f Complexes in Soft Mater PMMA Matrix  

PubMed Central

Four chiral Schiff base binuclear 3d-4f complexes (NdNi, NdCu, GdNi, and GdCu) have been prepared and characterized by means of electronic and CD spectra, IR spectra, magnetic measurements, and X-ray crystallography (NdNi). A so-called artifact peak of solid state CD spectra, which was characteristic of oriented molecules without free molecular rotation, appeared at about 470 nm. Magnetic data of the complexes in the solid state (powder) and in PMMA cast films or solutions indicated that only GdCu preserved molecular structures in various matrixes of soft maters. For the first time, we have used the changes of intensity of artifact CD peaks to detect properties of environmental (media solid state (KBr pellets), PMMA cast films, concentration dependence of PMMA in acetone solutions, and pure acetone solution) for chiral 3d-4f complexes (GdCu). Rigid matrix keeping anisotropic orientation exhibited a decrease in the intensity of the artifact CD peak toward negative values. The present results suggest that solid state artifact CD peaks can be affected by environmental viscosity of a soft mater matrix. PMID:22072930

Okamoto, Yu; Nidaira, Keisuke; Akitsu, Takashiro

2011-01-01

162

Nickel(II) complexes of fully and partially condensed Schiff-base ligands derived from tris(3aminopropyl)amine and acetylpyridine  

Microsoft Academic Search

In the presence of nickel(II), 2acetylpyridine condenses with tris(3aminopropyl)amine in absolute MeOH to give the fully condensed Schiff-base complex [Ni(tptpy3)]2+. Although the ligand is potentially heptadentate, the metal atom is effectively six-coordinate, interaction with the bridgehead nitrogen being rather weak. However, when aqueous MeOH is used, the condensation is limited to a single step, and a complex of the pentadentate

Hassan Keypour; Sadegh Salehzadeh; Robin G. Pritchard; R. V. Parish

1998-01-01

163

Synthesis, structural characterization, electrochemistry and spectroelectrochemistry of dinuclear copper(II) metal complexes stabilized by a tetradentate NOOO salicylaldimine ligands  

NASA Astrophysics Data System (ADS)

The synthesis, structure, spectroscopic and electro-spectrochemical properties of salicylaldimine Schiff-base ligands (L nH) ( n = 1, 2, and 3) (L 1H = N-[2-amino-8-hydroxyquinoline]-salicylaldimine, L 2H = N-[2-amino-8-hydroxyquinoline]-5-bromosalicylaldimine and L 3H = N-[2-amino-8-hydroxyquinoline]-5-methoxysalicylaldimine), respectively, and their dinuclear copper(II) complexes [Cu 2(L n) 2] are described. Three new dissymmetric tetradentate salicylaldimine ligands containing a donor set of NOOO were prepared by reaction of 2-amino-8-hydroxyquinoline with different salicylaldehydes. The dinuclear copper(II) metal complexes of these ligands were synthesized by treating an ethanolic solution of the appropriate ligand with an equimolar amount of Cu(Ac) 2H 2O. The ligands and their copper complexes were characterized by FT-IR, UV-vis, 1H NMR, elemental analysis, molar conductivity, mass spectra and thermal analysis methods in addition to magnetic susceptibility and spectroelectrochemical techniques. The reaction of these ligands in a 1:1 mole ratio with copper(II) acetate afforded dinuclear Cu(II) metal complexes. The room temperature magnetic moments of [Cu 2(L n) 2] complexes are found between 1.12 and 1.28 BM for per Cu(II) molecule.

Tas, E.; Onal, I. H.; Yilmaz, I.; Kilic, A.; Durgun, M.

2009-06-01

164

Synthesis and characterization of water soluble O-carboxymethyl chitosan Schiff bases and Cu(II) complexes.  

PubMed

In this study, mono-imine was synthesized (3a and 4a) via a condensation reaction between 2,4-pentadion and aminobenzoic acid (meta or para) in alcohol (1:1). The second-imine (CS-3a and CS-4a) was obtained as a result of the reaction of the free oxo groups of mono-imine (3a and 4a) with the amino groups on the chitosan (CS). Their structures were characterized with FTIR and (13)C CP-MAS. Then, the water soluble forms of CS-3a and CS-4a were obtained through oxidation of the hydroxide groups on the chitosan to carboxymethyl groups using monochloracetic acid ([O-CMCS-3a]2H2O and [O-CMCS-4a]2H2O). Thus, the solubility problem of chitosan in an aqueous media was overcome and Cu(II) complexes could be synthesized more easily. Characterization of the synthesized O-carboxymethyl chitosan Schiff base derivatives and their metal complexes, [O-CMCS-3a-Cu(OAc)2]2H2O and [O-CMCS-4a-Cu(OAc)2]2H2O, was conducted using FTIR, UV-Vis, TG/DTA, XRD, SEM, elemental analysis, conductivities and magnetic susceptibility measurements. PMID:25128824

Baran, Talat; Mente?, Ayfer; Arslan, Hlya

2015-01-01

165

Synthesis, Characterization, Antimicrobial, DNA Cleavage, and In Vitro Cytotoxic Studies of Some Metal Complexes of Schiff Base Ligand Derived from Thiazole and Quinoline Moiety  

PubMed Central

A novel Schiff base ligand N-(4-phenylthiazol-2yl)-2-((2-thiaxo-1,2-dihydroquinolin-3-yl)methylene)hydrazinecarboxamide (L) obtained by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 2-thioxo-1,2-dihydroquinoline-3-carbaldehyde and its newly synthesized Cu(II), Co(II), Ni(II), and Zn(II) complexes have been characterized by elemental analysis and various spectral studies like FT-IR, 1H NMR, ESI mass, UV-Visible, ESR, TGA/DTA, and powder X-ray diffraction studies. The Schiff base ligand (L) behaves as tridentate ONS donor and forms the complexes of type [ML(Cl)2] with square pyramidal geometry. The Schiff base ligand (L) and its metal complexes have been screened in vitro for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage activity of ligand and its metal complexes were studied using plasmid DNA pBR322 as a target molecule by gel electrophoresis method. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties for the ligand and its metal complexes against Artemia salina. The results showed that the biological activities of the ligand were found to be increased on complexation. PMID:24729778

Yernale, Nagesh Gunvanthrao; Bennikallu Hire Mathada, Mruthyunjayaswamy

2014-01-01

166

L-Ornithine Schiff base-copper and -cadmium complexes as new proteasome inhibitors and apoptosis inducers in human cancer cells.  

PubMed

Ubiquitin-proteasome system (UPS) plays a crucial role in many cellular processes such as cell cycle, proliferation and apoptosis. Aberrant activation of UPS may result in cellular transformation or other altered pathological conditions. Previous studies have shown that metal-based complexes could inhibit proteasome activity and induce apoptosis in certain human cancer cells. In the current study, we report that the cadmium and copper complexes with heterocycle-ornithine Schiff base are potent inhibitors of proteasomal chymotrypsin-like (CT-like) activity, leading to induction of apoptosis in cancer cells. Two novel copper-containing complexes and two novel cadmium-containing complexes with different heterocycle-ornithine Schiff base structures as ligands were synthesized and characterized. We found that complexes Cu1, Cd1 and Cd2 show proteasome-inhibitory activities in human breast cancer MDA-MB-231 and human prostate cancer LNCaP cells, resulting in the accumulation of p27, a natural proteasome substrate and other ubiquitinated proteins, followed by the induction of apoptosis. Our results suggest that metal complexes with heterocycle-ornithine Schiff base have proteasome-inhibitory capabilities and have the potential to be developed into novel anticancer drugs. PMID:25467055

Zhang, Zhongyu; Bi, Caifeng; Fan, Yuhua; Zhang, Nan; Deshmukh, Rahul; Yan, Xingchen; Lv, Xiuwen; Zhang, Pengfei; Zhang, Xia; Dou, Q Ping

2014-12-01

167

(E)3-2-(1-(2,4-Dihydroxyphenyl)ethyldeneamino)phenyl)-2-methylquinazoline-4(3H)-one Schiff Base and Its Metal Complexes: A New Drug of Choice against Methicillin-Resistant Staphylococcus aureus  

PubMed Central

The 3-(2-aminophenyl) quinazolin-2-methyl-4(3H)-one and 2,4-dihydroxyacetophenone undergo condensation to afford (E)3-2-(1-(2,4-dihydroxyphenyl)ethyldeneamino)phenyl)-2-methylquinazoline-4(3H)-one Schiff base (DHPEAPMQ). The newly synthesized Schiff base (DHPEAPMQ) and its metal complexes were evaluated for their antimicrobial activity against methicillin-resistant Staphylococcus aureus isolated from the Gulbarga region in India. The Cu(II), Ni(II), and Zn(II) complexes of Schiff base (DHPEAPMQ) showed good antimicrobial activity. So, this could be a new drug of choice. PMID:24733996

Siddappa, K.; Mane, Sunilkumar B.; Manikprabhu, Deene

2014-01-01

168

Novel tandem synthesis of bis(?-NN'-tetrazolate) bridged dinuclear nickel(ii) Schiff base complex via [3 + 2] cyclo-addition at ambient condition.  

PubMed

A novel bis(?-NN'-tetrazolate) bridged centrosymmetric dinuclear nickel(ii) Schiff base complex [Ni2(L)2(PTZ)2]2H2O2CH3CN (HL is a tridentate Schiff base, 2-((2-(ethylamino)ethylimino)methyl)-6-methoxyphenol and HPTZ is 5-pyrazinyltetrazole) has been synthesized via [3 + 2] cyclo-addition reaction of 2-cyanopyrazine and sodium azide in presence of nickel(ii) acetate tetrahydrate and HL. The structure of the complex is confirmed by single crystal X-ray diffraction analysis. The combination of H-bonding and C-H? interactions creates a 3(6)-hxl topological supramolecular network. The acetonitrile molecules are encapsulated as a hydrophobic guest within the 2D supramolecular network. PMID:24577138

Das, Mithun; Harms, Klaus; Chattopadhyay, Shouvik

2014-04-21

169

Zn(II), Ni(II), Cu(II) and Pb(II) complexes of tridentate asymmetrical Schiff base ligands: Synthesis, characterization, properties and biological activity  

NASA Astrophysics Data System (ADS)

New asymmetrical tridentate Schiff base ligands were synthesized using 1,2-phenylenediamine, 4-methyl-1,2-phenylenediamine, 2-hydroxy-1-napthaldehyde, 9-anthracenecarboxaldehyde. Schiff base ligands and their metal complexes were synthesised and characterized by using FT-IR, 1H NMR, 13C NMR, UV-Vis, XRD, ESR, elemental analysis and fluorescence studies. The antimicrobial activity of the ligands and their metal complexes were studied against Staphylococcus aureus ATCC 29213, S. aureus ATCC 25923, Streptococcus mutans RSHM 676, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853. The determination of the antibacterial activity was done using the broth microdilution methods. In general, it has been determined that the studied compounds have MIC values similar to Gram-positive and Gram-negative bacteria. It has been found that Ni, Pb, Zn derivatives of HL1A and ZnL2A has lower MIC values than ampicillin for P. aeruginosa ATCC 27853 strain.

?ahin, Mustafa; Koak, Nuriye; Erdenay, Damla; Arslan, U?ur

2013-02-01

170

Synthesis, spectral characterization and DNA binding of Schiff-base metal complexes derived from 2-amino-3-hydroxyprobanoic acid and acetylacetone.  

PubMed

Four new metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H3L) resulted from the condensation of the amino acid 2-amino-3-hydroxyprobanoic acid (serine) and acetylacetone have been synthesized and characterized by, elemental analyses, ES-MS, IR, UV-Vis., 1H NMR, 13C NMR, ESR, thermal analyses (TGA and DTG) and magnetic measurements. The results showed that the Schiff-base ligand acts as bi-negative tridentate through the azomethine nitrogen, the deprotonated carboxylate oxygen and the enolic carbonyl oxygen. The optical band gaps measurements indicated the semi-conducting nature of these complexes. Molecular docking was used to predict the binding between the Schiff base ligand with the receptor of prostate cancer mutant H874Y. The interactions between the Cu(II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA in an intercalative mode. PMID:24858353

Hosny, Nasser Mohammed; Hussien, Mostafa A; Radwan, Fatima M; Nawar, Nagwa

2014-11-11

171

Synthesis, spectral characterization and DNA binding of Schiff-base metal complexes derived from 2-amino-3-hydroxyprobanoic acid and acetylacetone  

NASA Astrophysics Data System (ADS)

Four new metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H3L) resulted from the condensation of the amino acid 2-amino-3-hydroxyprobanoic acid (serine) and acetylacetone have been synthesized and characterized by, elemental analyses, ES-MS, IR, UV-Vis., 1H NMR, 13C NMR, ESR, thermal analyses (TGA and DTG) and magnetic measurements. The results showed that the Schiff-base ligand acts as bi-negative tridentate through the azomethine nitrogen, the deprotonated carboxylate oxygen and the enolic carbonyl oxygen. The optical band gaps measurements indicated the semi-conducting nature of these complexes. Molecular docking was used to predict the binding between the Schiff base ligand with the receptor of prostate cancer mutant H874Y. The interactions between the Cu(II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA in an intercalative mode.

Hosny, Nasser Mohammed; Hussien, Mostafa A.; Radwan, Fatima M.; Nawar, Nagwa

2014-11-01

172

Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: synthesis, characterization, properties and biological activity.  

PubMed

A series of metal complexes were synthesized from equimolar amounts of Schiff bases: 1,4-bis[3-(2-hydroxy-1-naphthaldimine)propyl]piperazine (bappnaf) and 1,8-bis[3-(2-hydroxy-1-naphthaldimine)-p-menthane (damnaf) with metal chlorides. All of synthesized compounds were characterized by elemental analyses, spectral (UV-vis, IR, (1)H-(13)C NMR, LC-MS) and thermal (TGA-DTA) methods, magnetic and conductance measurements. Schiff base complexes supposed in tetragonal geometry have the general formula [M(bappnaf or damnaf)]Cl.nH(2)O, where M=Cr(III), Co(III) and n=2, 3. But also Fe(III) complexes have octahedral geometry by the coordination of two water molecules and the formula is [Fe(bappnaf or damnaf)(H(2)O)(2)]Cl. The changes in the selected vibration bands in FT-IR indicate that Schiff bases behave as (ONNO) tetradentate ligands and coordinate to metal ions from two phenolic oxygen atoms and two azomethine nitrogen atoms. Conductance measurements suggest 1:1 electrolytic nature of the metal complexes. The synthesized compounds except bappnaf ligand have the antimicrobial activity against the bacteria: Escherichia coli (ATCC 11230), Yersinia enterocolitica (ATCC 1501), Bacillus magaterium (RSKK 5117), Bacillus subtilis (RSKK 244), Bacillus cereus (RSKK 863) and the fungi: Candida albicans (ATCC 10239). These results have been considerably interest in piperazine derivatives due to their significant applications in antimicrobial studies. PMID:17904895

Keskio?lu, Eren; Gndzalp, Ayla Balaban; Cete, Servet; Hamurcu, Fatma; Erk, Birgl

2008-08-01

173

Switching and redox isomerism in first-row transition metal complexes containing redox active Schiff base ligands.  

PubMed

The reversible redox isomerisms in first row transition metal complexes of the type ML2 were studied. The six ML2 complexes (M = Mn(III) (), Fe(II) (), Co(III) (), Ni(II) (), Cu(II) () and Zn(II) ()) were synthesized with a redox active Schiff base ligand [2-(3,5-di-tert-butyl-2-hydroxyphenylamino)-4-chlorophenol] (H3L) presenting different oxidation states from -2 to 0 (L(2-), L(-) and L(0)). EPR spectra and magnetic susceptibility measurements indicate the presence of complexes of the type [Mn(III)(L(2-))(L(-))] () with S = 1/2, [Fe(II)(L(-))2] () with S = 2, [Co(III)(L(2-))(L(-))] () with S = 1/2, [Ni(II)(L(-))2] () with S = 1, [Cu(II)(L(-))2] () with S = 1/2 and [Zn(II)(L(-))2] () with S = 0 at high temperatures. Temperature and solvents influence the electronic structures of the species and give several valence tautomers. At low temperatures these complexes present thermally induced metal-to-ligand (, , ) or ligand-to-ligand (in , ) electron transfer (partial or total), resulting in compounds of the type [Mn(IV)(L(2-))2] () with S = 1/2, [Fe(III)(L(-))(L(2-))] () with S = 1, [Ni(III)(L(2-))(L(-))] () with S = 0, [Cu(II)(L(2-))(L(0))] () with S = 1/2 and [Zn(II)(L(2-))(L(0))] () with S = 1. This electron transfer is in agreement with the general trend in the redox potentials of the first row transition metal ions from Mn(ii) to Zn(ii), and it allows us to prepare and stabilize reversibly switchable tautomeric forms in transition metal complexes with redox-active ligands. PMID:25233051

Sasmal, Ashok; Garribba, Eugenio; Gmez-Garca, Carlos J; Desplanches, Cdric; Mitra, Samiran

2014-11-14

174

A N,N'-dioxide-copper(II) complex as an efficient catalyst for the enantioselective and diastereoselective Mannich-type reaction of glycine Schiff bases with aldimines.  

PubMed

Mild mannered! A highly diastereo- and enantioselective Mannich-type reaction of glycine Schiff base 1 has been developed by using the N,N'-dioxide L-Cu(II) complex as a catalyst. Various optically active anti-alpha,beta-diamino acid esters were obtained in good yields with up to 96:4 d.r. and 97% ee. This straightforward method features a low catalyst loading and mild reaction conditions. PMID:19229921

Shang, Deju; Liu, Yanling; Zhou, Xin; Liu, Xiaohua; Feng, Xiaoming

2009-01-01

175

Catalytic formation of ethylene carbonate from supercritical carbon dioxide\\/ethylene oxide mixture with tetradentate Schiff-base complexes as catalyst  

Microsoft Academic Search

Various tetradentate Schiff-base aluminum complexes (designated as SalenAlX) were prepared and used as catalysts for the synthesis of ethylene carbonate from supercritical carbon dioxide\\/ethylene oxide mixture. Their catalytic activities can be markedly enhanced in the presence of a Lewis base or quaternary salt. With SalenAlCl\\/n-Bu4NBr as catalyst, the formation rate of ethylene carbonate is up to 2220 turnovers\\/h and about

Xiao-Bing Lu; Xiou-Juan Feng; Ren He

2002-01-01

176

Distinguishable Zn(II) and Pb(II) template effects on forming pendant-armed Schiff-base macrocyclic complexes including a remarkable Pb(II)-? macrocyclic complex.  

PubMed

36-Membered [2 + 2] half-fold Schiff-base macrocyclic dinuclear Zn(II) complexes (1a and 1b) and 18-membered [1 + 1] Schiff-base macrocyclic mononuclear Pb(II) complexes (2 and 3) are produced from the condensation between 1,3-propanediamine and a pair of extended dialdehydes with different functional pendant arms (H2hpdd and H2pdd) because of the distinguishable cationic template effects. It is very interesting to mention that a unique intramolecular Pb(II)-? macrocyclic complex 2 with an uncommon ?(3)-coordination type is achieved under ambient conditions and it can remain stable both in the solid state and in solution. The subtle variations of pendant-arms in the macrocyclic ligands H2hpdd and H2pdd yield different Pb(II) complexes, where the competition between Pb(II)-? and Pb(II)-NO3(-) electrostatic interactions as well as the combination of steric and electronic effects of pendant arms are believed to play important roles. PMID:25188754

Zhang, Kun; Geng, Jiao; Jin, Chao; Huang, Wei

2014-11-01

177

Photo- and electroluminescent properties of zinc(II) complexes with tetradentate Schiff bases, derivatives of salicylic aldehyde  

NASA Astrophysics Data System (ADS)

It is studied how the introduction of various substituents into the composition of organic ligands affects the photoluminescence spectra of new zinc(II) complexes with tetradentate Schiff bases H2L (derivatives of salicylic aldehyde (H2SAL1, H2SAL2) and o-vanillin (H2MO1, H2MO2) with ethylenediamine and o-phenylenediamine) in the form of bulk solids and thin films. It is demonstrated that the emission spectra of bulk solid complexes without o-phenylenediamine bridges (ZnSAL1 and ZnMO1) contain additional long-wavelength bands compared to the spectra of corresponding thin films. In the case of films obtained from [ZnSAL1]2 dimer complexes, the long-wavelength band is dominant. At the same time, the photoluminescence spectra of ZnSAL2 and ZnMO2 complexes with o-phenylenediamine bridges are similar in the case of solid samples and thin films. The electroluminescent properties of organic light-emitting diodes (OLEDs) with the ITO/?-NPD/ZnL/Ca:Al structure are studied. The bathochromic shift of the electroluminescence peaks of OLEDs with respect to the photoluminescence spectra of bulk solid samples and thin films is probably related to the formation of exciplexes at the ?-NPD/ZnL interface. The electroluminescence spectra of OLEDs based on [ZnSAL1]2 show a hypsochromic shift of the emission maximum, which can be caused by a shift of the recombination region into the ?-NPD layer.

Vashchenko, A. A.; Lepnev, L. S.; Vitukhnovskii, A. G.; Kotova, O. V.; Eliseeva, S. V.; Kuz'mina, N. P.

2010-03-01

178

Diorganotin(IV) complexes of biologically potent 4( 3H)-quinazolinone derived Schiff bases: Synthesis, spectroscopic characterization, DNA interaction studies and antimicrobial activity  

NASA Astrophysics Data System (ADS)

Four Schiff base ligands and their corresponding organotin(IV) complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR, MS and thermal studies. The Schiff bases are obtained by the condensation of 3-amino-2-methyl-4( 3H)-quinazolinone with different substituted aldehydes. The elemental analysis data suggest the stoichiometry to be 1:1 ratio formation. Infrared spectral data agreed with the coordination to the central metal ion through imine nitrogen, lactam oxygen and deprotonated phenolic oxygen atoms. All the synthesized compounds have been evaluated for antimicrobial activity against selected species of microorganisms. In addition, DNA binding/cleavage capacity of the compounds was analyzed by absorption spectroscopy, viscosity measurements and gel electrophoresis methods.

Prasad, Kollur Shiva; Kumar, Linganna Shiva; Chandan, Shivamallu; Jayalakshmi, Basvegowda; Revanasiddappa, Hosakere D.

2011-10-01

179

Synthesis of gadolinium(III) and samarium(III) complexes of new potentially heptadentate (N 4O 3) tripodal Schiff base ligands, and a theoretical study  

Microsoft Academic Search

Two new potentially heptadentate N4O3 Schiff base ligands {N[(CH2)3NCH(2-OH-3,5-t-Bu2C6H2)]3} (H3L1) and {N[(CH2)3NCH(2-OH-3,5-t-Bu2C6H2)]2 [(CH2)2NCH(2-OH-3,5-t-Bu2C6H2)]} (H3L2) were synthesized and characterized by various spectroscopic methods. The heptadentate N4O3 Schiff bases, H3L1 and H3L2, were derived from the condensation reaction of two tripodal tetraamine ligands, tris(3-aminopropyl)amine and (2-aminoethyl)-bis(3-aminopropyl)amine with 3 equiv. of 3,5-di-tert-butylsalicylaldehyde, respectively. The neutral gadolinium(III) and samarium(III) complexes, [Ln(L)], of these bulky

Sadegh Salehzadeh; Seyedeh Mahnaz Nouri; Hassan Keypour; Mojtaba Bagherzadeh

2005-01-01

180

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

PubMed

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 1.3710(5), 1.8110(5) and 3.2110(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. PMID:25555321

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

181

Hydrolysis of Letrozole catalyzed by macrocyclic Rhodium (I) Schiff-base complexes.  

PubMed

Ten mononuclear Rhodium (I) complexes were synthesized by macrocyclic ligands having N4 and N2O2 donor sites. Square planar geometry is assigned based on the analytical and spectral properties for all complexes. Rh(I) complexes were investigated as catalysts in hydrolysis of Nitrile group containing pharmaceutical drug Letrozole. A comparative study showed that all the complexes are efficient in the catalysis. The percent yields of all the catalytic reaction products viz. drug impurities were determined by spectrophotometric procedures and characterized by spectral studies. PMID:25554950

Reddy, P Muralidhar; Shanker, K; Srinivas, V; Krishna, E Ravi; Rohini, R; Srikanth, G; Hu, Anren; Ravinder, V

2015-03-15

182

Tailoring dicobalt Pacman complexes of Schiff-base calixpyrroles towards dioxygen reduction catalysis.  

PubMed

By modifying the mouth of a macrocyclic dicobalt Pacman complex, it is possible to both isolate new bridging-superoxo and hydroxyl complexes and to tune the reactivity of this system towards catalytic four-electron reduction of dioxygen to water. PMID:20087495

Askarizadeh, Elham; Yaghoob, Sahar Bani; Boghaei, Davar M; Slawin, Alexandra M Z; Love, Jason B

2010-02-01

183

Two one-dimension copper(II) coordination polymers based on imine-based bidentate Schiff-base ligand: Synthesis, crystal structure and luminescent properties  

NASA Astrophysics Data System (ADS)

Two new one-dimension copper(II) coordination polymers [CuL 2(NCS) 2] n ( 1) and [CuL 2(NO 3) 2] n ( 2) (L = (C 5H 4N)C(CH 3) dbnd N-N dbnd (CH 3)C(C 5H 4N)) have been synthesized and characterized by IR, elemental analysis, TG technique and X-ray crystallography. Each Cu(II) atom has a distorted octahedral N 6 ( 1) or N 4O 2 ( 2) environment with four pyridyl N atoms from four ligands and two N atoms from two NCS - anions for polymer 1 or two O atoms from two NO 3- anions for polymer 2, respectively. A pair of bis-monodentate bridging ligands links two Cu(II) centers to form one dimension chain structure containing bimetallic 22-membered macrometallacyclic rings. 1D chain is held together with its neighboring ones via C-H⋯S hydrogen bonds for 1 and C-H⋯O hydrogen bonds, C-H⋯? interactions for 2 to form a 3D supramolecular structure, respectively. The luminescent properties of the polymers 1 and 2 were investigated in the solid state at room temperature.

Dang, Dong-Bin; Li, Meng-Meng; Bai, Yan; Wang, Jun-Li

2011-12-01

184

Synthesis of novel p-tert-butylcalix[4]arene Schiff bases and their complexes with C60, potential HIV-Protease inhibitors  

NASA Astrophysics Data System (ADS)

Some p-tert-butylcalix[4]arene Schiff base crown ethers were synthesized, characterized using 1H, 13C-NMR, DEPT 135 and Mass spectrometry. Their complexes with C60 were isolated and characterized. The inhibition effect of these complexes on HIVP was studied and found that complexes of 9 and 10 have comparable Ki values to Pepstatine which is known as HIVP inhibitor and used as a control. The synthesis of the ligands, complexes and the inhibition behavior are discussed in this article.

Khadra, Khalid Abu; Mizyed, Shehadeh; Marji, Deeb; Haddad, Salim F.; Ashram, Muhammad; Foudeh, Ayat

2015-02-01

185

Crystal structure and antitumor activity of some rare earth metal complexes with Schiff base  

Microsoft Academic Search

The ligand 1-phenyl-3-methyl-5-hydroxy-4-pyrazolyl phenyl ketone (PMBP) isonicotinoyl hydrazone (H2L) was prepared by condensation of PMBP with isoniazid. Seven complexes of rare earth metals with H2L were synthesized and characterized on the basis of elemental analyses, IR, UV, 1H NMR spectra and thermal analyses. The general formula of the complexes is Ln(HL)33.5H2O (where Ln(III)=La, Eu, Gd, Tb, Dy, Ho and Er).

Zheng-Yin Yang; Ru-Dong Yang; Fa-Shen Li; Kai-Bei Yu

2000-01-01

186

A series of transition and non-transition metal complexes from a N?O? hexadentate Schiff base ligand: Synthesis, spectroscopic characterization and efficient antimicrobial activities.  

PubMed

Some transition and non-transition metal complexes of the hexadentate N?O? donor Schiff base ligand 1,8-N-bis(3-carboxy)disalicylidene-3,6-diazaoctane-1,8-diamine, abbreviated to H?fsatrien, have been synthesized. All the 14 metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic (UV-Vis, IR, NMR, ESR) data. The analytical data helped to elucidate the structures of the metal complexes. The Schiff base, H?fsatrien, is found to act as a dibasic hexadentate ligand using N?N?O? donor set of atoms (leaving the COOH group uncoordinated) leading to an octahedral geometry for the complexes around all the metal ions except VO(+) and UO?(+). However, surprisingly the same ligand functions as a neutral hexadentate and neutral tetradentate one towards UO?(+) and VO(+), respectively. In case of divalent metal complexes they have the general formula [M(H?fsatrien)] (where M stands for Cu, Co, Hg and Zn); for trivalent metal complexes it is [M(H?fsatrien)]XnH?O (where M stands for Cr, Mn, Fe, Co and X stands for CH?COO, Cl, NO?, ClO?) and for the complexes of VO(+) and UO?(+), [M(H?fsatrien)]Y (where M=VO and Y=SO?); M=UO? and Y=2 NO?). The Schiff base ligand and most of the complexes have been screened in vitro to judge their antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Aspergillus niger and Pencillium chrysogenum) activities. PMID:20801711

Sarkar, Saikat; Dey, Kamalendu

2010-11-01

187

DFT study on second-order nonlinear optical properties of a series of mono Schiff-base M(II) (M = Ni, Pd, Pt) complexes  

NASA Astrophysics Data System (ADS)

A series of mono Schiff-base M(II) (M = Ni, Pd, Pt) complexes based on the crystal data are designed. Density Functional Theory (DFT) method was employed to investigate the second-order nonlinear optical (NLO) properties of all metal complexes. The results show that the second-order NLO properties of metal complexes are intensively sensitive to the exchange of donor/acceptor because of the differences of the extent of charge separation and the intraligand charge transfer (ILCT) processes. The metal ions do not offer direct contributions to second-order NLO responses because they are as electron bridges for transferring electrons in CT processes.

Liu, Chun-Guang; Qiu, Yong-Qing; Sun, Shi-Ling; Chen, Hui; Li, Na; Su, Zhong-Min

2006-10-01

188

Anion-dependent assembly of four sensitized near-infrared luminescent heteronuclear Zn(II)-Yb(III) Schiff base complexes from a trinuclear Zn(II) complex.  

PubMed

Four anion-dependent 0D Zn(II)-Yb(III) heterometallic Schiff base complexes, [YbZn2L2(OAc)4]ClO4 (2), YbZnL2(NO3)3 (3), [(YbL)2(H2O)Cl(OAc)]2[ZnCl4]2 (4), and YbZnL(OAc)4 (5), were assembled through central metal substitution or reconstruction from homotrinuclear Zn(II) complex {[(Zn(OAc)(H2O)L]2Zn}(ClO4)24H2O [1; HL = 2-ethoxy-6-[(pyridin-2-ylmethylimino)methyl]phenol] with different Yb(III)X3 salts [X = ClO4 (2), NO3 (3), Cl (4), and OAc (5)], in which the Zn(II)-sensitized near-infrared luminescent performances in the four complexes 2-5 are closely related to their structural models. PMID:25158297

Zheng, Zhi-Peng; Ou, Yan-Jun; Hong, Xu-Jia; Wei, Lei-Ming; Wan, Lin-Tao; Zhou, Wo-Hua; Zhan, Qing-Guang; Cai, Yue-Peng

2014-09-15

189

DNA damage induced by a chromium(III) Schiff base complex is reversible under physiological condition.  

PubMed

[Cr(naphen)(H2O)(2)]+, where naphen is 1,2-bis(naphthylideneamino)ethane having the basic salen moiety, has been characterized structurally. [Cr(naphen)(H2O)(2)]+, which has an extended aromatic system and binds with calf thymus DNA (CT DNA) intercalatively, has been found to promote DNA cleavage in the presence of biological reductant such as ascorbate and oxidant like hydrogen peroxide. Results of electron paramagnetic resonance (EPR) experiments suggest involvement of hydroxyl radicals in the oxidative cleavage of DNA in the presence of the Cr(III) complex and hydrogen peroxide. The cell viability study on nicked DNA by [Cr(naphen)(H2O)(2)]+ has shown that the damage brought about to DNA could be repaired by Escherichia coli DNA repair enzymes. PMID:16202452

Vaidyanathan, V G; Weyhermuller, T; Nair, Balachandran Unni; Subramanian, J

2005-11-01

190

Structure, photochemistry and magnetic properties of tetrahydrogenated Schiff base chromium(III) complexes.  

PubMed

Four mononuclear chromium(III) complexes [Cr(L((1)))(en)]Br0.3Cl0.7 (1), [Cr(L((1)))(pr)]Cl (2), [Cr(L((2)))(en)]ClO4 (3), [Cr(L((2)))(pr)]Cl (4) along with one dinuclear ?-methoxo [Cr(?-OMe)(L1)]2 (5) were synthesized (en=1,2-ethanediamine, pr=1,3-diaminopropane H2L((1))=Tetrahydrosalen=H2[H4]salen=N,N'-bis(2-hydroxybenzyl)-1,2-ethanediamine, H2L((2))=Tetrahydrosalpr=H2[H4]salpr=N,N'-bis(2-hydroxybenzyl)-1,3-diaminopropane). The competitive reactions in the presence of EDTA were carried out and the first-order rate constants k(1)=(5.20.2)10(-3)h(-1)complex 5 exhibits a strong antiferromagnetic coupling with the J=-10.8cm(-1). PMID:25637815

Liu, Bin; Chai, Jie; Feng, SiSi; Yang, BinSheng

2015-04-01

191

Metal complexes of a new potentially heptadentate(N 7) tripodal Schiff base ligand. Synthesis, NMR studies and ab initio calculations  

Microsoft Academic Search

Tris(3-aminopropyl)amine, 2-pyridinecarboxaldehyde and a number of metal ions were used to prepare metal complexes of a new fully condensed potentially heptadentate(N7) tripodal Schiff base ligand (L333). The resulting complexes, [M(L333)](ClO4)2 {M= Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II); L333=[N(CH2CH2CH2NCH(C5H4N))3]}, were characterized by microanalysis, IR and electronic spectra in all cases and by NMR spectra in the case of Zn(II)

Sadegh Salehzadeh; Seyed Amrollah Javarsineh; Hassan Keypour

2006-01-01

192

Synthesis, characterization, and X-ray crystal structure analysis of Cd(??) and Cu(II) complexes of an acyclic pentadentate Schiff base  

Microsoft Academic Search

Cd(??) and Cu(II) complexes of an acyclic pentadentate Schiff base were prepared by template condensation of two equivalents of 2-acetylpyridine with one equivalent of bis(3-aminopropyl)amine in methanol. The resulting complexes [CdL(NO3)]ClO4 (1) and [CuL](ClO4)2 CH3CN (2) were characterized by X-ray crystallography, elemental analysis, IR and mass spectrometry in both cases and by NMR in the case of 1. The

Sadegh Salehzadeh; Reza Golbedaghi; Allan G. Blackman

2010-01-01

193

Synthesis, characterization, and crystal structure of a Ni(II) complex of an acyclic pentadentate Schiff base; an agreement between the experimental and theoretical results  

Microsoft Academic Search

A Ni(II) complex of an acyclic pentadentate Schiff base was prepared by template condensation of two equivalents of 2-acetylpyridine with one equivalent of bis(3-aminopropyl)amine in the presence of Ni(II) in methanol. The resulting complex, [NiL33(MeOH)](ClO4)2 CH3OH, was characterized by X-ray crystallography, elemental analysis, and IR spectrophotometry. The X-ray crystallographic structure revealed a six-coordinate, distorted octahedral geometry in which the

Sadegh Salehzadeh; Reza Golbedaghi; Hamid Reza Khavasi

2009-01-01

194

Synthesis and Crystal Structure of a Dibridged Dinuclear Cadmium(II) Complex with Schiff Base 2-[(2-Dimethylaminoethylimino)methyl]-6-methoxyphenol  

Microsoft Academic Search

A tetradentate Schiff base compound 2-[(2-dimethylaminoethylimino)methyl]-6-methoxyphenol (HL) reacts with cadmium nitrate and ammonium thiocyanate in a methanol solution to give a dinuclear complex [Cd2L2(?1,1-NCS)(NCS)(OH2)]. The complex was characterized by physico-chemical and spectroscopic methods. X-ray crystallography indicates that each Cd(II) atom is in a distorted octahedral coordination. The two metal atoms are bridged by one phenolate O and one end-on thiocyanate

San-Jun Peng; Hai-Yun Hou; Qiong Wang; Tao Yang; Cong-Shan Zhou

2008-01-01

195

Synthesis, characterization and electrochemical behaviour of cobalt(II) and cobalt(III):O 2- complexes, respectively, with linear and tripodal tetradentate ligands derived from Schiff bases  

NASA Astrophysics Data System (ADS)

New octahedral cobalt complexes with linear and tripodal tetradentate ligands derived from Schiff bases have been synthesized and characterized using elemental analysis, molar conductance, IR spectra, magnetic measurements, electronic and ESR spectra. The experimental results support the binding of linear ligands with two N and two O donor sites to cobalt ion. They show a square planar geometry and tripodal ligands coordinated to the metal ion by only one nitrogen atom, giving an arrangement of NO 3 donor groups, the other axial sites being occupied by the molecular oxygen and/or the aquo molecules. From the results of cyclic voltammetry it is shown that chelate structure and ligand geometry and electron donating effect of the ligand substituents are among the factors influencing the redox potentials of the complexes. Linear ligands lead to high-spin cobalt(II) complexes. They do not interact with dioxygen and stabilize the Co(II) state counter to their related Schiff-base complexes. The low-spin complexes with tripodal ligands are O 2 adducts and the configuration in these complexes is best formulated as [Co IIIO 2-].

Djebbar-Sid, S.; Benali-Baitich, O.; Deloume, J. P.

2001-07-01

196

2-Hydroxynaphthalene-1-carbaldehyde- and 2-(aminomethyl)pyridine-based Schiff base Cu(II) complexes for DNA binding and cleavage.  

PubMed

Three mononuclear Cu(II) complexes, [CuCl(naph-pa)] (1), [Cu(bipy)(naph-pa)]Cl (2), and [Cu(naph-pa)(phen)]Cl (3) ((naph-pa)=Schiff base derived from the condensation of 2-hydroxynaphthalene-1-carbaldehyde and 2-picolylamine (=2-(aminomethyl)pyridine), bipy=2,2'-bypiridine, and phen=1,10-phenanthroline) were synthesized and characterized. Complex 1 exhibits square-planar geometry, and 2 and 3 exhibit square pyramidal geometry, where Schiff base and bipy/phen act as NNO and as NN donor ligands, respectively. CT (Calf thymus)-DNA-binding studies revealed that the complexes bind through intercalative mode and show good binding propensity (intrinsic binding constant K(b): 0.9810(5), 2.2210(5), and 2.6710(5) M(-1) for 1-3, resp.). The oxidative and hydrolytic DNA-cleavage activity of these complexes has been studied by gel electrophoresis: all the complexes displayed chemical nuclease activity in the presence and absence of H(2)O(2). From the kinetic experiments, hydrolytic DNA cleavage rate constants were determined as 2.48, 3.32, and 4.10 h(-1) for 1-3, respectively. It amounts to (0.68-1.14)10(8)-fold rate enhancement compared to non-catalyzed DNA cleavage, which is impressive. The complexes display binding and cleavage propensity to DNA in the order of 3>2>1. PMID:23081926

Reddy, Pulimamidi Rabindra; Shilpa, Addla

2012-10-01

197

Synthesis, spectroscopic and catalytic studies of Cu(II), Co(II) and Ni(II) complexes immobilized on Schiff base modified chitosan  

NASA Astrophysics Data System (ADS)

A new class of bidentate (N, O) Schiff base ligand (L) has been derived from the functional biopolymer (chitosan) and 1,2-diphenylethanedione in 1:1 M ratio. This ligand has been used to synthesise the new first row transition metal complexes of Cu(II), Co(II) and Ni(II). The structural properties of the ligand and the synthesized tetra-coordinated complexes have been investigated by elemental analysis, magnetic study, molar conductance measurement and spectroscopic methods viz. FT-IR, UV-Vis., 1H NMR, 13C NMR and XRD. The spectral evidences strongly suggested the square planar geometry to the complexes. The XRD studies proved that crystallinity of chitosan has been diminished after Schiff base formation and metal complexation of L. Thermal and surface properties of the complexes have been also discussed from the investigation of their TG-DTG curves and SEM images, respectively. In addition, the catalytic efficiency of these complexes has been studied in the cyclohexane oxidation reaction using H2O2 as oxidant at 70 C.

Antony, R.; Theodore David Manickam, S.; Saravanan, K.; Karuppasamy, K.; Balakumar, S.

2013-10-01

198

Chemopreventive Evaluation of a Schiff Base Derived Copper (II) Complex against Azoxymethane-Induced Colorectal Cancer in Rats  

PubMed Central

Background Based on the potential of Schiff base compounds to act as sources for the development of cancer chemotherapeutic agents, this in vivo study was performed to investigate the inhibitory properties of the synthetic Schiff base compound Cu(BrHAP)2 on colonic aberrant crypt foci (ACF). Methodology This study involved five groups of male rats. The negative control group was injected with normal saline once a week for 2 weeks and fed 10% Tween 20 for 10 weeks, the cancer control group was subcutaneously injected with 15 mg/kg azoxymethane once per week for two consecutive weeks, the positive control group was injected with 15 mg/kg azoxymethane once per week for two consecutive weeks and 35 mg/kg 5-fluorouracil (injected intra-peritoneally) for 4 weeks, and the experimental groups were first injected with 15 mg/kg azoxymethane once per week for two consecutive weeks and then fed 2.5 or 5 mg/kg of the Schiff base compound once a day for 10 weeks. Application of the Schiff base compound suppressed total colonic ACF formation by up to 72% to 74% (P<0.05) when compared with the cancer control group. Analysis of colorectal specimens revealed that treatments with the Schiff base compound decreased the mean crypt scores in azoxymethane-treated rats. Significant elevations of superoxide dismutase, glutathione peroxidase and catalase activities and a reduction in the level of malondialdehyde were also observed. Histologically, all treatment groups exhibited significant decreases in dysplasia compared to the cancer control group (P<0.05). Immunohistochemical staining demonstrated down-regulation of the PCNA protein. Comparative western blot analysis revealed that COX-2 and Bcl2 were up-regulated and Bax was down-regulated compared with the AOM control group. Conclusion The current study demonstrated that the Cu(BrHAP)2 compound has promising chemoprotective activities that are evidenced by significant decreases in the numbers of ACFs in azoxymethane-induced colon cancer. PMID:24618844

Hajrezaie, Maryam; Hassandarvish, Pouya; Moghadamtousi, Soheil Zorofchian; Gwaram, Nura Suleiman; Golbabapour, Shahram; NajiHussien, Abdrabuh; Almagrami, Amel Abdullah; Zahedifard, Maryam; Rouhollahi, Elham; Karimian, Hamed; Fani, Somaye; Kamalidehghan, Behnam; Majid, Nazia Abdul; Ali, Hapipah Mohd; Abdulla, Mahmood Ameen

2014-01-01

199

Spectral characterization, optical band gap calculations and DNA binding of some binuclear Schiff-base metal complexes derived from 2-amino-ethanoic acid and acetylacetone  

NASA Astrophysics Data System (ADS)

Bi-nuclear metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H2L) resulted from the condensation of 2-amino-ethanoic acid (glycine) and acetylacetone have been synthesized and characterized by elemental analyses, Raman spectra, FT-IR, ES-MS, UV-Vis., 1H NMR, ESR, thermal analyses (TG, DTG and DTA) and magnetic measurements. The results showed that, the Schiff base ligand can bind two metal ions in the same time. It coordinates to the first metal ion as mono-negative bi-dentate through azomethine nitrogen and enolic carbonyl after deprotonation. At the same time, it binds to the second metal ion via carboxylate oxygen after deprotonation. The thermodynamic parameters E?, ?H?, ?G? and ?S? have been calculated by Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. The optical band gaps of the isolated complexes have been calculated from absorption spectra and the results indicated semi-conducting nature of the investigated complexes. The interactions between the copper (II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA.

Hussien, Mostafa A.; Nawar, Nagwa; Radwan, Fatima M.; Hosny, Nasser Mohammed

2015-01-01

200

Structural, spectral and biological studies of binuclear tetradentate metal complexes of N 3O Schiff base ligand synthesized from 4,6-diacetylresorcinol and diethylenetriamine  

NASA Astrophysics Data System (ADS)

The binuclear Schiff base, H 2L, ligand was synthesized by reaction of 4,6-diacetylresorcinol with diethylenetriamine in the molar ratio 1:2. The coordination behavior of the H 2L towards Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cr(III), VO(IV) and UO 2(VI) ions has been investigated. The elemental analyses, magnetic moments, thermal studies and IR, electronic, 1H NMR, ESR and mass spectra were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with two N 3O-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The bonding sites are the nitrogen atoms of the azomethine and amine groups and the oxygen atoms of the phenolic groups. The metal complexes exhibit either square planar, tetrahedral, square pyramid or octahedral structures. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria ( Staphylococcus aureus and Streptococcus pyogenes) as Gram-positive bacteria, and ( Pseudomonas fluorescens and Pseudomonas phaseolicola) as Gram-negative bacteria and two pathogenic fungi ( Fusarium oxysporum and Aspergillus fumigatus) to assess their antimicrobial properties. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

Emara, Adel A. A.

2010-09-01

201

Computational evidence of preferred energy and preferred binding energy in the formation of 1 + 1 versus 2 + 2 macrocyclic Schiff base complexes  

Microsoft Academic Search

This work reports a theoretical study on 1+1 versus 2+2 cyclocondensation reactions between 2,6-diacetylpyridine and 3,6-dioxaoctane-l,8-diamine in the presence of Mg(II) and Pb(II) metal ions. The results of calculations at DFT(B3LYP) level of theory using LanL2DZ, SDD and CEP-121G basis sets were consistent with the experimental observations and all showed that 1+1 and 2+2 macrocyclic Schiff base complexes are preferred

Sadegh Salehzadeh; Mehdi Bayat

2011-01-01

202

A theoretical study on the formation of 1 + 1 versus 2 + 2 macrocyclic Schiff base complexes in the absence of coordinated anions  

Microsoft Academic Search

This work reports a theoretical study on 1+1 against 2+2 cyclocondensation reactions between 2,6-diacetylpyridine and 3,6-dioxaoctane-l,8-diamine in the presence of Mg(II) and Pb(II) metal ions. The results of calculations at DFT(B3LYP) level of theory using LanL2DZ, SDD and CEP-121G basis sets indicate that in the absence of a coordinated anion the 1+1 macrocyclic Schiff base complexes are the preferred products

Sadegh Salehzadeh; Mehdi Bayat

2011-01-01

203

A novel chelate-assisted C?C bond formation on a Cd(II) complex of an asymmetric heptadentate(N 7) tripodal Schiff base ligand  

Microsoft Academic Search

Cadmium(II) complexes of some potentially heptadentate tripodal Schiff base ligands with the general formula N{(CH2)nNCHC5H4N}2{(CH2)mNCHC5H4N}) (where n=m=2, L222; n=2, m=3, L322; n=3, m=2, L332) have been studied. These ligands are products of the full condensation of a number of tripodal tetraamines with 2-pyridinecarboxaldehyde. An unusual reaction of an additional 2-pyridine-carboxaldehyde with a methylene group adjacent to the imine bond only

Sadegh Salehzadeh; Michael D. Ward; Harry Adams

2009-01-01

204

Cu(II) Schiff base complex as a highly efficient catalyst for the synthesis of polyhydroquinoline derivatives via Hantzsch condensation in water.  

PubMed

In the present study, Cu(II) Schiff-base complex is introduced as a highly efficient and green solid catalyst for the unsymmetrical Hantzsch condensation through a four-component coupling of various aldehydes, dimedone, ethyl acetoacetate and ammonium acetate to form polyhydroquinoline derivatives in good to excellent yields. This reaction was carried out in the presence of 1 mol% of catalysts in water at room temperature. The reusability of the catalysts was demonstrated by a five-run test. Remarkable features of this new procedure are cleaner reaction profiles, shorter reactiontimes, simple experimental and work-up procedures. PMID:23701007

Vahdat, Seyed Mohammad

2013-12-01

205

Catalytic asymmetric 1,4-additions of beta-keto esters to nitroalkenes promoted by a bifunctional homobimetallic Co2-Schiff base complex.  

PubMed

Catalytic asymmetric 1,4-addition of beta-keto esters to nitroalkenes is described. 2.5 mol % of a homobimetallic Lewis acid/Brnsted base bifunctional Co2-Schiff base complex smoothly promoted the reaction in excellent yield (up to 99%), diastereoselectivity, and enantioselectivity (up to >30:1 dr and 98% ee). Catalyst loading was successfully reduced to 0.1 mol %. Mechanistic studies suggested that intramolecular cooperative functions of the two Co-metal centers are important for high catalytic activity and stereoselectivity. PMID:20110907

Furutachi, Makoto; Chen, Zhihua; Matsunaga, Shigeki; Shibasaki, Masakatsu

2010-01-01

206

A Schiff Base-Derived Copper (II) Complex Is a Potent Inducer of Apoptosis in Colon Cancer Cells by Activating the Intrinsic Pathway  

PubMed Central

Metal-based drugs with extensive clinical applications hold great promise for the development of cancer chemotherapeutic agents. In the last few decades, Schiff bases and their complexes have become well known for their extensive biological potential. In the present study, we examined the antiproliferative effect of a copper (II) complex on HT-29 colon cancer cells. The Cu(BrHAP)2 Schiff base compound demonstrated a potent antiproliferative effect in HT-29 cells, with an IC50 value of 2.87??g/ml after 72?h of treatment. HT-29 cells treated with Cu (II) complexes underwent apoptosis death, as exhibited by a progressive elevation in the proportion of the G1 cell population. At a concentration of 6.25??g/ml, the Cu(BrHAP)2 compound caused significant elevation in ROS production following perturbation of mitochondrial membrane potential and cytochrome c release, as assessed by the measurement of fluorescence intensity in stained cells. Furthermore, the activation of caspases 3/7 and 9 was part of the Cu (II) complex-induced apoptosis, which confirmed the involvement of mitochondrial-mediated apoptosis. Meanwhile, there was no significant activation of caspase-8. Taken together, these results imply that the Cu(BrHAP)2 compound is a potential candidate for further in vivo and clinical colon cancer studies to develop novel chemotherapeutic agents derived from metal-based agents. PMID:24737979

Hajrezaie, Maryam; Paydar, Mohammadjavad; Zorofchian Moghadamtousi, Soheil; Hassandarvish, Pouya; Gwaram, Nura Suleiman; Zahedifard, Maryam; Rouhollahi, Elham; Karimian, Hamed; Looi, Chung Yeng; Ali, Hapipah Mohd; Abdul Majid, Nazia; Abdulla, Mahmood Ameen

2014-01-01

207

Synthesis, experimental and theoretical characterization of N,N'-dipyridoxyl (1,4-butanediamine) Schiff-base ligand and its Cu(II) complex.  

PubMed

A new N,N'-dipyridoxyl(1,4-butanediamine) [=H(2)BS] Schiff-base ligand and its Cu(II) salen complex, [Cu(BS)(H(2)O)(CH(3)OH)], were synthesized and characterized by IR, UV-vis, (1)H NMR, mass spectrometry and elemental analysis. Also, full optimization of the geometries, (1)H NMR chemical shifts (for the H(2)BS) and vibrational frequencies were calculated by using density functional theory (DFT) method. Structure of the H(2)BS ligand is not planar, i.e. two pyridine rings are not in the same plane. In the structure of the Cu complex, the Schiff-base ligand acts as a dianionic tetradentate ligand in N, N, O(-), O(-) manner. The coordinating atoms of BS(2-) occupy equatorial positions of the octahedral complex, where the H(2)O and CH(3)OH ligands locate at axial positions. The calculated results are in good agreement with the experimental data, confirming the suitability of the proposed and optimized structures for the H(2)BS ligand and its Cu complex. PMID:21233009

Eshtiagh-Hosseini, Hossein; Housaindokht, Mohammad R; Beyramabadi, S Ali; Tabatabaei, S Hamid Mir; Esmaeili, Abbas Ali; Khoshkholgh, Malihe Javan

2011-03-01

208

An unexpected Schiff base-type Ni(II) complex: Synthesis, crystal structures, fluorescence, electrochemical property and SOD-like activities  

NASA Astrophysics Data System (ADS)

An unexpected Schiff base-type Ni(II) complex, [Ni(L2)2]?CH3OH (HL2 = 1-(2-{[(E)-3, 5-dibromo-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), has been synthesized via complexation of Ni(II) acetate tetrahydrate with HL1 (2-(3,5-dibromo-2-hydroxyphenyl)-4-methyl-1,2-dihydroquinazoline 3-oxide) originally. HL1 and its corresponding Ni(II) complex were characterized by IR, 1H NMR spectra, as well as by elemental analysis, UV-Vis and emission spectroscopy, respectively. Crystal structures of the ligand and complex have been determined by single-crystal X-ray diffraction. Each complex links two other molecules into an infinite 1-D chain via intermolecular hydrogen bonding interactions. Moreover, the electrochemical property of the nickle complex was studied by cyclic voltammetry. In addition, SOD-like activities of HL1 and Ni(II) complex were also investigated.

Chai, Lan-Qin; Zhang, Hong-Song; Huang, Jiao-Jiao; Zhang, Yu-Li

2015-02-01

209

Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: synthesis, characterization, fluorescence and corrosion inhibitors of ligands.  

PubMed

Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans. PMID:24858346

Ali, Omyma A M

2014-11-11

210

Pd(II) and Zn(II) Based Complexes with Schiff Base Ligands: Synthesis, Characterization, Luminescence, and Antibacterial and Catalytic Activities  

PubMed Central

Two new metal complexes involving Schiff base ligands, namely, [Pd(L1)2] (1) and [Zn(L2)2] (2), [HL1: 2,4-dibromo-6-((E)-(mesitylimino)methyl)phenol and HL2: 2-((E)-(2,6-diisopropylphenylimino)methyl)-4,6-dibromophenol], have been solvothermally synthesized and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Both 1 and 2 are mononuclear cyclometalated complexes with square planar and tetrahedral coordination geometry, respectively. 1 and 2 display photoluminescence in the solid state at 298?K (fluorescence lifetimes ? = 5.521??s at 508?nm for 1; ? = 3.697??s at 506?nm for 2). These Schiff base ligands and their metal complexes have been screened for antibacterial activity against several bacteria strains, and the results are compared with the activity of penicillin. Moreover, the Suzuki reaction of 4-bromoanisole with phenylboronic acid by 1 has also been studied. PMID:24307886

Feng, Zhi-Qiang; Yang, Xiao-Li; Ye, Yuan-Feng

2013-01-01

211

Synthesis, spectroscopy and biological investigations of manganese(III) Schiff base complexes derived from heterocyclic ?-diketone with various primary amine and 2,2'-bipyridyl  

NASA Astrophysics Data System (ADS)

The mixed ligand mononuclear complex [Mn(bipy)(HPMFP)(OAc)]ClO 4 was synthesized by reaction of Mn(OAc) 32H 2O with HPMFP and 2,2'-bipyridyl. The corresponding Schiff base complexes were prepared by condensation of [Mn(bipy)(HPMFP)(OAc)]ClO 4 with ethylenediamine, ethanolamine and glycine (where HPMFP = 1-phenyl-3methyl-4-formyl-2-pyrazolin-5one, bipy = 2,2'-bipyridyl). All the compounds have been characterized by elemental analysis, magnetic susceptibility, conductometry measurements and 1H and 13C NMR, FT-IR, mass spectrometry. Electronic spectral and magnetic susceptibility measurements indicate square pyramidal geometry around manganese(III) ion. The thermal stabilities, activation energy E*, entropy change ? S*, enthalpy change ? H* and heat capacity of thermal degradation for these complexes were determined by TGA and DSC. The in vitro antibacterial and antifungal activity of four coordination compounds and ligand HPMFP were investigated. In vitro activates of Bacillus subtillis (MTCC-619), Staphylococcus aureus (MTCC-96), Escherichia coli (MTCC-722) and Klebsiella pneumonia (MTCC-109) bacteria and the fungus Candida albicans (ATCC-90028) were determined. All the compounds showed good antimicrobial activity. The antimicrobial activities increased as formation of Schiff base.

Surati, Kiran R.

2011-06-01

212

Synthesis, spectroscopy and biological investigations of manganese(III) Schiff base complexes derived from heterocyclic ?-diketone with various primary amine and 2,2'-bipyridyl.  

PubMed

The mixed ligand mononuclear complex [Mn(bipy)(HPMFP)(OAc)]ClO(4) was synthesized by reaction of Mn(OAc)(3)2H(2)O with HPMFP and 2,2'-bipyridyl. The corresponding Schiff base complexes were prepared by condensation of [Mn(bipy)(HPMFP)(OAc)]ClO(4) with ethylenediamine, ethanolamine and glycine (where HPMFP=1-phenyl-3methyl-4-formyl-2-pyrazolin-5one, bipy=2,2'-bipyridyl). All the compounds have been characterized by elemental analysis, magnetic susceptibility, conductometry measurements and (1)H and (13)C NMR, FT-IR, mass spectrometry. Electronic spectral and magnetic susceptibility measurements indicate square pyramidal geometry around manganese(III) ion. The thermal stabilities, activation energy E*, entropy change ?S*, enthalpy change ?H* and heat capacity of thermal degradation for these complexes were determined by TGA and DSC. The in vitro antibacterial and antifungal activity of four coordination compounds and ligand HPMFP were investigated. In vitro activates of Bacillus subtillis (MTCC-619), Staphylococcus aureus (MTCC-96), Escherichia coli (MTCC-722) and Klebsiella pneumonia (MTCC-109) bacteria and the fungus Candida albicans (ATCC-90028) were determined. All the compounds showed good antimicrobial activity. The antimicrobial activities increased as formation of Schiff base. PMID:21458364

Surati, Kiran R

2011-06-01

213

La(III) complex involving the O,N-donor environment of quinazoline-4(3H)-one Schiffs base and their antimicrobial attributes against methicillin-resistant Staphylococcus aureus (MRSA)  

NASA Astrophysics Data System (ADS)

The incidence of methicillin-resistant Staphylococcus aureus increased during the past few decades, so there is an urgent need of new antimicrobial agents if public health is concerned. Though the Schiffs bases and La(III) complex have enormous biological activity, but less attention was given in their synthesis. In the present investigation, we synthesized a new (E)-3-((2-hydroxynaphthalen-1-yl) methyleneamino)-2-methylquinazoline-4(3H)-one HNMAMQ Schiffs base by the condensation of 3-(2-aminophenyl) quinazolin-2-methyl-4(3H)-one and 2-hydroxy-1-naphthaldehyde. The Schiffs base HNMAMQ and its La(III) complex were characterized by elemental analyses, IR, NMR, mass spectra, and thermal studies. The newly synthesized Schiffs base HNMAMQ and its La(III) complex were evaluated for their antimicrobial activity against methicillin-resistant Staphylococcus aureus isolated from the Gulbarga region in India. The Schiffs base HNMAMQ and its La(III) complex showed good antimicrobial activity and thus represents a potential new drug of choice.

Siddappa, K.; Mane, Sunilkumar B.; Manikprabhu, Deene

2014-09-01

214

La(III) complex involving the O,N-donor environment of quinazoline-4(3H)-one Schiff's base and their antimicrobial attributes against methicillin-resistant Staphylococcus aureus (MRSA).  

PubMed

The incidence of methicillin-resistant Staphylococcus aureus increased during the past few decades, so there is an urgent need of new antimicrobial agents if public health is concerned. Though the Schiff's bases and La(III) complex have enormous biological activity, but less attention was given in their synthesis. In the present investigation, we synthesized a new (E)-3-((2-hydroxynaphthalen-1-yl) methyleneamino)-2-methylquinazoline-4(3H)-one HNMAMQ Schiff's base by the condensation of 3-(2-aminophenyl) quinazolin-2-methyl-4(3H)-one and 2-hydroxy-1-naphthaldehyde. The Schiff's base HNMAMQ and its La(III) complex were characterized by elemental analyses, IR, NMR, mass spectra, and thermal studies. The newly synthesized Schiff's base HNMAMQ and its La(III) complex were evaluated for their antimicrobial activity against methicillin-resistant Staphylococcus aureus isolated from the Gulbarga region in India. The Schiff's base HNMAMQ and its La(III) complex showed good antimicrobial activity and thus represents a potential new drug of choice. PMID:24813293

Siddappa, K; Mane, Sunilkumar B; Manikprabhu, Deene

2014-09-15

215

Synthesis and characterization of bioactive zinc(II) and cadmium(II) complexes with new Schiff bases derived from 4-nitrobenzaldehyde and acetophenone with ethylenediamine.  

PubMed

The new Schiff bases N,N'-bis (4-nitro benzaldehyde) ethylenediamine (L(1)) and N,N'-bis (acetophenone) ethylenediamine (L(2)) and its Zn(II), Cd(II) complexes were synthesized and characterized by different physicochemical studies. Vibrational spectra indicate coordination of metal ion through azomethine nitrogen and acetate/nitrate ions. The presence of water molecule in all the complexes has been supported by TG/DTA studies. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML complexes. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The bioefficacy of the ligands and their complexes have been examined against the growth of bacteria in vitro to evaluate their antimicrobial potential. The results indicate that the ligand and their metal complexes possess notable antimicrobial properties. X-ray powder diffraction determines the cell parameters of the complexes. PMID:20418153

Prakash, Anant; Singh, Bibhesh K; Bhojak, Narendar; Adhikari, Devjani

2010-08-01

216

Synthesis and characterization of bioactive zinc(II) and cadmium(II) complexes with new Schiff bases derived from 4-nitrobenzaldehyde and acetophenone with ethylenediamine  

NASA Astrophysics Data System (ADS)

The new Schiff bases N, N' -bis (4-nitro benzaldehyde) ethylenediamine (L 1) and N, N' -bis (acetophenone) ethylenediamine (L 2) and its Zn(II), Cd(II) complexes were synthesized and characterized by different physicochemical studies. Vibrational spectra indicate coordination of metal ion through azomethine nitrogen and acetate/nitrate ions. The presence of water molecule in all the complexes has been supported by TG/DTA studies. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML complexes. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The bioefficacy of the ligands and their complexes have been examined against the growth of bacteria in vitro to evaluate their antimicrobial potential. The results indicate that the ligand and their metal complexes possess notable antimicrobial properties. X-ray powder diffraction determines the cell parameters of the complexes.

Prakash, Anant; Singh, Bibhesh K.; Bhojak, Narendar; Adhikari, Devjani

2010-08-01

217

Construction and NIR luminescent property of hetero-bimetallic Zn Nd complexes from two chiral salen-type Schiff-base ligands  

NASA Astrophysics Data System (ADS)

Two new near-infrared (NIR) luminescent Zn-Nd complexes [ZnL 1Nd(OAc)(NO 3) 2] ( 3) and [ZnL 2Nd(DMF) 2(NO 3) 3] ( 4) have been obtained with two salen-type Schiff-base ligands H 2L 1 and H 2L 2, ( H 2L 1 = N, N'-bis(3-methoxysalicylidene)-(1s, 2s)-(-)1,2-dipheneylethylenediamine and H 2L 2 = N, N'-bis(3-methoxysalicylidene)-(s)-2,2-diamine-1,1'-binaphthyl) from the reaction of different chiral diamines with o-vanillin. The X-ray crystal structure analysis reveals that both of them crystallize in the chiral space groups with P2(1), a = 10.1669(6), b = 19.3775(11), c = 17.4639(10) , ? = 94.8710(10), V = 3428.1(3) 3, Z = 4 for 3, and C2, a = 22.1914(13), b = 9.7886(6), c = 22.0138(13) , ? = 118.9590(10), V = 4372.5(4) 3, Z = 4 for 4. Complexes 3- 4 are both dinuclear Zn-Nd structures, while suitable choice of chiral Schiff-base ligands could induce the different complexions of ligands and metal ions, and the functional control of ligand character shows a potentially effective way to the fine-tuning properties of NIR luminescence from Nd ions.

Bi, Wei-Yu; L, Xing-Qiang; Chai, Wen-Li; Song, Ji-Rong; Wong, Wai-Yeung; Wong, Wai-Kwok; Jones, Richard A.

2008-11-01

218

Spin Crossover Properties of Iron(ii) Complexes with a N4O2 Donor Set by Extended ?-CONJUGATED Schiff-Base Ligands  

NASA Astrophysics Data System (ADS)

The preparation and magnetic properties of three Fe(II) Schiff-base complexes, [Fe(qnal-21)2]CH2Cl2 (1), [Fe(qnal-12)2]2C6H6 (2) and [Fe(Hqsalc)2] (3), (Hqnal-21 = N-(8'-quinolyl)-2-hydroxy-1-naphthaldimine, Hqnal-12 = N-(8'-quinolyl)-1-hydroxy-2-naphthaldimine, H2qsalc = 4-hydroxy-3-[(8-quinolinylimino)methyl]benzoic acid) are reported. X-ray single crystal structure analyses of 1 and 2 reveal that an Fe(II) ion in each complex is coordinated by two Schiff-base ligands, qnal-21 or qnal-12, in a meridional fashion. Molecular packing of 2 shows that a qnal-12 interacts with neighboring two qnal-12's through ?-? interactions, which results in the formation of one-dimensional chain. Although the magnetic property of 2 shows a high-spin state at all the temperature range measured, the ?T-T plot of 3 shows abrupt spin crossover behavior with a wide hysteresis of 21 K, probably due to the hydrogen-bond network originated by carboxyl groups.

Kuroda, Takayoshi

2013-09-01

219

Synthesis, characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with bidentate Schiff bases derived by heterocyclic ketone.  

PubMed

A series of metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized with newly prepared biologically active ligands. These ligands were prepared by the condensation of 4-amino-5-mercapto-3-methyl-s-triazole (AMMT), 4-Amino-3-ethyl-5-mercapto-s-triazole (AEMT) with 2-acetylpyridine. The structure of the complexes have been proposed by elemental analyses, spectroscopic data i.e. IR, 1H NMR, electronic and magnetic measurements. Thermal studies of the complexes are also reported. Antibacterial activities of 10 complexes have been studied in vitro. Heterocyclic bidentate Schiff bases were associated with substantially higher antibacterial activities than some commercial antibiotics. PMID:16271421

Singh, Kiran; Barwa, Manjeet Singh; Tyagi, Parikshit

2006-01-01

220

Synthesis, spectroscopic characterization and magnetic properties of homo- and heterodinuclear complexes of transition and non-transition metal ions with a new Schiff base ligand.  

PubMed

Four homodinuclear complexes of Ni(II)-Ni(II), Cu(II)-Cu(II), Co(II)-Co(II) and Co(III)-Co(II) and five heterodinuclear complexes of Co(III)-Zn(II), Co(III)-Cu(II), Co(III)-Ni(II), Cu(II)-Zn(II) and Zn(II)-Cu(II) with the octadentate Schiff base compartmental ligand 1,8-N-bis(3-carboxy)disalicylidene-3,6-diazaoctane-1,8-diamine (H4fsatrien) have been synthesized. The complexes have been characterized with the help of elemental analyses, molecular weights, molar conductances, magnetic susceptibilities and spectroscopic (UV-vis, IR, ESR) data. Cryomagnetic data also helped to elucidate the structural features of the Cu(II) complexes. PMID:18650125

Sarkar, Saikat; Biswas, Susobhan; Dey, Kamalendu

2008-12-15

221

Heterobimetallic transition metal/rare earth metal bifunctional catalysis: a Cu/Sm/Schiff base complex for syn-selective catalytic asymmetric nitro-Mannich reaction.  

PubMed

The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)(2)/Sm(O-iPr)(3)/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)(3), we reoptimized the catalyst preparation method, and a catalyst derived from Sm(5)O(O-iPr)(13) showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)(3). The optimal system with Sm(5)O(O-iPr)(13) was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm(5)O(O-iPr)(13). PMID:20218689

Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

2010-04-01

222

Nano structure zinc (II) Schiff base complexes of a N3-tridentate ligand as new biological active agents: Spectral, thermal behaviors and crystal structure of zinc azide complex.  

PubMed

In this work, synthesis of some new five coordinated zinc halide/pseudo-halide complexes of a N3-tridentate ligand is presented. All complexes were subjected to spectroscopic and physical methods such as FT-IR, UV-visible, (1)H and (13)C NMR spectra, thermal analyses and conductivity measurements for identification. Based on spectral data, the general formula of ZnLX2 (X=Cl(-), Br(-), I(-), SCN(-) and N3(-)) was proposed for the zinc complexes. Zinc complexes have been also prepared in nano-structure sizes under ultrasonic irradiation. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied for confirmation of nano-structure character for the complexes. Among the complexes, zinc azide complex structure was analyzed by X-ray crystallography. This complex crystallizes as a triplet in trigonal system with space group of P31. The coordination sphere around the zinc center is well shown as a distorted trigonal bipyramidal with three nitrogen atoms from Schiff base ligand and two terminal azide nitrogen atoms attached to zinc ion. Various intermolecular interactions such as NH?N, CH?N and CH?? hydrogen bonding interactions stabilize crystalline lattice so that they causes a three dimensional supramolecular structure for the complex. In vitro screening of the compounds for their antimicrobial activities showed that ZnLI2, ZnL(N3)2, ZnLCl2 and ZnL(NCS)2 were found as the most effective compound against bacteria of Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli respectively. Also ZnLI2 and ZnLCl2 complexes were found more effective against two selected fungi than others. Finally, thermal behaviors of the zinc complexes showed that they are decomposed via 2-4 thermal steps from room temperature up to 1000C. PMID:25528511

Montazerozohori, M; Mojahedi Jahromi, S; Masoudiasl, A; McArdle, P

2015-03-01

223

Synthesis, spectroscopic characterization and antimicrobial studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with Schiff bases derived from 5-bromo-salicylaldehyde  

NASA Astrophysics Data System (ADS)

In this study, the new Schiff base ligands derived from condensation of amine and 5-bromo-salicylaldehyde were characterized. All compounds, the Schiff bases and the metal complexes, were characterized by elemental analyzes, FT-IR, 1H NMR, 13C NMR and magnetic susceptibility measurements. The synthesized ligands, along with their metal (II) complexes, were screened for their in vitro antibacterial activity against four Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella enteritidis) and four Gram-positive (Streptococcus pyogones, Bacillus cereus, Staphylococcus aureus and Methicillin-resistant S. aureus) bacterial strains by using disc diffusion and broth microdilution techniques.

Kursunlu, Ahmed Nuri; Guler, Ersin; Sevgi, Fatih; Ozkalp, Birol

2013-09-01

224

Biological activity of palladium(II) and platinum(II) complexes of the acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate and the X-ray crystal structure of the [Pd(asme) 2] (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) complex  

Microsoft Academic Search

Palladium(II) and platinum(II) complexes of general empirical formula, [M(NS)2] (NS=uninegatively charged acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate; M=PtII and PdII) have been prepared and characterized by a variety of physicochemical techniques. Based on conductance, IR and electronic spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(asme)2] complex (asme=anionic form of

Mohammad Akbar Ali; Aminul Huq Mirza; Raymond J Butcher; M. T. H Tarafder; Tan Boon Keat; A. Manaf Ali

2002-01-01

225

Synthesis, crystal structure and spectroscopic properties of some cadmium(II) complexes with three polyamine and corresponding macroacyclic Schiff base ligands  

Microsoft Academic Search

Three Cd(II) macroacyclic Schiff base complexes [CdL4(NO3)2] (4), [CdL5(NO3)2] (5), [CdL6(NO3)2] (6) were prepared by template condensation of 2-pyridinecarboxaldehyde with N1-(2-nitrobenzyl)-N1-(2-aminoethyl)ethane-1,2-diamine (L1), N1-(2-nitrobenzyl)-N1-(2-aminoethyl)propane-1,3-diamine (L2) or N1-(2-nitrobenzyl)-N1-(3-aminopropyl)propane-1,3-diamine (L3), in the presence of cadmium metal ion, respectively. Three Cd(II) complexes with L1, L2 and L3 were also synthesized. All complexes have been studied with IR, 1H NMR, 13C NMR, DEPT, COSY, HMQC

Hassan Keypour; Reza Azadbakht; Sadegh Salehzadeh; Hamid Khanmohammadi; Hamidreza Khavasi; Harry Adams

2008-01-01

226

Grafting of a rhenium-oxo complex on Schiff base functionalized graphene oxide: an efficient catalyst for the oxidation of amines.  

PubMed

A rhenium-oxo complex such as methyltrioxorhenium (MTO) has been homogeneously immobilized on a Schiff base modified graphene oxide (GrO) support via covalent bonding. The loading of MTO on GrO nanosheets was monitored by FTIR, TG-DTA, and elemental analyses. The developed heterogeneous catalyst is found to be efficient for the oxidation of various amines to the corresponding N-oxides using hydrogen peroxide as an oxidant in high to excellent yields. At the end of the reaction, the catalyst is readily recovered by filtration and reused for subsequent runs. After the third run, the catalyst showed a marginal decrease in catalytic activity owing to the leaching of the MTO complex from the support. PMID:24718600

Khatri, Praveen K; Choudhary, Shivani; Singh, Raghuvir; Jain, Suman L; Khatri, Om P

2014-06-01

227

Biological activity of palladium(II) and platinum(II) complexes of the acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate and the X-ray crystal structure of the [Pd(asme)2] (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) complex.  

PubMed

Palladium(II) and platinum(II) complexes of general empirical formula, [M(NS)(2)] (NS=uninegatively charged acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate; M=Pt(II) and Pd(II)) have been prepared and characterized by a variety of physicochemical techniques. Based on conductance, IR and electronic spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(asme)(2)] complex (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted cis-square planar structure with the ligands coordinated to the palladium(II) ions as uninegatively charged bidentate NS chelating agents via the azomethine nitrogen and the mercaptide sulfur atoms. The distortion from a regular square-planar geometry is attributed to the restricted bite angles of the ligands. Antimicrobial tests indicate that the Schiff bases exhibit strong activities against the pathogenic bacteria, Bacillus subtilis (mutant defective DNA repair), methicillin-resistant Staphylococcus aureus, B. subtilis (wild type) and Pseudomonas aeruginosa and the fungi, Candida albicans (CA), Candida lypotica (2075), Saccharomyces cerevisiae (20341) and Aspergillus ochraceous (398)-the activities exhibited by these compounds being greater than that of the standard antibacterial and antifungal drugs, streptomycin and nystatin, respectively. The palladium(II) and platinum(II) complexes are inactive against most of these organisms but, the microbe, Pseudomonas aeruginosa shows strong sensitivity to the platinum(II) complexes. Screening of the compounds for their cytotoxicities against T-lymphoblastic leukemia cancer cells has shown that the acetone Schiff base of S-methyldithiocarbazate (Hasme) exhibits a very weak activity, whereas the S-benzyl derivative (Hasbz) is inactive. However, the palladium(II) complexes exhibit strong cytotoxicities against this cancer; their activities being more than that of the standard anticancer drug, tamoxifen. The [Pt(asme)(2)] complex exhibits a very weak cytotoxicity, whereas [Pt(asbz)(2)] is inactive against leukemic cells. PMID:12433421

Akbar Ali, Mohammad; Mirza, Aminul Huq; Butcher, Raymond J; Tarafder, M T H; Keat, Tan Boon; Ali, A Manaf

2002-11-25

228

Structurally Diverse Copper(II) Complexes of Polyaza Ligands Containing 1,2,3-Triazoles: Site Selectivity and Magnetic Properties  

E-print Network

Structurally Diverse Copper(II) Complexes of Polyaza Ligands Containing 1,2,3-Triazoles: Site, Florida 32306-4390, United States *S Supporting Information ABSTRACT: Copper(II) acetate mediated coupling, was observed in the copper(II) complexes of L1 -L6 . The preference of copper(II) to two common bidentate 1

Weston, Ken

229

Synthesis, spectral and antimicrobial activity of Zn(II) complexes with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and benzaldehyde/2-hydroxyacetophenone/indoline-2,3-dione.  

PubMed

Zn(II) complexes have been synthesized by reacting zinc acetate with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and 2-hydroxyacetophenone/benzaldehyde/indoline-2,3-dione. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non electrolytes. Elemental analyses suggest that the complexes have 1:2 metal to ligands stoichiometry of the types [ZnL2(H2O)2](L=monoanionic Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and 2-hydroxyacetophenone/indoline-2,3-dione) [ZnL2(')(OOCCH3)2(H2O)2](L'=neutral Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and benzaldehyde), and they were characterized by IR, (1)H NMR, and (13)C NMR. Particle sizes of synthesized compounds were measured with dynamic light scattering (DLS) analyser which indicates that particle diameter are of the range ca. 100-200nm. All these Schiff bases and their complexes have also been screened for their antibacterial (Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and antifungal activities (Colletotrichum falcatum (C. falcatum), Aspergillus niger (A. niger), Fusarium oxysporium (F. oxysporium) Curvularia pallescence (C. pallescence). The antimicrobial activities have shown that upon complexation the activity increases. PMID:23747379

Singh, Ajay K; Pandey, O P; Sengupta, S K

2013-09-01

230

Immobilized molybdenum-thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles as a new nanocatalyst for the epoxidation of olefins  

NASA Astrophysics Data System (ADS)

In this work, a new magnetically recoverable nanocatalyst was developed by immobilization of thiosemicarbazide ligand on the surface of silica coated magnetite nanoparticles (SCMNPs) through Schiff base condensation and followed complexation with MoO2(acac)2. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as Fourier transform infrared (FT-IR) and atomic absorption spectroscopies, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions.

Mohammadikish, M.; Masteri-Farahani, M.; Mahdavi, S.

2014-03-01

231

Photoinduced electron transfer from PbS quantum dots to cobalt(III) Schiff base complexes: light activation of a protein inhibitor  

PubMed Central

This paper describes the activation of a biologically inert Co(III) Schiff base (SB) complex to its protein inhibitor form by photoinduced electron transfer (PET) from a colloidal PbS quantum dot (QD, radii = 1.5 1.7 nm) to the cobalt center, with a charge separation time constant of 125 ns. Reduction of the Co(III)-SB initiates release of the native axial ligands, promoting replacement with the histidine mimic 4-methylimidazole. The rate of ligand displacement increases by approximately a factor of eight upon exposure of the PbS QD/Co(III)-SB mixture to light of energy greater than the energy of the first excitonic state of the QDs, from which PET occurs. These results suggest an approach for the preparation of inorganic therapeutic agents that can be specifically coupled to a biologically active site by cooperative redox-binding ligation. PMID:23931454

Peterson, Mark D.; Holbrook, Robert J.; Meade, Thomas J.; Weiss, Emily A.

2013-01-01

232

Oxophily of gadolinium(III) and synthesis of dissymmetric di(Schiff bases) and dissymmetric dinuclear compounds. Crystal structure of [Cu[sub 2]L[prime](OH)](ClO[sub 4])[sub 2][center dot]H[sub 2]O with L[prime] = 2-[N-(2-pyridylethyl)formimidoyl]-6-[N-((dimethylamino)propyl)formimidoyl]phenolato  

SciTech Connect

The strong oxophilic character of the Gd(III) ion has been utilized to protect one of the carbonyl functions of 2,6-diformyl-4-methylphenol, which has allowed the quantitative synthesis of mono(Schiff bases), then dissymmetric di(Schiff bases). The synthetic process is as follows: the reaction of 2,6-diformyl-4-methylphenol with a primary amine RNH[sub 2] in the presence of Gd(III) affords a complex in which Gd(III) is coordinated to two mono(Schiff bases) through their carbonyl and phenolic oxygen atoms. The mono(Schiff base) may be isolated by precipitation of Gd(III) in the form of gadolinium(III) oxalate. The reaction of another primary amine, R[prime]NH[sub 2], on this mono(Schiff base) affords a dissymmetric di(Schiff base), from which dissymmetric dinuclear compounds can be synthesized. For example, this reaction has been carried out with RNH[sub 2] = 2-(2-aminoethyl)pyridine and R[prime]NH[sub 2] = N,N-dimethylpropylenediamine. The mono(Schiff base) 2-formyl-6-(N-(2-pyridylethyl)formimidoyl)-4-methylphenol (HL) and the di(Schiff base) 2-[N-(2-pyridylethyl)formimidoyl]-6-[N-((dimethylamino)propyl)formimidoyl]-4-methylphenol (HL[prime]) have been unambiguously characterized from their [sup 1]H NMR spectra. The copper(II) dinuclear compound [CuL[prime](OH)](ClO[sub 4])[sub 2][center dot]H[sub 2]O obtained from this di(Schiff base) has been synthesized, and its crystal structure has been solved. 36 refs., 2 figs., 5 tabs.

Andruh, M.; Kahn, O.; Sainton, J. (Universite de Paris Sud, Orsay (France)); Dromzee, Y.; Jeannin, S. (Universite Pierre et Marie Curie, Paris (France))

1993-04-28

233

Induced chirality-at-metal and diastereoselectivity at ?/?-configured distorted square-planar copper complexes by enantiopure Schiff base ligands: combined circular dichroism, DFT and X-ray structural studies.  

PubMed

Bidentate enantiopure Schiff base ligands, (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminato-?(2)N,O, diastereoselectively yield ?/?-chiral four-coordinated, non-planar Cu(N^O)2 complexes [Ar = C6H5 R/S-L1, m-C6H4OMe R-L2, p-C6H4OMe R/S-L3, and p-C6H4Br R/S-L4]. Two N,O-chelate ligands coordinate to the copper(II) atom in distorted square-planar mode, and induce metal-centered ?/?-chirality at the copper atom in the C2-symmetric complexes. In the solid state, the R-L1 (or R-L4) ligand chirality diastereoselectively induces a ?-Cu configuration in ?-Cu-R-L1 (or ?-Cu-R-L4), the S-L1 ligand a ?-Cu configuration in ?-Cu-S-L1, forming enantiopure crystals upon crystallization. Conversely, the R-L2 ligand combines both ?/?-Cu-R-L2 as a diastereomeric pair in the crystals. In solution, electronic circular dichroism (CD) spectra show full or partial diastereoselectivity towards ?-Cu for R ligands and towards ?-Cu for S ligands. The electronic CD spectra measured on all complexes obtained from R ligands (or S ligands), e.g. Cu-R-L1, Cu-R-L2, Cu-R-L3, and Cu-R-L4 (or Cu-S-L1, Cu-S-L3, and Cu-S-L4), show consistent spectral features. TDDFT calculations of the electronic CD spectra for the diastereomers ?-Cu-R-L1 and ?-Cu-R-L1 suggest that the CD spectra are largely dominated by the configuration at the metal center (? vs. ?). The experimental CD spectrum of Cu-R-L1 agrees well with the one calculated for the ?-Cu-R-L1 configuration. Cyclic voltammetry of Cu-R-L1 reveals a quasi-reversible redox wave corresponding to one-electron transfer for the [Cu(II)L2](0)/[Cu(I)L2](-1) couple in acetonitrile. DSC analyses for the complexes show an exothermic peak between 377 and 478 K (?H = -12 to -43 kJ mol(-1)), corresponding to a phase transformation from distorted square-planar/tetrahedral to regular tetrahedral geometry on heating. PMID:24366532

Enamullah, Mohammed; Uddin, A K M Royhan; Pescitelli, Gennaro; Berardozzi, Roberto; Makhloufi, Gamall; Vasylyeva, Vera; Chamayou, Anne-Christine; Janiak, Christoph

2014-02-28

234

Synthesis and characterization of xanthene-bridged Schiff-base dimanganese(III) complexes: bimetallic catalysts for asymmetric oxidation of sulfides.  

PubMed

Dimanganese(III) complexes of salen-type ligands anchored by 9,9-dimethylxanthene-4,5-diyl spacers were synthesized. Two types of structures, cyclic and acyclic forms, are presented. The 2 + 2 Schiff-base condensation of 5,5'-(9,9-dimethylxanthene-4,5-diyl)bis(salicylaldehyde) and 1,2-diaminobenzene gave a macrocyclic ligand, from which a cyclic dimanganese(III) complex was synthesized. A similar dimanganese(III) complex with stereogenic centers was synthesized by the metal-assisted condensation reaction using (1R,2R)-1,2-diaminocyclohexane. Acyclic dimanganese(III) complexes anchored by one xanthene spacer were obtained by metal-assisted stepwise condensation reactions using the xanthene-bridged bis(salicylaldehyde), (1R,2R)-1,2-diaminocyclohexane monohydrochloride, and salicylaldehydes. X-Ray crystal structure analysis confirmed that both cyclic and acyclic complexes have two cofacially oriented salen-type manganese(III) units in a complex cation, showing an Mn...Mn distance of ca. 5.1 A. Asymmetric oxidation of sulfides was performed by using the chiral dimeric complexes as catalysts, which showed enantiomeric excesses ranging from 5 to 19%. The addition of 4-(dimethylamino)pyridine to the reaction system improved the enantioselectivity up to 39% ee. This effect was not observed for the corresponding mononuclear catalyst. PMID:20023944

Hirotsu, Masakazu; Ohno, Naoki; Nakajima, Takashi; Kushibe, Chie; Ueno, Keiji; Kinoshita, Isamu

2010-01-01

235

Synthesis and Characterisation of Copper(II) Complexes with Tridentate NNO Functionalized Ligand: Density Function Theory Study, DNA Binding Mechanism, Optical Properties, and Biological Application  

PubMed Central

The photo physical properties of two mononuclear pentacoordinated copper(II) complexes formulated as [Cu(L)(Cl)(H2O)] (1) and [Cu(L)(Br)(H2O)] (2) HL?=?(1-[(3-methyl-pyridine-2-ylimino)-methyl]-naphthalen-2-ol) were synthesized and characterized by elemental, physicochemical, and spectroscopic methods. The density function theory calculations are used to investigate the electronic structures and the electronic properties of ligand and complex. The interactions of copper(II) complexes towards calf thymus DNA were examined with the help of absorption, viscosity, and fluorescence spectroscopic techniques at pH 7.40. All spectroscopy's result indicates that complexes show good binding activity to calf thymus DNA through groove binding. The optical absorption and fluorescence emission properties of microwires were characterized by fluorescence microscope. From a spectroscopic viewpoint, all compounds strongly emit green light in the solid state. The microscopy investigation suggested that microwires exhibited optical waveguide behaviour which are applicable as fluorescent nanomaterials and can be used as building blocks for miniaturized photonic devices. Antibacterial study reveals that complexes are better antimicrobial agents than free Schiff base due to bacterial cell penetration by chelation. Moreover, the antioxidant study of the ligand and complexes is evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assays, which demonstrate that the complexes are of higher antioxidant activity than free ligand. PMID:25386109

Hazra, Madhumita; Dolai, Tanushree; Pandey, Akhil; Dey, Subrata Kumar; Patra, Animesh

2014-01-01

236

Synthesis and Characterisation of Copper(II) Complexes with Tridentate NNO Functionalized Ligand: Density Function Theory Study, DNA Binding Mechanism, Optical Properties, and Biological Application.  

PubMed

The photo physical properties of two mononuclear pentacoordinated copper(II) complexes formulated as [Cu(L)(Cl)(H2O)] (1) and [Cu(L)(Br)(H2O)] (2) HL?=?(1-[(3-methyl-pyridine-2-ylimino)-methyl]-naphthalen-2-ol) were synthesized and characterized by elemental, physicochemical, and spectroscopic methods. The density function theory calculations are used to investigate the electronic structures and the electronic properties of ligand and complex. The interactions of copper(II) complexes towards calf thymus DNA were examined with the help of absorption, viscosity, and fluorescence spectroscopic techniques at pH 7.40. All spectroscopy's result indicates that complexes show good binding activity to calf thymus DNA through groove binding. The optical absorption and fluorescence emission properties of microwires were characterized by fluorescence microscope. From a spectroscopic viewpoint, all compounds strongly emit green light in the solid state. The microscopy investigation suggested that microwires exhibited optical waveguide behaviour which are applicable as fluorescent nanomaterials and can be used as building blocks for miniaturized photonic devices. Antibacterial study reveals that complexes are better antimicrobial agents than free Schiff base due to bacterial cell penetration by chelation. Moreover, the antioxidant study of the ligand and complexes is evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assays, which demonstrate that the complexes are of higher antioxidant activity than free ligand. PMID:25386109

Hazra, Madhumita; Dolai, Tanushree; Pandey, Akhil; Dey, Subrata Kumar; Patra, Animesh

2014-01-01

237

Ferrocenyl-L-amino acid copper(II) complexes showing remarkable photo-induced anticancer activity in visible light.  

PubMed

Ferrocene-conjugated copper(ii) complexes [Cu(Fc-aa)(aip)](ClO4) () and [Cu(Fc-aa)(pyip)](ClO4) () of l-amino acid reduced Schiff bases (Fc-aa), 2-(9-anthryl)-1H-imidazo[4,5-f][1,10]phenanthroline (aip) and 2-(1-pyrenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (pyip), where Fc-aa is ferrocenylmethyl-l-tyrosine (Fc-Tyr in , ), ferrocenylmethyl-l-tryptophan (Fc-Trp in , ) and ferrocenylmethyl-l-methionine (Fc-Met in , ), were prepared and characterized, and their photocytotoxicity was studied (Fc = ferrocenyl moiety). Phenyl analogues, viz. [Cu(Ph-Met)(aip)](ClO4) () and [Cu(Ph-Met)(pyip)](ClO4) (), were prepared and used as control compounds. The bis-imidazophenanthroline copper(ii) complexes, viz. [Cu(aip)2(NO3)](NO3) () and [Cu(pyip)2(NO3)](NO3) (), were also prepared and used as controls. Complexes having a redox inactive cooper(ii) center showed the Fc(+)-Fc redox couple at ?0.5 V vs. SCE in DMF-0.1 mol [Bu(n)4N](ClO4). The copper(ii)-based d-d band was observed near 600 nm in DMF-Tris-HCl buffer (1?:?1 v/v). The ferrocenyl complexes showed low dark toxicity, but remarkably high photocytotoxicity in human cervical HeLa and human breast adenocarcinoma MCF-7 cancer cells giving an excellent photo-dynamic effect while their phenyl analogues were inactive. The photo-exposure caused significant morphological changes in the cancer cells when compared to the non-irradiated ones. The photophysical processes were rationalized from the theoretical studies. Fluorescence microscopic images showed and localizing predominantly in the endoplasmic reticulum (ER) of the cancer cells, thus minimizing any undesirable effects involving nuclear DNA. PMID:24971754

Goswami, Tridib K; Gadadhar, Sudarshan; Balaji, Babu; Gole, Bappaditya; Karande, Anjali A; Chakravarty, Akhil R

2014-08-21

238

DNA cleavage, antibacterial, antifungal and anthelmintic studies of Co(II), Ni(II) and Cu(II) complexes of coumarin Schiff bases: Synthesis and spectral approach  

NASA Astrophysics Data System (ADS)

The metal complexes of Co(II), Ni(II) and Cu(II) have been synthesized from 6-formyl-7,8-dihydroxy-4-methylcoumarin with o-toluidine/3-aminobenzotrifluoride. The synthesized Schiff bases and their metal complexes were structurally characterized based on IR, 1H NMR, 13C NMR, UV-visible, ESR, magnetic, thermal, fluorescence, mass and ESI-MS studies. The molar conductance values indicate that complexes are non-electrolytic in nature. Elemental analysis reveals ML22H2O [M = Co(II), Ni(II) and Cu(II)] stoichiometry, where 'L' stands for a singly deprotonated ligand. The presence of co-ordinated water molecules were confirmed by thermal studies. The spectroscopic studies suggest the octahedral geometry. Redox behavior of the complexes were confirmed by cyclic voltammetry. All the synthesized compounds were screened for their antibacterial (Escherichia coli, Pseudomonas auregenosa, klebsiella, Proteus, Staphylococcus aureus and salmonella) antifungal (Candida, Aspergillus niger and Rhizopus), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activity.

Patil, Sangamesh A.; Prabhakara, Chetan T.; Halasangi, Bhimashankar M.; Toragalmath, Shivakumar S.; Badami, Prema S.

2015-02-01

239

Synthesis, spectroscopic studies, antimicrobial activities and antitumor of a new monodentate V-shaped Schiff base and its transition metal complexes.  

PubMed

Reaction of 4-aminoacetophenone and 4-bromobenzaldehyde in ethanol resulted in the formation of the monodentate V-shaped Schiff base (E)-1-(4-((4-bromo-benzylidene)amino)phenyl)ethanone (L). Interaction of L with different di- and trivalent metal ions revealed disubstituted derivatives. The ligand and its complexes were characterized by elemental analysis, mass, IR and NMR spectrometry. Biological activities of the ligand and complexes against the Escherchia coli and Staphylococcus aureus bacterias, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of the compounds were checked as antitumor agents on liver carcinoma cell line (HepG2). They exhibited in vitro broad range of antitumor activities towards the cell line; the [ZnL2(H2O)2](NO3)2 complex was stronger antitumor towards HepG2 cell line as well as two breast cancer cell lines (MCF7 and T47D) relative to cis-platin. PMID:24887503

Ramadan, Ramadan M; Abu Al-Nasr, Ahmad K; Noureldeen, Amani F H

2014-11-11

240

Nickel(II) and copper(II) complexes with pyridine-containing macrocycles bearing an aminopropyl pendant arm: synthesis,  

E-print Network

Nickel(II) and copper(II) complexes with pyridine-containing macrocycles bearing an aminopropyl that were used for the preparation of the copper(II) complexes. The structures of three nickel(II) complexes and two copper(II) complexes were determined by X-ray crystallography. Protonation of the pendant arm (p

Nazarenko, Alexander

241

Synthesis and spectroscopic characterization of copper(II) complexes with the polydentate chelating ligand 4,4'-[1,4-phenylenedi(nitrilo)dipente-2-one  

NASA Astrophysics Data System (ADS)

A new series of complexes of 4,4'-[1,4-phenylenenedi(nitilo)]dipenten-2-one, (H 2L) with CuX 2 nH 2O, X = Cl, Br, ClO 4, NO 3 and OAc; n = 1-6 as well as their ethylenediamine adducts have been synthesized and characterized by different physical techniques. The formulation of the complexes is assumed based on their elemental analysis and the molar conductivity. The products are found to be pH-dependent. The IR data showed that the ligand acts as dibasic tetradentate coordinated to copper(II) ions through the enolato-oxygen and the azomethine nitrogen atoms. Electronic, ESR spectra and room temperature magnetic moments indicate that complexes 1- 9 are square planar while complexes 10 and 11 are square based pyramidal. The different electronic spectral and ESR parameters are calculated and used to describe the nature of ligand-metal bonding ( ? and ?) as well as to estimate the extent of distortion. A macrocyclic containing copper(II) complex, 12 have been isolated by the reaction of Schiff-base with copper(II)-ethylenediamine mixture. The ligand (H 2L) is designed as a building block for larger molecules and superamolecular assemblies.

Shauib, Nadia M.; Elassar, Abdel-Zaher A.; El-Dissouky, Ali

2006-03-01

242

Synthesis, characterization of N,N?-bis(2-hydroxynaphthalidene)phenylene-1,2-diamine with M(II)(M = Ni, Zn and Fe) Schiff-base complexes and their non-linear optical studies by z-scan technique  

NASA Astrophysics Data System (ADS)

Schiff-base complexes of N, N'-bis(2-hydroxynaphthalidene)phenylene-1,2-diamine ligand with metal M (M = Ni(II), Zn(II) and Fe(II)) have been synthesized and characterized by their UV, FT-IR, NMR, elemental analysis and magnetic susceptibility measurements. Non-linear optical measurements carried out using nanosecond laser pulses at 532 nm show that these complexes can be used for optical limiting applications.

Sampath Kumar, H. C.; Ramachandra Bhat, B.; Rudresha, B. J.; Ravindra, R.; Philip, Reji

2010-07-01

243

Synthesis, characterization of N, N?-bis(2-hydroxynaphthalidene)phenylene-1,2-diamine with M(II)(M = Ni, Zn and Fe) Schiff-base complexes and their non-linear optical studies by z-scan technique  

Microsoft Academic Search

Schiff-base complexes of N,N?-bis(2-hydroxynaphthalidene)phenylene-1,2-diamine ligand with metal M (M=Ni(II), Zn(II) and Fe(II)) have been synthesized and characterized by their UV, FT-IR, NMR, elemental analysis and magnetic susceptibility measurements. Non-linear optical measurements carried out using nanosecond laser pulses at 532nm show that these complexes can be used for optical limiting applications.

H. C. Sampath Kumar; B. Ramachandra Bhat; B. J. Rudresha; R. Ravindra; Reji Philip

2010-01-01

244

Discovery and investigation of anticancer ruthenium-arene Schiff-base complexes via water-promoted combinatorial three-component assembly.  

PubMed

The structural diversity of metal scaffolds makes them a viable alternative to traditional organic scaffolds for drug design. Combinatorial chemistry and multicomponent reactions, coupled with high-throughput screening, are useful techniques in drug discovery, but they are rarely used in metal-based drug design. We report the optimization and validation of a new combinatorial, metal-based, three-component assembly reaction for the synthesis of a library of 442 Ru-arene Schiff-base (RAS) complexes. These RAS complexes were synthesized in a one-pot, on-a-plate format using commercially available starting materials under aqueous conditions. The library was screened for their anticancer activity, and several cytotoxic lead compounds were identified. In particular, [(?6-1,3,5-triisopropylbenzene)RuCl(4-methoxy-N-(2-quinolinylmethylene)aniline)]Cl (4) displayed low micromolar IC50 values in ovarian cancers (A2780, A2780cisR), breast cancer (MCF7), and colorectal cancer (HCT116, SW480). The absence of p53 activation or changes in IC50 value between p53+/+ and p53-/- cells suggests that 4 and possibly the other lead compounds may act independently of the p53 tumor suppressor gene frequently mutated in cancer. PMID:25023617

Chow, Mun Juinn; Licona, Cynthia; Yuan Qiang Wong, Daniel; Pastorin, Giorgia; Gaiddon, Christian; Ang, Wee Han

2014-07-24

245

Synthesis and DNA binding studies of Ni(II), Co(II), Cu(II) and Zn(II) metal complexes of N 1,N 5-bis[pyridine-2-methylene]-thiocarbohydrazone Schiff-base ligand  

NASA Astrophysics Data System (ADS)

The thiocarbohydrazone Schiff-base ligand with a nitrogen and sulphur donor was synthesized through condensation of pyridine-2-carbaldehyde and thiocarbohydrazide. Schiff-base ligands have the ability to conjugate with metal salts. A series of metal complexes with a general formula [MCl 2(H 2L)] nH 2O (M dbnd Ni, Co, Cu and Zn) were synthesized by forming complexes of the N 1,N 5-bis[pyridine-2-methylene]-thiocarbohydrazone (H 2L) Schiff-base ligand. These metal complexes and ligand were characterized by using ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FT-IR), 1H and 13C NMR spectroscopy and mass spectroscopy, physicochemical characterization, CHNS and conductivity. The biological activity of the synthesized ligand was investigated by using Escherichia coli DNA as target. The DNA interaction of the synthesized ligand and complexes on E. coli plasmid DNA was investigated in the aqueous medium by UV-Vis spectroscopy and the binding constant ( Kb) was calculated. The DNA binding studies showed that the metal complexes had an improved interaction due to trans-geometrical isomers of the complexes than ligand isomers in cis-positions.

Tiwari, A. D.; Mishra, A. K.; Mishra, S. B.; Mamba, B. B.; Maji, B.; Bhattacharya, S.

2011-09-01

246

Spectroscopic Elucidation of the Inhibitory Mechanism of Cys2His2 Zinc Finger Transcription Factors by CobaltIII Schiff Base Complexes  

PubMed Central

Transcription factors are key regulators in both normal and pathological cell processes. Affecting the activity of these proteins is a promising strategy for understanding gene regulation and developing effective therapeutics. CoIII Schiff base complexes ([Co(acacen)(L)2]+ where L = labile axial ligands) have been shown to be potent inhibitors of a number of zinc metalloproteins including Cys2His2 zinc finger transcription factors. Inhibition by [Co(acacen)(L)2]+ of the target protein is believed to occur through a dissociative exchange of the labile axial ligands for histidine (His) residues essential for function. Here, we report a series of spectroscopic investigations with model peptides of zinc fingers that elucidate the interaction between [Co(acacen)(L)2]+ complexes and zinc finger transcription factors. Observed changes in NMR chemical shifts and 2D 1H-1H NOESY NMR spectra demonstrate the preference of [Co(acacen)(L)2]+ complexes to coordinate His residues over other amino acids. The conformation of [Co(acacen)(L)2]+ upon His-coordination was characterized by 1H NMR, near-UV circular dichroism, and electronic absorption. These studies reveal that the resulting His-coordinated [Co(acacen)(L)2]+ complex possesses an octahedral structure. The effects of [Co(acacen)(L)2]+ complexes on the zinc finger structure were assessed by the degree of hydrogen bonding (probed by 2D NMR) and secondary structure profiles measured by far-UV circular dichroism. These structural studies demonstrate the ability of [Co(acacen)(L)2]+ complexes to disrupt the ??? structure of zinc fingers, resulting in primarily random coil conformations. A mechanism is described wherein [Co(acacen)(L)2]+ complexes inhibit zinc finger transcription factor activity through selectively coordinating His residues in the zinc finger via dissociative ligand exchange and disrupting the ??? structural motif required for gene regulation. PMID:24203451

Heffern, Marie C.; Kurutz, Josh

2014-01-01

247

Synthesis, spectroscopic, antimicrobial and DNA cleavage studies of new Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes with naphthofuran-2-carbohydrazide Schiff base  

NASA Astrophysics Data System (ADS)

A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes have been synthesized with newly synthesized Schiff base derived from naphthofuran-2-carbohydrazide and cinnamaldehyde. The elemental analyses of the complexes are confined to the stoichiometry of the type MLCl2 [M = Co(II) and Cu(II)], ML2Cl2 [M = Ni(II), Cd(II), Zn(II) and Hg(II)] respectively, where L is Schiff base ligand. Structures have been proposed from elemental analyses, IR, electronic, mass, 1H NMR, ESR spectral data, magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Spectroscopic studies suggest coordination occurs through azomethine nitrogen and carbonyl oxygen of the ligand with the metal ions. The Schiff base and its complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium and Candida albicans) activities by minimum inhibitory concentration (MIC) method. The DNA cleavage studies by agarose gel electrophoresis method was studied for all the complexes.

Halli, Madappa B.; Sumathi, R. B.

2012-08-01

248

Spectroscopic studies of bimetallic complexes derived from tridentate or tetradentate Schiff bases of some di- and tri-valent transition metals.  

PubMed

Two series of new binuclear complexes with Schiff base ligands, H(4)L(a) or H(2)L(b), derived from the reaction of 4,6-diacetylresorcinol and ethylenediamine, in the molar ratio 1:1 and 1:2 have been prepared, respectively. The two ligands react with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Cr(III) and Fe(III)-nitrates to get binuclear complexes. The ligands were characterized by elemental analysis, IR, UV-vis, (1)H NMR and mass spectra. The complexes were synthesized by direct and template methods. Different types of products were obtained for the same ligand and metal salts according to the method of preparation. The H(4)L(a) ligand behaves as a macrocyclic tetrabasic with two N(2)O(2) sits, while the H(2)L(b) ligand behaves as a dibasic with two N(2)O sites. The H(4)L(a) ligand is a compartmental ligand which hosts the two metal ions at the centers of two cis-N(2)O(2) sites, while the metal complexes of H(2)L(b) ligand are binuclear, where the ligand hosts two metal ions at the centers of two N(2)O sites. In both cases, deprotonation of the hydrogen atoms of the phenolic OH groups occur except in the case of the Ni(II), Fe(III) and Cr(III) complexes. Electronic spectra and magnetic moments of the complexes indicate that the geometries of the metal centers are either octahedral or tetrahedral. The structures are consistent with the IR, UV-vis, ESR, (1)H NMR, mass spectra, and thermal gravimetric analysis (TGA/DTA) as well as conductivity and magnetic moment measurements. PMID:16332449

Emara, Adel A A; Abou-Hussen, Azza A A

2006-07-01

249

Electronic structure of the nickel(II) complex of the Schiff base of (S)-N-(2-benzoylphenyl)-1-benzylprolinamide and glycine.  

PubMed

The experimental charge density of the Ni(II) complex of the Schiff base of (S)-N-(2-benzoylphenyl)-1-benzylprolinamide and glycine was derived from high-resolution single-crystal X-ray diffraction data (lambda = 0.5604 A) at low temperature (100 K) with synchrotron radiation at the beamline F1 using a CCD area detector. The central Ni atom is pseudo-square-planar coordinated by three N atoms [1.9414 (3), 1.8559 (3) and 1.8533 (3) A] and by one O atom [1.8620 (4) A]. The N(1) atom is 0.359 A above the plane defined by the atoms Ni(1), N(2) and N(3). The d-orbital population analysis reveals an oxidation state for the Ni atom of +2 with the configuration d(8) and a hole mainly in the d(x(2)-y(2)) orbital, located in the plane of the four ligating atoms. The prochiral reaction centre was examined by topological analysis. PMID:15477692

Kozsek, Jozef; Fronc, Marek; Skubk, Pavol; Popkov, Alexander; Breza, Martin; Fuess, Hartmut; Paulmann, Carsten

2004-09-01

250

Synthesis and crystal structure determination of some asymmetrical and symmetrical CR-type macrocyclic Schiff base complexes, with a single pendant coordinating 2-aminoethyl arm.  

PubMed

A novel, totally asymmetrical tripodal 2,3',4"-tetraamine ligand, N((CH2)2NH2)((CH2)3NH2)((CH2)4NH2), epb, has been synthesized. In the presence of copper(II) and nickel(II) ions it condenses with 2,6-diacetylpyridine in 1:1 ethanol-water solution, producing some new CR-type complexes with a pendant primary amino group. The X-ray crystal structure of the resulting copper(II) complex, [Cu(3,4(2)-CR)](PF6)2 (1), and two other related complexes, [Cu(2,4(2)-CR)](ClO4)2 (2) and [Cu(3,3(2)-CR)](ClO4)2 (3), are reported. Crystal data: complex 1, monoclinic, P2(1)/n, a = 8.366(3) A, b = 15.549(3) A, c = 20.283(2) A, beta = 98.73(2) degrees, V = 2607.8(11) A3, Z = 4, R1 = 0.0621, wR2 = 0.1615; complex 2, monoclinic, P2(1)/c, a = 7.981(10) A, b = 18.882(3) A, c = 15.185(3) A, beta = 96.40(2) degrees, V = 2275.7(6) A3, Z = 4, R1 = 0.0773, wR2 = 0.1635; complex 3, monoclinic, P2(1)/n, a = 7.8764(10) A, b = 15.361(2) A, c = 19.370(2) A, beta = 100.330(10) degrees, V = 2305.7(5) A3, Z = 4, R1 = 0.0537, wR2 = 0.1397. In all of these, copper atoms are bonded to four nitrogens of a macrocyclic ring and a nitrogen of the pendant arm. The arrangements are slightly distorted square-pyramidal in which the primary amino groups occupy apical positions and have the longest Cu-N distances. For all isomers, copper(II) ions are somewhat above the plane of the imino-pyridine system of the macrocylic ring in the direction of the pendant coordinated primary amino group. PMID:11153507

Keypour, H; Salehzadeh, S; Pritchard, R G; Parish, R V

2000-12-11

251

Trinuclear heterometallic Cu(II)-Mn(II) complexes of a salen type Schiff base ligand: anion dependent variation of phenoxido bridging angles and magnetic coupling.  

PubMed

Five new trinuclear heterometallic Cu(II)-Mn(II) complexes [(CuL)2Mn(O2CPh)2] (1), [(CuL)2Mn(N3)2] (2), [(CuL)2Mn(NCO)2] (3), [(CuL)2Mn(NO3)2] (4) and [(CuL)2Mn(Sal)2]CH2Cl2 (5) have been synthesized with the di-Schiff base ligand H2L (where H2L = N,N'-bis(salicylidene)-1,3-propanediamine and Sal = salicylate). These complexes with different anionic co-ligands have been synthesized to attain a large variation in phenoxido bridging angles and to investigate its consequence on magnetic properties. Single crystal X-ray diffraction analyses reveal that complexes 1, 2, 4 and 5 are linear, whereas 3 has an angular geometry. Variable temperature magnetic susceptibility measurements suggest that all five complexes possess an overall antiferromagnetic interaction between Cu(II) and Mn(II) ions, which results in a final ferrimagnetic ground state with spin 3/2 in the Cu(II)-Mn(II)-Cu(II) trinuclear structure. The weakest antiferromagnetic interaction (J(Cu-Mn) = -7.0 cm(-1)) is observed for 2 having the lowest value of the Cu-O-Mn angle (92.0), while the strongest antiferromagnetic interaction (J(Cu-Mn) = -26.5 cm(-1)) is observed for 3 having the largest Cu-O-Mn angle (101.4). Complexes 1, 4 and 5 show average Cu-O-Mn angles of 98.2, 97.6 and 97.7, respectively, that lead to intermediate antiferromagnetic interactions (J(Cu-Mn) = -9.6, -9.7, -9.3 cm(-1) respectively). PMID:24162065

Seth, Piya; Ghosh, Soumavo; Figuerola, Albert; Ghosh, Asutosh

2014-01-21

252

Synthesis of alpha-amino acids via asymmetric phase transfer-catalyzed alkylation of achiral nickel(II) complexes of glycine-derived Schiff bases.  

PubMed

Achiral, diamagnetic Ni(II) complexes 1 and 3 have been synthesized from Ni(II) salts and the Schiff bases, generated from glycine and PBP (7) and PBA (11), respectively, in MeONa/MeOH solutions. The requisite carbonyl-derivatizing agents pyridine-2-carboxylic acid(2-benzoyl-phenyl)-amide 7 (PBP) and pyridine-2-carboxylic acid(2-formyl-phenyl)-amide 11 (PBA) were readily prepared from picolinic acid and o-aminobenzophenone or picolinic acid and methyl o-anthranilate, respectively. The structure of 1 was established by X-ray crystallography. Complexes 1 and 3 were found to undergo C-alkylation with alkyl halides under PTC conditions in the presence of beta-naphthol or benzyltriethylammonium bromide as catalysts to give mono- and bis-alkylated products, respectively. Decomposition of the complexes with aqueous HCl under mild conditions gave the required amino acids, and PBP and PBA were recovered. Alkylation of 1 with highly reactive alkyl halides, carried out under the PTC conditions in the presence of 10% mol of (S)- or (R)-2-hydroxy-2'-amino-1,1'-binaphthyl 31a (NOBIN) and/or its N-acyl derivatives and by (S)- or (R)-2-hydroxy-8'-amino-1,1'-binaphthyl 32a (iso-NOBIN) and its N-acyl derivatives, respectively, gave rise to alpha-amino acids with high enantioselectivities (90-98.5% ee) in good-to-excellent chemical yields at room temperature within several minutes. An unusually large positive nonlinear effect was observed in these reactions. The Michael addition of acrylic derivatives 37 to 1 was conducted under similar conditions with up to 96% ee. The (1)H NMR and IR spectra of a mixture of the sodium salt of NOBIN and 1 indicated formation of a complex between the two components. Implications of the association and self-association of NOBIN for the observed sense of asymmetric induction and nonlinear effects are discussed. PMID:14558835

Belokon, Yuri N; Bespalova, Natalia B; Churkina, Tatiana D; Csarov, Ivana; Ezernitskaya, Marina G; Harutyunyan, Syuzanna R; Hrdina, Radim; Kagan, Henri B; Kocovsk, Pavel; Kochetkov, Konstantin A; Larionov, Oleg V; Lyssenko, Konstantin A; North, Michael; Polsek, Miroslav; Peregudov, Alexander S; Prisyazhnyuk, Vladimir V; Vyskocil, Stepn

2003-10-22

253

Influence of the geometry around the manganese ion on the peroxidase and catalase activities of Mn(III)-Schiff base complexes.  

PubMed

The peroxidase and catalase activities of eighteen manganese-Schiff base complexes have been studied. A correlation between the structure of the complexes and their catalytic activity is discussed on the basis of the variety of systems studied. Complexes 1-18 have the general formulae [MnL(n)(D)(2)](X)(H(2)O/CH(3)OH)(m), where L(n)=L(1)-L(13); D=H(2)O, CH(3)OH or Cl; m=0-2.5 and X=NO(3)(-), Cl(-), ClO(4)(-), CH(3)COO(-), C(2)H(5)COO(-) or C(5)H(11)COO(-). The dianionic tetradentate Schiff base ligands H(2)L(n) are the result of the condensation of different substituted (OMe-, OEt-, Br-, Cl-) hydroxybenzaldehyde with diverse diamines (1,2-diaminoethane for H(2)L(1)-H(2)L(2); 1,2-diamino-2-methylethane for H(2)L(3)-H(2)L(4); 1,2-diamino-2,2-dimethylethane for H(2)L(5); 1,2-diphenylenediamine for H(2)L(6)-H(2)L(7); 1,3-diaminopropane for H(2)L(8)-H(2)L(11); 1,3-diamino-2,2-dimethylpropane for H(2)L(12)-H(2)L(13)). The new Mn(III) complexes [MnL(1)(H(2)O)Cl](H(2)O)(2.5) (2), [MnL(2)(H(2)O)(2)](NO(3))(H(2)O) (4), [MnL(6)(H(2)O)(2)][MnL(6)(CH(3)OH)(H(2)O)](NO(3))(2)(CH(3)OH) (8), [MnL(6)(H(2)O)(OAc)](H(2)O) (9) and [MnL(7)(H(2)O)(2)](NO(3))(CH(3)OH)(2) (12) were isolated and characterised by elemental analysis, magnetic susceptibility and conductivity measurements, redox studies, ESI spectrometry and UV, IR, paramagnetic (1)H NMR, and EPR spectroscopies. X-ray crystallographic studies of these complexes and of the ligand H(2)L(6) are also reported. The crystal structures of the rest of the complexes have been previously published and herein we have only revised their study by those techniques still not reported (EPR and (1)H NMR for some of these compounds) and which help to establish their structures in solution. Complexes 1-12 behave as more efficient mimics of peroxidase or catalase in contrast with 13-18. The analysis between the catalytic activity and the structure of the compounds emphasises the significance of the existence of a vacant or a labile position in the coordination sphere of the catalyst. PMID:22071076

Vzquez-Fernndez, M ngeles; Bermejo, Manuel R; Fernndez-Garca, M Isabel; Gonzlez-Riopedre, Gustavo; Rodrguez-Doutn, M Jess; Maneiro, Marcelino

2011-12-01

254

Synthesis and characterization of a series of transition metal complexes with a new symmetrical polyoxaaza macroacyclic Schiff base ligand: X-ray crystal structure of cobalt(II) and nickel(II) complexes and their antibacterial properties  

NASA Astrophysics Data System (ADS)

A new symmetrical [N4O2] hexadentate Schiff base ligand, (E)-N-(pyridin-2-ylmethylene)-2-(3-(2-((E)-pyridin-2-lmethyleneamino)phenoxy)naphthalen-2-yloxy)benzenamine, abbreviated to L, and its complexes of Ni(II), Cu(II), Zn(II), Co(II), Cd(II) and Mn(II) have been synthesized in the presence of metal ions. The complexes were structurally characterized by elemental analyses, IR, UV-Vis, NMR and molar conductivity. The crystal structures of two complexes, [NiL(ONO2)2]2H2O and [CoLCl2]CH3OH0.5H2O, have been determined by a single crystal X-ray diffraction study. In these complexes, the ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms. The metal ions complete their six coordination with two coordinated nitrate or chloride ions, forming a distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epid and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The activity data show that the complexes are more potent antibacterials than the parent Schiff base.

Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Valencia, Laura

2013-01-01

255

Asymmetric C-C Bond Formation between Chiral N-Phosphonyl Imines and Ni(II)-Complex of Glycine Schiff Base Provides a GAP Synthesis of ?,?-syn-Diamino Acid Derivatives.  

PubMed

The GAP asymmetric synthesis of ?,?-diamino acid derivatives has been achieved by reacting chiral N-phosphonyl imines with Ni(II)-complex of glycine ester-based enolate without the use of traditional purifications of chromatography and recrystallization. The successful control of synstereochemistry of vicinal diamino products complements our previous methods which afforded anti stereoisomers and enables all four individual isomers to be synthesized by simply changing enolate geometry. In contrast to our previous synthesis where required at least 5 equiv of glycine Schiff base enolate for complete conversion, the new synthesis only needs 1.1 equiv of glycine Schiff base enolate to give complete diastereoselectivity (>99% de) and yields (91% - 97%). The absolute stereochemistry has been unambiguously determined by X-ray structural analysis. PMID:25309122

Sun, Hao; Zhang, Haowei; Han, Jianlin; Pan, Yi; Li, Guigen

2013-08-01

256

cis-{MoO2}(2+) assisted Mannich-type addition of acetylacetonate methine to the azomethine of tridentate Schiff bases: racemic complexes with chiral transformed ligands.  

PubMed

Reactions of [MoO2(acac)2] (acac(-) = acetylacetonate) with the potential N2O-donor 5,5-membered fused chelate rings forming Schiff bases 2-(2-pyridylaldimine)ethanol (HL(1)) and 4/5-R-2-(2-pyridylaldimine)phenols (HL(n); n = 2-5 for R = H, 4-Cl, 4-Me and 5-Me, respectively) lead to the facile formation of racemic complexes of the general formula cis-[MoO2(acacL(1-5))] () in 80-85% yield. Here, (acacL(n))(2-) represents a chiral N2O2-donor ligand system formed by a novel Mannich-type reaction that involves acetylacetonate and the azomethine fragment of HL(n) both coordinated to the cis-{MoO2}(2+) unit. The characterization of has been performed with the help of microanalytical (CHN), spectroscopic (ESI-MS, IR, UV-Vis and (1)H- and (13)C-NMR) and electrochemical measurements. The molecular structures of all the complexes except for are authenticated by single crystal X-ray crystallography. The Mo(vi) center in each of these analogous complexes is in a distorted octahedral N2O4 coordination sphere assembled by the chiral N2O2-donor transformed ligand (acacL(n))(2-) and the two mutually cis-oriented oxo ligands. In the crystal lattice, each of exists as a centrosymmetric discrete dimer via a pair of reciprocal N-HO hydrogen bonds between its enantiomeric pairs. PMID:25554121

Kurapati, Sathish Kumar; Pal, Samudranil

2015-01-20

257

Synthesis of photo-luminescent Zn(ii) Schiff base complexes and its derivative containing Pd(ii) moiety  

Microsoft Academic Search

using Sonogashira coupling for the immobilisation of chiral Mn-salen complexes on gold electrodes and surfaces. As the growth of in- terest in the use of chiral zinc and other metal salen complexes in asymmetric Lewis acid-catalyzed reactions becomes more signifi- cant, 1,5 we are interested to see if the aryl alkynylated salen metal complexes could be readily prepared and how

Ku-Hsien Chang; Chiung-Cheng Huang; Yi-Hung Liu; Ya-Hui Hu; Pi-Tai Chou; Ying-Chih Lin

2004-01-01

258

Comprehensive study on the binding of iron schiff base complex with DNA and determining the binding mode.  

PubMed

The iron (III) [N, N' Bis (5-(triphenyl phosphonium methyl) salicylidene)-1, 2 ethanediamine] chloride [Fe Salen]Cl, has been synthesized and characterized as described previously. The interaction of iron complex with calf thymus (CT) DNA has been studied extensively by experimental techniques. Absorption spectra showed both hypochromism and hyperchromism. Thermal denaturation study of DNA with complex revealed the ?Tm of 5C. Competitive binding study shows that the enhanced emission intensity of ethidium bromide (EB) in the presence of DNA was quenched by adding of the iron complex indicating that it displaces EB from its binding site in DNA and the apparent binding constant has been estimated to be 5??10(6)??M(-1). Fluorescence Scatchard plot revealed type B behavior for interaction of complex to DNA. Circular dichroism (CD) spectra measurements showed that the complex interacts with DNA via surface and groove bindings. Linear dichroism (LD) measurements confirmed the bending of DNA in the presence of complex. Furthermore, Isothermal titration calorimetry (ITC) experiments approved that the binding of complex is based on both electrostatic and hydrophobic interactions. More, ITC profile exhibits the existence of two binding phases for the complex. PMID:23519527

Nejat Dehkordi, Maryam; Lincoln, Per

2013-07-01

259

Synthesis and characterisation of nickel Schiff base complexes containing the meso-1,2-diphenylethylenediamine moiety: selective interactions with a tetramolecular DNA quadruplex.  

PubMed

As part of a program of preparing metal complexes which exhibit unique affinities towards different DNA structures, we have synthesised the novel Schiff base complex N,N'-bis-4-(hydroxysalicylidine)meso-diphenylethylenediaminenickel(ii) (), via the reaction of meso-1,2-diphenylethylenediamine and 2,4-dihydroxybenzaldehyde. This compound was subsequently reacted with 1-(2-chloroethyl)piperidine or 1-(2-chloropropyl)piperidine, to afford the alkylated complexes N,N'-bis-(4-((1-(2-ethyl)piperidine)oxy)salicylidine)meso-1,2-diphenylethylenediaminenickel(ii) () and N,N'-bis-(4-((1-(3-propyl)piperidine)oxy)-salicylidine)meso-1,2-diphenylethylenediaminenickel(ii) (), respectively. These complexes were characterised by microanalysis and X-ray crystallography in the solid state, and in solution by (1)H and (13)C NMR spectroscopy. Electrospray ionisation mass spectrometry (ESI-MS) was used to confirm the identity of () and (). The affinities of () and () towards a discrete 16 mer duplex DNA molecule, and examples of both tetramolecular and unimolecular DNA quadruplexes, was explored using a variety of techniques. In addition, the affinity of two other complexes () and (), towards the same DNA molecules was examined. Complexes () and () were prepared by methods analogous to those which afforded () and (), however 1,2-phenylenediamine was used instead of meso-1,2-diphenylethylenediamine in the initial step of the synthetic procedure. The results of ESI-MS and DNA melting temperature measurements suggest that () and () exhibit a lower affinity than () and () towards the 16 mer duplex DNA molecule, while circular dichroism (CD) spectroscopy suggested that none of the four complexes had a major effect on the conformation of the nucleic acid. In contrast, ESI-MS and CD spectroscopy suggested that both () and () show significant binding to a tetramolecular DNA quadruplex. The results of ESI-MS and Fluorescence Resonance Energy Transfer (FRET) assays indicated that () and () did not bind as tightly to a unimolecular DNA quadruplex, although both complexes had a major effect on the CD spectrum of the latter. These results highlight that the presence of the meso-1,2-diphenylethylenediamine moiety in metal complexes of this type may provide a general method for instilling selectivity for some DNA quadruplexes over dsDNA. PMID:25572696

Davis, Kimberley J; Richardson, Christopher; Beck, Jennifer L; Knowles, Brett M; Gudin, Aurore; Mergny, Jean-Louis; Willis, Anthony C; Ralph, Stephen F

2015-02-01

260

Binding Studies of a New Water-Soluble Iron(III) Schiff Base Complex to DNA Using Multispectroscopic Methods  

PubMed Central

A novel iron(III) complex [Fe(SF)](ClO4)3.2H2O; in which SF?=?N,N0-bis{5-[(triphenylphosphonium chloride)-methyl] salicylidene}-o-phenylenediamine) has been synthesized and characterized using different physicochemical methods. The binding of this complex with calf thymus (CT) DNA was investigated by circular dichroism, absorption studies, emission spectroscopy, voltammetric studies, and viscosity measurements. The results showed that this complex can bind to DNA via external and groove binding modes. PMID:22899896

Shahabadi, Nahid; Ghasemian, Zeinab; Hadidi, Saba

2012-01-01

261

Microwave-assisted synthesis, characterization and biological activities of organotin (IV) complexes with some thio Schiff bases  

NASA Astrophysics Data System (ADS)

Microwave-assisted synthesis and characterization of the organotin (IV) complexes are reported. Trigonal bipyramidal and octahedral complexes of tin (IV) have been synthesized by the reaction of dimethyltin (IV) dichloride with 4-nitrobenzanilide- S-benzyldithiocarbazate (L 1H), 4-chlorobenzanilide- S-benzyldithiocarbazate (L 2H), 4-nitrobenzanilidebenzothiazoline (L 3H) and 4-chlorobenzanilidebenzothiazoline (L 4H). The complexes so formed were characterized by elemental analysis, conductance measurements, molecular weight determinations and spectral data viz. IR, UV-Visible, 1H and 13C NMR. The anti-microbial activities of the ligands and their corresponding organotin (IV) complexes have been screened against various strains of bacteria and fungi. Antifertility activity against male albino rats has also been reported.

Singh, Ran Vir; Chaudhary, Pratibha; Chauhan, Shikha; Swami, Monika

2009-03-01

262

Mixed?Ligand Complexes of a Schiff Base, 8?Hydroxyquinoline and Oxalic Acid with Cu(II), Ni(II), Zn(II), and Fe(III) Ions: Pyrolytic Products and Biological Activities  

Microsoft Academic Search

Binary mononuclear complexes of the Schiff base ligand 1,4?di(hydroxybenzylidene)thiosemicarbazide (H2L) and the transition metal ions Cu(II), Ni(II), Zn(II), and Fe(III) were prepared in the presence of various molar ratios of LiOH. The binary complexes react with 8?hydroxyquinoline (8?HOqu) and oxalic acid (H2Ox) to form mixed?ligand complexes. The mixed ligand complexes were prepared by using various molar ratios of LiOH. The

Mahmoud M. Mashaly; A. A. Faheim

2004-01-01

263

Synthesis and In Vitro Antitumor Activity of Two Mixed-Ligand Oxovanadium(IV) Complexes of Schiff Base and Phenanthroline  

PubMed Central

Two oxovanadium(IV) complexes of [VO(msatsc)(phen)], (1) (msatsc = methoxylsalicylaldehyde thiosemicarbazone, phen = phenanthroline) and its novel derivative [VO (4-chlorosatsc)(phen)], (2) (4-chlorosatsc = 4-chlorosalicylaldehyde thiosemicarbazone), have been synthesized and characterized by elemental analysis, IR, ES-MS, 1H NMR, and magnetic susceptibility measurements. Their antitumor effects on BEL-7402, HUH-7, and HepG2 cells were studied by MTT assay. The antitumor biological mechanism of these two complexes was studied in BEL-7402 cells by cell cycle analysis, Hoechst 33342 staining, Annexin V-FITC/PI assay, and detection of mitochondrial membrane potential (??m). The results showed that the growth of cancer cells was inhibited significantly, and complexes 1 and 2 mainly caused in BEL-7402 cells G0/G1 cell cycle arrest and induced apoptosis. Both 1 and 2 decreased significantly the ??m, causing the depolarization of the mitochondrial membrane. Complex 2 showed greater antitumor efficiency than that of complex 1. PMID:23424390

Zhang, Yongli; Wang, Xiangsheng; Fang, Wei; Cai, Xiaoyan; Chu, Fujiang; Liao, Xiangwen; Lu, Jiazheng

2013-01-01

264

Synthesis and crystal structure of some new cadmium (II) macrocyclic Schiff-base complexes containing piperazine moiety  

Microsoft Academic Search

The metal templated Cd(II) cyclocondensation of 2,6-diacetylpiridine or 2,6-pyridinedicarbaldehyde and two different amines containing piperazine moieties have been investigated. The resulting ligands, L1 and L2 are 16- and L3 and L4 17-membered pentaaza macrocycles. The complexes have been characterized by a variety of methods including IR, 1H, 13C NMR, DEPT, COSY(H,H), HMQC(H,C), FAB spectrometry and conductivimetry measurements. The crystal structures

Hassan Keypour; Majid Rezaeivala; Laura Valencia; Sadegh Salehzadeh; Paulo Perez-Lourido; Hamid Reza Khavasi

2009-01-01

265

Synthesis, characterization and antioxidant activity of water soluble MnIII complexes of sulphonato-substituted Schiff base ligands.  

PubMed

Two new Mn(III) complexes Na[Mn(5-SO(3)-salpnOH)(H(2)O)]5H(2)O (1) and Na[Mn(5-SO(3)-salpn)(MeOH)]4H(2)O (2) (5-SO(3)-salpnOH=1,3-bis(5-sulphonatosalicylidenamino)propan-2-ol, 5-SO(3)-salpn=1,3-bis(5-sulphonatosalicylidenamino)propane) have been prepared and characterized. Electrospray ionization-mass spectrometry, UV-visible and (1)H NMR spectroscopic studies showed that the two complexes exist in solution as monoanions [Mn(5-SO(3)-salpn(OH))(solvent)(2)](-), with the ligand bound to Mn(III) through the two phenolato-O and two imino-N atoms located in the equatorial plane. The E(1/2) of the Mn(III)/Mn(II) couple (-47.11 (1) and -77.80mV (2) vs. Ag/AgCl) allows these complexes to efficiently catalyze the dismutation of O(2)(-), with catalytic rate constants 2.4x10(6) (1) and 3.6x10(6) (2) M(-1)s(-1), and IC(50) values of 1.14 (1) and 0.77 (2) muM, obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutase assay, in aqueous solution of pH 7.8. The two complexes are also able to disproportionate up to 250 equivalents of H(2)O(2) in aqueous solution of pH 8.0, with initial turnover rates of 178 (1) and 25.2 (2) mM H(2)O(2) min(-1)mM(-1)catalyst(-1). Their dual superoxide dismutase/catalase activity renders these compounds particularly attractive as catalytic antioxidants. PMID:20129671

Moreno, Diego; Daier, Vernica; Palopoli, Claudia; Tuchagues, Jean-Pierre; Signorella, Sandra

2010-05-01

266

Cd(??) and Mn(??) complexes of a new hexadentate Schiff base ligand derived from an asymmetric tripodal tetraamine and 2-pyridinecarboxaldehyde  

Microsoft Academic Search

Two new compounds, [CdL22pyfp(NO3)](ClO4) (1) and [MnL22pyfpCl](ClO4) (2), were prepared by the template condensation of a previously known ligand, (L22py), and 2-pyridinecarboxaldehyde in the presence of Cd(NO3)24H2O or MnCl24H2O in equimolar ratios. The resulting compounds were characterized by elemental analysis, IR and single crystal X-ray diffraction, and by NMR in the case of the Cd(II) complex. The Cd(II) ion is

Sadegh Salehzadeh; Reza Golbedaghi; Ian S. Tidmarsh; Nawal K. Al-Rasbi; Harry Adams; Michael D. Ward

2008-01-01

267

Complete ?* intramolecular aromatic hydroxylation mechanism through O2 activation by a Schiff base macrocyclic dicopper(I) complex  

PubMed Central

Summary In this work we analyze the whole molecular mechanism for intramolecular aromatic hydroxylation through O2 activation by a Schiff hexaazamacrocyclic dicopper(I) complex, [CuI 2(bsH2m)]2+. Assisted by DFT calculations, we unravel the reaction pathway for the overall intramolecular aromatic hydroxylation, i.e., from the initial O2 reaction with the dicopper(I) species to first form a CuICuII-superoxo species, the subsequent reaction with the second CuI center to form a ?-?2:?2-peroxo-CuII 2 intermediate, the concerted peroxide OO bond cleavage and CO bond formation, followed finally by a proton transfer to an alpha aromatic carbon that immediately yields the product [CuII 2(bsH2m-O)(?-OH)]2+. PMID:23616799

Sol, Miquel

2013-01-01

268

Synthesis aspects, structural, spectroscopic, antimicrobial and room temperature ferromagnetism of zinc iodide complex with Schiff based ligand  

NASA Astrophysics Data System (ADS)

In this paper, we report the successful growth of complex compound of zinc iodide with thiocarbamide by slow evaporation method. The single crystal XRD study reveals that the crystal belongs to monoclinic system with centrosymmetric space group and powder XRD analysis shows that the perfect crystalline nature of the crystal. The presence of functional group and element were confirmed from FT-IR and EDAX analysis. Optical absorbance of the grown crystal was studied by UV-Vis spectrophotometer. The optical constants were calculated from the optical absorbance data such as refractive index (n), extinction coefficient (K) and reflectance (R). The optical band gap (Eg) of thiocarbamide zinc iodide crystal is 4.22 eV. The magnetic properties of grown crystal have been determined by Vibrating Sample Magnetometry (VSM). Room temperature magnetization revealed a ferromagnetic behaviour for the grown crystal. The antibacterial and antifungal activities of the title compound were performed by well diffusion method and MIC method against the standard bacteria like Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and against fungus like Aspergillus niger, Rhizopus sps and Penicillium sps. Thermal behaviour of the crystal has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA).

Shakila, K.; Kalainathan, S.

2015-01-01

269

Observation of an organic acid mediated spin state transition in a Co(II)-Schiff base complex: an EPR, HYSCORE, and DFT study.  

PubMed

The interactions of a weak organic acid (acetic acid, HOAc) with a toluene solution of the Co(II)-Schiff base type complex, (R,R')-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamino Co(II) (labeled [Co(1)]), was investigated using EPR, HYSCORE, and DFT computations. This activated [Co(II)(1)] system is extremely important within the context of asymmetric catalysts (notably the hydrolytic kinetic resolution of epoxides) despite the lack of detailed structural information about the nature of the paramagnetic species present. Under anaerobic conditions, the LS [Co(II)(1)] complex with a |yz, (2)A(2)? ground state is converted into a low-spin (LS) and a high-spin (HS) complex in the presence of the acid. The newly formed LS state is assigned to the coordinated [Co(II)(1)]-(HOAc) complex, possessing a |z(2), (2)A(1)? ground state (species A; g(x) = 2.42, g(y) = 2.28, g(z) = 2.02, A(x) = 100, A(y) = 120, A(z) = 310 MHz). The newly formed HS state is assigned to an acetate coordinated [Co(II)(1)]-(OAc(-)) complex, possessing an S = 3/2 spin ground state (species B, responsible for a broad EPR signal with g ? 4.6). These spin ground states were confirmed with DFT calculations using the hybrid BP86 and B3LYP functionals. Under aerobic conditions, the LS and HS complexes (species A and B) are not observed; instead, a new HS complex (species C) is formed. This complex is tentatively assigned to a paramagnetic superoxo bridged dimer (AcO(-))[Co(II)(1)O(2)(-)Co(III)(1)](HOAc), as distinct from the more common diamagnetic peroxo bridged dimers. Species C is characterized by a very broad HS EPR signal (g(x) = 5.1, g(y) = 3.9, g(z) = 2.1) and is reversibly formed by oxygenation of the LS [Co(II)(1)]-(HOAc) complex to the superoxo complex [Co(III)(1)O(2)(-)](HOAc), which subsequently forms the association complex C by interaction with the HS [Co(II)(1)](OAc(-)) species. The LS and HS complexes were also identified using other organic acids (benzoic and propanoic acid). Thermal annealing-quenching experiments revealed the additional presence of [Co(III)(1)O(2)(-)](HOAc) adducts, corroborating the presence of species C and the presence of diamagnetic dimer complexes in the solution, such as the EPR silent (HOAc)[Co(III)(1)(O(2)(2-))Co(III)(1)](HOAc). Overall, it appears that a facile interconversion of the [Co(1)] complex, possessing a LS ground state, occurs in the presence of acetic acid, producing both HS and LS Co(II) states, prior to formation of the oxidized active form of the catalyst, [Co(III)(1)](OAc(-)). PMID:22830538

Vinck, Evi; Carter, Emma; Murphy, Damien M; Van Doorslaer, Sabine

2012-08-01

270

Evaluation of DNA Binding, Cleavage, and Cytotoxic Activity of Cu(II), Co(II), and Ni(II) Schiff Base Complexes of 1-Phenylindoline-2,3-dione with Isonicotinohydrazide  

PubMed Central

One new series of Cu(II), Co(II), and Ni(II) Schiff base complexes was prepared through the condensation reaction between 1-phenylindoline-2,3-dione with isonicotinohydrazide followed by metalation, respectively. The Schiff base ligand(L), (E)-N?-(2-oxo-1-phenylindolin-3-lidene)isonicotinohydrazide, and its complexes were found soluble in DMF and DMSO solvents and characterized by using the modern analytical and spectral techniques such as elemental analysis, conductivity, magnetic moments, IR, NMR, UV-visible, Mass, CV, and EPR. The elemental analysis data of ligand and their complexes were well agreed with their calculated values in which metal and ligand stoichiometry ratio 1?:?2 was noted. Molar conductance values indicated that all the complexes were found to be nonelectrolytes. All the complexes showed octahedral geometry around the central metal ions. Herein, we better characterized DNA binding with the complexes by UV-visible and CD spectroscopy and cyclic voltammetry techniques. The DNA cleavage experiments were carried out by Agarose gel electrophoresis method and the cytotoxicity experiments by MTT assay method. Based on the DNA binding, cleavage, and cytotoxicity studies, Cu and Ni complexes were found to be good anticancer agents against AGS-human gastric cancer cell line. PMID:24744691

Gomathi, Ramadoss; Ramu, Andy; Murugan, Athiappan

2014-01-01

271

Influence of the Pendant Arm, Halide, and Solvent on High-Efficient-Tuning [1 + 1] and [2 + 2] Schiff-Base Macrocyclic Complexes via a Zinc-Ion Template.  

PubMed

A series of pendant-armed Schiff-base macrocyclic complexes 1-7 have been prepared by the condensation between extended dialdehydes with pendant arms (H2hpdd/H2pdd) and 1,3-propanediamine in the presence of ZnX2 (X = Cl, Br, I), where 18-membered [1 + 1] mononuclear and 36-membered [2 + 2] half-fold trinuclear macrocyclic zinc(II) complexes are yielded. Three experimental variables, i.e., the pendant arm, halide, and solvent, are found to influence the organization of final macrocyclic complexes, in addition to the conventional metal-ion template effect promoting reversible formation and cleavage of Schiff-base imine bonds. It is noted that all of the reactions produce singular macrocyclic complexes in high yields if the experimental variables are fixed, and the selection of different pendant arms and halide counterions will generate different [1 + 1] mononuclear and [2 + 2] trinuclear macrocyclic zinc(II) complexes. More interestingly, [1 + 1] and [2 + 2] macrocyclic zinc(II) complexes 2 and 3 can be produced in methanol and ethanol, respectively, in the case of the reaction between ZnBr2, H2pdd, and 1,3-propanediamine. Further experiments reveal that red solid 2 and yellow-green solid 3 can be transformed to each other just by altering the type of solvent, and this tuning is complete and reversible. PMID:25535804

Zhang, Kun; Qian, Huifen; Zhang, Lei; Huang, Wei

2015-01-20

272

Spectroscopic characterization of copper(II) complexes of indoxyl N(4)-methyl thiosemicarbazone  

NASA Astrophysics Data System (ADS)

New copper(II) complexes of indoxyl thiosemicarbazone (ITSC) of general composition CuL 2X 2 (where L: ITSC; X: Cl -, NO 3-, ClO 4-, NCS -) have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements and spectral (electronic, IR, EPR, 1H NMR , Mass) studies. Cyclic voltammetry measurements show quasi-reversible Cu 2+/Cu 1+ couple. Various physico-chemical techniques suggest a tetragonal structure for these copper(II) complexes.

Chandra, Sulekh; Kumar, Umendra

2004-10-01

273

Synthesis, Physicochemical, and Antimicrobial Screening Studies of Complexes of Co(II), Ni(II), Cu(II), and Zn(II) with 18-membered Schiff Base Octaazamacrocyclic Ligand  

Microsoft Academic Search

A [2 + 2] condensation reaction between 1,8-diaminonaph-thalene and N,N?-diacetylhydrazine in 1:1 molar ratio in methanol resulted in a novel Schiff base macrocyclic ligand, (L): 7,9:16,18-dinaphthyl-1,3,4,6,10,12,13,15-octaazacyclooctadecane-1,5,10,14-tetraene. Metal complexes have been synthesized by the reaction of L with the corresponding metal salts. The results of elemental analyses, ESI-mass, and Job's method ascertain their stoichiometry while the spectral data obtained from H

Tahir Ali Khan; Sultana Naseem; Rafat Hajra; Mohammad Shakir

2010-01-01

274

Copper(II) complexes with heterocyclic hydroxyimino-containing ligands  

SciTech Connect

The reaction of oximes (R = Ph (L'), C=N (L'')) with the copper(II) salts CuA/sub 2/ in methanol has given the complexes CuL/sub 2/ ' x H/sub 2/O and CuL/sub 2//sup ''/ x 2H/sub 2/O (I) (A = Acet/sup -/), CuHLCl/sub 2/ x H/sub 2/O (II) (A = Cl/sup -/), CuLOH(ClO/sub 4/)/sub 2/ x 2H/sub 2/O (III) (A = ClO/sub 4//sup -/) and the complexes Cu/sub 3/L/sub 3//sup '/OH(NO/sub 3/)/sub 2/ and Cu/sub 3/L/sub 3//sup ''/(OH)/sub 2/NO/sub 3/ (IV) (A = NO/sub 3//sup -/). Their physicochemical properties have been studied by the methods of IR spectroscopy and magnetochemistry. It has been shown that complexes I have a chelate structure and that their magnetic moments are not dependent on the temperature. An anti-ferromagnetic exchange interaction takes place in complexes II-IV. On the basis of magnetochemical measurements over a broad temperature range and data calculated in the framework of the Heisenberg-Dirac-Van Vleck model of isotropic exchange interactions, a dimeric structure has been proposed for the complexes of type II, and a trinuclear cluster structure has been proposed for complexes III and IV.

Kogan, V.A.; Burlov, A.S.; Popov, L.D.; Lukov, V.V.; Koshchienko, Yu.V.; Tsupak, E.B.; Barchan, G.P.; Chigarenko, G.G.; Bolotnikov, V.S.

1988-05-01

275

Synthesis, spectral characterization, DNA binding studies and antimicrobial activity of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) complexes with 4-aminoantipyrine Schiff base of ortho-vanillin.  

PubMed

A series of transition metal complexes of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) have been synthesized involving the Schiff base, 2,3-dimethyl-1-phenyl-4-(2-hydroxy-3-methoxy benzylideneamino)-pyrazol-5-one(L), obtained by condensation of 4-aminoantipyrine with 3-methoxy salicylaldehyde. Structural features were obtained from their FT-IR, UV-vis, NMR, ESI Mass, elemental analysis, magnetic moments, molar conductivity and thermal analysis studies. The Schiff base acts as a monovalent bidentate ligand, coordinating through the azomethine nitrogen and phenolic oxygen atom. Based on elemental and spectral studies six coordinated geometry is assigned to Co(II), Ni(II), Fe(III) and VO(IV) complexes and four coordinated geometry is assigned to Zn(II) complex. The interaction of metal complexes with Calf thymus DNA were carried out by UV-VIS titrations, fluorescence spectroscopy and viscosity measurements. The binding constants (K(b)) of the complexes were determined as 5??10(5) M(-1) for Co(II) complex, 1.33??10(4) M(-1) for Ni(II) complex, 3.33??10(5) M(-1) for Zn(II) complex, 1.25??10(5) M(-1) for Fe(III) complex and 8??10(5) M(-1) for VO(IV) complex. Quenching studies of the complexes indicate that these complexes strongly bind to DNA. Viscosity measurements indicate the binding mode of complexes with CT DNA by intercalation through groove. The ligand and it's metal complexes were screened for their antimicrobial activity against bacteria. The results showed the metal complexes to be biologically active, while the ligand to be inactive. PMID:24781660

Anupama, B; Sunita, M; Shiva Leela, D; Ushaiah, B; Gyana Kumari, C

2014-07-01

276

Chiral vanadium(V) complexes with 2-aminoglucose Schiff-base ligands and their solution configurations: synthesis, structures, and DFT calculations.  

PubMed

The sugar-modified Schiff-base ligands derived from benzyl 2-deoxy-2-salicylideneamino-?-D-glucopyranoside (H2L(5-Br) and H2L(3-OMe)) were used to prepare the chiral oxidovanadium(V) complexes [VO(L(5-Br))(OMe)] (1) and [VO(L(3-OMe))(OMe)] (2) which can be isolated from a methanol solution as the six-coordinate complexes with an additional methanol ligand [VO(L(5-Br))(OMe)(MeOH)] (1-MeOH) and [VO(L(3-OMe))(OMe) (MeOH)] (2-MeOH). Both complexes crystallize in the orthorhombic space group P2(1)2(1)2(1) together with two solvent molecules of methanol as 1-MeOH2MeOH and 1-MeOH2MeOH. In both crystal structures, only diastereomers with A configuration at the chiral vanadium centre (OC-6-24-A) are observed which corresponds to an cis configuration of the oxido group at the vanadium centre and the benzyl group at the anomeric carbon of the sugar backbone. Upon recrystallization of 2-MeOH from chloroform, the five-coordinate complex 2 was obtained which crystallizes in the monoclinic space group P2(1) with one co-crystallized chloroform molecule (2CHCl3). For the chiral vanadium centre in 2CHCl3, a C configuration (SPY-5-43-C) is observed which corresponds to an trans structure as far as the orientations of the oxido and benzyl groups are concerned. (1)H and (51)V NMR spectra of 1 and 2 indicate the presence of two diastereomers in solution. Their absolute configurations can be assigned based on the magnetic anisotropy effect of the oxidovanadium group. This effect leads to significant differences for the (1)H NMR chemical shifts of the H-2 (1.1 ppm) and H-3 protons (0.3 ppm) of the glucose backbone of the two diastereomers, with the downfield shift observed for the H-2 proton of the C-configured and the H-3 proton of the A-configured diastereomer at the vanadium centre. For 1 and 2 the difference between the (51)V NMR chemical shifts of the two diastereomers is 30 and 28 ppm, respectively. Also in the (13)C NMR significant chemical shift differences between the two diastereomers are observed for the carbon atoms C2 (2 ppm) and C3 (4 ppm). DFT calculations of the NMR chemical shift parameters have been performed which are in good agreement with the experimental data. Moreover, the isomerization mechanism between the diastereomers is analysed on the basis of DFT calculations which indicate the required presence of methanol molecules as protic donors. PMID:23760018

Mohammadnezhad, Gholamhossein; Bhme, Michael; Geibig, Daniel; Burkhardt, Anja; Grls, Helmar; Plass, Winfried

2013-09-01

277

Synthesis, spectral characterization, solution equilibria, in vitro antibacterial and cytotoxic activities of Cu(II), Ni(II), Mn(II), Co(II) and Zn(II) complexes with Schiff base derived from 5-bromosalicylaldehyde and 2-aminomethylthiophene.  

PubMed

Schiff base namely 2-aminomethylthiophenyl-4-bromosalicylaldehyde (ATS)(4-bromo-2-(thiophen-2-yl-imino)methylphenol) and its metal complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, ESR and thermal analysis (TGA). The analytical data of the complexes show the formation of 1:2 [M:L] ratio of the formula [ML2], where M represents Ni(II), Zn(II) and Cu(II) ions, while L represents the deprotonated Schiff base. IR spectra show that ATS is coordinated to the metal ions in a bidentate manner through azomethine-N and phenolic-oxygen groups. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria. A cytotoxicity of the compounds against colon (HCT116) and larynx (HEP2) cancer cells have been studied. Protonation constants of (ATS) ligand and stability constants of its Cu2+, Co2+, Mn2+, Zn2+ and Ni2+ complexes were determined by potentiometric titration method in 50% (v/v) DMSO-water solution at ionic strength of 0.1 M NaNO3. PMID:21705267

El-Sherif, Ahmed A; Eldebss, Taha M A

2011-09-01

278

Synthesis, spectral characterization, solution equilibria, in vitro antibacterial and cytotoxic activities of Cu(II), Ni(II), Mn(II), Co(II) and Zn(II) complexes with Schiff base derived from 5-bromosalicylaldehyde and 2-aminomethylthiophene  

NASA Astrophysics Data System (ADS)

Schiff base namely 2-aminomethylthiophenyl-4-bromosalicylaldehyde (ATS)(4-bromo-2-(thiophen-2-yl-imino)methylphenol) and its metal complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, ESR and thermal analysis (TGA). The analytical data of the complexes show the formation of 1:2 [M:L] ratio of the formula [ML 2], where M represents Ni(II), Zn(II) and Cu(II) ions, while L represents the deprotonated Schiff base. IR spectra show that ATS is coordinated to the metal ions in a bidentate manner through azomethine-N and phenolic-oxygen groups. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria. A cytotoxicity of the compounds against colon (HCT116) and larynx (HEP2) cancer cells have been studied. Protonation constants of (ATS) ligand and stability constants of its Cu 2+, Co 2+, Mn 2+, Zn 2+ and Ni 2+ complexes were determined by potentiometric titration method in 50% (v/v) DMSO-water solution at ionic strength of 0.1 M NaNO 3.

El-Sherif, Ahmed A.; Eldebss, Taha M. A.

2011-09-01

279

Synthesis, spectroscopic characterization and biological activities of N4O2 Schiff base ligand and its metal complexes of Co(II), Ni(II), Cu(II) and Zn(II)  

NASA Astrophysics Data System (ADS)

The Schiff base ligand, bis(indoline-2-one)triethylenetetramine (L) obtained from condensation of triethylenetetramine and isatin was used to synthesize the complexes of type, [ML]Cl2 [M = Co(II), Ni(II), Cu(II) and Zn(II)]. L was characterized on the basis of the results of elemental analysis, FT-IR, 1H and 13C NMR, mass spectroscopic studies. The stoichiometry, bonding and stereochemistries of complexes were ascertained on the basis of results of elemental analysis, magnetic susceptibility values, molar conductance and various spectroscopic studies. EPR, UV-vis and magnetic moments revealed an octahedral geometry for complexes. L and its Cu(II) and Zn(II) complexes were screened for their antibacterial activity. Analgesic activity of Cu(II) and Zn(II) complexes was also tested in rats by tail flick method. Both complexes were found to possess good antibacterial and moderate analgesic activity.

Al-Resayes, Saud I.; Shakir, Mohammad; Abbasi, Ambreen; Amin, Kr. Mohammad Yusuf; Lateef, Abdul

280

Transition metal complexes of neocryptolepine analogues. Part I: Synthesis, spectroscopic characterization, and invitro anticancer activity of copper(II) complexes.  

PubMed

New generation of copper(II) complexes with aminoalkylaminoneocryptolepine as bidentate ligands has been synthesized and it is characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, (1)H NMR and ESR) and thermal studies. The IR data suggest the coordination modes for ligands which behave as a bidentate with copper(II) ion. Based on the elemental analysis, magnetic studies, electronic and ESR data, binuclear square planar geometry was proposed for complexes 7a, 7b, square pyramidal for 9a, 9b and octahedral for 8a, 8b, 10a, 10b. The molar conductance in DMF solution indicates that all complexes are electrolyte except 7a and 7b. The ESR spectra of solid copper(II) complexes in powder form showed an axial symmetry with (2)B1g as a ground state and hyperfine structure. The thermal stability and degradation of the ligands and their metal complexes were studied employing DTA and TG methods. The metal-free ligands and their copper(II) complexes were tested for their in vitro anticancer activity against human colon carcinoma (HT-29). The results showed that the synthesized copper(II) complexes exhibited higher anticancer activity than their free ligands. Of all the studied copper(II) complexes, the bromo-substituted complex 9b exhibited high anticancer activity at low micromolar inhibitory concentrations (IC50=0.58?M), compared to the other complexes and the free ligands. PMID:24867072

Emam, Sanaa Moustafa; El Sayed, Ibrahim El Tantawy; Nassar, Nagla

2015-03-01

281

Copper(I) and copper(II) complexes of an ethylene cross-bridged cyclam  

E-print Network

Copper(I) and copper(II) complexes of an ethylene cross-bridged cyclam Timothy J. Hubin,a Nathaniel and crystal structures of (4,11-dibenzyl- 1,4,8,11-tetraazabicyclo[6.6.2]hexadecane- 4 N)copper(I) hexa)- copper(II) bis(hexa¯uorophosphate), [Cu(C2H3N)(C26H38- N4)](PF6)2, are described. The CuI ion

Hubin, Tim

282

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)

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.

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

2014-04-01

283

Organotin(IV) complexes derived from Schiff base N'-[(1E)-(2-hydroxy-3-methoxyphenyl)methylidene]pyridine-4-carbohydrazone: synthesis, in vitro cytotoxicities and DNA/BSA interaction.  

PubMed

Five organotin(IV) compounds were synthesized from N'-[(1E)-(2-hydroxy-3-methoxyphenyl)methylidene]pyridine-4-carbohydrazone and the corresponding dialkyltin(IV) or trialkyltin(IV) precursor. Solid state structures were determined by IR, elemental analysis, NMR spectroscopy, and for 1, 2, 4 and 5 single crystal X-ray diffraction analysis. Compounds 1, 2 and 4 are monomers with the tin atoms five-coordinated in distorted trigonal bipyramid, of which the deprotonated Schiff base ligand chelate to tin center in the enolic tridentate mode. Differently, in compound 5, the enolization does not occur for the Schiff base ligand, and only the pyridinyl N atom and the deprotonated phenol hydroxyl oxygen atom participate in the coordination. Fascinatingly, six trimethyltin(IV) coordination units are linked by the Sn?N weak interaction atoms and form a 72-membered crown-like macrocycle. Preliminary invitro cytotoxicity studies on five human tumor cells lines (HL-60, A549, HT-29, HCT-116 and Caco-2) by MTT assay reveal that di-n-butyltin(IV) complex 2 and diphenyltin(IV) complex 4 triggered significant antiproliferative effects in cultured tumor cells, and their cytotoxic activity correlates with intracellular organotin(IV) concentration. The interaction of the complexes with calf thymus DNA (CT-DNA) has been explored by absorption and emission titration methods, which revealed that complexes 2 and 4 interact with CT-DNA through groove-binding and partial intercalation of the extended planar ligand with the DNA base stack. Further, the albumin interactions of complexes 2 and 4 were investigated using fluorescence quenching spectra and synchronous fluorescence spectra. Studies reveal that di-n-butyltin(IV) complex 2 with higher cytotoxicity show stronger DNA/BSA interaction than diphenyltin(IV) complex 4. PMID:25216377

Hong, Min; Geng, Honglin; Niu, Meiju; Wang, Fei; Li, Dacheng; Liu, Jifeng; Yin, Handong

2014-10-30

284

Catechol oxidase activity of dinuclear copper(II) complexes of Robson type macrocyclic ligands: Syntheses, X-ray crystal structure, spectroscopic characterization of the adducts and kinetic studies  

Microsoft Academic Search

Five dinuclear copper(II) complexes, [Cu2L1(N3)22H2O] (1), [Cu2L2(N3)22H2O] (2), [Cu2L3(N3)22H2O] (3), [Cu2L4(N3)22H2O] (4) and [Cu2L5(N3)22H2O] (5) of Robson type macrocyclic Schiff-base ligands derived from [2+2] condensation of 4-methyl-2,6-diformylphenol with 1,3-diaminopropane (H2L1), 1,2-diaminoethane (H2L2), 1,2-diaminopropane (H2L3), 1,2-diamino-2-methylpropane (H2L4) and 1,2-diaminocyclohexane (H2L5), respectively have been synthesized and characterized. Catecholase activity of those complexes using 3,5-di-tert-butylcatechol as substrate has been investigated in two solvents,

Kazi Sabnam Banu; Tanmay Chattopadhyay; Arpita Banerjee; Santanu Bhattacharya; Ennio Zangrando; Debasis Das

2009-01-01

285

Continuous flow catalysis with a biomimetic copper(II) complex covalently immobilized on graphite felt  

E-print Network

of the complex on the surface was achieved by a two steps method. First the porous graphite felt support Catechol oxidase, biomimetic, flow, heterogeneous catalysis, copper complex, diazonium salts, graphite felt1 Continuous flow catalysis with a biomimetic copper(II) complex covalently immobilized on graphite

Paris-Sud XI, Université de

286

Electrochemistry of copper(II) induced complexes in mycorrhizal maize plant tissues.  

PubMed

Aim of the present paper was to study the electrochemical behavior of copper(II) induced complexes in extracts obtained from mycorrhizal and non-mycorrhizal maize (Zea mays L.) plants grown at two concentrations of copper(II): physiological (31.7 ng/mL) and toxic (317 ?g/mL). Protein content was determined in the plant extracts and, after dilution to proper concentration, various concentrations of copper(II) ions (0, 100, 200 and 400 ?g/mL) were added and incubated for 1h at 37C. Further, the extracts were analyzed using flow injection analysis with electrochemical detection. The hydrodynamic voltammogram (HDV), which was obtained for each sample, indicated the complex creation. Steepness of measured dependencies was as follows: control 317 ?g/mL of coppercopper(II) ions to upper parts of a plant by means of adsorbing of copper(II) in roots. Rapid complex formation was determined under applied potentials 300, 500 and 600 mV during the measuring HDVs. It was also verified that mycorrhizal colonization reduced root to shoot translocation of Cu(II) ions. PMID:22209587

Zitka, Ondrej; Merlos, Miguel-Angel; Adam, Vojtech; Ferrol, Nuria; Pohanka, Miroslav; Hubalek, Jaromir; Zehnalek, Josef; Trnkova, Libuse; Kizek, Rene

2012-02-15

287

Ag/ThioClickFerrophos-catalyzed enantioselective Mannich reaction and amination of glycine Schiff base.  

PubMed

The AgOAc/ThioClickFerrophos complex catalyzed the asymmetric Mannich reaction of glycine Schiff base with N-tosylimines effectively to give a mixture of syn and anti adducts (syn/anti = 60/40-70/30) at high yields with high enantioselectivities (up to 98% ee). The complex also catalyzed the asymmetric amination of glycine Schiff base with di-tert-butyl azodicarboxylate with high enantioselectivity. PMID:21410238

Imae, Kazumi; Shimizu, Kenta; Ogata, Kenichi; Fukuzawa, Shin-ichi

2011-05-01

288

Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff's base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes.  

PubMed

Novel Schiff's base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, (1)H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen-sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand. PMID:25262143

Chandra, Sulekh; Gautam, Seema; Rajor, Hament Kumar; Bhatia, Rohit

2015-02-25

289

Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff's base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes  

NASA Astrophysics Data System (ADS)

Novel Schiff's base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, 1H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen-sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand.

Chandra, Sulekh; Gautam, Seema; Rajor, Hament Kumar; Bhatia, Rohit

2015-02-01

290

Electron spin resonance and magnetic studies on some copper(II) azobarbituric and azothiobarbituric acid complexes.  

PubMed

Electron spin resonance and magnetic susceptibility on some copper(II) complexes prepared from phenylazobarbituric and phenylazothiobarbituric acid compounds containing 2,5-dichloro and 2,5-dimethyl groups were discussed. The thio complexes exist in dimer-monomer mixture. The corresponding copper(II) complexes of the oxygen homologous failed to exhibit association. Singlet-triplet separation values equal to -321 and -263 cm(-1) for the 2,5-dimethyl and 2,5-dichloro complexes, respectively, of the thio series. An empirical measure of the amount of tetrahedral deformation based on the values of g||/A|| assigned the square-planar geometry of the dimethyl-oxygen complex while the other complexes are with tetrahedral planar geometries. The effect of temperature on the ESR data was discussed. The diamagnetic properties of the complexes derived from 2,5-dichloro and 2,5-dimethyl thiobarbituric acid suggested the formation of Cu(I) complexes. PMID:15683807

Masoud, M S; Khalil, E A; Hafez, A M; El-Husseiny, A F

2005-03-01

291

A pulse radiolysis study of catalytic dismutation of superoxide anion by copper(II) complex of biscyclam dioxotetraamine  

NASA Astrophysics Data System (ADS)

The reaction kinetics of superoxide anion dismutation by copper(II) complex of macrocyclic dioxotetraamine was studied using pulse radiolysis and dismutation rate constants were obtained. By using the spectra, electrochemical data and captured intermediate, we verified that Cu(III) complex is the intermediate in catalytical cycle of the complex. This is similar to the view presented by Goldstein [Goldstein, S., Gidon Czapki and Meyerstein D. (1990) J. Am. Chem. Soc.112, 6489] for copper(II) complexes of peptides.

Qin-Hui, Luo; Shou-Rong, Zhu; Meng-Chang, Shen; Jun, Wang

1995-02-01

292

Synthesis, spectroscopic, thermal and electrical conductivity studies of three charge transfer complexes formed between 1,3-di[( E)-1-(2-hydroxyphenyl)methylideneamino]-2-propanol Schiff base and different acceptors  

NASA Astrophysics Data System (ADS)

Charge-transfer complexes (CTC) resulting from interactions of 1,3-di[( E)-1-(2-hydroxyphenyl) methylideneamino]-2-propanol Schiff base with some acceptors such as iodine (I2), bromine (Br2), and picric acid (PiA) have been isolated in the solid state in a chloroform solvent at room temperature. Based on elemental analysis, UV-Vis, infrared, and 1H NMR spectra, and thermogravimetric analysis (TG/DTG) of the solid CTC, [(Schiff)(I2)] (1), [(Schiff)(Br2)] complexes with a ratio of 1:1 and [(Schiff)(PiA)3] complexes with 1:3 have been prepared. In the picric acid complex, infrared and 1H NMR spectroscopic data indicate that the charge-transfer interaction is associated with a hydrogen bonding, whereas the iodine and bromine complexes were interpreted in terms of the formation of dative ion pairs [Schiff+, I{2/-}] and [Schiff+, Br{2/-}], respectively. Kinetic parameters were obtained for each stage of thermal degradation of the CT complexes using Coats-Redfern and Horowitz-Metzger methods. DC electrical properties as a function of temperature of these charge transfer complexes have been studied.

Refat, Moamen S.; Ibrahim, Mohamed M.; Moussa, Mohamed A. A.

2012-01-01

293

Two water-soluble copper(II) complexes: synthesis, characterization, DNA cleavage, protein binding activities and in vitro anticancer activity studies.  

PubMed

Two water-soluble ternary copper(II) complexes of [Cu(L)Cl](ClO4) (1) and [Cu(L)Br2] (2) (L=(2-((quinolin-8-ylimino)methyl)pyridine)) were prepared and characterized by various physico-chemical techniques. Both 1 and 2 were structurally characterized by X-ray crystallography. The crystal structures show the presence of a distorted square-pyramidal CuN3Cl2 (1) or CuN3Br2 (2) geometry in which Schiff-base L acts as a neutral tridentate ligand. Both complexes present intermolecular ?-? stacking interactions between quinoline and pyridine rings. The interaction of two complexes with CT-DNA (calf thymus-DNA) and BSA (bovine serum albumin) was studied by means of various spectroscopy methods, which revealed that 1 and 2 could interact with CT-DNA through intercalation mode, and could quench the intrinsic fluorescence of BSA in a static quenching process. Furthermore, the competition experiment using Hoechst 33258 indicated that two complexes may bind to CT-DNA by a minor groove. DNA cleavage experiments indicate that the complexes exhibit efficient DNA cleavage activities without any external agents, and hydroxyl radical (HO) and singlet oxygen ((1)O2) may serve as the major cleavage active species. Notably, the in vitro cytotoxicity of the complexes on three human tumor cells lines (HeLa, MCF-7, and A549) demonstrates that two compounds have broad-spectrum antitumor activity with quite low IC50 ranges of 0.43-1.85?M. Based on the cell cycle experiments, 1 and 2 could delay or inhibit cell cycle progression through the S phase. PMID:24803026

Lu, Jing; Sun, Qian; Li, Jun-Ling; Jiang, Lin; Gu, Wen; Liu, Xin; Tian, Jin-Lei; Yan, Shi-Ping

2014-08-01

294

Polyethyleneimine anchored copper(II) complexes: Synthesis, characterization, in vitro DNA binding studies and cytotoxicity studies.  

PubMed

The water soluble polyethyleneimine-copper(II) complexes, [Cu(phen)(L-tyr)BPEI]ClO4 (where phen=1,10-phenanthroline, L-tyr=L-tyrosine and BPEI=branched polyethyleneimine) with various degree of copper(II) complex units in the polymer chain were synthesized and characterized by elemental analysis and electronic, FT-IR, EPR spectroscopic techniques. The binding of these complexes with CT-DNA was studied using UV-visible absorption titration, thermal denaturation, emission, circular dichroism spectroscopy and cyclic voltammetric methods. The changes observed in the physicochemcial properties indicated that the binding between the polymer-copper complexes and DNA was mostly through electrostatic mode of binding. Among these complexes, the polymer-copper(II) complex with the highest degrees of copper(II) complex units (higher degrees of coordination) showed higher binding constant than those with lower copper(II) complex units (lower degrees of coordination) complexes. The complex with the highest number of metal centre bound strongly due to the cooperative binding effect. Therefore, anticancer study was carried out using this complex. The cytotoxic activity for this complex on MCF-7 breast cancer cell line was determined adopting MTT assay, acridine orange/ethidium bromide (AO/EB) staining and comet assay techniques, which revealed that the cells were committed to specific mode of cell death either apoptosis or necrosis. PMID:25499104

Lakshmipraba, Jagadeesan; Arunachalam, Sankaralingam; Riyasdeen, Anvarbatcha; Dhivya, Rajakumar; Akbarsha, Mohammad Abdulkader

2015-01-01

295

Synthesis, characterization, thermal study and biological evaluation of Cu(II), Co(II), Ni(II) and Zn(II) complexes of Schiff base ligand containing thiazole moiety  

NASA Astrophysics Data System (ADS)

The novel Schiff base ligand 2-(4-(dimethylamino)benzylidene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide (L) obtained by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 4-dimethylaminobenzaldehyde and its newly synthesized Cu(II), Co(II), Ni(II) and Zn(II) complexes have been characterized by microanalysis, magnetic susceptibility, molar conductance, thermal analysis, FT-IR, 1H NMR, ESI mass, UV-Visible, ESR spectroscopy and powder X-ray diffraction data. The newly synthesized ligand behaves as a bidentate ON donor. The IR results confirmed the bidentate binding of the ligand involving oxygen atom of amide carbonyl and azomethine nitrogen. 1H NMR spectral data of the ligand (L) and its Zn(II) complex agreed well with the proposed structures. In order to evaluate the effect of antimicrobial activity of metal ions upon chelation, the newly synthesized ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage activities were studied using plasmid DNA pBR322 as a target molecule by agarose gel electrophoresis method. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties of all the compounds against Artemia salina. Furthermore, the antioxidant activity of the ligand (L) and its metal complexes were determined in vitro by reduction of 1,1-diphenyl-2-picryl hydrazyl (DPPH), the ligand exhibited potent in vitro - antioxidant activity than its metal complexes.

Nagesh, G. Y.; Mahendra Raj, K.; Mruthyunjayaswamy, B. H. M.

2015-01-01

296

Nickel(II) and copper(II) complexes of macrocyclic and acyclic Schiff-base ligands derived from new asymmetrical tripodal tetraamines and 2,6-diacetylpyridine  

Microsoft Academic Search

The asymmetrical tripodal 4,2,2'-tetraamine N{(CH2)4NH2}{(CH2)2NH2}2 bee, 3,2,2'-tetraamine N{(CH2)3NH2} {(CH2)2NH2}2 pee, and 3,3',2-tetraamine N{(CH2)3NH2}2{(CH2)2NH2} ppe ligands have been prepared. In the presence of CuII or NiII ions, these ligands condense with 2,6-diacetylpyridine. In some cases, cyclization occurs and new isomers of CR-type with a pendant primary amine group are formed. In the other cases ring closure does not occur and coordinated

Hassan Keypour; Sadegh Salehzadeh

2000-01-01

297

A new dinuclear unsymmetric copper(II) complex as model for the active site of catechol oxidase  

Microsoft Academic Search

The crystal structure, magnetic, redox and spectroscopic properties of a novel unsymmetrical dinuclear copper(II) complex, prepared by the reaction between copper(II) perchlorate, sodium acetate and the unsymmetrical, binucleating ligand HTPPNOL, where HTPPNOL is N,N,N?-tris-(2-pyridylmethyl)-1,3-diaminopropan-2-ol, is reported. HTPPNOL (1 equiv.) reacted with 1 equiv. of copper(II) ion, in methanol, and produced the mononuclear copper complex [Cu(TPPNOL)](ClO4)(BPh4) (1). On the other hand,

Christiane Fernandes; Ademir Neves; Adailton J Bortoluzzi; Antnio S Mangrich; Eva Rentschler; Bruno Szpoganicz; Erineu Schwingel

2001-01-01

298

Batch and hydrodynamic monitoring of vitamin C using novel periodate selective sensors based on a newly synthesized Ni(II)-Schiff bases complexes as a neutral receptors.  

PubMed

A highly selective membrane electrodes based on a two newly synthesized nickel (II) Schiff bases, [NiL(1)] and [NiL(2)] where L(1) and L(2) are N,N/bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H(2)L(1)) and N,N/bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H(2)L(2)) were used as a neutral carrier ionophores for static and hydrodynamic potentiometric mode of operations for the determination of periodate. Under static mode of operation, the sensors displayed a near-Nernstian slope of -66.1+/-0.8 and -59.9+/-1.1mV decade(-1) of activity and detection limits to 5.2x10(-6) and 7.3x10(-6)molL(-1) for the sensors based on [NiL(1)] and [NiL(2)], respectively. Under hydrodynamic mode of operation (FIA), the slope of the calibration plot, limit of detection, and working linear range were -71.1mV decade(-1) of activity, 7.3x10(-6) and 1.0x10(-5) to 1.0x10(-3)molL(-1), respectively. The response time of the sensors in whole concentration ranges was very short (<10s). The response of the sensors was independent on the pH range of 3-8. A tubular version was further developed and coupled to a flow injection system for ascorbic acid (AA) determination in beverages and pharmaceutical preparations. This approach was achieved by selecting a 50-cm reactor and an overall flow of 3mLmin(-1), and injecting volume 100microL of AA standards in a 1.0x10(-4)molL(-1) IO(4)(-) solution. Under these conditions, a linearity range of 2-13microgmL(-1), with a slope of 4.97mV (mg/L)(-1) (r(2)=0.9995), detection limit 0.9mgL(-1) and a reproducibility of +/-1.1mV (n=5) was recorded. This simple and inexpensive flow injection analysis manifold, with a good potentiometric detector, enabled the analysis of approximately 50 samples h(-1) without requiring pretreatment procedures. An average recovery of 98.8% and a mean standard deviation of 1.3% were obtained. PMID:20006099

Aziz, Ayman A Abdel; Kamel, Ayman H

2010-01-15

299

Copper(II) complexation by pituitary adenylate cyclase activating polypeptide fragments.  

PubMed

Results are reported from potentiometric and spectroscopic (UV-Vis, CD, and ESR) studies of the protonation constants and Cu2+ complex stability constants of pituitary adenylate cyclase activating polypeptide fragments (HSDGI-NH2, TDSYS-NH2, RKQMAVKKYLAAVL-NH2). With HSDGI-NH2, the formation of a dimeric complex Cu2H-2L2 was found in the pH range 5-8, in which the coordination of copper(II) is glycylglycine-like, while the fourth coordination site is occupied by the imidazole N3 nitrogen atom, forming a bridge between two copper(II) ions. The formation of dimeric species does not prevent the deprotonation and coordination of the amide nitrogen, and in pH above 8 the CuH-2L complex is formed. Aspartic acid in the third position of peptide sequence stabilizes the CuH-2L species and prevents the coordination of a fourth nitrogen donor. Aspartic acid residue in the second position of TDSYS-NH2 stabilizes the CuL (2N) complex but does not prevent deprotonation and binding of the second and third peptide nitrogens to give 3N and 4N complexes at higher pH. The tetradecapeptide amide forms with copper(II) ions unusually stable 3N and 4N complexes compared to pentaalanine amide. PMID:10530007

Kowalik-Jankowska, T; Jasionowski, M; Lankiewicz, L

1999-07-30

300

Synthesis and structural features of U VI and V IV chelate complexes with (hhmmbH)ClH 2O [hhmmb = {3-hydroxyl-5-(hydroxymethyl)-2-methylpyridine-4-yl-methylene}benzohydrazide], a new Schiff base ligand derived from vitamin B6  

NASA Astrophysics Data System (ADS)

The Schiff base ligand {3-hydroxyl-5-(hydroxymethyl)-2-methylpyridine-4-yl-methylene}benzohydrazide hydrochloride monohydrated {(hhmmbH)ClH 2O} ( 1) was prepared by reaction of pyridoxine hydrochloride with benzoic acid hydrazide. The reaction of 1 with [VO(acac) 2] and triethylamine yields the neutral vanadium IV complex [VO 2(hhmmb)]Py ( 2), with a distorted quadratic pyramidal configuration. The Schiff base 1 reacts also with UO 2(NO 3) 26H 2O and triethylamine under deprotonation giving the uranium VI cationic complexes [UO 2(hhmmb)(H 2O)Cl] + ( 3) and [UO 2(hhmmb)(CH 3OH)Cl] + ( 4), both showing the classical pentagonal bipyrimidal geometry of UO22+ complexes. The structural features of all compounds are discussed.

Back, Davi Fernando; Ballin, Marco Aurlio; de Oliveira, Gelson Manzoni

2009-10-01

301

New dimanganese(III) complexes of pentadentate (N2O3) Schiff base ligands with the [Mn2(mu-OAc)(mu-OR)2]3+ core: synthesis, characterization and mechanistic studies of H2O2 disproportionation.  

PubMed

Two new diMn(III) complexes [Mn(2)(III)L(1)(mu-AcO)(mu-MeO)(methanol)(2)]Br (1) and [Mn(2)(III)L(2)(mu-AcO)(mu-MeO)(methanol)(ClO(4))] (2) (L(1)H(3)=1,5-bis(2-hydroxybenzophenylideneamino)pentan-3-ol; L(2)H(3)=1,5-bis(2-hydroxynaphtylideneamino)pentan-3-ol) were synthesized and structurally characterized. Structural studies evidence that these complexes have a bis(mu-alkoxo)(mu-carboxylato) triply bridged diMn(III) core in the solid state and in solution, with two substitution-labile sites--one on each Mn ion--in cis-position. The two complexes show catalytic activity toward disproportionation of H(2)O(2), with saturation kinetics on [H(2)O(2)], in methanol and dimethyl formamide at 25 degrees C. Spectroscopic monitoring of the H(2)O(2) disproportionation reaction suggests that (i) complexes 1 and 2 dismutate H(2)O(2) by a mechanism involving redox cycling between Mn(2)(III) and Mn(2)(IV), (ii) the complexes retain the dinuclearity during catalysis, (iii) the active form of the catalyst contains bound acetate, and (iv) protons favors the formation of inactive Mn(II) species. Comparison to other dimanganese complexes of the same family shows that the rate of catalase reaction is not critically dependent on the redox potential of the catalyst, that substitution of phenolate by naphtolate in the Schiff base ligand favors formation of the catalyst-substrate adduct, and that, in the non-protic solvent, the bulkier substituent at the imine proton position hampers the binding to the substrate. PMID:16843530

Biava, Hernn; Palopoli, Claudia; Shova, Sergiu; De Gaudio, Mnica; Daier, Vernica; Gonzlez-Sierra, Manuel; Tuchagues, Jean-Pierre; Signorella, Sandra

2006-10-01

302

Electronic spectra of carotenoids. Schiff's bases of carotenal and carotenones  

Microsoft Academic Search

Visible absorption bands of beta-apo-8'-carotenal, citranaxanthin, and reticulataxanthin Schiff's bases are measured and analyzed in relation to the visual chromophore, retinal Schiff's base. The former shows a strong red shift of the absorption maxima upon protonation in ethanol, and the magnitude of the band shift is comparable to that of retinal Schiff's base. Molecular orbital analysis of the ground and

Thomas A. Moore; Pill-Soon Song

1974-01-01

303

An unusual 3D interdigitated architecture assembled from Keggin polyoxometalates and dinuclear copper(II) complexes  

SciTech Connect

A novel organic-inorganic hybrid compound, [Cu{sub 2}(bipy){sub 3}({mu}{sub 1}-H{sub 2}O){sub 2}({mu}{sub 2}-H{sub 2}O)({mu}{sub 2}-OH)(H{sub 2}BW{sub 12}O{sub 40})]{center_dot}4 H{sub 2}O (1) (bipy=4,4 Prime -bipy), has been synthesized in hydrothermal condition and characterized by elemental analysis, IR spectrum, TG analysis and single-crystal X-ray diffraction. Compound 1 possesses poly-pendant layered motifs composed of 12-tungstoborates and dinuclear copper(II) complexes, in which the mono-coordinated bipy molecules are orderly appended to both sides of the layer, respectively. Adjacent layers mutually engage in a zipper-like pattern to result in a novel 3D interdigitated architecture. The variable-temperature magnetic susceptibility of 1 showed that there existed weak antiferromagnetic interaction in 1. Toward the reduction of hydrogen peroxide, 1 has good electrocatalytic activity and remarkable stability. - A new compound has been obtained, which represents the first interdigitated architecture assembled by POMs and dinuclear copper(II) complexes. Highlights: Black-Right-Pointing-Pointer The first example of interdigitated architecture assembled by POMs and dinuclear copper(II) complexes is observed. Black-Right-Pointing-Pointer A zipper-like pattern is observed in the structure. Black-Right-Pointing-Pointer The IR, TG, XRPD, magnetism and electrochemical property of the title compound were studied.

Pang, Haijun; Yang, Ming; Kang, Lu [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China)] [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China); Ma, Huiyuan, E-mail: mahy017@nenu.edu.cn [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China)] [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China); Liu, Bo, E-mail: liubo200400@vip.sina.com [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China)] [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China); Li, Shaobin; Liu, Heng [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China)] [Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin 150040 (China)

2013-02-15

304

A unique example of structural and magnetic diversity in four interconvertible copper(II)-azide complexes with the same schiff base ligand: a monomer, a dimer, a chain, and a layer.  

PubMed

Four new Cu(II)-azido complexes of formula [CuL(N(3))] (1), [CuL(N(3))](2) (2), [Cu(7)L(2)(N(3))(12)](n) (3), and [Cu(2)L(dmen)(N(3))(3)](n) (4) (dmen = N,N-dimethylethylenediamine) have been synthesized using the same tridentate Schiff base ligand HL (2-[1-(2-dimethylaminoethylimino)ethyl]phenol, the condensation product of dmen and 2-hydroxyacetophenone). The four compounds have been characterized by X-ray structural analyses and variable-temperature magnetic susceptibility measurements. Complex 1 is mononuclear, whereas 2 is a single mu-1,1 azido-bridged dinuclear compound. The polymeric compound 3 possesses a 2D structure in which the Cu(II) ions are linked by phenoxo oxygen atoms and two different azide bridges (mu-1,1 and mu-1,1,3). The structure of complex 4 is a double helix in which two mu-1,3-azido-bridged alternating one-dimensional helical chains of CuL(N(3)) and Cu(dmen)(N(3))(2) are joined together by weak mu-1,1 azido bridges and H-bonds. The complexes interconvert in solution and can be obtained in pure form by carefully controlling the conditions. The magnetic properties of compounds 1 and 2 show the presence of very weak antiferromagnetic exchange interactions mediated by a ligand pi overlap (J = -1.77) and by an asymmetric 1,1-N(3) bridge (J = -1.97 cm(-1)), respectively. Compound 3 presents, from the magnetic point of view, a decorated chain structure with both ferro- and antiferromagnetic interactions. Compound 4 is an alternating helicoidal chain with two weak antiferromagnetic exchange interactions (J = -1.35 and -2.64 cm(-1)). PMID:20560664

Naiya, Subrata; Biswas, Chaitali; Drew, Michael G B; Gmez-Garca, Carlos J; Clemente-Juan, Juan M; Ghosh, Ashutosh

2010-07-19

305

Chelating ability and biological activity of hesperetin Schiff base.  

PubMed

Hydrazone hesperetin Schiff base (HHSB) - N-[()-[5,7-dihydroxy-2-(3-hydroxy-4-methoxy-phenyl)chroman-4-ylidene]amino]benzamide has been synthesized and its crystal structure was determined. This compound was used for the formation of Cu(II) complexes in solid state and in solution which were characterized using different spectroscopic methods. The analyses of potentiometric titration curves revealed that monomeric and dimeric complexes of Cu(II) are formed above pH7. The ESI-MS (electrospray ionization-mass spectrometry) spectra confirmed their formation. The EPR and UV-visible spectra evidenced the involvement of oxygen and nitrogen atoms in Cu(II) coordination. Hydrazone hesperetin Schiff base can show keto-enol tautomerism and coordinate Cu(II) in the keto (O(-), N, Oket) and in the enolate form (O(-), N, O(-)enol). The semi-empirical molecular orbital method PM6 and DFT (density functional theory) calculations have revealed that the more stable form of the dimeric complex is that one in which the ligand is present in the enol form. The CuHHSB complex has shown high efficiency in the cleavage of plasmid DNA in aqueous solution, indicating its potential as chemical nuclease. Studies on DNA interactions, antimicrobial and cytotoxic activities have been undertaken to gain more information on the biological significance of HHSB and copper(II)-HHSB chelate species. PMID:25486205

Lodyga-Chruscinska, Elzbieta; Symonowicz, Marzena; Sykula, Anna; Bujacz, Anna; Garribba, Eugenio; Rowinska-Zyrek, Magdalena; Oldziej, Stanislaw; Klewicka, Elzbieta; Janicka, Magdalena; Krolewska, Karolina; Cieslak, Marcin; Brodowska, Katarzyna; Chruscinski, Longin

2014-11-28

306

Spectroscopic and structural studies of the Schiff base 3-methoxy-N-salicylidene-o-amino phenol complexes with some transition metal ions and their antibacterial, antifungal activities.  

PubMed

Spectroscopic (IR, Raman, NMR, UV-visible, and ESR), and structural studies of the ligand 3-methoxy-N-salicylidene-o-amino phenol (H2L) and its synthesized complexes with some transition metal ions (Mn(II), Co(II), Ni(II)), Cu(II) and Zn(II)) were recorded and analyzed. The magnetic properties and thermal gravimetric analysis (TGA and DTA) were also measured for the complexes. The metal complexes were found to have The structural formula ML?H2O and the metal ions Mn(II), Co(II), Ni(II)) and Zn(II) were found to form tetrahedral complexes with the ligand whereas Cu(II) formed a square planar one. Antimicrobial activity of the ligand and its complexes were also investigated and discussed. PMID:25459625

Abo-Aly, M M; Salem, A M; Sayed, M A; Abdel Aziz, A A

2015-02-01

307

Spectroscopic and structural studies of the Schiff base 3-methoxy-N-salicylidene-o-amino phenol complexes with some transition metal ions and their antibacterial, antifungal activities  

NASA Astrophysics Data System (ADS)

Spectroscopic (IR, Raman, NMR, UV-visible, and ESR), and structural studies of the ligand 3-methoxy-N-salicylidene-o-amino phenol (H2L) and its synthesized complexes with some transition metal ions (Mn(II), Co(II), Ni(II)), Cu(II) and Zn(II)) were recorded and analyzed. The magnetic properties and thermal gravimetric analysis (TGA and DTA) were also measured for the complexes. The metal complexes were found to have The structural formula ML?H2O and the metal ions Mn(II), Co(II), Ni(II)) and Zn(II) were found to form tetrahedral complexes with the ligand whereas Cu(II) formed a square planar one. Antimicrobial activity of the ligand and its complexes were also investigated and discussed.

Abo-Aly, M. M.; Salem, A. M.; Sayed, M. A.; Abdel Aziz, A. A.

2015-02-01

308

A novel tridentate Schiff base dioxo-molybdenum(VI) complex: synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, H NMR and C NMR spectra.  

PubMed

A new dioxo-molybdenum(VI) complex [MoO(2)(L)(H(2)O)] has been synthesized, using 5-methoxy 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H(2)L) and MoO(2)(acac)(2). The yellow crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the UV-visible, FTIR, (1)H NMR and (13)C NMR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TDDFT) method is used to calculate the electronic transitions of the complex. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR shielding tensors computed at the B3LYP/DGDZVP level of theory is in agreement with experimental (1)H NMR spectra. However, the (13)C NMR shielding tensors computed at the B3LYP level, employing a combined basis set of DGDZVP for Mo and 6-31+G(2df,p) for other atoms, are in better agreement with experimental (13)C NMR spectra. The electronic transitions calculated at the B3LYP/DGDZVP level by using TD-DFT method is in accordance with the observed UV-visible spectrum of the compound. PMID:22613121

Saheb, Vahid; Sheikhshoaie, Iran; Stoeckli-Evans, Helen

2012-09-01

309

Synthesis, spectroscopic studies and crystal structure of the Schiff base ligand L derived from condensation of 2-thiophenecarboxaldehyde and 3,3?-diaminobenzidine and its complexes with Co(II), Ni(II), Cu(II), Cd(II) and Hg(II): Comparative DNA binding studies of L and its Co(II), Ni(II) and Cu(II) complexes  

Microsoft Academic Search

The Schiff base ligand, N,N?-bis-(2-thiophenecarboxaldimine)-3,3?-diaminobenzidine (L) obtained from condensation of 2-thiophenecarboxaldehyde and 3,3?-diaminobenzidine, was used to synthesize the complexes of type, [M2L2]Cl4 [M=Co(II), Ni(II), Cu(II), Cd(II) and Hg(II)]. The newly synthesized ligand (L) was characterized on the basis of the results of elemental analysis, FT-IR, 1H NMR, 13C NMR, mass spectroscopic studies and single crystal X-ray crystallography. The characteristic resonance

Mohammad Shakir; Ambreen Abbasi; Mohammad Azam; Asad U. Khan

2011-01-01

310

Spectroscopic, crystal structural and electrochemical studies of zinc(II)-Schiff base complex obtained from 2,3-diaminobenzene and 2-hydroxy naphthaldehyde  

NASA Astrophysics Data System (ADS)

Mononuclear zinc(II) complex, [Zn(II)L], where L is a dianionic ligand, has been synthesized and characterized by elemental analysis, electronic, IR and NMR [1H, 13C, DEPT, 1H-1H COSY, ROESY, HSQC and HMBC] spectroscopic techniques. Structural analysis of the complex by single crystal X-ray crystallography shows the presence of a distorted square planar coordination geometry (NNOO) of the metal center. The crystal of the title complex C28H18N2O2Zn belongs to the orthorhombic system with space group Pmn21. Electrochemical behavior of the Zn(II)L complex has been investigated by cyclic voltammetry on glassy carbon and platinum electrodes in DMF at 100 mV/s scan rate.

Ouari, Kamel; Bendia, Sabrina; Weiss, Jean; Bailly, Corinne

2015-01-01

311

Spectroscopic, crystal structural and electrochemical studies of zinc(II)-Schiff base complex obtained from 2,3-diaminobenzene and 2-hydroxy naphthaldehyde.  

PubMed

Mononuclear zinc(II) complex, [Zn(II)L], where L is a dianionic ligand, has been synthesized and characterized by elemental analysis, electronic, IR and NMR [(1)H, (13)C, DEPT, (1)H-(1)H COSY, ROESY, HSQC and HMBC] spectroscopic techniques. Structural analysis of the complex by single crystal X-ray crystallography shows the presence of a distorted square planar coordination geometry (NNOO) of the metal center. The crystal of the title complex C28H18N2O2Zn belongs to the orthorhombic system with space group Pmn21. Electrochemical behavior of the Zn(II)L complex has been investigated by cyclic voltammetry on glassy carbon and platinum electrodes in DMF at 100 mV/s scan rate. PMID:25128674

Ouari, Kamel; Bendia, Sabrina; Weiss, Jean; Bailly, Corinne

2015-01-25

312

Asymmetric synthesis of ?-amino acids via homologation of Ni(II) complexes of glycine Schiff bases. Part 3: Michael addition reactions and miscellaneous transformations.  

PubMed

The major goal of this review is a critical discussion of the literature data on asymmetric synthesis of ?-amino acids via Michael addition reactions involving Ni(II)-complexes of amino acids. The material covered is divided into two conceptually different groups dealing with applications of: (a) Ni(II)-complexes of glycine as C-nucleophiles and (b) Ni(II)-complexes of dehydroalanine as Michael acceptors. The first group is significantly larger and consequently subdivided into four chapters based on the source of stereocontrolling element. Thus, a chiral auxiliary can be used as a part of nucleophilic glycine Ni(II) complex, Michael acceptor or both, leading to the conditions of matching vs. mismatching stereochemical preferences. The particular focus of the review is made on the practical aspects of the methodology under discussion and mechanistic considerations. PMID:24888480

Acea, Jos Luis; Sorochinsky, Alexander E; Soloshonok, Vadim

2014-09-01

313

Synthesis, spectral characterization, molecular modeling and in vitro antibacterial activity of complexes designed from O2, NO and NO donor Schiff-base ligand  

NASA Astrophysics Data System (ADS)

A new chelating agent, N?-(4-methoxybenzylidene)-2-oxo-2-(phenylamino)acetohydrazide (H2OMPH) and its complexes with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and U(IV)O22+ ions have been prepared and characterized by conventional techniques. The spectral data indicated that the ligand coordinates as neutral bidentate with Cu(II), Mn(II), U(IV)O22+ and Hg(II), neutral tridentate with Ni(II), mononegative tridentate with Co(II) and binegative tetradentate with Zn(II) ions. On basis of magnetic and electronic spectral data an octahedral geometry for Mn(II), Co(II) and Ni(II) complexes and a square planar geometry for Cu(II) complex have been proposed and confirmed by applying geometry optimization and conformational analysis. The protonation constants of H2OMPH and the stepwise stability constants of its complexes are calculated at 298, 308 and 318 k as well as their thermodynamic parameters. Also, the Kinetic parameters (Ea, A, ?H*, ?S* and ?G*) were determined for each thermal degradation stage of some complexes using Coats-Redfern and Horowitz-Metzger methods. Moreover, the ligand and some complexes were screened for in vitro antibacterial activity against Staphylococcus epidermalies (St. epid); Streptococcus pyagenies (Strp. py.) as Gram +ve bacteria and Escherichia coli (E. coli); Klebsiella spp. (kleb. spp.) as Gram -ve bacteria using inhibition zone diameter.

El-Gammal, Ola A.; Abu El-Reash, G.; Ahmed, S. F.

2015-01-01

314

Solid state isostructural behavior and quantified limiting substitution kinetics in Schiff-base bidentate ligand complexes fac-[Re(O,N-Bid)(CO)3(MeOH)](n).  

PubMed

A range of N,O-donor atom salicylidene complexes of the type fac-[M(O,N-Bid)(CO)3(L)](n) (O,N-Bid = anionic N,O-bidentate ligands; L = neutral coordinated ligand) have been studied. The unique feature of the complexes which crystallize in a monoclinic isostructural space group for complexes containing methanol in the sixth position (L = MeOH) is highlighted. The reactivity and stability of the complexes were evaluated by rapid stopped-flow techniques, and the methanol substitution by a range of pyridine type ligands indicates significant activation by the N,O-salicylidene type of bidentate ligands as observed from the variation in the second-order rate constants. In particular, following the introduction of the sterically demanding and electron rich cyclohexyl salicylidene moiety on the bidentate ligand, novel limiting kinetic behavior is displayed by all entering ligands, thus enabling a systematic probe and manipulation of the limiting kinetic constants. Clear evidence of an interchange type of intimate mechanism for the methanol substitution is produced. The equilibrium and rate constants (25 C) for the two steps in the dissociative interchange mechanism for methanol substitution in fac-[Re(Sal-Cy)(CO)3(MeOH)] (5) by the pyridine type ligands 3-chloropyridine, pyridine, 4-picoline, and DMAP are k3 (s(-1)), 40 4, 13 2, 10.4 0.7, and 2.11 0.09, and K2 (M(-1)), 0.13 0.01, 0.21 0.03, 0.26 0.02, and 1.8 0.1, respectively. PMID:25393647

Brink, Alice; Visser, Hendrik G; Roodt, Andreas

2014-12-01

315

Acute Toxicity and Gastroprotection Studies of a New Schiff Base Derived Copper (II) Complex against Ethanol-Induced Acute Gastric Lesions in Rats  

PubMed Central

Background Copper is an essential element in various metabolisms. The investigation was carried out to evaluate acute gastroprotective effects of the Copper (II) complex against ethanol-induced superficial hemorrhagic mucosal lesions in rats. Methodology/Principal Findings Rats were divided into 7 groups. Groups 1 and 2 were orally administered with Tween 20 (10% v/v). Group 3 was orally administered with 20 mg/kg omeprazole (10% Tween 20). Groups 47 received 10, 20, 40, and 80 mg/kg of the complex (10% Tween 20), respectively. Tween 20 (10% v/v) was given orally to group 1 and absolute ethanol was given orally to groups 27, respectively. Rats were sacrificed after 1 h. Group 2 exhibited severe superficial hemorrhagic mucosal lesions. Gastric wall mucus was significantly preserved by the pre-treatment complex. The results showed a significant increase in glutathione (GSH), superoxide dismutase (SOD), nitric oxide (NO), and Prostaglandin E2 (PGE2) activities and a decrease in malondialdehyde (MDA) level. Histology showed marked reduction of hemorrhagic mucosal lesions in groups 47. Immunohistochemical staining showed up-regulation of Hsp70 and down-regulation of Bax proteins. PAS staining of groups 47 showed intense stain uptake of gastric mucosa. The acute toxicity revealed the non-toxic nature of the compound. Conclusions/Significance The gastroprotective effect of the Copper (II) complex may possibly be due to preservation of gastric wall mucus; increase in PGE2 synthesis; GSH, SOD, and NO up-regulation of Hsp70 protein; decrease in MDA level; and down-regulation of Bax protein. PMID:23251568

Hassandarvish, Pouya; Gwaram, Nura Suleiman; A. Hadi, A. Hamid; Mohd Ali, Hapipah; Majid, Nazia; Abdulla, Mahmood Ameen

2012-01-01

316

[Increase in lipophilicity of enalaprilat by complexation with copper(II) or zinc(II) Ions].  

PubMed

Enalaprilat (H2L), which is the active metabolite of the pro-drug enalapril, is an angiotensin-converting enzyme inhibitor. Some side effects such as neurodegeneration and taste disorder can be related to copper or zinc deficiency, which would be caused by the metal complex formation of dianionic elalaprilat (L(2-)). For a better understanding of this phenomenon, we investigated the solution species of enalaprilat in the presence of copper(II) or zinc(II) ions by pH titration analysis with I=0.10 M (NaCl) at 25?. The 1:1 complex formation constants (KML=[ML]/[M(2+)][L(2-)] M(-1)) of 10(7.4) for CuL and 10(4.4) for ZnL complexes were evaluated, indicating the presence of those complexes at a physiological pH. Furthermore, partition experiments with a two-phase system of 1-butanol/water at 25? disclosed that copper(II) and zinc(II) complexes of enalaprilat were partially extracted into the organic layer. In the absence of those metal ions, enalaprilat was not soluble in the 1-butanol phase. The increase in lipophilicity of enalaprilat by metal complexation suggests that the long-term administration of enalapril could be a possible risk factor for the disrupted distribution of those metal ions in biological systems. PMID:23903258

Fujioka, Haruto; Hieda, Yuhzo; Kuramoto, Yasuhiro; Konishi, Kanayo; Kinoshita-Kikuta, Emiko; Kinoshita, Eiji; Koike, Tohru

2013-01-01

317

An unprecedented "linear-bent" isomerism in tri-nuclear Cu2(II)Zn(II) complexes with a salen type di-Schiff base ligand.  

PubMed

Two new trinuclear hetero-metallic copper(II)-zinc(II) complexes [(CuL)(2)Zn(N(3))(2)] (1A and 1B) have been synthesized using [CuL] as a so-called "metalloligand" (where H(2)L = N,N'-bis(salicylidene)-1,3-propanediamine) and structurally characterized. Complexes 1A and 1B have the same molecular formula but crystallize in different crystal systems (triclinic for 1A and monoclinic for 1B) with space group P1 for 1A and P2(1)/c for 1B. 1A is an angular trinuclear species, in which two terminal four-coordinate square planar "metalloligand" [CuL] are coordinated to a central Zn(II) through double phenoxido bridges. The Zn(II) is in a six-coordinate distorted octahedral environment being bonded additionally to two mutually cis nitrogen atoms of terminal azide ions. In complex 1B, in addition to the double phenoxido bridge, the two terminal Cu(II) ions are linked to the central Zn(II) via a ?(-l,l) azido bridge giving rise to a square pyramidal environment around the Cu(II) ions and consequently the structure becomes linear. These two species can be considered as "linear-bent" isomers. EPR spectra and ESI mass spectra show that the two isomers are identical in solution. The DFT calculation reveals that the energy of 1A is 7.06 kcal mol(-1) higher than that of 1B. The existence of both isomers in the solid state suggests that crystal packing interactions in are more efficient and probably compensate for the difference in energy. PMID:22858718

Das, Lakshmi Kanta; Park, Sung-Woo; Cho, Seung Joo; Ghosh, Ashutosh

2012-08-28

318

Ultraviolet spectrophotometric characterization of copper(II) complexes with imidazole N-methyl derivatives of ?-histidine in aqueous solution  

NASA Astrophysics Data System (ADS)

In this study we considered ?-methyl- L-histidine (?-methis) and ?-methyl- L-histidine (?-methis) as ligands for copper(II) ion, in order to clarify, by means of ultraviolet (UV) spectroscopy in aqueous solution ( T=25 C, I=0.1 M), some aspects of the co-ordination mode with respect to other ligands of a previous study in which copper(II) complexes of L-histidine, N-acetyl- L-histidine, histamine, L-histidine methyl ester or carnosine were investigated. Particularly, UV spectra (300-400 nm) were recorded on solutions at various pH values, containing each binary system Cu-L; afterwards, an UV absorption spectrum for single complexes was calculated, taking into account the chemical model previously assessed, in order to fulfil a correct spectrum-structure correlation. The problem related to the eventual superimposition of the CT shoulder (?330 nm) to copper(II) of OH - and imidazole pyridine nitrogen groups were now solved by means of a comparison of the UV spectra of dimer species formed by both ?-methis or ?-methis. Finally, copper(II) complex formation with 2,2'-bipyridine was taken into account to compare the behaviour of pyridine (from 2,2'-bipyridine) and pyridine imidazole nitrogens (from ?-methis or ?-methis) with respect to the UV charge transfer process to copper(II) ion.

Prenesti, Enrico; Berto, Silvia; Daniele, Pier Giuseppe

2003-01-01

319

Zeolite encapsulated Ni(II)-Schiff-base complex: a novel size-selective electro-catalyst for the determination of the purity of stevioside.  

PubMed

Ship-in-a-bottle complex of nickel(II) containing the ligand N,N'-bis(2,4-dihydroxyacetophenone)-2,2-dimethylpropandiimine (H2{salnptn(4-OH)2}) has been synthesized in zeolite Y. The characteristics of the encapsulated complex are identified by the methods of EDX, SEM, XRD, FT-IR and cyclic voltammetry. A catalytic effect in the electrochemical oxidation of glucose, fructose and sucrose, and a blocking effect in stevioside oxidation are demonstrated on the Ni(II){salnptn(4-OH)2}-Y/CPE. The effects of some parameters, such as potential scan rate and concentration of carbohydrates are investigated. The rate constants for the catalytic reaction (k') of carbohydrates are also obtained. The size-selective electro-catalyst shows a good linear dependency on carbohydrates' concentration in the range of 0.01-0.06 M with the detection limit of 6.4mM at the signal-to-noise ratio of 3. Furthermore, the modified electrode exhibits no interference with the simultaneous presence of stevioside. In brief, these results demonstrate that Ni(II){salnptn(4-OH)2}-Y composites have a great potential for synthesizing size-selective electrocatalysts for determining the purity of stevioside. PMID:23601865

Avei, Mehdi Rashvand; Jafarian, Majid; Etezadi, Sedigheh; Gobal, Fereydoon; Khakali, Maryam; Rayati, Saeed; Mahjani, Mohammad Ghasem

2013-04-15

320

Complexation of nitrogen and sulphur donor Schiff's base ligand to Cr(III) and Ni(II) metal ions: synthesis, spectroscopic and antipathogenic studies.  

PubMed

2,6-diacetyl pyridine based ligand was synthesized by the reaction of 2,6-diacetyl pyridine with thiocarbohydrazide in presence of acetic acid. The coordination compounds with Cr(III) and Ni(II) metal ions having [Cr(L)X]X2 and [Ni(L)X]X compositions (where L=ligand and X=NO3-, Cl- and CH3COO-) were synthesized and characterized by physicochemical and spectral studies. The studies like elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV-Vis, NMR, mass and EPR reveal that the complexes are octahedral. The compounds were examined against the pathogenic fungal and bacterial strains like Alternaria brassicae, Aspergillus niger, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa. A. niger causes the diseases Apergillosis and Otomycosis in humans. PMID:21094079

Sharma, Amit Kumar; Chandra, Sulekh

2011-01-01

321

Novel dipodal Schiff base compounds: Synthesis, characterization and spectroscopic studies  

NASA Astrophysics Data System (ADS)

Two novel dipodal Schiff base compounds 1,2-benzyloxy-bis-[2-(benzylideneamino)phenol, L1 and 1,2-benzyloxy-bis[3-(benzylideneamino)pyridine], L2 were synthesized. Their sensing actions were confirmed by UV-Vis absorbance and emission spectroscopic studies in presence of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II) in methanol medium (1 10-4 M). It was found that the dipodal compounds can selectively bind to Cu(II) and Pb(II) metal ions with a significant change in its emission and absorption spectra, while the addition of other metal ions (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II)) produces insignificant or minor changes. The host-guest complexes formed were determined by Job's plot method. As a chemosensor, L1 and L2 dipodal Schiff base compounds shows a specific selectivity towards Cu(II) and Pb(II) ions in according to all spectroscopic data.

Obali, Aslihan Yilmaz; Ucan, Halil Ismet

2015-02-01

322

Mixed-ligand Cu(II)-vanillin Schiff base complexes; effect of coligands on their DNA binding, DNA cleavage, SOD mimetic and anticancer activity.  

PubMed

SOD mimics with varying coligand are momentous in developing potential chemotherapeutic drugs. Cu(II) based SOD mimics 1-4 [CuLH(OAc)(H(2)O)Y)] (LH = 2-((E)-(1,3-dihydroxy-2-methylpropan-2-ylimino)methyl)-6-methoxyphenol, OAc = CH(3)COO, 1: Y = H(2)O; 2: Y = phen (1,10-phenanthroline), 3: Y = tpimH (2,4,5-triphenylimidazole); 4: Y = tfbimH (2-(trifluoromethyl)benzimidazole) were synthesized and thoroughly characterized. Their interaction with CT-DNA showed different non-covalent binding behaviour. SOD activity of 2 was highest among 1-4 which was further validated by gel electrophoresis. The pBR322 plasmid strand break offered by 2 + O?? system reveals oxidative cleavage mechanism. In vitro antimicrobial activity of 1-4 was shown by percent inhibition data while in vitro anticancer activity of 1-4 was screened using 16 human carcinoma cell lines of different histological origin. Complex 2 showed higher efficacy towards 14 cell lines. PMID:23291123

Tabassum, Sartaj; Amir, Samira; Arjmand, Farukh; Pettinari, Claudio; Marchetti, Fabio; Masciocchi, Norberto; Lupidi, Giulio; Pettinari, Riccardo

2013-02-01

323

Synthesis and characterization of Schiff's bases of sulfamethoxazole  

PubMed Central

Background Schiff's bases are excellent ligands which are synthesized from the condensation of primary amines with carbonyl groups. Findings The classical reaction for the synthesis of Schiff's bases in an ethanolic solution and glacial acetic acid as a catalyst was followed in the synthesis of substituted sulfamethoxazole compounds. Conclusions Some Schiff's bases containing sulfamethoxazole nucleus have been synthesized and characterized. The present compounds are hoped to be applied in the photostability of PVC. PMID:24576663

2014-01-01

324

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

325

Novel copper(II) homobinuclear macrocyclic complexes: Cyclic voltammetry, biological properties and spectral studies  

NASA Astrophysics Data System (ADS)

A series of five new copper(II) macrocyclic complexes have been synthesized by template condensation. The bonding and stereochemistry of the complexes have been characterized by elemental analysis, molar conductance, magnetic susceptibility, IR, UV-visible, EPR spectral studies and electrochemical properties. g-Values are calculated for all of the complexes in polycrystalline form as well as in DMSO solution. The magnetic and spectral data indicate square planar geometry for all the complexes. Cyclic voltammograms for all the complexes are similar and involve two quasi-reversible redox processes. Cu IICu II ? Cu IICu I ? Cu ICu I. Their biological properties have also been studied. The macrocyclic complexes show more anti-bacterial than controlled one. The anti-bacterial activities of the compounds were tested against Streptococcus fecalis and Escherichia coli with different concentrations.

Chandra, Sulekh; Gupta, Nidhi; Gupta, Rachna

2006-03-01

326

Hexa- and heptacoordinated manganese(II) dicyanamide complexes containing a tetradentate N-donor Schiff base: Syntheses, composition tailored architectures and magnetic properties  

NASA Astrophysics Data System (ADS)

Two 1D coordination polymers [Mn(L)(?1,5-dca)(MeOH)]n(ClO4)n (1) and [Mn(L)(?1,5-dca)]n(PF6)n (2) and a dinuclear compound [Mn2(L)2(?1,5-dca)2(dca)2]?H2O (3) [L = N,N'-(bis-(pyridin-2-yl)benzylidene)-ethane-1,2-diamine; dca = dicyanamide] have been isolated using one-pot synthesis of the building components in appropriate molar ratios and characterized. X-ray structural studies reveal that 1 forms a zigzag 1D chain through single Mn-(NCNCN)-Mn units in which each heptacoordinated manganese(II) center adopts a distorted pentagonal bipyramidal geometry with an MnN6O chromophore occupied with four N atoms of L, two nitrile N atoms of monobridged ?1,5-dca and one O atom of MeOH. In 2, each hexacoordinated metal(II) center has a distorted octahedral coordination environment with an MnN6 chromophore bound by four N atoms of L and two nitrile N atoms of two different single bridged ?1,5-dca units; the latter connects other neighboring metal centers in a non-ending fashion affording a linear 1D chain. Complex 3 is dinuclear where two [Mn(L)]2+ units are connected by double ?1,5-dca bridges with a distorted pentagonal bipyramidal environment. Variable-temperature magnetic susceptibility measurements of 1-3 show weak antiferromagnetic interactions among the metal centers through ?1,5-dca bridges.

Bhar, Kishalay; Sutradhar, Dipu; Choubey, Somnath; Ghosh, Rajarshi; Lin, Chia-Her; Ribas, Joan; Ghosh, Barindra Kumar

2013-11-01

327

Heterometallic Co(III)4Fe(III)2 Schiff base complex: structure, electron paramagnetic resonance, and alkane oxidation catalytic activity.  

PubMed

The heterometallic complex [Co(4)Fe(2)OSae(8)]4DMFH(2)O (1) was synthesized by one-pot reaction of cobalt powder with iron chloride in a dimethylformamide solution of salicylidene-2-ethanolamine (H(2)Sae) and characterized by single crystal X-ray diffraction analysis, magnetic measurements, high frequency electron paramagnetic resonance (HF-EPR), and Mssbauer spectroscopies. The exchange coupling in the Fe(III)-Fe(III) pair is of antiferromagnetic behavior with J/hc = -190 cm(-1). The HF-EPR spectra reveal an unusual pattern with a hardly detectable triplet signal of the Fe(III) dimer. The magnitude of D (ca. 13.9 cm(-1)) was found to be much larger than in related dimers. The catalytic investigations disclosed an outstanding activity of 1 toward oxidation of cycloalkanes with hydrogen peroxide, under mild conditions. The most efficient system showed a turnover number (TON) of 3.57 10(3) with the concomitant overall yield of 26% for cyclohexane, and 2.28 10(3)/46%, respectively, for cyclooctane. A remarkable turnover frequency (TOF) of 1.12 10(4) h(-1) (the highest initial rate W(0) = 3.5 10(-4) M s(-1)) was achieved in oxidation of cyclohexane. Kinetic experiments and selectivity parameters led to the conclusion that hydroxyl radicals are active (attacking C-H bonds) species. Kinetic and electrospray ionization mass spectrometry (ESI-MS) data allowed us to assume that the trinuclear heterometallic particle [Co(2)Fe(Sae)(4)](+), originated from 1 in solution, could be responsible for efficient generation of hydroxyl radicals from hydrogen peroxide. PMID:22853695

Nesterov, Dmytro S; Chygorin, Eduard N; Kokozay, Volodymyr N; Bon, Volodymyr V; Bo?a, Roman; Kozlov, Yuriy N; Shul'pina, Lidia S; Jezierska, Julia; Ozarowski, Andrew; Pombeiro, Armando J L; Shul'pin, Georgiy B

2012-08-20

328

Interactions between Copper(II) Complexes of Mono-, Bis-, and Tris(macrocyclic) Ligands and Inorganic or Organic Guests  

E-print Network

FULL PAPER Interactions between Copper(II) Complexes of Mono-, Bis-, and Tris(macrocyclic) Ligands. Prikhod'ko,[b] and Hans Pritzkow[a] Keywords: Copper / Host-guest complexes / Macrocycles / Molecular recognition Template synthesis The copper(II)-assisted condensation of [Cu(2,3,2-tet)]2+ [2,3,2-tet = bis

Nazarenko, Alexander

329

Molecular compounds of dichloro- p-benzoquinone derivatives with hydroxy aromatic Schiff's bases  

NASA Astrophysics Data System (ADS)

The molecular complexes of some hydroxy aromatic Schiff's bases with 2,3-dichloro-5,6-dicyano- p-benzoquinone and chloranilic acid are prepared and investigated using electronic absorption, i.r. and 1H-NMR spectroscopy. Molecular compounds with the former reagent are formed through charge transfer while those with chloranilic acid are formed through proton and electron transfer.

Issa, Y. M.

330

Characterization and biological activities of two copper(II) complexes with dipropylenetriamine and diamine as ligands  

NASA Astrophysics Data System (ADS)

Two new mixed-ligand copper(II) complexes, [Cu(dipn)(Nsbnd N)]Br2(1-2) [dipn = dipropylenetriamine, Nsbnd N = ethylenediamine (en) (1) and propylenediamine (pn) (2)], have been synthesized. These complexes were characterized by spectroscopic and thermal techniques. Crystal structure for 2 shows a distorted trigonal-bipyramidal geometry around Cu(II) ion with one solvate water molecule. Antimicrobial and antiproliferative assays were conducted to evaluate the biological activities of these complexes. The complexes exhibit a promising antimicrobial effect against an array of microbes at 200 ?g/mL concentration. The antiproliferative assay shows a high potential of these complexes to target Human keratinocyte cell line with IC50 values of 155 and 152 ?M. The absorption spectrum of 2 in water was modeled by time-dependent density functional theory (TD-DFT).

AL-Noaimi, Mousa; Choudhary, Mohammad I.; Awwadi, Firas F.; Talib, Wamidh H.; Hadda, Taibi Ben; Yousuf, Sammer; Sawafta, Ashraf; Warad, Ismail

2014-06-01

331

Synthesis, spectral characterization, structural investigation and antimicrobial studies of mononuclear Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) complexes of a new potentially hexadentate N2O4 Schiff base ligand derived from salicylaldehyde  

NASA Astrophysics Data System (ADS)

A new potentially hexadentate N2O4 Schiff base ligand, H2L derived from condensation reaction of an aromatic diamine and salicylaldehyde, and its metal complexes were characterized by elemental analyses, IR, UV-Vis, EI-MS, 1H and 13C NMR spectra, as well as conductance measurements. It has been originated that the Schiff base ligand with Cu(II), Ni(II), Co(II), Cd(II) and Zn(II) ions form mononuclear complexes on 1:1 (metal:ligand) stoichiometry. The conductivity data confirm the non-electrolytic nature of the complexes. Also the crystal structures of the complexes [ZnL] and [CoL] have also been determined by using X-ray crystallographic technique. The Zn(II) and Co(II) complexes show a tetrahedral configuration. Electronic absorption spectra of the Cu(II) and Ni(II) complexes suggest a square-planar geometry around the central metal ion. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Bacillus cereus, Enterococcus faecalis and Listeria monocytogenes and also against the three Gram-negative bacteria: Salmonella paraB, Citrobacter freundii and Enterobacter aerogenes. The results showed that in some cases the antibacterial activity of complexes were more than nalidixic acid and amoxicillin as standards.

Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Elerman, Yalcin; Buyukgungor, Orhan

2013-01-01

332

Thermodynamics of the formation of copper(II) complexes with L-histidine in aqueous solution  

NASA Astrophysics Data System (ADS)

The heat effects from the reaction between L-histidine solutions and Cu(NO3)2 solutions at 298.15 K in the 0.2 to 1.0 (KNO3) range of ionic strength are measured by means of direct calorimetry. The experimental data is treated with allowance for the simultaneous proceeding of several processes. The heat effects of the formation of complexes Cu(His)+, Cu(His)2, CuHHis2+, CuH(His){2/+} and CuH2(His){2/2+} are calculated from calorimetric measurements. The standard enthalpies of formation for complexes of L-histidine with Cu2+ ions are obtained via extrapolation to zero ionic strength. The relationship between the thermodynamic characteristics of the formation of complexes of copper(II) with L-histidine and their structure is determined.

Gorboletova, G. G.; Metlin, A. A.

2015-02-01

333

Syntheses, structures and electrochemical properties of two co-crystal copper(II) melamine complexes  

NASA Astrophysics Data System (ADS)

Two new co-crystal copper(II) melamine complexes, [Cu(HBA) 2(MA) 2] [Cu(HBA) 2] ( 1) and [Cu 2(OAc) 4(MA)(H 2O)] 2[Cu(HPE) 2] ( 2), MA, melamine; HBA, 2-hydroxybenzaldehyde; HPE, 1-(2-hydroxyphenyl)ethanone, have been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction. Crystal structural analysis reveals that 1 and 2 all are co-crystal complexes and composed of two neutral coordination units. In 1, two mononuclear units adopt square planar and distorted octahedral coordination environments, respectively. In 2, one is a mononuclear unit with a square planar geometry and the other is a dinuclear unit with a paddle wheel structure in which the apical positions are rarely occupied by two different donor ligands. The 2D supramolecular structures are formed through strong hydrogen bonds with different modes. The electrochemical behaviors of complexes 1 and 2 were investigated.

Xu, Li-Feng; Chen, Xiao-Li; Hu, Huai-Ming; Wang, Bao-Cheng

2008-12-01

334

Cytoprotective effect of copper(II) complexes against ethanol-induced damage to rat gastric mucosa.  

PubMed

The cytoprotective effect of various copper(II) complexes on the gastric mucosa damage induced by acute intragastric administration of ethanol was investigated. For in vitro experiments, the following copper(II) complexes were tested: Cu(II)(L-Trp)(L-Phe), Cu(II)(L-Leu)Cu(II)(L-Leu-Leu)(L-Leu), Cu(II)(L-Phe-L-Leu), Cu(II)(Gly-His-Lys), and Cu(II)(cyHis)2(ClO4)2. Inorganic copper such as CuSO4 was also tested. The free radical generating system, acting for 2 hr on cardial and fundic mucosa scrapings or mucosal microsomes, was Fe++ (20 microM)/ascorbate (0.25 mM). We found a marked inhibition to 75% of lipid peroxidation in the range 10-100 mM, regardless of whether copper was given in complexed or inorganic form. The results suggest that nontoxic copper(II)-amino acid complexes are able to neutralize oxygen-derived free radicals. In addition, copper(II) complexes suppressed membrane lipid peroxidation when mucosa homogenates were exposed to t-butyl hydroperoxide (1-20 microM) plus Fe++ (50 microM). In vivo experiments on rat stomachs, pretreated p.o. by gavage either with Cu(II)(L-Trp)(L-Phe) as paradigmatic agent or with copper sulphate at equivalent doses in the range 3-30 mg/kg body weight showed a significant decrease (30 min after 95% ethanol administration) in the number and severity of mucosal hemorrhagic lesions. In the gastric mucosa scrapings of copper-treated rats after ethanol exposure, we found that malondialdehyde and conjugated diene levels were unchanged compared to those of untreated controls; five enzyme activities released from lysosomes were near control values. In isolated mucosal cells, whether or not pretreated with 200 microM solution of either Cu(II)(L-Trp)(L-Phe) or CuSO4, the release of cathepsin D activity was also unmodified. The results suggest that the cytoprotective effect of Cu(II) complexes against ethanol-induced mucosal lesions was not associated in vivo to lipid peroxidation. PMID:1619401

Alberghina, M; Lupo, G; La Spina, G; Mangiameli, A; Gulisano, M; Sciotto, D; Rizzarelli, E

1992-03-01

335

Solvent effects on the stability of nifuroxazide complexes with cobalt(II), nickel(II) and copper(II) in alcohols  

Microsoft Academic Search

A spectrophotometric study of the complexation of nifuroxazide with cobalt(II), nickel(II) and copper(II) was carried out in different alcohols. The formation of a complex in each case is reported and their stability constants have been calculated. For a given solvent, the stability of the complexes increases from cobalt to copper. In the case of copper(II), the stability varies as an

Mustayeen A. Khan; S. Kauser Ali; Gilles M. Bouet

2002-01-01

336

Synthesis, spectroscopic studies and structures of square-planar nickel(II) and copper(II) complexes derived from 2-{(Z)-[furan-2-ylmethyl]imino]methyl}-6-methoxyphenol  

NASA Astrophysics Data System (ADS)

Two new nickel(II) [ Ni(L)2] and copper(II) [ Cu(L)2] complexes have been synthesized with bidentate NO donor Schiff base ligand (2-{(Z)-[furan-2-ylmethyl]imino]methyl}-6-methoxyphenol) ( HL) and both complexes Ni(L)2 and Cu(L)2 have been characterized by elemental analyses, IR, UV-vis, 1H, 13C NMR, mass spectroscopy and room temperature magnetic susceptibility measurement. The tautomeric equilibria (phenol-imine, O-H⋯N and keto-amine, O⋯H-N forms) have been systemetically studied by using UV-vis absorption spectra for the ligand HL. The UV-vis spectra of this ligand HL were recorded and commented in polar, non-polar, acidic and basic media. The crystal structures of these complexes have also been determined by using X-ray crystallographic techniques. The complexes Ni(L)2 and Cu(L)2 crystallize in the monoclinic space group P2 1/ n and P2 1/ c with unit cell parameters: a = 10.4552(3) and 12.1667(4) , b = 8.0121(3) and 10.4792(3) , c = 13.9625(4) and 129.6616(3), V = 1155.22(6) 3 and 1155.22(6) 3, Dx = 1.493 and 1.476 g cm -3 and Z = 2 and 2, respectively. The crystal structures were solved by direct methods and refined by full-matrix least squares to a find R = 0.0377 and 0.0336 of for 2340 and 2402 observed reflections, respectively.

nver, Hseyin; Hayvali, Zeliha

2010-02-01

337

Synthetic, Structural, and Biochemical Studies of Organotin(IV) With Schiff Bases Having Nitrogen and Sulphur Donor Ligands  

PubMed Central

Three bidentate Schiff bases having nitrogen and sulphur donor sequences were prepared by condensing S-benzyldithiocarbazate (NH2NHCS2CH2C6H5) with heterocyclic aldehydes. The reaction of diphenyltin dichloride with Schiff bases leads to the formation of a new series of organotin(IV) complexes. An attempt has been made to prove their structures on the basis of elemental analyses, conductance measurements, molecular weights determinations, UV, infrared, and multinuclear magnetic resonance (1H, 13C, and 119Sn) spectral studies. Organotin(IV) complexes were five- and six-coordinate. Schiff bases and their corresponding organotin complexes have also been screened for their antibacterial and antifungal activities and found to be quite active in this respect. PMID:17497003

Singh, Har Lal; Varshney, A. K.

2006-01-01

338

Copper(II) and zinc(II) complexes with 2-formylpyridine-derived hydrazones  

Microsoft Academic Search

In the present work 2-formylpyridine-para-chloro-phenyl hydrazone (H2FopClPh) and 2-formylpyridine-para-nitro-phenyl hydrazone (H2FopNO2Ph) were obtained, as well as their copper(II) and zinc(II) complexes [Cu(H2FopClPh)Cl2] (1), [Cu(2FopNO2Ph)Cl] (2), [Zn(H2FopClPh)Cl2] (3) and [Zn(H2FopNO2Ph)Cl2] (4). Upon re-crystallization in DMSO:acetone conversion of 2 into [Cu(2FopNO2Ph)Cl(DMSO)] (2a) and of 4 into [Zn(2FopNO2Ph)Cl(DMSO)] (4a) occurred. The crystal structures of 1, 2a, 3 and 4a were determined.

Angel A. Recio Despaigne; Jeferson G. da Silva; Ana Cerlia M. do Carmo; Flavio Sives; Oscar E. Piro; Eduardo E. Castellano; Heloisa Beraldo

2009-01-01

339

An unusual 3D interdigitated architecture assembled from Keggin polyoxometalates and dinuclear copper(II) complexes  

NASA Astrophysics Data System (ADS)

A novel organic-inorganic hybrid compound, [Cu2(bipy)3(?1-H2O)2(?2-H2O)(?2-OH)(H2BW12O40)]4 H2O (1) (bipy=4,4'-bipy), has been synthesized in hydrothermal condition and characterized by elemental analysis, IR spectrum, TG analysis and single-crystal X-ray diffraction. Compound 1 possesses poly-pendant layered motifs composed of 12-tungstoborates and dinuclear copper(II) complexes, in which the mono-coordinated bipy molecules are orderly appended to both sides of the layer, respectively. Adjacent layers mutually engage in a zipper-like pattern to result in a novel 3D interdigitated architecture. The variable-temperature magnetic susceptibility of 1 showed that there existed weak antiferromagnetic interaction in 1. Toward the reduction of hydrogen peroxide, 1 has good electrocatalytic activity and remarkable stability.

Pang, Haijun; Yang, Ming; Kang, Lu; Ma, Huiyuan; Liu, Bo; Li, Shaobin; Liu, Heng

2013-02-01

340

Magnetic properties of copper(II) complexes containing peptides. Crystal structure of [Cu(phe-leu)  

NASA Astrophysics Data System (ADS)

A novel copper(II) complex containing the peptide phe-leu has been prepared and characterized. The crystal structure of [Cu(phe-leu)] ( 1) was determined by X-ray diffraction. The presence of carboxylate and amido bridges allows the formation of an extended 2D arrangement. This structure is similar to those found in [Cu(gly-val)] 1/2H 2O ( 2), [Cu(val-gly)] ( 3), [Cu(val-phe)] ( 4), and [Cu(phe-phe)] ( 5). The magnetic properties of compounds 1- 5 were studied and analyzed comparatively. The experimental data show that the magnetic interactions are mainly transmitted through ? 2-COO - bridges, being ferromagnetic for 1 and 3, and antiferromagnetic for 2, 4 and 5.

Sanchiz, J.; Kremer, C.; Torre, M. H.; Facchin, G.; Kremer, E.; Castellano, E. E.; Ellena, J.

2006-09-01

341

Anomeric and tautomeric equilibria in D-2-glucosamine Schiff bases  

NASA Astrophysics Data System (ADS)

The structure of some glucosamine Schiff bases has been studied by means of ab initio RHF and DFT calculation and CP/MAS 13C and 15N NMR measurements. The anomeric and tautomeric equilibria in a DMSO solution have been studied by 1H, 13C and 15N NMR spectroscopy. The anomeric composition of D-2-glucosamine Schiff bases in the solid state and in DMSO solution has been shown to depends on the tautomeric form of Schiff bases and electronic properties of substituents on the aromatic ring.

Ko?odziej, B.; Grech, E.; Schilf, W.; Kamie?ski, B.; Makowski, M.; Rozwadowski, Z.; Dziembowska, T.

2007-11-01

342

Synthesis, crystal structure, DNA interaction and anticancer activity of tridentate copper(II) complexes.  

PubMed

Three new tridentate copper(II) complexes [Cu(dthp)Cl(2)] (1) (dthp=2,6-di(thiazol-2-yl)pyridine), [Cu(dmtp)Cl(2)] (2) (dmtp=2,6-di(5-methyl-4H-1,2,4-triazol-3-yl)pyridine) and [Cu(dtp)Cl(2)] (3) (dtp=2,6-di(4H-1,2,4-triazol-3-yl)pyridine) have been synthesized and characterized. Crystal structure of complex 1 shows that the complex existed as distorted square pyramid with five co-ordination sites occupied by the tridentate ligand and the two chlorine anions. Ethidium bromide displacement assay, viscosity measurements, circular dichroism studies and cyclic voltammetric experiments suggested that these complexes bound to DNA via an intercalative mode. Three Cu(II) complexes were found to efficiently cleave DNA in the presence of sodium ascorbate, and singlet oxygen ((1)O(2)) and hydrogen peroxide were proved to contribute to the DNA cleavage process. They exhibited anticancer activity against HeLa, Hep-G2 and BEL-7402 cell lines. Nuclear chromatin cleavage has also been observed with AO/EB staining assay and the alkaline single-cell gel electrophoresis (comet assay). The results demonstrated that three Cu(II) complexes cause DNA damage that can induce the apoptosis of BEL-7402 cells. PMID:23186647

Li, Guan-Ying; Du, Ke-Jie; Wang, Jin-Quan; Liang, Jie-Wen; Kou, Jun-Feng; Hou, Xiao-Juan; Ji, Liang-Nian; Chao, Hui

2013-02-01

343

Monopicolinate cross-bridged cyclam combining very fast complexation with very high stability and inertness of its copper(II) complex.  

PubMed

The synthesis of a new cross-bridged 1,4,8,11-tetraazacyclotetradecane (cb-cyclam) derivative bearing a picolinate arm (Hcb-te1pa) was achieved by taking advantage of the proton sponge properties of the starting constrained macrocycle. The structure of the reinforced ligand as well as its acid-base properties and coordination properties with Cu(2+) and Zn(2+) was investigated. The X-ray structure of the free ligand showed a completely preorganized conformation that lead to very fast copper(II) complexation under mild conditions (instantaneous at pH 7.4) or even in acidic pH (3 min at pH 5) at room temperature and that demonstrated high thermodynamic stability, which was measured by potentiometry (at 25 C and 0.10 M in KNO3). The results also revealed that the complex exists as a monopositive copper(II) species in the intermediate pH range. A comparative study highlighted the important selectivity for Cu(2+) over Zn(2+). The copper(II) complex was synthesized and investigated in solution using different spectroscopic techniques and DFT calculations. The kinetic inertness of the copper(II) complex in acidic medium was evaluated by spectrophotometry, revealing the very slow dissociation of the complex. The half-life of 96 days, in 5 M HClO4, and 465 min, in 5 M HCl at 25 C, show the high kinetic stability of the copper(II) chelate compared to that of the corresponding complexes of other macrocyclic ligands. Additionally, cyclic voltammetry experiments underlined the perfect electrochemical inertness of the complex as well as the quasi-reversible Cu(2+)/Cu(+) redox system. The coordination geometry of the copper center in the complex was established in aqueous solution from UV-vis and EPR spectroscopies. PMID:24758339

Lima, Lus M P; Halime, Zakaria; Marion, Ronan; Camus, Nathalie; Delgado, Rita; Platas-Iglesias, Carlos; Tripier, Raphal

2014-05-19

344

A novel Schiff-base as a Cu(II) ion fluorescent sensor in aqueous solution  

NASA Astrophysics Data System (ADS)

A new fluorescent Cu(II) sensor (L) obtained from the Schiff base of 5,5?-methylene-bis-salicylaldehyde with amidol (2,4-diaminophenol) was synthesized and characterized by FT-IR, MS, 1H NMR, 13C NMR techniques. In the presence of pH 6.5 (KHPO4-Na2HPO4) buffer solutions, copper reacted with L to form a stable 2:1 complex. Fluorescence spectroscopic study showed that Schiff base is highly sensitive towards Cu(II) over other metal ions (K+, Na+, Al3+, Ni2+, Co2+, Fe3+, Zn2+, Pb2+) in DMSO/H2O (30%, v/v). The sensor L was successfully applied to the determination of copper in standard reference material. The structural properties and molecular orbitals of the complex formed between L and Cu2+ ions were also investigated using quantum chemical computations.

Gndz, Z. Yurtman; Gndz, C.; zp?nar, C.; Urucu, O. Ayd?n

2015-02-01

345

Recent pharmacological advancements in schiff bases: a review.  

PubMed

Schiff bases are the biologically privileged scaffolds in organic chemistry, commonly synthesized from the condensation reaction of carbonyl functional group with amines. Naturally occurring and synthetically prepared Schiff bases are active molecules with many pharmacological activities like antibacterial, anti-cancer, anti-fungal, anti-malarial, antioxidant and many more. This review article summarizes pharmacological developments in the recent few years and gives a brief overview of their therapeutic potential. PMID:25272879

Murtaza, Ghulam; Mumtaz, Amara; Khan, Farhan Ahmed; Ahmad, Saeed; Azhar, Saira; Khan, Shujaat Ali; Najam-Ul-Haq, Muhammad; Atif, Muhammad; Khan, Shujaat Ali; Maalik, Aneela; Azhar, Saira; Murtaza, Ghulam

2014-01-01

346

Formation of bis(?-tetrazolato)dinickel(II) complexes with N,N,O-donor Schiff bases via in situ 1,3-dipolar cyclo-additions: isolation of a novel bi-cyclic trinuclear nickel(II)-sodium(I)-nickel(II) complex.  

PubMed

A dinuclear and a novel bi-cyclic hetero trinuclear bis(?-tetrazolato) bridged nickel(II) Schiff base complexes [Ni2(L(1))2(PTZ)2] (1) and [Ni2(L(2))2(PTZ)2Na(H2O)]ClO4H2O (2) {where HL(1) = 2-((2-(dimethylamino)ethylimino)methyl)-6-methoxyphenol, HL(2) = 2-((2-(methylamino)ethylimino)methyl)-6-methoxyphenol and HPTZ = 5-(2-pyridyl)tetrazole} have been synthesized by in situ 1,3-dipolar cyclo-addition and characterized by spectral analysis, X-ray crystallography, and variable-temperature magnetic susceptibility measurements. Both the complexes crystallize in monoclinic space group P2(1)/c. Both the complexes feature double ?-NN'-tetrazolato bridged dinickel(II) structures, in which each nickel(II) is coordinated meridionally by a depronated terdentate Schiff base [(L(1))(-) for 1 and (L(2))(-) for 2] and two nitrogen atoms of the (PTZ)(-). A nitrogen atom from a symmetry related bridging (PTZ)(-) coordinates to complete the distorted octahedral geometry of nickel(II). The phenoxo and methoxo oxygen atoms from two [NiL(2)] units and a water molecule coordinate to a sodium(I) to form the unique bi-cyclic trinuclear nickel(II)-sodium(I)-nickel(II) core in complex 2. Very strong ?? stacking is observed in complex 2 to form a supramolecular chain. The variable-temperature (1.8-300 K) magnetic susceptibility measurements show the presence of anti-ferromagnetic coupling between two nickel(II) centers for both complexes with J = -2.14(1) cm(-1) (for 1) and J = -1.20(2) cm(-1) (for 2). To obtain a better understanding of the magnetic exchange mechanism, quantum mechanical (DFT) calculations have been performed. The calculated J values [J(theo) = -4.53 cm(-1) (for 1) and J(theo) = -2.48 cm(-1) (for 2)] are in agreement with the values obtained experimentally. PMID:24346055

Das, Mithun; Chatterjee, Sudipta; Harms, Klaus; Mondal, Tapan Kumar; Chattopadhyay, Shouvik

2014-02-21

347

Catalytic enantioselective desymmetrization of meso-glutaric anhydrides using a stable Ni2-Schiff base catalyst.  

PubMed

We describe the desymmetrization of meso-glutaric anhydrides to chiral hemiesters using a bench-stable homodinuclear Ni(2)-(Schiff base) complex as the catalyst in good to excellent yield (up to 99%) and enantioselectivity (up to 94%). Using the opposite enantiomer of the catalyst, we obtained the same yield and enantioselectivity with the opposite configuration, thereby gaining access to both hemiester enantiomers. PMID:22339049

Gopinath, Purushothaman; Watanabe, Takumi; Shibasaki, Masakatsu

2012-03-01

348

Synthesis, structure, and catecholase activity of bispyrazolylacetate copper(II) complexes.  

PubMed

A series of six-coordination copper(ii) complexes containing bis(3,5-di-t-butylpyrazol-1-yl)acetate (bdtbpza) and N-heterocycles or chelating aliphatic ligands have been synthesized. The steric bulkiness of bis(pyrazol-1-yl)acetate anchors two bdtbpza to situate a trans position and to adopt an O-bound monodentate coordination mode with other nitrogen bases occupying the basal plane. Five mononuclear mixed ligand complexes, [Cu(bdtbpza)2(py)4] , [Cu(bdtbpza)2(t-Bupy)4] , [Cu(bdtbpza)2(pym)2(MeOH)2] , [Cu(bdtbpza)2(eda)2] , [Cu(bdtbpza)2(tmeda)(H2O)2] , where py = pyridine, t-Bupy = tert-butylpyridine, pym = pyrimidine, eda = ethylenediamine, and tmeda = tetramethylethylenediamine, were isolated and thoroughly characterized. Intriguingly, the heteroleptic complex , which has two aquo-ligands oriented in the cis positions, demonstrates higher catecholase-like activity in performing aerial oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) than other bis(pyrazolyl)acetate-embedded copper complexes reported herein, which suggests the essential role of labile cis-aquo ligands to promote the catalytic reaction. PMID:25146734

Gajewska, Ma?gorzata J; Ching, Wei-Min; Wen, Yuh-Sheng; Hung, Chen-Hsiung

2014-10-21

349

Schiff's Bases and Crown Ethers as Supramolecular Sensing Materials in the Construction of Potentiometric Membrane Sensors  

PubMed Central

Ionophore incorporated PVC membrane sensors are well-established analytical tools routinely used for the selective and direct measurement of a wide variety of different ions in complex biological and environmental samples. Potentiometric sensors have some outstanding advantages including simple design and operation, wide linear dynamic range, relatively fast response and rational selectivity. The vital component of such plasticized PVC members is the ionophore involved, defining the selectivity of the electrodes' complex formation. Molecular recognition causes the formation of many different supramolecules. Different types of supramolecules, like calixarenes, cyclodextrins and podands, have been used as a sensing material in the construction of ion selective sensors. Schiff's bases and crown ethers, which feature prominently in supramolecular chemistry, can be used as sensing materials in the construction of potentiometric ion selective electrodes. Up to now, more than 200 potentiometric membrane sensors for cations and anions based on Schiff's bases and crown ethers have been reported. In this review cation binding and anion complexes will be described. Liquid membrane sensors based on Schiff's bases and crown ethers will then be discussed.

Faridbod, Farnoush; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Norouzi, Parviz; Riahi, Siavash

2008-01-01

350

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

NASA Astrophysics Data System (ADS)

Six new mixed-ligand copper(II) complexes were synthesized namely [Cu(phen)2OAc]ClO4?H2O(1), [Cu(bpy)2OAc]ClO4?H2O(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.

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

2014-10-01

351

Synthesis, structure, and magnetic properties of two 1-D helical coordination polymeric Cu(II) complexes  

NASA Astrophysics Data System (ADS)

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.

Bian, He-Dong; Yang, Xiao-E.; Yu, Qing; Chen, Zi-Lu; Liang, Hong; Yan, Shi-Ping; Liao, Dai-Zheng

2008-01-01

352

A new azido-bridged copper(II) complex containing nitronyl nitroxide radicals: Syntheses, crystal structures  

NASA Astrophysics Data System (ADS)

A new azido-bridged copper(II) complex with nitronyl nitroxide radicals Cu ( NITpPy)4(N3)2 ( NITpPy = 4-pyridyl-4,4,5,5-tetramethylimidaz-line-3-oxide-1-oxyl) has been prepared and structurally characterized by single-crystal X-ray diffraction. The complex crystallizes in triclinic, space group , Z = 1. Crystal data: C48H64CuN18O8, M r = 1084.71, a = 7.1334(11), b = 13.718(2), c = 14.136(2) , ? = 88.425(2), ? = 78.528(2), ? = 87.390(2), V = 1354.0(4) 3, D c = 1.330 g/cm3, ?(Mo K?) = 0.472 mm-1, F(000) = 571, R = 0.0735 and wR = 0.1140 for 4962 observed reflections with I > 2?( I). The X-ray analysis reveals that Cu(II) ion resides in a perfect octahedron center. The units of [Cu ( NITpPy)4(N3)2] were connected as 3-D network structure by the nonclassical intermolecular H-bonds.

Liu, G.; Chen, B.; Cheng, J. T.

2014-12-01

353

Solvent effects on the stability of nifuroxazide complexes with cobalt(II), nickel(II) and copper(II) in alcohols.  

PubMed

A spectrophotometric study of the complexation of nifuroxazide with cobalt(II), nickel(II) and copper(II) was carried out in different alcohols. The formation of a complex in each case is reported and their stability constants have been calculated. For a given solvent, the stability of the complexes increases from cobalt to copper. In the case of copper(II), the stability varies as an inverse function of the dielectric constant of the solvent. A possible structure of the complex is proposed. PMID:12009257

Khan, Mustayeen A; Ali, S Kauser; Bouet, Gilles M

2002-05-21

354

Tautomeric design of ortho-hydroxyheterocyclic Schiff bases  

NASA Astrophysics Data System (ADS)

The article reports on the synthesis and crystallographic and theoretical studies on various heterocyclic derivatives of ortho-hydroxy Schiff bases. The prevailing of one of the two (enolimine - OH and ketoamine - NH) tautomeric forms has been stated in studied compounds depending on the substitutes in heterocyclic formation, the nitrogen and carbon atoms of the imine group. A specific situation has been shown in (1E)-1-(5-chloro-2-hydroxy-3-nitrophenyl)ethanone oxime compound. The potentials on the proton transfer of the hydrogen bridges in these compounds have been found out. Grounded on the obtained potential curves the influence of the protonation on nitrogen in the pyridoxal derivative of the studied ortho-hydroxy Schiff bases has been analysed. The most efficient method of the impact (by means of various substitutes) on the intramolecular tautomeric equilibrium in ortho-hydroxy Schiff bases has been presented.

Kwocz, Agnieszka; Kochel, Andrzej; Chudoba, Dorota; Filarowski, Aleksander

2015-01-01

355

Copper(II), nickel(II) and zinc(II) complexes of the N-terminal nonapeptide fragment of amyloid-? and its derivatives.  

PubMed

Copper(II), nickel(II) and zinc(II) complexes of the nonapeptide fragment of amyloid-? A?(1-9) (NH2-DAEFRHDSG-NH2) and its two derivatives: NH2-DAAAAHAAA-NH2 and NH2-DAAAAAHAA-NH2 have been studied by potentiometric, UV-visible and CD spectroscopic methods. The results reveal the primary role of the amino terminus of peptides in copper(II) and nickel(II) binding. The formation of dinuclear complexes was also possible in the copper(II) containing systems but only the first six amino acids from the amino terminus were involved in metal binding in the physiologically relevant pH range. The coordination chemistry of the two alanine mutated peptides is almost the same as that of the native nonapeptide, but the thermodynamic stability of the copper(II) complexes of the mutants is significantly reduced. This difference probably comes from the secondary interactions of the polar side chains of Asp, Glu, Ser and Arg residues present in the native peptide. Moreover, this difference reveals that the amino acid sequence of the N-terminal domains of amyloid peptides is especially well suited for the complexation with copper(II) ions. PMID:24973554

Grencs, gnes; Svg, Imre

2014-10-01

356

Copper(II) complexes with 4-hydroxyacetophenone-derived acylhydrazones: Synthesis, characterization, DNA binding and cleavage properties  

NASA Astrophysics Data System (ADS)

Two new Cu(II) complexes of Schiff base-hydrazone ligands, hydroxy-N?-[(1Z)-1-(4-hydroxyphenyl)ethylidene]benzohydrazide [H3L1] and ethyl 2-(4-(1-(2-(4-(2-ethoxy-2-oxoethoxy)benzoyl)hydrazono)ethyl)phenoxy)acetate (HL2) have been synthesized and then characterized by microcopy and spectral studies. X-ray powder diffraction illustrates that [Cu(L2)2] complex is crystalline in nature whereas [Cu(H2L1)2]2H2O has an amorphous structure. Binding of the copper complexes with Calf thymus DNA (CT-DNA) has been investigated by UV-visible spectra, exhibiting non-covalent binding to CT-DNA. DNA cleavage experiments have been also investigated by agarose gel electrophoresis in the presence and absence of an oxidative agent (H2O2). The effect of complex concentration on the DNA cleavage reaction has been also studied. Both copper complexes show nuclease activity, which significantly depends on concentrations of the complexes, in the presence of H2O2 through oxidative mechanism whereas they slightly cleavage DNA in the absence an oxidative agent.

Gup, Ramazan; Gke, Cansu; Aktrk, Seluk

2015-01-01

357

Crystal structures of copper(II) nitrate, copper(II) chloride, and copper(II) perchlorate complexes with 2-formylpyridine semicarbazone  

SciTech Connect

Compounds dinitrato(2-formylpyridinesemicarbazone)copper (I), dichloro(2-formylpyridinesemicarbazone) copper hemihydrate (II), and bis(2-formylpyridinesemicarbazone)copper(2+) perchlorate hydrate (III) are synthesized and their crystal structures are determined. In compounds I-III, the neutral 2-formylpyridine semicarbazone molecule (L) is tridentately attached to the copper atom via the N,N,O set of donor atoms. In compounds I and II, the Cu: L ratio is equal to 1: 1, whereas, in III, it is 1: 2. In complex I, the coordination sphere of the copper atom includes two nitrate ions with different structural functions in addition to the L ligand. The structure is built as a one-dimensional polymer in which the NO{sub 3} bidentate group fulfills a bridging function. The coordination polyhedron of the copper(2+) atom can be considered a distorted tetragonal bipyramid (4 + 1 + 1). Compound II has an ionic structure in which the main element is the [CuLCl{sub 2} . Cu(H{sub 2}O)LCl]{sup +} dimer. In the dimer, the copper atoms are linked via one of the {mu}{sub 2}-bridging chlorine atoms. The coordination polyhedra of the central atoms of the Cu(H{sub 2})LCl and CuLCl{sub 2} complex fragments are tetragonal bipyramid and tetragonal pyramid, respectively. In compound III, the copper atom is octahedrally surrounded by two L ligands in the mer configuration.

Chumakov, Yu. M. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Tsapkov, V. I. [State University of Moldova (Moldova, Republic of); Antosyak, B. Ya. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Bairac, N. N. [State University of Moldova (Moldova, Republic of); Simonov, Yu. A., E-mail: simonov.xray@phys.asm.md [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Bocelli, G. [National Research Council (IMEM-CNR), Institute of Materials for Electronics and Magnetism (Italy); Pahontu, E. [University of Medicine and Pharmacy (Romania); Gulea, A. P. [State University of Moldova (Moldova, Republic of)

2009-05-15

358

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

NASA Astrophysics Data System (ADS)

Aspartame adduct of copper(II) chloride Cu(Asp) 2Cl 22H 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.

ak?r, S.; Co?kun, E.; Naumov, P.; Bier, E.; Bulut, ?.; ?budak, H.; ak?r, O.

2002-08-01

359

Schiff Base Metal Derivatives Enhance the Expression of HSP70 and Suppress BAX Proteins in Prevention of Acute Gastric Lesion  

PubMed Central

Schiff base complexes have appeared to be promising in the treatment of different diseases and disorders and have drawn a lot of attention to their biological activities. This study was conducted to evaluate the regulatory effect of Schiff base metal derivatives on the expression of heat shock proteins (HSP) 70 and BAX in protection against acute haemorrhagic gastric ulcer in rats. Rats were assigned to 6 groups of 6 rats: the normal control (Tween 20 5% v/v, 5?mL/kg), the positive control (Tween 20 5% v/v, 5?mL/kg), and four Schiff base derivative groups named Schiff_1, Schiff_2, Schiff_3, and Schiff_4 (25?mg/kg). After 1?h, all of the groups received ethanol 95% (5?mL/kg) but the normal control received Tween 20 (Tween 20 5% v/v, 5?mL/kg). The animals were euthanized after 60?min and the stomachs were dissected for histology (H&E), immunohistochemistry, and western blot analysis against HSP70 and BAX proteins. The results showed that the Schiff base metal derivatives enhanced the expression of HSP70 and suppressed the expression of BAX proteins during their gastroprotection against ethanol-induced gastric lesion in rats. PMID:24298554

Gwaram, Nura Suleiman; Al-Obaidi, Mazen M. Jamil; Soleimani, A. F.; Ali, Hapipah Mohd; Abdul Majid, Nazia

2013-01-01

360

Copper(II) complexes derived from di-2-pyridyl ketone- N4-phenyl-3-semicarbazone: Synthesis and spectral studies  

NASA Astrophysics Data System (ADS)

Five copper(II) complexes [CuLCl] 2CuCl 24H 2O ( 1), [CuLOAc] ( 2), [CuLNO 3] 2 ( 3), [CuLN 3] ( 4) and [CuLNCS]3/2H 2O ( 5) of di-2-pyridyl ketone- N4-phenyl-3-semicarbazone (HL) were synthesized and characterized by elemental analyses and electronic, infrared and EPR spectral techniques. In all these complexes the semicarbazone undergoes deprotonation and coordinates through enolate oxygen, azomethine and pyridyl nitrogen atoms. All the complexes are EPR active due to the presence of an unpaired electron. EPR spectra of all the complexes in DMF at 77 K suggest axial symmetry and the presence of half field signals for the complexes 1 and 3 indicates dimeric structures.

Reena, T. A.; Kurup, M. R. Prathapachandra

2010-08-01

361

A comparative study of in vitro cytotoxic, antioxidant, and antimicrobial activity of Pt(II), Zn(II), Cu(II), and Co(III) complexes with N-heteroaromatic Schiff base (E)-2-[N'-(1-pyridin-2-yl-ethylidene)hydrazino]acetate.  

PubMed

In search for novel biologically active metal based compounds, an evaluation of in vitro cytotoxic, antioxidant, and antimicrobial activity of new Pt(II) complex and its Zn(II), Cu(II), and Co(III) analogues, with NNO tridentately coordinated N-heteroaromatic Schiff base ligand (E)-2-[N'-(1-pyridin-2-yl-ethylidene)hydrazino]acetate, was performed. Investigation of antioxidative properties showed that all of the compounds have strong radical scavenging potencies. The Zn(II) complex showed potent inhibition of DNA cleavage by hydroxyl radical. A cytotoxic action of investigated compounds was evaluated on cultures of human promyelocitic leukaemia (HL-60), human glioma (U251), rat glioma (C6), and mouse melanoma (B16) cell lines. It was shown that binuclear pentacoordinated Zn(II) complex possesses a strong dose-dependent cytotoxic activity, of the same order of magnitude as cisplatin on B16, C6, and U251 cells. Furthermore, Zn(II) complex causes oxidative stress-induced apoptotic death of HL-60 leukemic cells, associated with caspase activation, phosphatidylserine externalization, and DNA fragmentation. PMID:24302597

Filipovi?, Nenad R; Markovi?, Ivanka; Miti?, Dragana; Polovi?, Natalija; Mil?i?, Milo; Dulovi?, Marija; Jovanovi?, Maja; Savi?, Milena; Niki?, Miomir; An?elkovi?, Katarina; Todorovi?, Tamara

2014-03-01

362

Dinuclear Copper(II) Complexes Incorporating a New Septadentate Polyimidazole Ligand.  

PubMed

The dinuclear copper(II) complexes [Cu(2)(tmihpn)(prz)](ClO(4))(2).2CH(3)CN (6) and [Cu(2)(tmihpn)(O(2)CCH(3))](ClO(4))(2).CH(3)CN (7) were prepared, where tmihpn is the deprotonated form of N,N,N',N'-tetrakis[(1-methylimidazol-2-yl)methyl]-1,3-diaminopropan-2-ol and prz is the pyrazolate anion. The crystal structures of 6 and 7 were determined and revealed that both complexes contain bridging alkoxide ligands as well as bridging pyrazolate and acetate ions, respectively. Crystal data: compound 6, triclinic, P&onemacr;, a = 18.089(2) , b = 22.948(3) , c = 9.597(2) , alpha = 93.37(2) degrees, beta = 94.49(2) degrees, gamma = 81.69(2) degrees, V = 3925.1 (3), Z = 4; compound 7, triclinic, P&onemacr;, a = 12.417(2) , b = 15.012(3) , c = 10.699(2) , alpha = 104.76(2) degrees, beta = 102.63(2) degrees, gamma = 99.44(2) degrees, V = 1830.1 (3), Z = 2. In compound 6, the coordination geometry around both copper centers resembles a distorted square pyramid, while the stereochemistry around the copper centers in 7 is best described as trigonal bipyramidal. Both complexes display well-resolved isotropically shifted (1)H NMR spectra. Selective substitution studies and integration data have been used to definitively assign several signals to specific ligand protons. Results from the solution (1)H NMR studies suggest that the basal and apical imidazole groups do not exchange rapidly on the NMR time scale and the solid state structures of the complexes are retained in solution. In addition, the magnetochemical characteristics of 6 and 7 were determined and provide evidence for "magnetic orbital switching". Antiferromagnetic coupling in 6 (J = -130 cm(-)(1)) is strong, while the copper centers in compound 7 are ferromagnetically coupled (J = +16.4 cm(-1)). Differences in the magnetic behavior of the two copper centers have been rationalized using the "ligand orbital complementary" concept. The ground state magnetic orbitals involved in spin coupling in 6 (d(x)()()2(-)(y)()()2) are different from those in 7 (d(z)()()2). PMID:11666535

Nie, Hanlin; Aubin, Sheila M. J.; Mashuta, Mark S.; Porter, Richard A.; Richardson, John F.; Hendrickson, David N.; Buchanan, Robert M.

1996-05-22

363

Development of novel pillared clays for the encapsulation of inorganic complexes.  

PubMed

Several pillared clays were prepared by using a polyalcohol (ethylene glycol or poly(vinyl alcohol)) or a poly(ethylene oxide) surfactant as an interlayer gallery template and an aluminum oligomer species as the pillaring agent. The use of polyalcohols or nonionic surfactants, such as Tergitol, gave materials which, in general, presented larger basal spacing than those found for the solids prepared by a similar procedure but without additives. The initial positive effect in the expansion of the clay interlayers was not totally retained after calcination of the materials; most probably, at the end, the basal spacing is still ruled by the intercalating aluminum species. The pillared clay with the largest basal spacing and specific surface area was used to encapsulate copper(II) complexes with pentadentate N3O2 Schiff base ligands derived from copper(II) acetylacetonate by in situ synthesis. The characterization made (X-ray diffraction, X-ray photoelectron spectroscopy, FTIR spectroscopy, chemical analysis, and low-temperature N2 adsorption) provided evidence that copper(II) complexes with pentadentate N3O2 Schiff base ligands were efficiently entrapped within the lower dimension pores of the pillared clay and that they interact strongly with the pillared clay matrix. PMID:15835164

Pires, Joo; Francisco, Joana; Carvalho, Ana; de Carvalho, M Brotas; Silva, Ana Rosa; Freire, Cristina; de Castro, Baltazar

2004-03-30

364

Thermally induced oxidative decarboxylation of copper complexes of amino acids and formation of strecker aldehyde.  

PubMed

In the Maillard reaction, independent degradations of amino acids play an important role in the generation of amino-acid-specific products, such as Strecker aldehydes or their Schiff bases. Such oxidative decarboxylation reactions are expected to be enhanced in the presence of metals. Preliminary studies performed through heating of alanine and various metal salts (Cu, Fe, Zn, and Ca) under pyrolytic conditions indicated that copper(II) and iron(III) because of their high oxidation potentials were the only metals able to induce oxidative decarboxylation of amino acids and formation of Strecker aldehyde or its derivatives as detected by gas chromatography/mass spectrometry. Furthermore, studies performed with synthetic alanine and glycine copper complexes indicated that they constituted the critical intermediates undergoing free-radical oxidative degradation, followed by the loss of carbon dioxide and the generation of Strecker aldehydes, which were detected either as stable Schiff base adducts or incorporated in moieties, such as pyrazine or pyridine derivatives. PMID:25078730

Nashalian, Ossanna; Yaylayan, Varoujan A

2014-08-20

365

Mixed-ligand copper(II) phenolate complexes: Synthesis, spectral characterization, phosphate-hydrolysis, antioxidant, DNA interaction and cytotoxic studies  

NASA Astrophysics Data System (ADS)

A series of phenol-based mixed-ligand copper(II) complexes of the type [CuL1-4(diimine)] (1-8), where L1-4 = N1,N2-bis(5-substituted-2-hydroxybenzylidene)-1,2-ethylene/phenylenediimine and diimine = 2,2?-bipyridyl (bpy) or 1,10-phenanthroline (phen), have been isolated and fully characterized by analytical and spectral techniques. Electronic spectra of complexes suggest Cu(II) cation has a d9 electronic configuration, adopting distorted octahedral geometry with axial elongation, due to Jahn-Teller effect. Electrochemical studies of complexes evidenced one-electron irreversible reduction wave in the cathodic region. The observed rate constant (k) values for the hydrolysis of 4-nitrophenylphosphate (4-NPP) are in the range of 0.25-3.82 10-2 min-1. The obtained room temperature magnetic moment values (1.79-1.90 BM) lies within the range observed for octahedral copper(II) complexes. Antioxidant studies revealed that these complexes possess considerable radical scavenging potency against DPPH. The binding studies of complexes with calf thymus DNA (CT-DNA) revealed intercalation with minor-groove binding, and the complex 4 exhibits highest binding activity than the other complexes. The cleavage activity on supercoiled pBR322 DNA revealed the involvement of hydroxyl radical and singlet-oxygen as reactive oxygen species, and complexes encourage binding to minor-groove. Further, the cytotoxicity of complex 4 on human hepatocellular liver carcinoma HepG2 cell line implies the cell death through apoptosis.

Gurumoorthy, Perumal; Mahendiran, Dharmasivam; Prabhu, Durai; Arulvasu, Chinnasamy; Rahiman, Aziz Kalilur

2015-01-01

366

Ligand effects on the structures and magnetic properties of tricyanomethanide-containing copper(II) complexes.  

PubMed

The preparation, crystal structure and magnetic properties of four heteroleptic copper(II) complexes with the tricyanomethanide (tcm(-)) and the heterocyclic nitrogen donors 3,6-bis(2-pyridyl)pyridazine (dppn), 2,5-bis(2-pyridyl)pyrazine (2,5-dpp), 2,3-bis(2-pyridyl)pyrazine (2,3-dpp) and 2,3-bis(2-pyridyl)quinoxaline (2,3-dpq) are reported, {[Cu(2)(dppn)(OH)(tcm)(2)] x tcm}(n) (1), {[Cu(2,5-dpp)(tcm)] x tcm}(n) (2), {[Cu(2)(2,3-dpp)(2)(tcm)(3)(H(2)O)(0.5)] x tcm x 0.5H(2)O}(n) (3) and [Cu(2,3-dpq)(tcm)(2)](n) (4). 1 has a ladder-like structure with single mu-1,5-tcm ligands forming the sides and a bis-bidentate dppn and a single mu-hydroxo providing the rung. Each copper atom in 1 exhibits a distorted square pyramidal CuN(4)O surrounding: the basal plane is built by the hydroxo-oxygen, a nitrile-nitrogen atom from a tcm group and one pyrazine and a pyridyl nitrogen atoms from the dppn whereas the apical position is filled by a nitrile-nitrogen atom from a symmetry-related tcm ligand. The structures of 2-4 consists of zig-zag (2 and 3)/linear (4) chains of copper(II) ions which are bridged by either bis-bidentate 2,5-dpp (2) and 2,3-dpp (3) molecules or single mu-1,5-tcm (4) groups. The copper atoms in 2 and 4 are five coordinated with distorted trigonal bipyramidal (2) and square pyramidal (4) CuN(5) surroundings. The axial positions in 2 are occupied by two pyridyl-nitrogen atoms from two 2,5-dpp ligands whereas the trigonal plane is built by a nitrile-nitrogen from a terminally bound tcm group and two pyrazine nitrogen atoms from two 2,5-dpp molecules. The basal plane in 4 is defined by a pyridyl and a pyrazine nitrogen atoms from the bidentate 2,3-dpq ligand and two nitrile nitrogen atoms from two tcm groups (one terminal and the other bridging) whereas the apical position is filled by a nitrile nitrogen from another tcm ligand. The crystallographically independent copper atoms in 3 [Cu(1) and Cu(2)] exhibit elongated octahedral geometries being defined by four nitrogen atoms from two 2,3-dpp groups [Cu(1) and Cu(2)] either two terminally bound tcm ligands [Cu(1)] or a water molecule and a monodentate tcm ligand [Cu(2)] in cis positions. Magnetic susceptibility measurements for 1-4 in the temperature range 1.9-295 K reveal the occurrence of strong [J ca.-1000 cm(-1) (1); H = -JS(A) x S(B)] and weak [J = -0.13 (2), -0.67 (3) and -0.18 cm(-1) (4); H = -J Sigma(I)S(i) x S(i+1)] antiferromagnetic interactions in agreement with the different nature of the exchange pathways involved, diazine and single mu-hydroxo (1) and the extended 2,5-dpp (2), 2,3-dpp (3) and single mu-1,5-tcm (4) bridges with copper-copper separations of 3.363(8) (1), 7.111(1) (2), 6.823(1) and 7.056(1) (3) and 7.446(1) A (4). PMID:17985027

Yuste, Consuelo; Bentama, Abdeslem; Stiriba, Salah-Eddine; Armentano, Donatella; De Munno, Giovanni; Lloret, Francesc; Julve, Miguel

2007-11-28

367

Synthesis, spectra and crystal structure of 2-(?[3-(methyl?3-[(2-hydroxybenzylidene)amino]propyl? amino)propyl]imino?methyl)phenol copper(II) complex  

NASA Astrophysics Data System (ADS)

A copper(II) complex, [Cu(salenN3], [salenN3H2=2-({[3-(methyl{3-[(2-hydroxybenzylidene)amino]propyl}amino)propyl]imino}methyl)phenol] was synthesized and characterized by elemental analyses, FTIR spectra and single crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P21/ c with a=6.877(3), b=14.109(6), c=20.106(8) , ?=92.231(14), V=1949.5(14) 3. The salen ligand loses two phenolic hydrogens being a dianion and coordinates to the copper(II) ion as a pentadentate ligand through its two O and three N atoms. The copper(II) complex is five-coordinate, lying between perfect square pyramidal and trigonal-bipyramidal extremes. Use of the structural index parameter ( ?) for five coordinate metal complexes indicated that the copper(II) complex exhibits a grater tendency toward trigonal-based-pyramidal geometry ( ?>0.5). The individual molecules in the crystal are held together by C-H⋯? and H⋯H interactions. The IR and electronic spectra of the complex were discussed in detail.

Yilmaz, Veysel T.; Degirmencioglu, Ismail; Andac, Omer; Karabocek, Serdar; Slawin, Alexandra M. Z.

2003-06-01

368

Characterisation of the interactions between substrate, copper(ii) complex and DNA and their role in rate acceleration in DNA-based asymmetric catalysis.  

PubMed

Interactions of the azachalcone derived substrate Aza with copper(ii) complexes in the presence and absence of st-DNA were studied in detail by UV/Vis absorption, EPR and Raman and (UV and vis) resonance Raman spectroscopies. The binding of Aza to the Lewis acidic copper(ii) complexes, which results in activation of the substrate, was established spectroscopically. It was shown that the binding of Aza differs between Cu(II)dmbpy and Cu(II)terpy, consistent with the observed differences in catalytic asymmetric Diels-Alder reactions with regard to both the rate and enantiomeric preference. Finally, it was shown that DNA has a major beneficial effect on the binding of Aza to the copper(ii) complex due to the fact that both bind to the DNA. The result is a high effective molarity of both the copper complexes and the Aza substrate, which leads to a significant increase in binding of Aza to the copper(ii) complex. This effect is a key reason for the observed rate acceleration in the catalyzed reactions brought about by the presence of DNA. PMID:25491950

Draksharapu, Apparao; Boersma, Arnold J; Browne, Wesley R; Roelfes, Gerard

2015-02-10

369

Novel supramolecular assembly of symmetrical mixed-metal-ligand complexes of dioxouranium(VI).  

PubMed

Some binary and ternary novel complexes of dioxouranium(VI) with 8-hydroxy-7-quinolinecarboxaldehyde (OXH) have been prepared and characterized by elemental analyses, magnetic susceptibility measurements and spectral studies. Coordination effects on the vibrational spectra of the ligands have been investigated. The amine exchange reactions of coordinated Schiff bases in these complexes have been also studied, which reveal symmetrical tetradentate Schiff base complexes. Metal exchange reaction of dioxouranium(VI) complexes was obtained when reacted with tetradentate Schiff base complexes of Cu(II) with ZrCl(4)/UO(2)(CH(3)COO)(2) giving heterobinuclear complexes. Magnetic, electronic and IR spectral data suggest the configurations of distorted square planar ligand field copper(II) complexes. The ligands behave as bi-(O,O) and tetradentate (N(2),O(2)) donors. El-Sonbati equation has been used to evaluate the symmetric stretching frequency from which the F(U-O) and F(UO,UO)(-) were calculated. The bond distances of these complexes were also investigated. PMID:16843709

Mubarak, Ahmed T

2006-12-01

370

Spectrophotometric investigation of interaction between iodine and pentadentate Schiff base ligands.  

PubMed

The interaction between iodine as an electron acceptor (A), and three pentadentate Schiff bases, 1,3-bis(salicylideneamino)-2-propanol (SB1), 1,3-bis(2-hydroxy-1-naphthylideneamino)-2-propanol (SB2), and 1,3-bis[1-(pyridine-2-yl)methylideneamino]-2-propanol (SB3), as electron donor systems (D), was studied spectrophotometrically in methanol at 28 C. Equilibrium constants K(AD) and molar extinction coefficients ?(AD) of the donor-acceptor complexes (AD) were determined using the modified Benesi-Hildebrand equation in conjunction with the non linear fit analysis. The method shows the formation of 1:1 type complexes as major species in solution. The free energy changes ?G and the energy of the charge transfer band E(CT) were also calculated for all complexes. The iodine complex derived from SB2 seems to be more stable than those derived from SB3 and SB1. On the other hand, the ionization potential I(D) of each Schiff base was estimated from the corresponding complex band energy, using an empirical equation. An inverse relationship between I(D) and K(AD) values was found. Blue and red shift observed for the 445 nm band of iodine were also discussed on the basis of theoretical considerations. PMID:24530710

Khouba, Z; Benabdallah, T; Maschke, U

2014-05-01

371

Simultaneous and sensitive analysis of aliphatic carboxylic acids by ion-chromatography using on-line complexation with copper(II) ion.  

PubMed

A new approach to ion chromatography is proposed to improve the UV detection of aliphatic carboxylic acids separated by anion-exchange chromatography. When copper(II) ion added to the mobile phase, it forms complexes with carboxylic acids that can be detected at 240nm. The absorbance was found to increase with increasing copper(II) ion concentration. The retention times of ?-hydroxy acids were also found to depend on the copper(II) ion concentration. Addition of acetonitrile to the mobile phase improved the separation of aliphatic carboxylic acids. The detection limits of the examined carboxylic acids (formate, glycolate, acetate, lactate, propionate, 3-hydroxypropionate, n-butyrate, isobutyrate, n-valerate, isovalerate, n-caproate) calculated at S/N=3 ranged from 0.06 to 3?M. The detector signal was linear over three orders of magnitude of carboxylic acid concentration. The proposed method was successfully applied to analyze aliphatic carboxylic acids in rainwater and bread. PMID:25523885

Kemmei, Tomoko; Kodama, Shuji; Yamamoto, Atsushi; Inoue, Yoshinori; Hayakawa, Kazuichi

2015-01-01

372

Cyclen derivatives with two trans-methylnitrophenolic pendant arms: a structural study of their copper(II) and zinc(II) complexes.  

PubMed

Two new cyclen derivatives, H(2)do2nph and H(2)cb-do2nph, containing two trans-2-methyl-4-nitrophenol pendant arms and the latter including also an ethylene cross-bridge, were prepared in good yields using the bisaminal synthetic route. The two ligands were studied comparatively regarding their metal complexation behaviour. The copper(II) and zinc(II) complexes of H(2)do2nph and H(2)cb-do2nph were studied in dimethylsulfoxide-water (9 : 1 v/v) solution by a range of spectroscopic techniques. Copper(II) complexes were also studied in solid state by X-ray single crystal diffraction. These studies showed that the copper(II) and zinc(II) complexes of H(2)do2nph exhibited a distorted square pyramidal coordination environment with the four nitrogen atoms of the cyclen ring defining the basal plane, and that one of the nitrophenolate arms did not coordinate to the metal, independently of its protonation state. On the other hand, depending on the protonation state of one of the nitrophenolic arms, the cross-bridged derivative forms copper(II) complexes with distorted square pyramidal or octahedral geometries with one or two arms coordinated to the metal centre, respectively. In the complex with distorted octahedral geometry, the two phenolic oxygen atoms are coordinated to the metal centre in a cis-fashion. Acid-assisted dissociation assays in 1 mol dm(-3) HCl DMSO-H(2)O (9 : 1 v/v) solution at 298.2 K allowed one to determine the half-life of both copper(II) complexes, which is lower for the derivative without a cross-bridge as expected, while for the other one it is quite high and in line with similar cross-bridged cyclen derivatives from the literature. PMID:23328713

Esteves, Catarina V; Lima, Lus M P; Mateus, Pedro; Delgado, Rita; Brando, Paula; Flix, Vtor

2013-05-01

373

A new mixed-ligand copper(II) complex of (E)-N";-(2-hydroxybenzylidene) acetohydrazide: Synthesis, characterization, NLO behavior, DFT calculation and biological activities  

NASA Astrophysics Data System (ADS)

A tridentate hydrazone Schiff base ligand, (E)-N";-(2-hydroxybenzylidene)acetohydrazide [HL], and its mixed-ligand Cu(II) complex [CuL(phen)], have been synthesized and characterized by elemental analyses, FT-IR, molar conductivity, UV-Vis spectroscopy. The structure of the complex has been determined by X-ray diffraction. This complex has square pyramidal geometry and the positions around central atom are occupied with donor atoms of Schiff base ligand and two nitrogens of 1,10-phenanthroline. Computational studies of compounds were performed by using DFT calculations. The linear polarizabilities and first hyperpolarizabilities of the studied molecules indicate that these compounds can be good candidates of nonlinear optical materials. It is in accordance with experimental data. In addition, invitro antimicrobial results show that these compounds specially [CuL(phen)] have great potential of antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes bacteria and antifungal activity against Candida Albicans in comparison to some standard drugs.

Yousef Ebrahimipour, S.; Sheikhshoaie, Iran; Crochet, Aurelien; Khaleghi, Moj; Fromm, Katharina M.

2014-08-01

374

Highly cytotoxic DNA-interacting copper(II) coordination compounds.  

PubMed

Four new Schiff-base ligands have been designed and prepared by condensation reaction between hydrazine derivatives (i.e. 2-hydrazinopyridine or 2-hydrazinoquinoline) and mono- or dialdehyde (3-tert-butyl-2-hydroxybenzaldehyde and 5-tert-butyl-2-hydroxyisophthalaldehyde, respectively). Six copper(II) coordination compounds of various nuclearities have been obtained from these ligands, which are formulated as [Cu(L1)Cl](CH3OH) (1), [Cu(L2)NO3] (2), [Cu2(L3)(ClO4)2(CH3O)(CH3OH)](CH3OH) (3), [Cu2(L4)(ClO4)(OH)(CH3OH)](ClO4) (4), [Cu8(L3)4(NO3)4(OH)5](NO3)3(CH3OH)5(H2O)8 (5) and [Cu3(HL2')4Cl6](CH3OH)6 (6), as revealed by single-crystal X-ray studies. Their DNA-interacting abilities have been investigated using different characterization techniques, which suggest that the metal complexes act as efficient DNA binders. Moreover, cytotoxicity assays with several cancer cell lines show that some of them are very active, as evidenced by the sub-micromolar IC50 values achieved in some cases. PMID:25096758

Brissos, Rosa F; Torrents, Ester; dos Santos Mello, Francyelli Mariana; Carvalho Pires, Wanessa; Silveira-Lacerda, Elisngela de Paula; Caballero, Ana B; Caubet, Amparo; Massera, Chiara; Roubeau, Olivier; Teat, Simon J; Gamez, Patrick

2014-10-01

375

Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N(4)-methyl-3-thiosemicarbazone: Crystal structure of a novel sulfur bridged copper(II) box-dimer.  

PubMed

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, ?=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 [Formula: see text] ground state. The thermal stabilities of some of the complexes were also determined. PMID:25546494

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

2015-03-15

376

Copper(II) complexes of 3,4,5-trisubstituted pyrazolates: in situ formation of pyrazole rings from different carbon centers.  

PubMed

The synthesis and characterization of two pyrazolate-bridged dicopper(II) complexes, [Cu(2)(L(1))(2)(H(2)O)(2)](ClO(4))(2) (1, HL(1)=3,5-dipyridyl-4-(2-keto-pyridyl)pyrazole) and [Cu(2)(L(2))(2)(H(2)O)(2)](ClO(4))(2) (2, HL(2)=3,5-dipyridyl-4-benzoylpyrazole), are discussed. These copper(II) complexes are formed from the reactions between pyridine-2-aldehyde, 2-acetylpyridine (for compound 1) or acetophenone (for compound 2), and hydrazine hydrate with copper(II) perchlorate hydrate under ambient conditions. The single-crystal X-ray structure of compound 12H(2)O establishes the formation of a pyrazole ring from three different carbon centers through C-C bond-forming reactions, mediated by copper(II) ions. The free pyrazoles (HL(1) and HL(2)) are isolated from their corresponding copper(II) complexes and are characterized by using various analytical and spectroscopic techniques. A mechanism for the pyrazole-ring synthesis that proceeds through C-C bond-forming reactions is proposed and supported by theoretical calculations. PMID:23281166

Das, Oindrila; Malakar, Tanmay; Mandal, Arghya; Paul, Ankan; Paine, Tapan Kanti

2013-03-01

377

The role of the retinylidene Schiff base counterion in rhodopsin in determining wavelength absorbance and Schiff base pKa.  

PubMed Central

Glu-113 serves as the retinylidene Schiff base counterion in bovine rhodopsin. Purified mutant rhodopsin pigments were prepared in which Glu-113 was replaced individually by Gln (E113Q), Asp (E113D), Asn (E113N), or Ala (E113A). E113Q, E113N, and E113A existed as pH-dependent equilibrium mixtures of unprotonated and protonated Schiff base (PSB) forms. The Schiff base pKa values determined by spectrophotometric titration were 6.00 (E113Q), 6.71 (E113N), and 5.70 (E113A). Thus, mutation of Glu-113 markedly reduced the Schiff base pKa. The addition of NaCl promoted the formation of a PSB in E113Q and E113A. An exogenously supplied solute anion replaced Glu-113 to compensate for the positive charge of the PSB in these mutants. The lambda max values of the PSB forms of the mutants in NaCl were 496 nm (E113Q), 506 nm (E113A), 510 nm (E113D), and 520 nm (E113N). To evaluate the effect of different types of solute anions on lambda max values, mutants were prepared in sodium salts of halides, perchlorate, and a series of carboxylic acids of various sizes and acidity. The lambda max values of E113Q and E113A depended on the solute anion present and ranged from 488 nm to 522 nm for E113Q and from 486 nm to 528 nm for E113A. The solute anion affected the lambda max values of E113N and E113D to lesser degrees. The reactivities of the mutants to hydroxylamine were also studied. Whereas rhodopsin was stable to hydroxylamine in the dark, E113N reacted slowly and E113Q reacted rapidly under these conditions, indicating structural differences in the Schiff base environments. The lambda max values and solute anion dependencies of the Glu-113 mutants indicate that interactions between Schiff base and its counterion play a significant role in determining the lambda max of rhodopsin. PMID:2014228

Sakmar, T P; Franke, R R; Khorana, H G

1991-01-01

378

Synthesis and degradation of schiff bases containing heterocyclic pharmacophore.  

PubMed

This paper reports on the synthesis and characterization of two Schiff bases bearing 1,2,4-triazolic moieties, namely 4H-4-(2-hydroxy-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole and 4H-4-(4-nitro-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole using thin layer chromatography, melting interval, elemental analysis, spectroscopy and thermal stability studies. PMID:25590299

Lede?i, Ionu?; Alexa, Anda; Bercean, Vasile; Vlase, Gabriela; Vlase, Titus; ?uta, Lenu?a-Maria; Fulia?, Adriana

2014-01-01

379

Synthesis and Degradation of Schiff Bases Containing Heterocyclic Pharmacophore  

PubMed Central

This paper reports on the synthesis and characterization of two Schiff bases bearing 1,2,4-triazolic moieties, namely 4H-4-(2-hydroxy-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole and 4H-4-(4-nitro-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole using thin layer chromatography, melting interval, elemental analysis, spectroscopy and thermal stability studies. PMID:25590299

Lede?i, Ionu?; Alexa, Anda; Bercean, Vasile; Vlase, Gabriela; Vlase, Titus; ?uta, Lenu?a-Maria; Fulia?, Adriana

2015-01-01

380

Synthesis and structure of a new copper(II) complex with 3,4'-bi-1,2,4-triazolate.  

PubMed

The salt diaquo-diammine-bis(3,4'-bi-1,2,4-triazolate) copper(II) of the formula [Cu(bTA-)2(NH3)2(H2O)2] has been synthesized and structurally characterized by X-ray single crystal diffraction analysis. This complex adopts a monomeric structure. This monomer crystallizes in the triclinic system, space group P1 with a=5.9657 ?; b=6.8975 ?; c=9.9892 ?; ?=106.181; ?=97.868; ?=90.800 and Z=1. The Cu atom is coordinated by two nitrogen atoms of two monodentate bitriazolate ligands, two nitrogen atoms of NH3 and two water molecules in a distorted octahedral geometry. The complex has been also characterized by elemental analysis and studied by electronic and vibrational spectroscopy. The obtained results are in good agreement with the structure determined by X-ray diffraction analysis. PMID:21163689

Idouli, Y; Gudira, F; Rghioui, L; El Ammari, L; El Hajjaji, S; Zaydoun, S

2011-01-01

381

A new Schiff's base ligand immobilized agarose membrane optical sensor for selective monitoring of mercury ion.  

PubMed

A highly selective optical sensor was developed for the Hg(2+) determination by chemical immobilization of 2-[(2-sulfanylphenyl)ethanimidoyl]phenol (L), on an agarose membrane. Spectrophotometric studies of complex formation between the Schiff's base ligand L and Hg(2+), Sr(2+), Mn(2+), Cu(2+), Al(3+), Cd(2+), Zn(2+), Co(2+) and Ag(+) metal ions in methanol solution indicated a substantially larger stability constant for the mercury ion complex. Consequently, the Schiff's base L was used as an appropriate ionophore for the preparation of a selective Hg(2+) optical sensor, by its immobilization on a transparent agarose film. A distinct color change, from yellow to green-blue, was observed by contacting the sensing membrane with Hg(2+) ions at pH 4.5. The effects of pH, ionophore concentration, ionic strength and reaction time on the immobilization of L were studied. A linear relationship was observed between the membrane absorbance at 650 nm and Hg(2+) concentrations in a range from 110(-2) to 110(-5) mol L(-1) with a detection limit (3?) of 110(-6) mol L(-1). No significant interference from 100 times concentrations of a number of potentially interfering ions was detected for the mercury ion determination. The optical sensor was successfully applied to the determination of mercury in amalgam alloy and spiked water samples. PMID:21232854

Alizadeh, Kamal; Parooi, Razieh; Hashemi, Payman; Rezaei, Behrooz; Ganjali, Mohammad Reza

2011-02-28

382

Synthesis, characterization and biocidal activities of Schiff base polychelates containing polyurethane links in the main chain  

NASA Astrophysics Data System (ADS)

The concept of combining metallo-polymers with urethanes offers a versatile approach for the synthesis of new polymeric materials. Polyurethane containing transition metals was synthesized by the reaction of Schiff base metal complex with toluene 2,4 diisocyanate. The proposed structures were confirmed by elemental analysis, 1H NMR, 13C NMR and FT-IR. The geometry is determined by UV-Visible spectra and magnetic moment measurements, which reveals that the Mn(II), Co(II) and Ni(II) complexes have octahedral geometry while square planer geometry is reported for Cu(II) and tetrahedral for Zn(II) complex. The antimicrobial activities are determined using the agar well diffusion method with Staphylococcus aureus, Escherichia coli, Bacillus subtilis (bacteria), Aspergillus niger, Candida albicans and Aspergillus flavus (yeast). All the polymeric metal complexes show comparatively good biocidal activity, which is further enhanced after polymerization.

Hasnain, Sumaiya; Nishat, Nahid

383

Antioxidant, DNA binding and nuclease activities of heteroleptic copper(II) complexes derived from 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols and diimines  

NASA Astrophysics Data System (ADS)

A series of heteroleptic copper(II) complexes of the type [CuL1-4(diimine)](ClO4)2 (1-8) [L1-4 = 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols, and diimine = 2,2?-bipyridyl (bpy) or 1,10-phenanthroline (phen)], have been synthesized and characterized by spectroscopic methods. The IR spectra of complexes indicate the presence of uncoordinated perchlorate anions and the electronic spectra revealed the square pyramidal geometry with N4O coordination environment around copper(II) nuclei. Electrochemical studies of the mononuclear complexes evidenced one-electron irreversible reduction wave in the cathodic region. The EPR spectra of complexes with g|| (2.206-2.214) and A|| (154-172 10-4 cm-1) values support the square-based CuN3O coordination chromophore and the presence of unpaired electron localized in dx-y ground state. Antioxidant studies against DPPH revealed effective radical scavenging properties of the synthesized complexes. Binding studies suggest that the heteroleptic copper(II) complexes interact with calf thymus DNA (CT-DNA) through minor-groove and electrostatic interaction, and all the complexes display pronounced nuclease activity against supercoiled pBR322 DNA.

Ravichandran, J.; Gurumoorthy, P.; Imran Musthafa, M. A.; Kalilur Rahiman, A.

2014-12-01

384

Determination of cadmium(II), copper(II), manganese(II) and nickel(II) species in Antarctic seawater with complexing resins  

Microsoft Academic Search

The strong species of cadmium(II), copper(II), manganese(II) and nickel(II) in an Antarctic seawater sample are investigated by a method based on the sorption of metal ions on complexing resins. The resins compete with the ligands present in the sample to combine with the metal ions. Two resins with different adsorbing strengths were used. Very stable metal complexes were investigated with

Raffaela Biesuz; Giancarla Alberti; Girolamo D'Agostino; Emanuele Magi; Maria Pesavento

2006-01-01

385

Effects of copper ions on DNA binding and cytotoxic activity of a chiral salicylidene Schiff base.  

PubMed

A chiral Schiff base HL N-(5-bromo-salicylaldehyde)dehydroabietylamine (1) and its chiral dinuclear copper complex [Cu2L4]4DMF (2) have been synthesized and fully characterized. The interactions of 1 and 2 with salmon sperm DNA have been investigated by viscosity measurements, UV, fluorescence and circular dichroism (CD) spectroscopic techniques. Absorption spectral (Kb=3.30 10(5)M(-)(1) (1), 6.63 10(5)M(-)(1)(2)), emission spectral (Ksv=7.58 10(3)M(-)(1) (1), 1.52 10(4)M(-)(1) (2)), and viscosity measurements reveal that 1 and 2 interact with DNA through intercalation and 2 exhibits a higher DNA binding ability. In addition, CD study indicates 2 cause a more evident perturbation on the base stacking and helicity of B-DNA upon binding to it. In fluorimetric studies, the enthalpy (?H>0) and entropy (?S>0) changes of the reactions between the compounds with DNA demonstrate hydrophobic interactions. 1 and 2 were also screened for their cytotoxic ability and 2 demonstrates higher growth inhibition of the selected cancer cells at concentration of 50 ?M, this result is identical with their DNA binding ability order. All the experimental results show that the involvement of Cu (II) centers has some interesting effect on DNA binding ability and cytotoxicity of the chiral Schiff base. PMID:24583369

Fei, Bao-Li; Xu, Wu-Shuang; Tao, Hui-Wen; Li, Wen; Zhang, Yu; Long, Jian-Ying; Liu, Qing-Bo; Xia, Bing; Sun, Wei-Yin

2014-03-01

386

Synthesis, magnetic, spectral, and antimicrobial studies of Cu(II), Ni(II) Co(II), Fe(III), and UO 2(II) complexes of a new Schiff base hydrazone derived from 7-chloro-4-hydrazinoquinoline  

NASA Astrophysics Data System (ADS)

A new hydrazone ligand, HL, was prepared by the reaction of 7-chloro-4-hydrazinoquinoline with o-hydroxybenzaldehyde. The ligand behaves as monoprotic bidentate. This was accounted for as the ligand contains a phenolic group and its hydrogen atom is reluctant to be replaced by a metal ion. The ligand reacted with Cu(II), Ni(II), Co(II), Fe(III), and UO 2(II) ions to yield mononuclear complexes. In the case of Fe(III) ion two complexes, mono- and binuclear complexes, were obtained in the absence and presence of LiOH, respectively. Also, mixed ligand complexes were obtained from the reaction of the metal cations Cu(II), Ni(II) and Fe(III) with the ligand (HL) and 8-hydroxyquinoline (8-OHqu) in the presence of LiOH, in the molar ratio 1:1:1:1. It is clear that 8-OHqu behaves as monoprotic bidentate ligand in such mixed ligand complexes. The ligand, HL, and its metal complexes were characterized by elemental analyses, IR, UV-vis, mass, and 1H NMR spectra, as well as magnetic moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an extra square-planar geometry, while Ni(II) mixed complex has also formed a tetrahedral configuration and UO 2(II) complex which formed a favorable pentagonal biprymidial geometry. Magnetic moment of the binuclear Fe(III) complex is quite low compared to calculated value for two iron ions complex and thus shows antiferromagnetic interactions between the two adjacent ferric ions. The HL and metal complexes were tested against one stain Gram positive bacteria ( Staphylococcus aureus), Gram negative bacteria ( Escherichia coli), and fungi ( Candida albicans). The tested compounds exhibited higher antibacterial acivities.

El-Behery, Mostafa; El-Twigry, Haifaa

2007-01-01

387

Supramolecular control of a mononuclear biomimetic copper(II) center: bowl complexes vs funnel complexes.  

PubMed

Modeling the mononuclear site of copper enzymes is important for a better understanding of the factors controlling the reactivity of the metal center. A major difficulty stems from the difficult control of the nuclearity while maintaining free sites open to coordination of exogenous ligands. A supramolecular approach consists in associating a hydrophobic cavity to a tripodal ligand that will define the coordination spheres as well as access to the metal ion. Here, we describe the synthesis of a bowl Cu(II) complex based on the resorcinarene scaffold. This study supplements a previous work on Cu(I) coordination. It provides a complete picture of the cavity-copper system in its two oxidation states. The first XRD structure of such a bowl complex was obtained, evidencing a 5-coordinate Cu(II) ion with the three imidazole donors bound to the metal (two in the base of the pyramid, one in the apical position) and with an acetate anion, completing the base of the pyramid, and deeply included in the bowl. Solution studies conducted by EPR and UV-vis absorption spectroscopies as well as cyclic voltammetry highlighted interaction with coordinating solvents, various carboxylates that can sit either in the endo or in the exo position depending on their size as well as possible stabilization of hydroxo species in a mononuclear state. A comparison of the binding and redox properties of the bowl complex with funnel complexes based on the calix[6]arene core further highlights the importance of supramolecular features defining the first, second, and third coordination sphere for control of the metal ion. PMID:24901070

Gout, Jrme; Vinjevac, Aleksandar; Rat, Stphanie; Parrot, Arnaud; Hessani, Assia; Bistri, Olivia; Le Poul, Nicolas; Le Mest, Yves; Reinaud, Olivia

2014-06-16

388

Spectroscopic characterization, antioxidant and antitumour studies of novel bromo substituted thiosemicarbazone and its copper(II), nickel(II) and palladium(II) complexes.  

PubMed

A new, slightly distorted octahedral complex of copper(II), square planar complexes of nickel(II) and palladium(II) with 2,4'-dibromoacetophenone thiosemicarbazone (DBAPTSC) are synthesized. The ligand and the complexes are characterized by FT-IR, FT-Raman, powder X-ray diffraction studies. The IR and Raman data are correlated for the presence of the functional groups which specifically helped in the confirmation of the compounds. In addition, the free ligand is unambiguously characterized by (1)H and (13)C NMR spectroscopy while the copper(II) complex is characterized by electron paramagnetic resonance spectroscopy (EPR). The g values for the same are found to be 2.246 (g1), 2.012 (g2) and 2.005 (g3) which suggested rhombic distortions. The HOMO-LUMO band gap calculations for these compounds are found to be in between 0.5 and 4.0 eV and these compounds are identified as semiconducting materials. The synthesized ligand and its copper(II), nickel(II) and palladium(II) complexes are subjected to antitumour activity against the HepG2 human hepatoblastoma cell lines. Among all the compounds, nickel(II) complex is found to exert better antitumour activity with 57.6% of cytotoxicity. PMID:25064500

Jagadeesh, M; Lavanya, M; Kalangi, Suresh K; Sarala, Y; Ramachandraiah, C; Varada Reddy, A

2015-01-25

389

Spectroscopic characterization, antioxidant and antitumour studies of novel bromo substituted thiosemicarbazone and its copper(II), nickel(II) and palladium(II) complexes  

NASA Astrophysics Data System (ADS)

A new, slightly distorted octahedral complex of copper(II), square planar complexes of nickel(II) and palladium(II) with 2,4?-dibromoacetophenone thiosemicarbazone (DBAPTSC) are synthesized. The ligand and the complexes are characterized by FT-IR, FT-Raman, powder X-ray diffraction studies. The IR and Raman data are correlated for the presence of the functional groups which specifically helped in the confirmation of the compounds. In addition, the free ligand is unambiguously characterized by 1H and 13C NMR spectroscopy while the copper(II) complex is characterized by electron paramagnetic resonance spectroscopy (EPR). The g values for the same are found to be 2.246 (g1), 2.012 (g2) and 2.005 (g3) which suggested rhombic distortions. The HOMO-LUMO band gap calculations for these compounds are found to be in between 0.5 and 4.0 eV and these compounds are identified as semiconducting materials. The synthesized ligand and its copper(II), nickel(II) and palladium(II) complexes are subjected to antitumour activity against the HepG2 human hepatoblastoma cell lines. Among all the compounds, nickel(II) complex is found to exert better antitumour activity with 57.6% of cytotoxicity.

Jagadeesh, M.; Lavanya, M.; Kalangi, Suresh K.; Sarala, Y.; Ramachandraiah, C.; Varada Reddy, A.