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1

Novel homo- and hetero-nuclear copper(II) complexes of tetradentate Schiff bases: synthesis, characterization, solvent-extraction and catalase-like activity studies.  

PubMed

Twelve homo- and hetero-nuclear copper(II) complexes of tetradentate Schiff base ligands containing N(4) donor sets have been prepared by employing several steps. The characterization and nature of bonding of the complexes have been deduced from elemental analysis, FT-IR, molar conductivity, magnetic moment measurements and thermal analysis. The three Schiff base ligands were further identified using (1)H and (13)C NMR spectra. All copper(II) complexes are 1:2 electrolytes as shown by their molar conductivities (Lambda(M)) in DMF and paramagnetic. The subnormal magnetic moment values of the di- and tri-nuclear complexes explained by a very strong anti-ferromagnetic interaction. The extraction ability of the ligands has been examined by the liquid-liquid extraction of selected transition metal (Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Pb(2+), Cd(2+), Hg(2+)) cations. The ligands show strong binding ability toward copper(II) ion. Furthermore the homo- and hetero-nuclear copper(II) complexes were each tested for their ability to catalyse the disproportionation of hydrogen peroxide in the presence of the added base imidazole. PMID:18762369

Dede, Bülent; Karipcin, Fatma; Cengiz, Mustafa

2009-04-30

2

Synthesis, Spectral, and Biological Properties of Copper(II) Complexes of Thiosemicarbazones of Schiff Bases Derived from 4-Aminoantipyrine and Aromatic Aldehydes  

PubMed Central

We have synthesized a novel series of Schiff bases by condensation of 4-aminoantipyrine and various aromatic aldehydes followed by reaction with thiosemicarbazide. These thiosemicarbazones are potential ligands toward transition metal ions. The reaction of copper(II) salts with 4[N-(benzalidene)amino]antipyrinethiosemicarbazone (BAAPTS), 4[N-(4?-methoxybenzalidene) amino] antipyrinethiosemicarbozone (MBAAPTS), 4[N-(4?-dimethylamino benzalidene) amino] antipyrinethiosemicarbazone (DABAAPTS), and 4[N-(cinnamalidene) amino] antipyrinethiosemicarbazone (CAAPTS) resulted in the formation of solid complexes with the general composition CuX2 · (H2O)(L)(X = Cl, Br,NO3,NCS, or CH3COO; L = BAAPTS, MBAAPTS, DABAAPTS, or CAAPTS). These complexes were characterized through elemental analysis, molecular weight, electrical conductance, infrared, electronic spectra, and magnetic susceptibilities at room temperature. Copper(II) complexes with BAAPTS and MBAAPTS were screened for antibacterial and antifungal properties and have exhibited potential activity. Thermal stabilities of two representative complexes were also investigated. PMID:17497009

Agarwal, Ram K.; Singh, Lakshman; Sharma, Deepak Kumar

2006-01-01

3

Copper(II) and zinc(II) complexes with Schiff-base ligands derived from salicylaldehyde and 3-methoxysalicylaldehyde: Synthesis, crystal structures, magnetic and luminescence properties  

Microsoft Academic Search

The following Schiff bases were employed as ligands in synthesizing copper(II) and zinc(II) complexes: N-[(2-pyridyl)-methyl]-salicylimine (Hsalampy), N-[2-(N,N-dimethyl-amino)-ethyl]-salicylimine (Hsaldmen), and N-[(2-pyridyl)-methyl]-3-methoxy-salicylimine (Hvalampy). The first two ligands were obtained by reacting salicylaldehyde with 2-aminomethyl-pyridyne and N,N-dimethylethylene diamine, respectively, while the third one results from the condensation of 3-methoxysalicylaldehyde with 2-aminomethyl-pyridine. Four new coordination compounds were synthesized and structurally characterized: [Cu(salampy)(H2O)(ClO4)] 1, [Cu2(salampy)2(H2trim)2

Catalin Maxim; Traian D. Pasatoiu; Victor Ch. Kravtsov; Sergiu Shova; Christopher A. Muryn; Richard E. P. Winpenny; Floriana Tuna; Marius Andruh

2008-01-01

4

Synthesis, Physicochemical, and Biological Properties of Nickel(II), Copper(II), and Zinc(II) Complexes of an Unsymmetrical Tetradentate Schiff Base and Their Adducts  

Microsoft Academic Search

Nickel(II), copper(II) and zinc(II) complexes of unsymmetrical Schiff base derived from 2-hydroxy-1-naphthaldehyde, 2,4-pentanedione and p-phenylenediamine of the general formula [M(C10H6OCH:N(C6H4)N:C(CH3)CH:C(CH3)O)], [ML], and their adducts with 2,2?-bipyridine (bipy) and 1,10-phenanthroline (phen) have been synthesized and characterized by elemental analyses, conductance, room temperature magnetic susceptibility, and infrared and electronic spectral measurements. The ligand is tetradentate, coordinating via the imine N and enolic

Aderoju A. Osowole; Gabriel A. Kolawole; Obasola E. Fagade

2005-01-01

5

Synthesis and Characterization of Some Cobalt(II), Copper(II), and Nickel(II) Complexes with New Schiff Bases from the Reaction of p?Aminoazobenzene with Salicylaldehyde  

Microsoft Academic Search

Two new Schiff bases have been synthesized by the reaction of p?aminoazobenzene with salicylaldehyde (LH) and the oxidative polycondensation product of LH (LH2). The complexes of cobalt(II), copper(II), and nickel(II) with LH and LH2 have been prepared. The ligands and their complexes have been characterized by elemental analyses, IR spectra, electronic absorption spectra, mass spectra, H and C NMR spectra,

Esin Peker; Selahattin Serin

2004-01-01

6

Electrochemistry of transition metal complexes of Schiff base compartmental ligands  

Microsoft Academic Search

The electrochemical behaviour of a series of mononuclear and dinuclear complexes of dioxouranium(VI), nickel(II) and copper(II) ions with the Schiff base, H4fsalacen, derived from the condensation of 3-formylsalicylic acid and 1,2-diaminoethane, is reported.

Piero Zanello; Sergio Tamburini; Pietro Alessandro Vigato; Gian Antonio Mazzocchin

1984-01-01

7

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 Å) 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

8

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

9

DNA binding affinity and antioxidative activity of copper(II) and zinc(II) complexes with a novel hesperetin Schiff base ligand  

Microsoft Academic Search

A hesperetin Schiff base ligand (H4L) and its complexes, [H3CuL·OAc]·H2O and [H3ZnL·OAc]·2H2O, have been synthesized and characterized on the basis of elemental analysis, molar conductivity, 1H NMR, mass spectra, UV–Vis spectra and IR spectra. The binding of these two complexes and the ligand to DNA has been investigated by ultraviolet absorption spectroscopy, fluorescence spectroscopy and viscosity measurements. The experiments indicate

Yong Li; Zheng-yin Yang

2009-01-01

10

DNA binding, DNA cleavage and BSA interaction of a mixed-ligand copper(II) complex with taurine Schiff base and 1,10-phenanthroline.  

PubMed

The DNA-binding properties and DNA-cleavage activities of a Cu(II) complex, [Cu(sal-tau(phen)]·1.5H2O (sal-tau=a Schiff base derived from salicylaldehyde and taurine, phen=1,10-phenanthroline), have been investigated by using UV-Vis absorption, fluorescence, circular dichroism (CD) spectra and agarose gel electrophoresis. Results indicated that this Cu(II) complex can bind to calf thymus DNA (CT-DNA) via an intercalative mode and shows efficient cleavage activity in the absence and presence of reducer. Its intrinsic binding constant Kb (1.66×10(4)M(-1)) was calculated by absorption spectra and its linear Stern-Volmer quenching constant K(sq) (3.05) was obtained from florescence spectroscopy, as well as the cleaving reaction rate constant k1 (2.0×10(-4)s(-1)) was acquired from agarose gel electrophoresis. Meanwhile, the interactions of the complex with BSA have also been studied by spectroscopy. Results showed that the complex could quench the intrinsic fluorescence of bovine serum albumin (BSA) remarkably through a static quenching process, and induce a conformational change with the loss of helical stability of protein. PMID:23748130

Li, Lianzhi; Guo, Qiong; Dong, Jianfang; Xu, Tao; Li, Jinghong

2013-08-01

11

Antifungal Activities of Copper(II) with Biosensitive Macrocyclic Schiff Base Ligands Derived from 4-Aminoantipyrine Derivatives.  

PubMed

Novel copper(II) complexes have been synthesized from the macrocyclic Schiff bases derived from Knoevenagel condensed ?-ketoanilides (obtained by the condensation of acetoacetanilide and substituted benzaldehydes), 4-aminoantipyrine and o-phenylene diamine. The structural features have been determined from their analytical and spectral data. All the Cu(II) complexes exhibit square planar geometry. Their high molar conductance values support their 1: 2 electrolytic nature. The magnetic moment data provide evidence for the monomeric nature of the complexes. The X-band ESR spectra of the [CuL(1)](OAc)2 in DMSO solution at 300 and 77 K were recorded and their salient features are reported. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by well diffusion method. A comparative study of inhibition values of the Schiff bases and their complexes indicate that complexes exhibit higher antimicrobial activity than the Schiff bases. Copper ions proved to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. PMID:23983523

Gopalakrishnan, S; Joseph, J

2009-06-01

12

Antifungal Activities of Copper(II) with Biosensitive Macrocyclic Schiff Base Ligands Derived from 4-Aminoantipyrine Derivatives  

PubMed Central

Novel copper(II) complexes have been synthesized from the macrocyclic Schiff bases derived from Knoevenagel condensed ?-ketoanilides (obtained by the condensation of acetoacetanilide and substituted benzaldehydes), 4-aminoantipyrine and o-phenylene diamine. The structural features have been determined from their analytical and spectral data. All the Cu(II) complexes exhibit square planar geometry. Their high molar conductance values support their 1 : 2 electrolytic nature. The magnetic moment data provide evidence for the monomeric nature of the complexes. The X-band ESR spectra of the [CuL1](OAc)2 in DMSO solution at 300 and 77 K were recorded and their salient features are reported. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by well diffusion method. A comparative study of inhibition values of the Schiff bases and their complexes indicate that complexes exhibit higher antimicrobial activity than the Schiff bases. Copper ions proved to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. PMID:23983523

Joseph, J.

2009-01-01

13

Dinuclear and polynuclear transition metal complexes with macrocyclic ligands. 6. New dinuclear copper(ii) complexes with macrocyclic Schiff bases derived from 4- tert -butyl-2,6-diformylphenol  

Microsoft Academic Search

New dinuclear complexes containing CuII atoms in the cavity of a macrocyclic Schiff base were prepared by template condensation of 4-tert-butyl-2,6-diformylphenol with 1,3-diaminopropane in the presence of CuII trimethylacetate and chloride as well as by extra-ligand exchange. The mononuclear CuII complex with two 1,3-diaminopropane molecules can serve as an intermediate in this template synthesis. The reaction of CuII trimethylacetate with

V. V. Roznyatovsky; N. E. Borisova; M. D. Reshetova; Yu. A. Ustynyuk; G. G. Aleksandrov; I. L. Eremenko; I. I. Moiseev

2004-01-01

14

Cobalt(II), Nickel(II) and Copper(II) complexes of a tetradentate Schiff base as photosensitizers: Quantum yield of 1O2 generation and its promising role in anti-tumor activity  

NASA Astrophysics Data System (ADS)

In the present investigation, a Schiff base N'1,N'3-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant Kb of 2.6 × 104 M-1, 5.7 × 104 M-1 and 4.5 × 104 M-1, respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.

Pradeepa, S. M.; Bhojya Naik, H. S.; Vinay Kumar, B.; Indira Priyadarsini, K.; Barik, Atanu; Ravikumar Naik, T. R.

2013-01-01

15

Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds; Synthesis, characterization and biological evolution  

NASA Astrophysics Data System (ADS)

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 [M2+L]X2, where M2+ = 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.

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

2014-10-01

16

Synthesis, structure, magnetic properties and DNA cleavage of binuclear Cu(II) Schiff-base complexes.  

PubMed

Five binuclear Schiff base copper(ii) complexes [Cu(2)(L)(OAc)].3DMF (), [Cu(2)(L)(OAc)](2).3DMF (), [Cu(2)(L)(BNPP)].3CH(3)CN (), [Cu(2)(L)(Fa)].2DMF () and [Cu(2)(L)(Pa)].DMF () (H(3)L = N,N'-bis(3,5-tert-butylsalicylidene-2-hydroxy)-1,3-propanediamine, OAc = acetic acid, BNPP = bis(4-nitrophenyl)phosphate, Fa = 2-tetrahydrofuroic acid, Pa = benzoic acid) have been synthesized and characterized by X-ray single-crystal structure analysis. Variable-temperature magnetic susceptibility studies (2-300 K) indicate the existence of ferromagnetic coupling between the copper(ii) ions in complexes and , and antiferromagnetic coupling in complexes and . The interaction of these complexes with CT-DNA has been studied by using absorption and emission spectral methods. The apparent binding constant (K(app)) values for complexes , , and are 4.67 x 10(5), 9.48 x 10(5), 4.30 x 10(5) and 3.90 x 10(5) M(-1), respectively, which show that the complexes bind to DNA by moderate intercalative binding modes. Furthermore, all these complexes can cleave plasmid DNA to nicked DNA in a sequential manner as the concentrations or reaction times are increased in the absence of reducing agent. Their cleavage activities are promoted in the presence of hydrogen peroxide. The cleavage mechanisms between the complexes and plasmid DNA are likely to involve singlet oxygen (1)O(2) and OH as reactive oxygen species. PMID:19290371

Kou, Yingying; Tian, Jinlei; Li, Dongdong; Gu, Wen; Liu, Xin; Yan, Shiping; Liao, Daizheng; Cheng, Peng

2009-04-01

17

Chiral Schiff Base Ruthenium(II) Carbonyl Complexes: Synthesis, Characterization, Catalytic and Antibacterial Studies  

Microsoft Academic Search

Chiral Schiff base ruthenium(II) carbonyl complexes of the type [Ru(CO)(L?)(B)] (L?= tetradentate Schiff bases; B=PPh3, pyridine (py), piperidine (pip) or morpholine (morph)) has been synthesised by the reactions of [RuHCl(CO)(PPh3)2(B)] (B=PPh3 or py or pip or morph) with appropriate Schiff bases having the donor groups (O,N) viz., bis[3(1??naphthyl)salicylidenecyclohexanediimine] (L1)  or bis[3(1??naphthyl)salicylidenepropylenediimine] (L2) or bis[3(1??naphthyl)salicylidenediphenyldiimine] (L3) in 1?1 molar ratio. Complexes have

T. Daniel Thangadurai

2006-01-01

18

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

19

Stoichiometric and catalytic oxidations by dinuclear copper(I) and copper(II) complexes of a Schiff base ligand derived from the 2:2 condensation of pyridine 2,6-dicarboxaldehyde and 1,5,9-triazanonane  

Microsoft Academic Search

Dicopper(I) and dicopper(II) complexes of the macrocyclic ligand 3,7,11,19,23,27,33,34-octaazatricyclo[27.3.1.113,17]tetratriacontadeca-1(32),2,11,13,15,17(34)18,27,29(33),30-ene, (PD)2(DIPN)2, were prepared and examined for their reactivities. The dioxygen complex of [Cu2(PD)2(DIPN)2]2+ was generated in solution and was found to catalytically convert hydroquinone, t-butylhydroquinone, 2,6-di-t-butylphenol, and 2,6-dimethoxyphenols to their respective oxidation products, benzoquinone, t-butylbenzoquinone, 3,3?,5,5?-tetra-t-butyldiphenoquinone, 3,3?,5,5?-tetramethoxydiphenoquinone. The substrates 3,5-di-t-butylcatechol and 4-t-butylcatechol were converted to 3,5-di-t-butyl-1,2-benzoquinone and the ?-lactone of 3-hydroxy-4-t-butylmuconic

David A. Rockcliffe; Arthur E. Martell

1996-01-01

20

Synthesis, spectral, thermal and magnetic studies of Mn(II), Ni(II) and Cu(II) complexes with some benzopyran-4-one Schiff bases  

NASA Astrophysics Data System (ADS)

The Schiff bases of N 2O 2 dibasic ligands, H 2La and H 2Lb are prepared by the condensation of ethylenediamine (a) and trimethylenediamine (b) with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one. Also tetra basic ligands, H 4La and H 4Lb are prepared by the condensation of aliphatic amines (a) and (b) with 6-formyl-5,7-dihydroxy-2-methylbenzopyran-4-one. New complexes of H 4La and H 4Lb with metal ions Mn(II), Ni(II) and Cu(II) are synthesized, in addition Mn(II) complexes with ligands H 2La and H 2Lb are also synthesized. Elemental and thermal analyses, infrared, ultraviolet-visible as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. The structures of copper(II) complexes are also assigned based upon ESR spectra study. All the complexes separated with the stoichiometric ratio (1:1) (M:L) except Mn-H 4La and Mn-H 4Lb with (2:1) (M:L) molar ratio. In metal chelates of the type 1:1 (M:L), the Schiff bases behave as a dinegative N 2O 2 tetradentate ligands. Moreover in 2:1 (M:L) complexes, the Schiff base molecules act as mono negative bidentate ligand and binuclear complex is then formed. The Schiff bases were assayed by the disc diffusion method for antibacterial activity against Staphylococcus aureus and Escherichia coli. The antifungal activity of the Schiff bases was also evaluated against the fungi Aspergillus flavus and Candida albicans.

El-Ansary, Aida L.; Abdel-Fattah, Hussein M.; Abdel-Kader, Nora S.

2011-08-01

21

Synthesis, Crystal Structures and Antibacterial Activities of Two Schiff Base Zinc(II) Complexes  

Microsoft Academic Search

Two new mononuclear Schiff base zinc(II) complexes, [ZnBr2L1] · CH3OH (1) and [ZnBr2L2] · H2O (2) (L1=1?[(2?ethylaminoethylimino)methyl]naphthalen?2?olate, L2=4?bromo?2?[(2?methylaminoethylimino)methyl]phenolate), have been obtained from a similar synthetic procedure. The complexes have been characterized by elemental analyses and single crystal X?ray determinations. In each of the complexes, the zinc(II) atom is four?coordinated by one imine N and one phenolate O atoms from a Schiff base ligand, and

2006-01-01

22

A heterobimetallic Ga/Yb-Schiff base complex for catalytic asymmetric alpha-addition of isocyanides to aldehydes.  

PubMed

Development of a new heterobimetallic Ga(O-iPr)(3)/Yb(OTf)(3)/Schiff base 2d complex for catalytic asymmetric alpha-additions of isocyanides to aldehydes is described. Schiff base 2d derived from o-vanillin was suitable to utilize cationic rare earth metal triflates with good Lewis acidity in bimetallic Schiff base catalysis. The Ga(O-iPr)(3)/Yb(OTf)(3)/Schiff base 2d complex promoted asymmetric alpha-additions of alpha-isocyanoacetamides to aryl, heteroaryl, alkenyl, and alkyl aldehydes in good to excellent enantioselectivity (88-98% ee). PMID:19485325

Mihara, Hisashi; Xu, Yingjie; Shepherd, Nicholas E; Matsunaga, Shigeki; Shibasaki, Masakatsu

2009-06-24

23

Spectrometric study of tautomeric and protonation equilibria of o-vanillin Schiff base derivatives and their complexes with Cu(II).  

PubMed

Electronic absorption and emission properties of a series of Schiff bases derived from 2-hydroxy-3-methoxybenzaldehyde and 2-aminopyridine, 2,3-diaminopyridine, 2,6-diaminopyridine, or 3-aminomethylpyridine were studied in solvents of different polarities. The interconversion of the enolimine to the ketoamine tautomeric form was observed for compound 1, 6-methoxy-2-(3-pyridylmethyliminomethyl)phenol, and the corresponding equilibrium constant was estimated in several solvents. Protonation constants of all the investigated compounds were determined spectrophotometrically in the methanol/water 1/4 system. The effect of copper(II) ions on absorption and on the emission spectra of these ligands was examined in the buffered dioxane/water 1/1 system (pH 5.8). Strong complexation of Cu(II) and formation of a 1:1 complex were observed for the bis-Schiff base derived from 2,3-diaminopyridine. The complex of copper(II) with compound 1 was isolated and characterized by elemental analysis, magnetic susceptibility measurement, UV-vis and IR spectrometry. PMID:18456546

Gali?, Nives; Cimerman, Zvjezdana; Tomisi?, Vladislav

2008-12-15

24

Influence of Schiff base and lanthanide metals on the synthesis, stability, and reactivity of monoamido lanthanide complexes bearing two Schiff bases.  

PubMed

The monoamido lanthanide complexes stabilized by Schiff base ligand L(2)LnN(TMS)(2) (L = 3,5-Bu(t)(2)-2-(O)-C(6)H(2)CH?N-8-C(9)H(6)N, Ln = Yb (1), Y (2), Eu (3), Nd (4), and La (5)) were synthesized in good yields by the reactions of Ln[N(TMS)(2)](3) with 1.8 equiv of HL in hexane at room temperature. It was found that the stability of 1-5 depends greatly on the size of the lanthanide metals with the increasing trend of Yb ? Y < Nd < La. The amine elimination of Ln[N(TMS)(2)](3) with the bulky bidentate Schiff base HL' (L' = 3,5-Bu(t)(2)-2-(O)-C(6)H(2)CH?N-2,6-Pr(i)(2)-C(6)H(3)) afforded the monoamido lanthanide complexes L'(2)LnN(TMS)(2) (Ln = Yb (9), Y (10), Nd (11), and La (12)). While the amine elimination with the less bulky Schiff base HL'' (L'' = 3,5-Bu(t)(2)-2-(O)-C(6)H(2)CH?N-2,6-Me(2)-C(6)H(3)) yielded the desired monoamido complexes with the small metals of Y and Yb, L''(2)LnN(TMS)(2) (Ln = Yb (13) and Y (14)), and the more stable tris-Schiff base complexes with the large metals of La and Nd, yielded L''(3)Ln as the only product. Complexes 1-14 were fully characterized including X-ray crystal structural analysis. Complexes 1-5, 10, and 14 can serve as the efficient catalysts for addition of amines to carbodiimides, and the catalytic activity is greatly affected by the lanthanide metals with the active sequence of Yb < Y < Eu ? Nd ? La. PMID:21319780

Han, Fubin; Teng, Qiaoqiao; Zhang, Yong; Wang, Yaorong; Shen, Qi

2011-03-21

25

Synthesis, spectroscopic, structural characterization, electrochemical and antimicrobial activity studies of the Schiff base ligand and its transition metal complexes  

NASA Astrophysics Data System (ADS)

In this study, the Schiff base ligand trans-N,N'-bis[(2,4-dichlorophenyl) methylidene] cyclohexane-1,2-diamine (L) and its copper(II), nickel(II) and palladium(II) transition metal complexes were prepared and characterized by the analytical and spectroscopic methods. The 1H( 13C) NMR spectra of the ligand and its diamagnetic complexes were recorded in DMSO-d 6 solvent and obtained data confirm that the nitrogen atoms of the imine groups coordinated to the metal ions. Electrochemical properties of the ligand and its metal complexes were investigated in the DMF solvent at the 100 and 250 mV s -1 scan rates. The ligand and metal complexes showed both reversible and irreversible processes at these scan rates. The single crystal of the ligand (L) was obtained from MeOH solution, and its crystal structure was determined by X-ray diffraction. The C-H⋯Cl hydrogen bonding interactions in the molecule were seen which increase the stability of the crystal structure. The antimicrobial activity studies of the ligand and its metal complexes were carried out by using the various bacteria and fungi.

Aslanta?, Mehmet; Kendi, Engin; Demir, Necmettin; ?abik, Ali E.; Tümer, Mehmet; Kertmen, Metin

2009-10-01

26

In vivo cytogenetic studies on rat's bone-marrow cells of structurally related Schiff base complexes.  

PubMed

The in vivo interactions of structurally-related Ni(II) and Fe(III) Schiff base complexes based on N-(8-quinolyl)salicylaldimine (HL(1)) and N-(8-quinolyl)napthaldimine (HL(2)) ligands with DNA molecules in the bone-marrow cells of rats were demonstrated using chromosomal aberrations (CAs) assay. The complexes differ by one aromatic group on the aldehyde site of the Schiff base (basicity or lipophilicity), or by the type of the central metal ions (Ni(II) or Fe(III)). Animals were injected intraperitoneally (i.p) with different concentrations of each drug, and CAs were examined in bone-marrow cells, 15 hours later. A significant increase in the frequency of CAs was induced upon treatment with 15?mg / kg weight of L(1) complexes (P < 0.001), and not with L(2) complexes (P > 0.05). Also, the magnitude of aberrations induced by L(1)-Ni(II) was higher than that induced by L(1)-Fe(III) (P < 0.01). The binding data, estimated using UV-Visible absorption technique, showed that the metal binding of HL(1) was much greater than that of HL(2) and that the affinity of HL(1) towards Ni(II) is higher than that for Fe(III) ions. Thus, the trends in the presented in vivo results signify the important role of complex stability in predicting the clastogenicity of metal-ion-chelating Schiff base drugs. PMID:20958107

Saleh, Na'il; Khabour, Omar F; Esmadi, Fatima T; Al-Kofahi, Etizaz

2011-01-01

27

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

PubMed

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 (1)H-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). PMID:22622060

Selvi, Canan; Nartop, Dilek

2012-09-01

28

Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base  

NASA Astrophysics Data System (ADS)

Unusual Schiff base ligand, 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl)ethanimidoyl]benzene-1,3-diol, L, was synthesized via catalytic process involving the interaction of some metal ions with a macrocyclic Schiff base (MSB). The transition metal derivatives [ML(H2O)4](NO3)3, M = Cr(III) and Fe(III), [NiL(H2O)4](NO3)2, [ML(H2O)2](NO3)2, M = Zn(II) and Cd(II), [Cl2Pd(?-Cl)2PdL], [PtL(Cl)2] and [PtL(Cl)4] were also synthesized from the corresponding metal species with L. The Schiff bases and complexes were characterized by elemental analysis, mass spectrometry, IR and 1H NMR spectroscopy. The crystal structure of L was determined by X-ray analysis. The spectroscopic studies revealed a variety of structure arrangements for the complexes. The biological activities of L and metal complexes against the Escherchia coli as Gram-negative bacteria and Staphylococcus aureus as Gram-positive bacteria, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of [PtL(Cl)2] complex, a cis-platin analogous, was checked as an antitumor agent on two breast cancer cell lines (MCF7 and T47D) and human liver carcinoma cell line (HepG2).

Abu Al-Nasr, Ahmad K.; Ramadan, Ramadan M.

2013-03-01

29

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 ?5°C to 25°C,

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

2002-01-01

30

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

31

Charge-transfer complexes of pyrimidine Schiff bases with aromatic nitro compounds  

NASA Astrophysics Data System (ADS)

Charge-transfer (CT) complexes of pyrimidine Schiff bases, derived from condensation of 2-aminopyrimidine and substituted benzaldehydes, with some aromatic polynitro compounds were prepared and investigated using IR, UV, visible and 1H NMR spectroscopy. For all solid complexes, the main interaction between the donor and acceptor molecules takes place through the ?-?* interaction. Strong and some weak acidic acceptors, in addition interact through proton transfer from the acceptor molecule to the basic centre of the electron donor. Also, an n-?* transition was detected in some complexes.

Issa, Yousry M.; El Ansary, A. L.; Sherif, O. E.; Hassib, H. B.

2011-08-01

32

Antibacterial and Antifungal Studies on Some Schiff Base Complexes of Zinc(II).  

PubMed

Two Schiff base ligands L1and L2 were obtained by the condensation of glycylglycine respectively with imidazole-2-carboxaldehyde and indole-3-carboxaldehyde and their complexes with Zn(II) were prepared and characterized by microanalytical, conductivity measurement, IR, UV-Vis., XRD and SEM. The molar conductance measurement indicates that the Zn(II) complexes are 1: 1electrolytes. The IR data demonstrate the tetradentate binding of L1and tridentate binding of L2. The XRD data show that Zn(II) complexes with L1and L2 have the crystallite sizes of 53 and 61nm respectively. The surface morphology of the complexes was studied using SEM. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. A comparative study of inhibition values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. PMID:23990740

Joseyphus, R Selwin; Nair, M Sivasankaran

2008-06-01

33

Synthesis and spectral characterization of antifungal sensitive schiff base transition metal complexes.  

PubMed

New N2O2 donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and (1)H NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of 10~31 µg/ml. PMID:24015086

Raman, N; Sakthivel, A; Rajasekaran, K

2007-09-01

34

Antibacterial and Antifungal Studies on Some Schiff Base Complexes of Zinc(II)  

PubMed Central

Two Schiff base ligands L1 and L2 were obtained by the condensation of glycylglycine respectively with imidazole-2-carboxaldehyde and indole-3-carboxaldehyde and their complexes with Zn(II) were prepared and characterized by microanalytical, conductivity measurement, IR, UV-Vis., XRD and SEM. The molar conductance measurement indicates that the Zn(II) complexes are 1 : 1 electrolytes. The IR data demonstrate the tetradentate binding of L1 and tridentate binding of L2. The XRD data show that Zn(II) complexes with L1 and L2 have the crystallite sizes of 53 and 61 nm respectively. The surface morphology of the complexes was studied using SEM. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. A comparative study of inhibition values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. PMID:23990740

Joseyphus, R. Selwin

2008-01-01

35

Synthesis and Spectral Characterization of Antifungal Sensitive Schiff Base Transition Metal Complexes  

PubMed Central

New N2O2 donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and 1H NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of 10~31 µg/ml. PMID:24015086

Sakthivel, A.; Rajasekaran, K.

2007-01-01

36

Highly fluorescent BF2 complexes of hydrazine-Schiff base linked bispyrrole.  

PubMed

A series of BF2 complexes of hydrazine-Schiff base linked bispyrrole have been prepared from a simple two-step reaction from commercially available substances and are highly fluorescent in solution, film, and solid states with larger Stokes shift and excellent photostabilities comparable or even super to those of their BODIPY analogues. These resultant fluorescent dyes are highly susceptible to the postfunctionalization, as demonstrated in this work via the Knoevenagel condensation to introducing functionalities or tether groups to the chromophore. PMID:24850322

Yu, Changjiang; Jiao, Lijuan; Zhang, Ping; Feng, Zeya; Cheng, Chi; Wei, Yun; Mu, Xiaolong; Hao, Erhong

2014-06-01

37

Synthesis, physical studies and uptake behavior of: copper(II) and lead(II) by Schiff base chelating resins.  

PubMed

Two new chelating resins possessing multiple functional groups capable of coordinating with several metal ions are reported. The resins were synthesized by condensing Schiff bases derived from 2-aminophenol, 2-hydroxy-5-chloroaniline and terephthaldehyde with formaldehyde in an alkaline medium. The effects of pH and contact time of the Cu(2+) and Pb(2+) in aqueous solutions on the uptake behavior of the resins were studied. The metal ion uptake behavior of the resins was investigated by the batch method. Both the uptake and the selectivity of the resins towards the investigated metal ions were related to the structure of the resins, type of the metal ion and the uptake conditions. The resins showed maximum uptake capacity for Cu(2+) and Pb(2+) at pH 10. Cu(2+) was seen to undergo preferential adsorption in separate and mixture solutions of Cu(2+) and Pb(2+). Kinetic studies for the resins using Langmiur equation were also performed. The Schiff base monomers and their formaldehyde resins were characterized by elemental analyses, FTIR and (1)H NMR spectroscopy. The thermal stability of the resins was studied using TGA/DTG analysis. PMID:21320794

Othman, Mohammed K; Al-Qadri, Fatima A; Al-Yusufy, Fatima A

2011-05-01

38

Synthesis, physical studies and uptake behavior of: Copper(II) and lead(II) by Schiff base chelating resins  

NASA Astrophysics Data System (ADS)

Two new chelating resins possessing multiple functional groups capable of coordinating with several metal ions are reported. The resins were synthesized by condensing Schiff bases derived from 2-aminophenol, 2-hydroxy-5-chloroaniline and terephthaldehyde with formaldehyde in an alkaline medium. The effects of pH and contact time of the Cu 2+ and Pb 2+ in aqueous solutions on the uptake behavior of the resins were studied. The metal ion uptake behavior of the resins was investigated by the batch method. Both the uptake and the selectivity of the resins towards the investigated metal ions were related to the structure of the resins, type of the metal ion and the uptake conditions. The resins showed maximum uptake capacity for Cu 2+ and Pb 2+ at pH 10. Cu 2+ was seen to undergo preferential adsorption in separate and mixture solutions of Cu 2+ and Pb 2+. Kinetic studies for the resins using Langmiur equation were also performed. The Schiff base monomers and their formaldehyde resins were characterized by elemental analyses, FTIR and 1H NMR spectroscopy. The thermal stability of the resins was studied using TGA/DTG analysis.

Othman, Mohammed K.; Al-Qadri, Fatima A.; Al-Yusufy, Fatima A.

2011-05-01

39

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

40

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

41

The Synthesis of Star-Shaped Macromolecular Schiff Base Complexes Having Melamine Cores and their Magnetic and Thermal Behaviours  

Microsoft Academic Search

We aim to study magnetic and thermal behaviors of some melamine cored macromolecular Schiff base complexes. In this context, tripodal ligands were synthesized by reacting melamine with 4-carboxybenzaldehyde or 4-hydroxybenzaldehyde. Then, sixteen new trinuclear Fe(III), Cr(III), Mn(III) and Al(III) complexes were synthesized by reacting the ligands [tris-(4-carboxybenzimino)-1,3,5-triazine) or tris-(4-hydroxybenzimino)-1,3,5-triazine)] with pentadentate Schiff bases N,N?-bis(1-hydroxy-2-benzyliden)-1,7-diamino-4-azaheptane or N,N?-bis(salicylidene)pyridine-2,6-diamine. Later, ligands and complexes

?aban Uysal; Ziya Erdem Koç; ?eyma Çelikbilek; H. ?smet Uçan

2011-01-01

42

Preparation, spectral studies, theoretical, electrochemical and antibacterial investigation of a new Schiff base and its some metal complexes  

NASA Astrophysics Data System (ADS)

A new Schiff base ligand, 1,6-Bis(2-(5-bromo-2-hydroxybenzylideneamino)-4-chlorophenoxy)hexane was synthesized. Some Schiff metal complexes of the new Schiff base were prepared by the reaction of some metal salts and the Schiff base. The complexes are non-electrolytes as shown by their molar conductivities (?M). The structures of metal complexes are proposed from elemental analysis, FT-IR, UV-vis, magnetic susceptibility measurements, molar conductivity measurements, mass spectra and thermal gravimetric analysis. In addition theoretical 1H NMR, HOMO-LUMO studies of the ligand; antimicrobial and cyclic voltammetric studies of the compounds were also carried out. In this study antioxidant and antibacterial activities of the compounds were examined via in vitro methods.

Ilhan, S.; Baykara, H.; Seyitoglu, M. S.; Levent, A.; Özdemir, S.; Dündar, A.; Öztomsuk, A.; Cornejo, M. H.

2014-10-01

43

Preparation, characterization and biological activity of novel metal-NNNN donor Schiff base complexes.  

PubMed

Novel Schiff base (H(2)L) ligand is prepared via condensation of benzil and triethylenetetraamine. The ligand is characterized based on elemental analysis, mass, IR and (1)H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG and DTA). 1:1 [M]:[H(2)L] complexes are found from the elemental analyses data having the formulae [M(H(2)L)Cl(2)]xyH(2)O (M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)), [Fe(H(2)L)Cl(2)]ClxH(2)O, [Th(H(2)L)Cl(2)]Cl(2)x3H(2)O and [UO(2)(H(2)L)](CH(3)COO)(2)x2H(2)O. The metal chelates are found to be non-electrolytes except Fe(III), Th(IV) and UO(2)(II) complexes are electrolytes. IR spectra show that H(2)L is coordinated to the metal ions in a neutral tetradentate manner with 4Ns donor sites of the two azomethine N and two NH groups. The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats-Redfern method. The ligand (H(2)L), in comparison to its metal complexes, is screened for its antibacterial activity. The activity data show that the metal complexes have antibacterial activity more than the parent Schiff base ligand and cefepime standard against one or more bacterial species. PMID:20044308

Mohamed, Gehad G; Omar, M M; Ibrahim, Amr A

2010-02-01

44

Antibacterial activity of Pd(II) complexes with salicylaldehyde-amino acids Schiff bases ligands.  

PubMed

Palladium(II) complexes with Schiff bases ligands derived from salicylaldehyde and amino acids (Ala, Gly, Met, Ser, Val) have been synthesized and characterized by Fourier transform (FT)-IR, UV-Vis and (1)H-NMR spectroscopy. The electrospray mass spectrometry (ES-MS) spectrometry confirms the formation of palladium(II) complexes in 1/2 (M/L) molar ratio. All the Pd(II) complexes 1, [Pd(SalAla)2]Cl2; 2, [Pd(SalGly)2]Cl2; 3, [Pd(SalMet)2]Cl2; 4, [Pd(SalSer)2]Cl2; 5, [Pd(SalVal)2]Cl2; have shown antibacterial activity against Gram-positive bacteria Staphylococcus aureus and Gram-negative bacteria Escherichia coli. PMID:24390488

Rîmbu, Cristina; Danac, Ramona; Pui, Aurel

2014-01-01

45

Efficient water oxidation catalyzed by mononuclear ruthenium(II) complexes incorporating Schiff base ligands.  

PubMed

Four new charge-neutral ruthenium(II) complexes containing dianionic Schiff base and isoquinoline or 4-picoline ligands were synthesized and characterized by NMR and ESI-MS spectroscopies, elemental analysis, and X-ray diffraction. The complexes exhibited excellent chemical water oxidation activity and high stability under acidic conditions (pH?1.0) using (NH4)2Ce(NO3)6 as a sacrificial electron acceptor. The high catalytic activities of these complexes for water oxidation were sustained for more than 10?h at low concentrations. High turnover numbers of up to 3200 were achieved. A water nucleophilic attack mechanism was proposed. A Ru(V)=O intermediate was detected during the catalytic cycle by high-resolution mass spectrometry. PMID:24888489

Li, Ting-Ting; Chen, Yong; Li, Fu-Min; Zhao, Wei-Liang; Wang, Chuan-Jun; Lv, Xiao-Jun; Xu, Quan-Qing; Fu, Wen-Fu

2014-06-23

46

Sn(iv) Schiff base complexes: triplet photosensitizers for photoredox reactions.  

PubMed

We present the synthesis and characterization of a series of four fluorescent Sn(iv) Schiff base complexes, which also possess long-lived triplet excited states. The complexes absorb visible light (?max = 420 to 462 nm) and the optical properties are easily tunable without laborious synthetic elaboration. The triplet excited states are not luminescent, but can be observed and followed using nanosecond transient absorption spectroscopy. The lifetimes of the triplet excited states are on the order of 500 ?s-10 ms in PMMA matrices. The triplet state energies were estimated via energy transfer reactions with a series of organic triplet acceptors. In addition, the photoexcited complexes react with electron donors and acceptors in solution. These results demonstrate the potential for the development of photosensitizers based on main group elements with high spin orbit coupling constants. PMID:25043697

Grusenmeyer, Tod A; King, Albert W; Mague, Joel T; Rack, Jeffrey J; Schmehl, Russell H

2014-11-12

47

Synthesis, characterization, crystal structure determination, thermal study and catalytic activity of a new oxidovanadium Schiff base complex  

NASA Astrophysics Data System (ADS)

A new bidentate ON Schiff base ligand of HL (HL = 5-nitro-2-hydroxybenzyl-2-furylmethyl) imine), was synthesized by simple condensation reaction of 5-nitro-2-hydroxybenzaldehyde and 2-furfurylamine. Then by reaction of a methanolic solutions of the HL and VO(acac)2 in the ratio of 2:1, a new oxidovanadium(IV) Schiff base complex of VOL2 was synthesized. The Schiff base ligand and its vanadyl Schiff base complex were characterized by FT-IR, UV-vis spectra and CHN analysis. Single crystals suitable for X-ray analysis were obtained in DMSO as a VOL2(DMSO) complex. The crystal structure of the VOL2(DMSO) was determined by the single-crystal X-ray analysis. The coordination geometry around the vanadium center can be described as a distorted octahedron formed by two phenolato oxygen and two imine nitrogen atoms of the two Schiff base ligands in the equatorial position, the oxygen atom of DMSO and the oxido ion coordinated in the axial position. Thermogravimetric analysis of the VOL2 showed that the formation of mixed vanadium oxides at 450 ?C. In addition, decomposition of the vanadyl Schiff base complex (VOL2) in air at 660 °C resulted in the formation of the V2O5 nano particles with the average size of 52 nm. The catalytic activity of the VOL2 complex was evaluated in the epoxidation of cyclooctene (90% conversion and 100% epoxide) and oxidation of methyl phenyl sulfide (100% conversion and 100% sulfoxide).

Grivani, Gholamhossein; Ghavami, Abbaseh; Ku?eráková, Monika; Dušek, Michal; Khalaji, Aliakbar Dehno

2014-11-01

48

Zeolite-encapsulated Ru(III) tetrahydro-Schiff base complex: An efficient heterogeneous catalyst for the hydrogenation of benzene under mild conditions  

Microsoft Academic Search

A series of Ru(III) tetrahydro-Schiff base complexes (denoted as Ru[H4]-Schiff base with Schiff base=salen, salpn and salcn, see Scheme 1) were encapsulated in the supercages of zeolite Y by flexible ligand method. The prepared catalysts were characterized by X-ray diffraction, diffuse reflectance UV–Vis spectroscopy, Infrared spectroscopy, elemental analysis, as well as N2 adsorption techniques. It was shown that upon encapsulation

Ping Chen; Binbin Fan; Minggang Song; Chun Jin; Jinghong Ma; Ruifeng Li

2006-01-01

49

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 Förster 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

50

Pseudooctahedral Cobalt(III), Nickel(II), and Cadmium(II) Complexes of Linear, Sexadentate, Fluorinated Schiff Base Ligands.  

National Technical Information Service (NTIS)

New pseudooctahedral complexes, Ni(BTAT), Ni(BHAT), Cd(BTAT), C(BTAT)X, Co(BTAT)X. and (Co(BTAT))2CoY4 where X(-) = Br(-), I(-), NO3(-), and ClO4(-) and Y(-) = Cl(-) and SCN(-), have been prepared from the linear Schiff base ligands bis(trifluoroacetylace...

R. E. Sievers, S. C. Cummings

1971-01-01

51

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

52

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

PubMed

The ligation behavior of bis-benzoin ethylenediamine (B2ED) and benzoin thiosemicarbazone (BTS) Schiff bases towards Ru(3+), Rh(3+), Pd(2+), Ni(2+) and Cu(2+) 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 M(2+)/M(3+) and M(3+)/M(4+) (M=Ru(3+), Rh(3+)) 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. PMID:23792194

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

2013-09-01

53

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

54

Synthesis of new chiral heterocyclic Schiff base modulated Cu(II)/Zn(II) complexes: their comparative binding studies with CT-DNA, mononucleotides and cleavage activity.  

PubMed

New Schiff base ligand L derived from the condensation reaction of 2-amino-3-formylchromone with (R)-2-amino-2-phenylethanol was synthesized and characterized which involves combination element of ammine functionality and naturally occurring heterocyclic chromone, 4H-benzopyran-4-one. Subsequently, their complexes 1 and 2 with Cu(NO?)? and Zn(NO?)?, respectively were prepared. The DNA binding studies of the ligand L and complexes 1 and 2 with CT-DNA as compared to classical anticancer drug cisplatin were carried out by employing different optical methods viz, UV-vis, fluorescence, circular dichroism and viscosity measurements. Furthermore, the absorption studies, ¹H and ³¹P with mononucleotides were also monitored to examine the base specific interactions of the transition metal complexes which revealed a higher propensity of copper(II) complex 1 for 5'-GMP while for zinc(II) complex 2 towards 5'-TMP involving groove binding mechanism of the complexes towards DNA. The complex 1 exhibits a remarkable DNA cleavage activity with pBR322 DNA in presence of different activators and cleavage reaction involves various oxygen species suggesting the involvement of active oxygen species for the DNA scission. PMID:21459607

Arjmand, Farukh; Sayeed, Fatima; Muddassir, Mohd

2011-05-01

55

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

56

Seven-coordinate lanthanide sandwich-type complexes with a tetrathiafulvalene-fused Schiff base ligand.  

PubMed

Three seven-coordinate lanthanide(III) sandwich-type mononuclear complexes with ?-conjugated TTF-Schiff base ligand H2L (L(2-) = 2,2'-((2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-1,3-benzodithiole-5,6-diyl)bis(nitrilomethylidyne)bis(4-chlorophenolate)) and the tripodal ligand L(OEt)(-) (L(OEt)(-) = [(?(5)-C5H5)Co(P(?O)(OEt)2)3](-)), [(L(OEt))Ln(L)]·0.25H2O (Ln(3+) = Dy(3+), 1; Tb(3+), 2; Ho(3+), 3), have been synthesized and structurally characterized. All of the complexes are also characterized by absorption spectra and electrochemical, spectroelectrochemical, and magnetic studies. The Dy complex exhibits the field-induced slow relaxation of magnetization with an energy barrier of 41.6 K, indicating it shows single lanthanide-based SMM behavior. Introduction of the redox-active TTF unit into the sandwich-type lanthanide(III) complexes with interesting magnetic properties renders them promising for elaboration of new hybrid inorganic-organic materials. PMID:24063409

Gao, Feng; Cui, Long; Liu, Wei; Hu, Liang; Zhong, Yu-Wu; Li, Yi-Zhi; Zuo, Jing-Lin

2013-10-01

57

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

58

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

59

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

60

Theoretical spectroscopic study of seven zinc(II) complex with macrocyclic Schiff-base ligand  

NASA Astrophysics Data System (ADS)

Seven zinc complexes, which are [ZnL1]2+, [ZnL2]2+, [ZnL3]2+, [ZnL4]2+, [ZnL5]2+, [ZnL6]2+ and [ZnL7]2+, are studied as theoretically. Structural parameters, vibration frequencies, electronic absorption spectra and 1H and 13C NMR spectra are obtained for Zn(II) complexes of macrocyclic penta and heptaaza Schiff-base ligand. Vibration spectra of Zn(II) complexes are studied by using Density Functional Theory (DFT) calculations at the B3LYP/LANL2DZ. The UV-VIS and NMR spectra of the zinc complexes are obtained by using Time Dependent-Density Functional Theory (TD-DFT) method and Giao method, respectively. The agreements are found between experimental data of [ZnL5]2+, [ZnL6]2+ and [ZnL7]2+ complex ions and their calculated results. The geometries of complexes are found as distorted pentagonal planar for [ZnL1]2+, [ZnL2]2+ and [ZnL3]2+ complex ions, distorted tetrahedral for [ZnL4]2+ complex ion and distorted pentagonal bipyramidal for [ZnL5]2+, [ZnL6]2+ and [ZnL7]2+ complex ions. Ranking of biological activity is determined by using quantum chemical parameters and this ranking is found as: [ZnL7]2+ > [ZnL6]2+ > [ZnL5]2+ > [ZnL3]2+ > [ZnL2]2+ > [ZnL1]2+.

Sayin, Koray; Kariper, Sultan Erkan; Sayin, Tuba Alagöz; Karaka?, Duran

2014-12-01

61

Synthesis and spectral characterization of trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes with Schiff bases  

NASA Astrophysics Data System (ADS)

Some novel trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes of the general formula [Fe3O(OOCR)3(SB)3L3] (where R = C13H27, C15H31 or C17H35, HSB = Schiff bases and L = Ethanol) have been synthesized by the stepwise substitutions of acetate ions from ?3-oxo-hexa(acetato)tri(aqua)iron(II)diiron(III), first with straight chain carboxylic acids and then with Schiff bases. The complexes were characterized by elemental analyses, molecular weight determinations and spectral (electronic, infrared, FAB mass, Mössbauer and powder XRD) studies. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bridging nature of carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Mössbauer spectroscopic studies indicated two quadrupole-split doublets due to Fe(II) and Fe(III) ions at 80, 200 and 295 K, confirming the complexes are mixed-valence species. This was also supported by the observed electronic spectra of the complexes. Magnetic susceptibility measurements displayed octahedral geometry around iron in mixed-valence state and a net antiferromagnetic exchange coupling via ?-oxo atom. Trinuclear nature of the complexes was confirmed by their molecular weight determination and FAB mass spectra. A plausible structure for these complexes has been established on the basis of spectral and magnetic moment data.

Singh, Atresh Kumar; Singh, Alok Kumar

2012-10-01

62

Synthesis and spectral characterization of trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes with Schiff bases.  

PubMed

Some novel trinuclear, oxo-centered, carboxylate-bridged, mixed-valence iron complexes of the general formula [Fe(3)O(OOCR)(3)(SB)(3)L(3)] (where R=C(13)H(27), C(15)H(31) or C(17)H(35,) HSB=Schiff bases and L=Ethanol) have been synthesized by the stepwise substitutions of acetate ions from ?(3)-oxo-hexa(acetato)tri(aqua)iron(II)diiron(III), first with straight chain carboxylic acids and then with Schiff bases. The complexes were characterized by elemental analyses, molecular weight determinations and spectral (electronic, infrared, FAB mass, Mössbauer and powder XRD) studies. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bridging nature of carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Mössbauer spectroscopic studies indicated two quadrupole-split doublets due to Fe(II) and Fe(III) ions at 80, 200 and 295K, confirming the complexes are mixed-valence species. This was also supported by the observed electronic spectra of the complexes. Magnetic susceptibility measurements displayed octahedral geometry around iron in mixed-valence state and a net antiferromagnetic exchange coupling via ?-oxo atom. Trinuclear nature of the complexes was confirmed by their molecular weight determination and FAB mass spectra. A plausible structure for these complexes has been established on the basis of spectral and magnetic moment data. PMID:22939284

Singh, Atresh Kumar; Singh, Alok Kumar

2012-10-01

63

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

PubMed

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. PMID:25129626

Devi, Jai; Batra, Nisha

2015-01-25

64

Charge transfer complexes of adenosine-5 '-monophosphate and cytidine-5 '-monophosphate with water-soluble cobalt(II) Schiff base complexes in aqueous solution  

NASA Astrophysics Data System (ADS)

Water-soluble cobalt(II) tetradentate Schiff base complexes have been shown to form charge transfer (CT) complexes with a series of nucleoside monophosphates including adenosine-5 '-monophosphate (AMP) and cytidine-5 '-monophosphate (CMP). The investigated water-soluble cobalt(II) Schiff base complexes are (i) disodium[{bis(5-sulfo-salicylaldehyde)- o-phenylenediiminato}cobalt(II)], Na 2[Co(SO 3-salophen)] ( 1); (ii) disodium[{bis(5-sulfo-salicylaldehyde)-4,5-dimethyl- o-phenylenediiminato}cobalt(II)], Na 2[Co(SO 3-sal-4,5-dmophen)] ( 2) and (iii) disodium[{bis(4-methoxy-5-sulfo-salicylaldehyde)-4,5-dimethyl- o-phenylenediiminato}cobalt(II)], Na 2[Co(SO 3-4-meosal-4,5-dmophen)] ( 3). The formation constant and thermodynamic parameters for charge transfer complex formation of water-soluble cobalt(II) Schiff base complexes with nucleoside monophosphates were determined spectrophotometrically in aqueous solution at constant ionic strength ( I = 0.2 mol dm -3 KNO 3) under physiological condition (pH 7.0) and at various temperatures between 288 and 308 K. The stoichiometry has been found to be 1:1 (water-soluble cobalt(II) Schiff base complex: nucleoside monophosphate) in each case. Our spectroscopic and thermodynamic results show that the interaction of water-soluble cobalt(II) Schiff base complexes with the investigated nucleoside monophosphates occurs mainly through the phosphate group. The trend of the interaction according to the cobalt(II) Schiff base complexes due to electronic and steric factors is as follows: Na 2[Co(SO 3-salophen)] > Na 2[Co(SO 3-sal-4,5-dmophen)] > Na 2[Co(SO 3-4-meosal-4,5-dmophen)]. Also the trend of the interaction of a given cobalt(II) Schiff base complex according to the nucleoside monophosphate is as follows: CMP > AMP.

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2006-01-01

65

Synthesis, reactivity, and coordination chemistry relevant to the copolymerization of CO2 and epoxides by first row transition metal schiff base complexes  

E-print Network

demonstrates that new ligand systems are available beyond salen and deserve further attention. A class of manganese(III) Schiff base complexes was also synthesized and evaluated as catalysts. Although crystallographic data has shown that these complexes...

Frantz, Eric Benjamin

2009-05-15

66

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, Gökhan; Çelik, Cumali; Uru?, Serhan; Demirta?, ?brahim; Elmasta?, Mahfuz; Tümer, Mehmet

2011-10-01

67

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

68

Microwave assisted synthesis and characterization of unsymmetrical tetradentate Schiff base complexes of VO(IV) and MoO(V)  

NASA Astrophysics Data System (ADS)

Microwave synthesis, is green chemical method, simple, sensitive, reducing solvent amount and reaction time. The attempt was made to synthesize the unsymmetrical tetradentate N 2O 2 ligands and their VO(IV) and MoO(V) unsymmetrical tetradentate Schiff base complexes by classical and microwave techniques using domestic microwave oven. The resulting unsymmetrical Schiff base ligands L 1-L 3 characterized by different spectral methods. Their complexes with oxocations of VO(IV) and MoO(V) have been synthesized and characterized by elemental analyses, conductometric measurements, infrared and electronic absorption, 1H NMR spectra, mass spectrometry, ESR spectra, magnetic susceptibility measurement and thermal study. The study suggests that the oxo metal ion is bonded to the ligand through the oxygen and imino nitrogen and the geometry around metal ion is distorted octahedral.

Thaker, B. T.; Barvalia, R. S.

2011-12-01

69

Antibacterial Co(II), Cu(II), Ni(II) and Zn(II) Complexes of Thiadiazoles Schiff Bases.  

PubMed

Schiff bases were obtained by condensation of 2-amino-l,3,4-thiadiazole with 5-substituted-salicylaldehydes which were further used to obtain complexes of the type [M(L)(2)]Cl(2), where M=Co(II), Cu(II), Ni(II) or Zn(II). The new compounds described here have been characterized by physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of these Schiff bases increased upon chelation/complexation, against the tested bacterial species, opening new aproaches in the fight against antibiotic resistant strains. PMID:18475981

Chohan, Z H; Jaffery, M F; Supuran, C T

2001-01-01

70

Antibacterial Co(II), Cu(II), Ni(II) and Zn(II) Complexes of Thiadiazoles Schiff Bases  

PubMed Central

Schiff bases were obtained by condensation of 2-amino-l,3,4-thiadiazole with 5-substituted-salicylaldehydes which were further used to obtain complexes of the type [M(L)2]Cl2, where M=Co(II), Cu(II), Ni(II) or Zn(II). The new compounds described here have been characterized by physical, spectral and analytical data, and have been screened for antibacterial activity against several bacterial strains such as Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The antibacterial potency of these Schiff bases increased upon chelation/complexation, against the tested bacterial species, opening new aproaches in the fight against antibiotic resistant strains. PMID:18475981

Jaffery, Maimoon F.; Supuran, Claudiu T.

2001-01-01

71

Preparation and characterisation of new oxovanadium(IV) Schiff base complexes derived from amino acids and aromatic o-hydroxyaldehydes  

Microsoft Academic Search

A range of mostly new oxovanadium(IV) complexes is described. They contain coordinated Schiff bases, made from natural amino acids (glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, threonine, aspartic acid, and histidine) and salicylaldehyde or such derivatives as 3-, 4-, or 5-methoxy-salicylaldehyde. The coordination sphere is completed by simple ligands like water, 2,2?-bipyridyl or pyridine. The compounds are characterised and the

J. Costa Pessoa; I. Cavaco; I. Correia; M. T. Duarte; R. D. Gillard; R. T. Henriques; F. J. Higes; C. Madeira; I. Tomaz

1999-01-01

72

POLYMER SUPPORTED N,N?BIS(SALICYLIDENE) HYDRAZINE Co(II) SCHIFF BASE COMPLEX AND ITS CATALYTIC ACTIVITY  

Microsoft Academic Search

N,N?-bis(salicylidene)hydrazine cobalt (II) Schiff base complex immobilized on crosslinked polymer support has been prepared by suspension copolymerization of synthesized N,N?-bis(3-allylsalicylidene)hydrazine monomer along with styrene and divinyl benzene using azobisisobutyronitrile (AIBN) as initiator in the presence of poly(vinyl alcohol) and reacting prepared beads with cobalt (II) chloride solution in dimethyl formamide (DMF). The amount of divinyl benzene in suspension copolymerization has

K. C. Gupta; H. K. Abdul Kadir; S. Chand

2002-01-01

73

Synthesis, characterization and thermal study of some transition metal complexes of an asymmetrical tetradentate Schiff base ligand  

Microsoft Academic Search

Complexes of Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) with an asym- metric tetradentate Schiff base ligand derived from dehydroacetic acid, 4-me- thyl-o-phenylenediamine and salicylic aldehyde were synthesized and charac- terized by elemental analysis, conductometry, magnetic susceptibility, UV-Vis, IR, 1 H-NMR spectroscopy, X-ray diffraction analysis of powdered samples and thermal analysis, and screened for antimicrobial activity. The IR spectral data suggested

ACHUT S. MUNDE; AMARNATH N. JAGDALE; SARIKA M. JADHAV; TRIMBAK K. CHONDHEKAR

2010-01-01

74

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

PubMed

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, (1)H 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 77K 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. PMID:22982386

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

2012-12-01

75

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

76

Synthesis, Spectroscopic and Biological Investigations of the Ternary Metal Complexes of Schiff Bases Derived From 2-hydroxy-1-naphthaldehyde and Some Amino Acids  

Microsoft Academic Search

In this work the ternary metal complexes of Cu(II) and UO2(II) with some Schiff bases derived from 2-hydroxy-1-naphthaldehyde and some amino acids as a primary ligand and two different heterocyclic bases as a secondary ligand have been synthesised. FT-IR results disclosed that the Schiff bases are coordinated to the central metal ion as a bivalent tridentate ONO donor. Electronic absorption

Y. H. Ebead; H. M. A. Salman; Y. M. Shebany; M. A. Abdellah

2012-01-01

77

Synthesis of Styrene-Allylchloride Copolymer Supported Cobalt(II) Schiff Base Complex and Its Catalytic Activity  

Microsoft Academic Search

N,N?-bis(acetylacetone)o-phenylenediamine cobalt (II) Schiff base complex and its polymer bound analogue have been prepared and characterized for their structure and catalytic activity. To prepare heterogenized analogue of the cobalt (II) complex, a new crosslinked functional polymeric beads were prepared by suspension copolymerization of styrene (48.97 mmol, 5.1 g), allylchloride (48.97 mmol, 3.746 g) and divinylbenzene (1.50 mmol, 0.195 g) in the presence of azobisisobutyronitrile (9.0×10 mmol, 0.15 g)

K. C. Gupta; H. K. Abdulkadir; S. Chand

2003-01-01

78

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 Förster 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

79

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

PubMed

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 Förster 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. PMID:24996211

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

2014-12-10

80

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

81

Series of dicyanamide-interlaced assembly of zinc-Schiff-base complexes: crystal structure and photophysical and thermal studies.  

PubMed

Four new dicyanamide (dca) bridged multinuclear Zn(II)-Schiff-base complexes, {[Zn2L(1)(?1,5-dca)dca]·CH3OH}2 (1), [Zn2L(2)(?1,5-dca)dca]n (2), [Zn3L(3)2(?1,5-dca)2]n (3), and [(ZnL(4))2Zn(?1,5-dca)dca]n (4), have been synthesized using four different Schiff bases L(1)H2 = N,N(/)-bis(3-methoxysalicylidenimino)-1,3-diaminopentane, L(2)H2 = N,N'-bis(5-bromo-3-methoxysalicylidenimino)-1,3-diaminopropane, L(3)H2 = N,N'-bis(5-bromosalicylidenimino)-1,3-diaminopropane, and L(4)H2 = N,N'-bis(5-chlorosalicylidenimino)-1,3-diaminopropane and NaN(CN)2 in order to extend the metal-ligand assembly. The directional properties of linear end-to-end bridging dca ligands have resulted in different metal ion connectivities leading to unique variety of templates in each of the complexes. All the ligands and complexes have been characterized by microanalytical and spectroscopic techniques. The structures of the complexes have been conclusively determined by single crystal X-ray diffraction studies. Thermogravimetric analyses have been performed to investigate the thermal stability of the metal-organic frameworks. Finally, the photoluminescence properties of the complexes as well as their respective ligands have been investigated with a comparative approach. PMID:23113533

Maiti, Monami; Sadhukhan, Dipali; Thakurta, Santarupa; Roy, Syamantak; Pilet, Guillaume; Butcher, Ray J; Nonat, Aline; Charbonnière, Loïc J; Mitra, Samiran

2012-11-19

82

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

83

Synthesis, structural, thermal studies and biological activity of a tridentate Schiff base ligand and their transition metal complexes.  

PubMed

Schiff base (L) ligand is prepared via condensation of pyridine-2,6-dicarboxaldehyde with -2-aminopyridine. The ligand and its metal complexes are characterized based on elemental analysis, mass, IR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG and DTA). The molar conductance reveals that all the metal chelates are non-electrolytes. IR spectra shows that L ligand behaves as neutral tridentate ligand and bind to the metal ions via the two azomethine N and pyridine N. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Fe(III), Co(II), Ni(II), Cu(II), and Th(IV)) and tetrahedral (Mn(II), Cd(II), Zn(II), and UO2(II)). The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ?H*, ?S* and ?G* are calculated from the DTG curves using Coats-Redfern method. The synthesized ligand, in comparison to their metal complexes also was screened for its antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data shows that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species. PMID:21130026

Abd El-halim, Hanan F; Omar, M M; Mohamed, Gehad G

2011-01-01

84

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.

85

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

86

Synthesis, spectroscopic characterization and comparative DNA binding studies of Schiff base complexes derived from L-leucine and glyoxal.  

PubMed

The mononuclear Schiff base complexes of the type, [ML(CH(3)OH)(2)] [M = Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by template condensation of L-leucine and glyoxal. The complexes have been characterized on the basis of the results of the elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz, FT-IR, Mass, (1)H NMR and (13)C NMR spectra. The UV-vis and magnetic moment data revealed an octahedral geometry around Co(II), Ni(II) ion with distortion around Cu(II) ion complex confirmed by EPR data. The conductivity data show a non-electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that all the complexes exhibit a significant binding to calf thymus DNA. PMID:21807556

Shakir, Mohammad; Shahid, Nida; Sami, Naushaba; Azam, Mohammad; Khan, Asad U

2011-11-01

87

Spectral characterization, cyclic voltammetry, morphology, biological activities and DNA cleaving studies of amino acid Schiff base metal(II) complexes  

NASA Astrophysics Data System (ADS)

Metal complexes are synthesized with Schiff bases derived from o-phthalaldehyde (opa) and amino acids viz., glycine (gly) L-alanine (ala), L-phenylalanine (pal). Metal ions coordinate in a tetradentate or hexadentate manner with these N 2O 2 donor ligands, which are characterized by elemental analysis, molar conductance, magnetic moments, IR, electronic, 1H NMR and EPR spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Based on EPR studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values calculated for copper complexes at 300 K and in frozen DMSO (77 K) indicate the presence of the unpaired electron in the d orbital. The evaluated metal-ligand bonding parameters showed strong in-plane ?- and ?-bonding. X-ray diffraction (XRD) and scanning electron micrography (SEM) analysis provide the crystalline nature and the morphology of the metal complexes. The cyclic voltammograms of the Cu(II)/Mn(II)/VO(II) complexes investigated in DMSO solution exhibit metal centered electroactivity in the potential range -1.5 to +1.5 V. The electrochemical data obtained for Cu(II) complexes explains the change of structural arrangement of the ligand around Cu(II) ions. The biological activity of the complexes has been tested on eight bacteria and three fungi. Cu(II) and Ni(II) complexes show an increased activity in comparison to the controls. The metal complexes of opapal Schiff base were evaluated for their DNA cleaving activities with calf-thymus DNA (CT DNA) under aerobic conditions. Cu(II) and VO(II) complexes show more pronounced activity in presence of the oxidant.

Neelakantan, M. A.; Rusalraj, F.; Dharmaraja, J.; Johnsonraja, S.; Jeyakumar, T.; Sankaranarayana Pillai, M.

2008-12-01

88

Structure and physico-chemical properties of hexadentate Schiff base zinc complexes derived from salicylaldehydes and triethylenetetramine*1  

NASA Astrophysics Data System (ADS)

Two hexadentate Schiff base zinc complexes, ZnSal 2trien and ZnVan 2trien, where Sal=salicylaldehyde, Van= o-vanillin, and trien=triethylenetetramine, have been synthesized by the reaction between salicylaldehydes, triethylenetetramine and zinc acetate. The structure of ZnSal 2trien and ZnVan 2trien were determined by single crystal X-ray crystallography. It was found that both ZnSal 2trien and ZnVan 2trien have a bent-shaped structure. Properties of the complexes were examined using differential scanning calorimetry, polarized optical microscopy and small angle X-ray scattering. Protonation constants of the ligands Sal 2trien and Van 2trien and stability constants of their zinc complexes were determined by potentiometric titration. Binding energies of ZnSal 2trien and ZnVan 2trien complexes were obtained by quantum chemical calculations.

Chantarasiri, Nuanphun; Ruangpornvisuti, Vithaya; Muangsin, Nongnuj; Detsen, Hussadee; Mananunsap, Thussanee; Batiya, Chureephon; Chaichit, Narongsak

2004-09-01

89

Synthesis, Properties and Crystal Structures of Mononuclear Copper(II) Complexes with Bis(2-Pyridylmethyl)Amino Acids  

Microsoft Academic Search

Tetradentate Schiff-base carboxylate-containing ligands, bis(2-pyridylmethyl)amino-3-propionic acid (Hpmpa) and bis(2-pyridylmethyl)amino-4-butyric acid (Hpmba), react with CuCl2 to give rise to the mononuclear complexes [Cu(Hpmpa)Cl]Cl · 2H2O (1) and [Cu(Hpmba)Cl2]· H2O (2). These complexes have been characterized by X-ray crystallography, spectroscopic and cyclic voltammetry. Crystal structure of (1) shows that the copper(II) ion has a distorted square-pyramidal geometry with the three nitrogen atoms

Ki-Young Choi; Yong-Man Jeon; Kyu-Chul Lee; Suk-Nam Choi; Moon-Won Kim; Hae-Hwan Lim; Moon-Jip Kim

2004-01-01

90

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

91

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

92

Metal based biologically active compounds: design, synthesis, and antibacterial/antifungal/cytotoxic properties of triazole-derived Schiff bases and their oxovanadium(IV) complexes.  

PubMed

A new series of oxovanadium(IV) complexes have been designed and synthesized with a new class of triazole Schiff bases derived from the reaction of 3,5-diamino-1,2,4-triazole with 2-hydroxy-1-naphthaldehyde, pyrrole-2-carboxaldehyde, pyridine-2-carboxaldehyde and acetyl pyridine-2-carboxaldehyde, respectively. Physical (magnetic susceptibility, molar conductance), spectral (IR, (1)H NMR, (13)C NMR, mass and electronic) and analytical data have established the structures of these synthesized Schiff bases and their oxovanadium(IV) complexes. The Schiff bases, predominantly act as bidentate and coordinate with the vanadium(IV) metal to give a stoichiometric ratio of 1:2 [M:L], forming a general formulae, [M(L-H)(2)] and [M(L)(2)]SO(4) where L = (L(1))-(L(4)) and M = VO(IV) of these complexes in a square-pyramidal geometry. In order to evaluate the biological activity of Schiff bases and to assess the role of vanadium(IV) metal on biological activity, the triazole Schiff bases and their oxovanadium(IV) complexes have been studied for in vitro antibacterial activity against four Gram-negative (Escherichia coli, Shigella flexenari, Pseudomonas aeruginosa, Salmonella typhi) and two Gram-positive (Staphylococcus aureus, Bacillus subtilis) bacterial strains, in vitro antifungal activity against Trichophyton longifucus, Candida albican, Aspergillus flavus, Microscopum canis, Fusarium solani and Candida glaberata. The simple Schiff bases showed weaker to significant activity against one or more bacterial and fungal strains. In most of the cases higher activity was exhibited upon coordination with vanadium(IV) metal. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina. PMID:20338672

Chohan, Zahid H; Sumrra, Sajjad H; Youssoufi, Moulay H; Hadda, Taibi B

2010-07-01

93

Cd(II) and Cu(II) complexes of polydentate Schiff base ligands: synthesis, characterization, properties and biological activity  

Microsoft Academic Search

We report the synthesis of the Schiff base ligands, 4-[(4-bromo-phenylimino)-methyl]-benzene-1,2,3-triol (A1), 4-[(3,5-di-tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,2,3-triol (A2), 3-(p-tolylimino-methyl)-benzene-1,2-diol (A3), 3-[(4-bromo-phenylimino)-methyl]-benzene-1,2-diol (A4), and 4-[(3,5-di-tert-butyl-4-hydroxy-phenylimino)-methyl]-benzene-1,3-diol (A5), and their Cd(II) and Cu(II) metal complexes, stability constants and potentiometric studies. The structure of the ligands and their complexes was investigated using elemental analysis, FT-IR, UV–Vis, 1H and 13C NMR, mass spectra, magnetic susceptibility and conductance measurements. In the

Aysegul Golcu; Mehmet Tumer; Havva Demirelli; R. Alan Wheatley

2005-01-01

94

A novel centrosymmetric dinuclear cadmium(II) Schiff base complex with unusual bridging carboxylate: Synthesis, crystal structure and luminescence properties  

NASA Astrophysics Data System (ADS)

A novel centrosymmetric dinuclear Cd(II) complex [CdL (CH 3COO)] 2 ( 1) has been synthesized by the reaction of Cd(CH 3COO) 2·2H 2O with a Schiff base ligand HL [HL = ( E)-2-((pyridin-2-yl)methyleneamino)benzoic acid]. Title complex has been systematically characterized by elemental analysis, FT-IR, and thermal studies. Single crystal X-ray structural analysis reveals that Cd(II) centers in 1 adopt distorted monocapped octahedral geometry and held together by rare doubly ?-2, 2 carboxylato bridging which is believed to be first relating to anthranilic carboxylate. At room temperature, compound in the solid state exhibits moderate photoluminescence activities indicating its potential as promising photoactive material.

Shit, Shyamapada; Chakraborty, Joy; Samanta, Brajagopal; Pilet, Guillaume; Mitra, Samiran

2009-02-01

95

Synthesis, characterization, electrochemical and biological studies on some metal(II) Schiff base complexes containing quinoxaline moiety  

NASA Astrophysics Data System (ADS)

Novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff base derived from quinoxaline-2,3-(1,4H)-dione and 4-aminoantipyrine (QDAAP) were synthesized. The ligand and its complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., mass and 1H NMR spectral studies. The X band ESR spectrum of the Cu(II) complex at 300 and 77 K were also recorded. Thermal studies of the ligand and its complexes show the presence of coordinated water in the Ni(II) and Zn(II) complexes. The coordination behavior of QDAAP is also discussed. All the complexes are mono nuclear and tetrahedral geometry was found for Co(II) complex. For the Ni(II) and Zn(II) complexes, octahedral geometry was assigned and for the Cu(II) complex, square planar geometry has been suggested. The grain size of the complexes was estimated using powder XRD. The surface morphology of the compounds was studied using SEM analysis. Electrochemical behavior of the synthesized complexes in DMF at room temperature was investigated by cyclic voltammetry. The in vitro biological screening of QDAAP and its metal complexes were tested against bacterial species Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The fungal species include Aspergillus niger, Aspergillus flavus and Candida albicans. The DNA cleavage activity of QDAAP and its complexes were also discussed.

Justin Dhanaraj, Chellaian; Johnson, Jijo

2014-01-01

96

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

97

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.

98

Synthesis, spectroscopic, cytotoxic aspects and computational study of N-(pyridine-2-ylmethylene)benzo[d]thiazol-2-amine Schiff base and some of its transition metal complexes  

NASA Astrophysics Data System (ADS)

N-(pyridine-2-ylmethylene)benzo[d]thiazol-2-amine Schiff base (L) and its Cu(II), Fe(III), Co(II), Ni(II) and Zn(II) complexes were synthesized and characterized by a set of chemical and spectroscopic measurements using elemental analysis, electrical conductance, mass spectra, magnetic susceptibility and spectral techniques (IR, UV-Vis, 1H NMR). Elemental and mass spectrometric data are consistent with the proposed formula. IR spectra confirm the bidentate nature of the Schiff base ligand. The octahedral geometry around Cu(II), Fe(III), Ni(II) and Zn(II) as well as tetrahedral geometry around Co(II) were suggested by UV-Vis spectra and magnetic moment data. The thermal degradation behavior of the Schiff base and its complexes was investigated by thermogravimetric analysis. The structure of the Schiff base and its transition metal complexes was also theoretically studied using molecular mechanics (MM+). The obtained structures were minimized with a semi-empirical (PM3) method. The in vitro antitumor activity of the synthesized compounds was studied. The Zn-complex exhibits significant decrease in surviving fraction of breast carcinoma (MCF 7), liver carcinoma (HEPG2), colon carcinoma (HCT116) and larynx carcinoma (HEP2) cell lines human cancer.

Abd El-Aziz, Dina M.; Etaiw, Safaa Eldin H.; Ali, Elham A.

2013-09-01

99

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

100

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]NO3·3H2O, 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 298–310?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

101

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

102

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; Gölcü, Ay?egül; Tümer, Mehmet

2010-07-01

103

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

104

Axial ligand exchange of N-heterocyclic cobalt(III) Schiff base complexes: molecular structure and NMR solution dynamics.  

PubMed

The kinetic and thermodynamic ligand exchange dynamics are important considerations in the rational design of metal-based therapeutics and therefore, require detailed investigation. Co(III) Schiff base complex derivatives of bis(acetylacetone)ethylenediimine [acacen] have been found to be potent enzyme and transcription factor inhibitors. These complexes undergo solution exchange of labile axial ligands. Upon dissociation, Co(III) irreversibly interacts with specific histidine residues of a protein, and consequently alters structure and causes inhibition. To guide the rational design of next generation agents, understanding the mechanism and dynamics of the ligand exchange process is essential. To investigate the lability, pH stability, and axial ligand exchange of these complexes in the absence of proteins, the pD- and temperature-dependent axial ligand substitution dynamics of a series of N-heterocyclic [Co(acacen)(X)(2)](+) complexes [where X = 2-methylimidazole (2MeIm), 4-methylimidazole (4MeIm), ammine (NH(3)), N-methylimidazole (NMeIm), and pyridine (Py)] were characterized by NMR spectroscopy. The pD stability was shown to be closely related to the nature of the axial ligand with the following trend toward aquation: 2MeIm > NH(3) ? 4MeIm > Py > Im > NMeIm. Reaction of each [Co(III)(acacen)(X)(2)](+) derivative with 4MeIm showed formation of a mixed ligand Co(III) intermediate via a dissociative ligand exchange mechanism. The stability of the mixed ligand adduct was directly correlated to the pD-dependent stability of the starting Co(III) Schiff base with respect to [Co(acacen)(4MeIm)(2)](+). Crystal structure analysis of the [Co(acacen)(X)(2)](+) derivatives confirmed the trends in stability observed by NMR spectroscopy. Bond distances between the Co(III) and the axial nitrogen atoms were longest in the 2MeIm derivative as a result of distortion in the planar tetradentate ligand, and this was directly correlated to axial ligand lability and propensity toward exchange. PMID:23282130

Manus, Lisa M; Holbrook, Robert J; Atesin, Tulay A; Heffern, Marie C; Harney, Allison S; Eckermann, Amanda L; Meade, Thomas J

2013-01-18

105

Synthesis, spectroscopic and thermal studies of some IIB group complexes with a new N2-Schiff base ligand.  

PubMed

Synthesis, spectroscopic and thermal studies of some complexes of a new N(2)-Schiff base ligand of N(1),N(2)-bis((E)-2-methyl-3-phenylallylidene)ethane-1,2-diamine (L) with a general formula of MLX(2) (M = Zn(II), Cd(II) and Hg(II); X = Cl(-), Br(-), I(-), SCN(-) and N(3)(-)) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-vis spectra, FT-IR spectra, MS, (1)H NMR and (13)C NMR spectra. The conductivity measurement as well as spectral data indicated that the complexes are non-electrolyte. (1)H and (13)C NMR spectra have been studied in DMSO-d(6) and/or CDCl(3). The thermal behavior of the complexes shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. Activation thermodynamic parameters of decomposition such as E*, ?H*, ?S* and ?G* were calculated from TG curves. PMID:21733744

Montazerozohori, Morteza; Khani, Sara; Tavakol, Hosein; Hojjati, Ahmad; Kazemi, Mostafa

2011-10-15

106

Spectral, electrochemical, thermal, DNA binding ability, antioxidant and antibacterial studies of novel Ru(III) Schiff base complexes.  

PubMed

Four new air stable low spin Ru(III) complexes of the type [Ru(L(1-4))(H2O)2]Cl have been synthesized, where L=dianion of the tetradentate Schiff base ligands namely N,N'bis(salicylaldehyde)4,5-dimethy-l,2-phenylendiammine (L(1)H2), N,N'bis(salicylaldehyde)4,5-dichloro 1,2-phenylendiammine (L(2)H2), N,N'bis(o-vanillin)4,5-dimethy-1,2-phenylendiammine (L(3)H2) and N,N'bis(o-vanillin)4,5-dichloro-1,2-phenylendiammine (L(4)H2). The complexes have been fully characterized by elemental analysis, infrared spectroscopy, electronic spectroscopy, magnetic susceptibility and electron spin resonance spectroscopy. Elemental analyses and spectroscopic data have been showed that, the stoichiometries of complexes were 1:1 with an octahedral geometry for all the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. The redox behavior of the complexes has been investigated by the cyclic voltammetric technique. The interaction of these complexes with calf thymus DNA (CT-DNA) was explored by different techniques which revealed that the complexes could bind to CT-DNA through an intercalative mode. Furthermore, the antioxidant activity of the Ru(III) complexes against superoxide and hydroxyl radicals was evaluated by using spectrophotometer methods in vitro. The experiments on antioxidant activity show that the complexes were found to possess potent antioxidant activity. Additionally, as a potential application the antibacterial activity of the complexes was assessed by testing their effect on the growth of various strains of bacteria. PMID:24508879

Abdel Aziz, Ayman A; Elbadawy, Hemmat A

2014-04-24

107

Synthesis, spectroscopic characterization, potentiometric studies, cytotoxic studies and molecular docking studies of DNA binding of transition metal complexes with 1,1-diaminopropane-Schiff base  

NASA Astrophysics Data System (ADS)

A new series of Schiff base transition metal complexes with N,N'-bis(2-hydroxybenzylidene)-1,1-diaminopropane (H2BHBDAP) have been prepared and characterized by elemental analysis, spectroscopic and magnetic measurements. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 °C and ionic strength 0.10 M sodium perchlorate. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. Additionally in silico, the Docking studies and the calculated pharmacokinetic parameters show promising futures for application of the ligand and complexes as high potency agents for DNA binding activity.

Alaghaz, Abdel-Nasser M. A.; El-Sayed, Badr A.; El-Henawy, Ahmed A.; Ammar, Reda A. A.

2013-03-01

108

New coordination compounds of some rare-earth metal complexes with sulfur and nitrogen Schiff bases and their in vitro antibacterial and antifungal properties  

Microsoft Academic Search

A series of rare-earth metal complexes with Schiff bases have been prepared by the interactions of hydrated lanthanide(III) chloride with the sodium salts of 1-(2-thienyl)ethanone hydrazinecarbothioamide (LH) and 1-(2-thienyl)ethanonehydrazinecarboxamide (LH) in 1:3 molar ratios and characterized by their elemental analyses, molar conductance and IR, NMR (H and C) electronic and EPR spectral studies. The spectral data suggested that the complexes

Ritu Singh; Krishna Sharma; R. V. Singh

2010-01-01

109

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

110

Nickel(II)-Schiff base complex recognizing domain II of bovine and human serum albumin: Spectroscopic and docking studies  

NASA Astrophysics Data System (ADS)

It has been spectroscopically monitored that a mononuclear nickel(II)-Schiff base complex {[NiL]·CH3OH = NSC} exhibits greater binding affinity for bovine serum albumin (BSA) than that of its human counterpart (HSA). Moreover the modes of binding of NSC with the two serum albumins also differ significantly. Docking studies predict a relatively rare type of 'superficial binding' of NSC at domain IIB of HSA with certain mobility whereas for BSA such phenomena has not been detected. The mobile nature of NSC at domain IIB of HSA has been well correlated with the spectroscopic results. It is to be noted that thermodynamic parameters for the NSC interaction also differ for the two serum albumins. Occurrence of energy transfer between the donor (Trp of BSA and HSA) and acceptor (NSC) has been obtained by means of Förster resonance energy transfer (FRET). The protein stability on NSC binding has also been experimented by the GuHCl-induced protein unfolding studies. Interestingly it has been found that NSC-HSA interaction enhances the protein stability whereas NSC-BSA binding has no such impact. Such observations are indicative of the fact that the conformation of NSC is responsible in recognizing the two serum albumins and selectively enhancing protein stability.

Ray, Aurkie; Koley Seth, Banabithi; Pal, Uttam; Basu, Samita

111

Nickel(II)-Schiff base complex recognizing domain II of bovine and human serum albumin: spectroscopic and docking studies.  

PubMed

It has been spectroscopically monitored that a mononuclear nickel(II)-Schiff base complex {[NiL]·CH(3)OH=NSC} exhibits greater binding affinity for bovine serum albumin (BSA) than that of its human counterpart (HSA). Moreover the modes of binding of NSC with the two serum albumins also differ significantly. Docking studies predict a relatively rare type of 'superficial binding' of NSC at domain IIB of HSA with certain mobility whereas for BSA such phenomena has not been detected. The mobile nature of NSC at domain IIB of HSA has been well correlated with the spectroscopic results. It is to be noted that thermodynamic parameters for the NSC interaction also differ for the two serum albumins. Occurrence of energy transfer between the donor (Trp of BSA and HSA) and acceptor (NSC) has been obtained by means of Förster resonance energy transfer (FRET). The protein stability on NSC binding has also been experimented by the GuHCl-induced protein unfolding studies. Interestingly it has been found that NSC-HSA interaction enhances the protein stability whereas NSC-BSA binding has no such impact. Such observations are indicative of the fact that the conformation of NSC is responsible in recognizing the two serum albumins and selectively enhancing protein stability. PMID:22446763

Ray, Aurkie; Seth, Banabithi Koley; Pal, Uttam; Basu, Samita

2012-06-15

112

Synthesis, spectroscopic characterization, DNA interaction and antibacterial study of metal complexes of tetraazamacrocyclic Schiff base  

NASA Astrophysics Data System (ADS)

The template condensation reaction between benzil and 3,4-diaminotoulene resulted mononuclear 12-membered tetraimine macrocyclic complexes of the type, [MLCl2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The synthesized complexes have been characterized on the basis of the results of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz. FT-IR, 1H and 13C NMR, FAB mass, UV-vis and EPR. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for Cu(II) complex. Low conductivity data of all these complexes suggest their non-ionic nature. The interactive studies of these complexes with calf thymus DNA showed that the complexes are avid binders of calf thymus DNA. The in vitro antibacterial studies of these complexes screened against pathogenic bacteria proved them as growth inhibiting agents.

Shakir, Mohammad; Khanam, Sadiqa; Firdaus, Farha; Latif, Abdul; Aatif, Mohammad; Al-Resayes, Saud I.

113

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; Koçak, Nuriye; Erdenay, Damla; Arslan, U?ur

2013-02-01

114

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]·2H2O·2CH3CN (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

115

Z .Bioelectrochemistry and Bioenergetics 48 1999 5359 Redox characteristics of Schiff base manganese and cobalt complexes  

E-print Network

.7 V vs. NHE suggests that this complex can catalyze the oxidation of water and can, thus, simulate manganese and cobalt complexes related to water-oxidizing complex of photosynthesis S. Hotchandani a,) , U 06500, Turkey c Institute of Soil Science and Photosynthesis, RAS, Pushchino, Moscow Region 142292

Carpentier, Robert

116

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

117

Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies.  

PubMed

Tetradentate N(2)O(2), N(4) Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N(4)O(2) Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, (1)H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated. PMID:22070996

Ismail, Tarek M A; Saleh, Akila A; El Ghamry, Mosad A

2012-02-01

118

Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies  

NASA Astrophysics Data System (ADS)

Tetradentate N 2O 2, N 4 Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N 4O 2 Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, 1H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated.

Ismail, Tarek M. A.; Saleh, Akila A.; Ghamry, Mosad A. El

2012-02-01

119

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

NASA Astrophysics Data System (ADS)

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, 1H- 13C 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 2O, 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 2O) 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.

Keskio?lu, Eren; Gündüzalp, Ayla Balaban; Çete, Servet; Hamurcu, Fatma; Erk, Birgül

2008-08-01

120

(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

121

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

122

Metal-pyrazolyl diazine interaction: Synthesis, structure and electrochemistry of binuclear transition metal(II) complexes derived from an ‘end-off’ compartmental Schiff base ligand  

Microsoft Academic Search

Pyrazolyl diazine (?-NN) bridged late first row transition metal(II) complexes have been prepared by the interaction of metal(II) chlorides with an ‘end-off’ compartmental Schiff base ligand. The ligand system has a strong diazine bridging component and obtained as a condensation product between 1H-pyrazole-3,5-dicarbohydrazide and 3-acetylcoumarin in absolute ethanol. All synthesized compounds are characterized on the basis of various spectral and

Srinivasa Budagumpi; Vidyanand K. Revankar

2010-01-01

123

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

PubMed

Four Schiff base ligands and their corresponding organotin(IV) complexes have been synthesized and characterized by elemental analyses, IR, (1)H 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. PMID:21741298

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

2011-10-15

124

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)3·3.5H2O (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

125

Recognition of oxalate by a copper(II) polyaza macrobicyclic complex.  

PubMed

A new polyamine macrobicyclic compound was synthesised through a [1+1] "tripod-tripod coupling" strategy and using a Schiff base condensation reaction, followed by sodium borohydride reduction. The resulting compound is a heteroditopic cage (btpN(7)) in which one of the head units is appropriate for the coordination of copper(II), whereas the other head is available for additional hydrogen-bonding and electrostatic interactions with substrates. The acid-base behaviour of the new compound, the stability constants of its complex with the Cu(2+) ion and the association constants of the copper(II) cryptate with oxalate (oxa(2-)), malonate (mal(2-)), succinate (suc(2-)), maleate (male(2-)) and fumarate (fum(2-)) were determined by potentiometry at 298.2 K in aqueous solution and at an ionic strength of 0.10 mol dm(-3) in KNO(3). These studies revealed a clear preference of the receptor [CuH(h)btpN(7)H(2)O]((2+h)+) for oxa(2-) over the other dicarboxylate substrates. This arises from co-operativity between metal-anion coordination and electrostatic and hydrogen-bonding interactions, in accordance with the ideal size of this dicarboxylate, which allow it to take full advantage of the potential binding sites of the receptor. A qualitative indicator-displacement study, in agreement with the potentiometric studies, demonstrated that the copper cryptate receptor can be used as a selective visual sensor for oxalate. PMID:21557358

Mateus, Pedro; Delgado, Rita; Brandão, Paula; Félix, Vítor

2011-06-14

126

The complexes between Schiff base of gossypol with L-phenylalanine methyl ester and some monovalent cations studied by 1H NMR, ESI MS, FT-IR as well as PM5 semi-empirical methods  

NASA Astrophysics Data System (ADS)

The Schiff base of racemic gossypol with L-phenylalanine methyl ester and its complexes with H + and monovalent metal cations was synthesized and studied by FT-IR, 1H NMR spectroscopy and Electrospray Ionization mass spectrometry as well as by the PM5 semi-empirical method. The studied Schiff base exists in acetonitrile solution in the enamine-enamine tautomeric form. After the protonation, the tautomeric form changes into the imine-imine one. For this form of the Schiff base the existence of diastereoisomers was very well visible in the 1H NMR spectra. The structures of the protonated Schiff base and its 1:1 complex with K + cation as well as the respective hydrogen bonds within these structures are discussed.

Przybylski, Piotr; Brzezinski, Bogumil

2003-06-01

127

Spectrophotometric studies of molecular complex formation between water-soluble cobalt(II) Schiff base complex and nucleotides in mixed solvent systems  

NASA Astrophysics Data System (ADS)

The formation constants for 1:1 molecular complex formation between water-soluble cobalt(II) tetradentate Schiff base complex, disodium[{bis(4-methoxy-5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na 2[Co(SO 3-4-meosal-4,5-dmophen)], and nucleotides, adenosine-5'-triphosphate (ATP) and cytidine-5'-triphosphate (CTP), in mixed solvent systems of ethanol and water with different volume fractions of ethanol and water have been determined spectrophotometrically at constant ionic strength ( I = 0.2 mol dm -3 NaClO 4) and temperature 278 K. Trends in the values of formation constants according to the volume fractions of ethanol and water in ethanol and water mixed solvent systems, suggest that the trend of molecular complex formation increases with increasing the volume fraction of ethanol in mixed solvent systems.

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2005-10-01

128

Design, characterization, teratogenicity testing, antibacterial, antifungal and DNA interaction of few high spin Fe(II) Schiff base amino acid complexes  

NASA Astrophysics Data System (ADS)

In this study, new Fe(II) Schiff base amino acid chelates derived from the condensation of o-hydroxynaphthaldehyde with L-alanine, L-phenylalanine, L-aspartic acid, L-histidine and L-arginine were synthesized and characterized via elemental, thermogravimetric analysis, molar conductance, IR, electronic, mass spectra and magnetic moment measurements. The stoichiometry and the stability constants of the complexes were determined spectrophotometrically. Correlation of all spectroscopic data suggested that Schiff bases ligands exhibited tridentate with ONO sites coordinating to the metal ions via protonated phenolic-OH, azomethine-N and carboxylate-O with the general formulae [Fe(HL)2]·nH2O. But in case of L-histidine, the ligand acts as tetradentate via deprotonated phenolic-OH, azomethine-N, carboxylate-O and N-imidazole ring ([FeL(H2O)2]·2H2O), where HL = mono anion and L = dianion of the ligand. The structure of the prepared complexes is suggested to be octahedral. The prepared complexes were tested for their teratogenicity on chick embryos and found to be safe until a concentration of 100 ?g/egg with full embryos formation. Moreover, the interaction between CT-DNA and the investigated complexes were followed by spectrophotometric and viscosity measurements. It was found that, the prepared complexes bind to DNA via classical intercalative mode and showed a different DNA activity with the sequence: nhi > nari > nali > nasi > nphali. Furthermore, the free ligands and their complexes are screened for their in vitro antibacterial and antifungal activity against three types of bacteria, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus and three types of anti fungal cultures, Penicillium purpurogenium, Aspergillus flavus and Trichotheium rosium in order to assess their antimicrobial potential. The results show that the metal complexes are more reactive with respect to their corresponding Schiff base amino acid ligands.

Abdel-Rahman, Laila H.; El-Khatib, Rafat M.; Nassr, Lobna A. E.; Abu-Dief, Ahmed M.; Lashin, Fakhr El-Din

2013-07-01

129

Design, characterization, teratogenicity testing, antibacterial, antifungal and DNA interaction of few high spin Fe(II) Schiff base amino acid complexes.  

PubMed

In this study, new Fe(II) Schiff base amino acid chelates derived from the condensation of o-hydroxynaphthaldehyde with L-alanine, L-phenylalanine, L-aspartic acid, L-histidine and L-arginine were synthesized and characterized via elemental, thermogravimetric analysis, molar conductance, IR, electronic, mass spectra and magnetic moment measurements. The stoichiometry and the stability constants of the complexes were determined spectrophotometrically. Correlation of all spectroscopic data suggested that Schiff bases ligands exhibited tridentate with ONO sites coordinating to the metal ions via protonated phenolic-OH, azomethine-N and carboxylate-O with the general formulae [Fe(HL)2]·nH2O. But in case of L-histidine, the ligand acts as tetradentate via deprotonated phenolic-OH, azomethine-N, carboxylate-O and N-imidazole ring ([FeL(H2O)2]·2H2O), where HL=mono anion and L=dianion of the ligand. The structure of the prepared complexes is suggested to be octahedral. The prepared complexes were tested for their teratogenicity on chick embryos and found to be safe until a concentration of 100 ?g/egg with full embryos formation. Moreover, the interaction between CT-DNA and the investigated complexes were followed by spectrophotometric and viscosity measurements. It was found that, the prepared complexes bind to DNA via classical intercalative mode and showed a different DNA activity with the sequence: nhi>nari>nali>nasi>nphali. Furthermore, the free ligands and their complexes are screened for their in vitro antibacterial and antifungal activity against three types of bacteria, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus and three types of anti fungal cultures, Penicillium purpurogenium, Aspergillus flavus and Trichotheium rosium in order to assess their antimicrobial potential. The results show that the metal complexes are more reactive with respect to their corresponding Schiff base amino acid ligands. PMID:23665616

Abdel-Rahman, Laila H; El-Khatib, Rafat M; Nassr, Lobna A E; Abu-Dief, Ahmed M; Lashin, Fakhr El-Din

2013-07-01

130

Accommodation of Mn II, Mn III-N, O, O, O-donor Schiff base complexes in zeolite-Y: Synthesis, structural studies and CO adsorption  

NASA Astrophysics Data System (ADS)

Manganese (II)-, (III)-complexes with NO 3 Schiff base ligand (SPAB) derived from salicylaldehyde and p-aminobenzoic acid have been synthesized and immobilized in the zeolite-Y supercages by a flexible ligand method. The synthesized new host/guest materials have been characterized by various physicochemical techniques, in addition to surface area measurements and nitrogen adsorption studies. Investigation of the stereochemistry of these incorporated chelates elucidated that, Mn(II) complex is tetrahedral with involvement of zeolite oxygen in coordination meanwhile Mn(III) complex has octahedral configuration with Jahn-Teller distortion but without contribution of the lattice oxygen. The intrazeolitic Schiff base complexes are thermally stable up to ?600 °C without any decomposition. Catalytic activity towards CO adsorption for zeolite-encapsulated complexes has been investigated and compared with Mn II-Y using in situ FT-IR spectroscopy. The results pointed out that, encapsulation of manganese (II, III) complexes in zeolites enhances remarkably the selectivity towards the formation of unionized carboxyl (-COOH) species which is considered a characteristic property of the zeolite encapsulated Mn(II,III)-SPAB complexes over Mn II-Y. On the other hand, the in situ FT-IR data demonstrate that Mn II(SPAB)/Y and Mn III(SPAB)/Y can be used as reactive catalysts in water gas shift reaction (WGSR).

Ahmed, Ayman H.; El-Bahy, Zeinhom M.; Salama, Tarek M.

2010-04-01

131

Synthesis, Characterization, Antimicrobial, DNA Cleavage, and Antioxidant Studies of Some Metal Complexes Derived from Schiff Base Containing Indole and Quinoline Moieties  

PubMed Central

A new Schiff base of 5-chloro-3-phenyl-1H-indole-2-carboxyhydrazide and 3-formyl-2-hydroxy-1H-quinoline (HL), and its Cu(II), Co(II), Ni(II), Zn(II), Cd(II), and Hg(II) complexes have been synthesized and characterized in the light of microanalytical, IR, H1 NMR, UV-Vis, FAB-mass, ESR, XRD, and TGA spectral studies. The magnetic susceptibility measurements and low conductivity data provide evidence for monomeric and neutral nature of the complexes. On the basis of spectral studies and analytical data, it is evident that the Schiff base acts as tridentate ligand. The Cu(II), Co(II), and Ni(II) complexes were octahedral, whereas Zn(II), Cd(II), and Hg(II) complexes were tetrahedral in nature. The redox behavior of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. 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 cleavage experiment performed using agarose gel electrophoresis method showed the cleavage of DNA by all the metal complexes. The free radical scavenging activity of newly synthesized compounds has been determined at a different concentration range by means of their interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). PMID:24194692

Karekal, Mahendra Raj; Biradar, Vivekanand; Bennikallu Hire Mathada, Mruthyunjayaswamy

2013-01-01

132

DNA interaction, antimicrobial, electrochemical and spectroscopic studies of metal(II) complexes with tridentate heterocyclic Schiff base derived from 2?-methylacetoacetanilide  

NASA Astrophysics Data System (ADS)

A new Schiff base ligand (HL) was synthesized by the condensation reaction between 2'-methyleacetoacetanilide and 2-amino-3-hydroxypyridine. Its Co(II), Ni(II), Cu(II) and Zn(II) complexes were prepared by the interaction of the ligand with metal(II) chloride. They were characterized by elemental analysis, IR, 1H NMR, EPR, UV-Vis, magnetic susceptibility measurements, conductivity measurements and FAB-mass spectra. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by UV absorption, viscosity and cyclic voltammetry methods, and the mode of CT-DNA binding to the complexes has been explored. Furthermore, the DNA cleavage activity by the complexes was performed. It was found to be oxidative hydroxyl radical cleavage in the presence of 3-mercaptopropionic acid (MPA). The Schiff base and its complexes have been screened for their antibacterial ( Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal ( Aspergillus niger, Rhizopus stolonifer, Rhizoctonia bataicola and Candida albicans) activities and the data reveal that the complexes have higher activity than the free ligand.

Raman, Natarajan; Pothiraj, Krishnan; Baskaran, Thanasekaran

2011-08-01

133

Synthesis, crystal structure and interaction of L-valine Schiff base divanadium(V) complex containing a V2O3 core with DNA and BSA  

NASA Astrophysics Data System (ADS)

A divanadium(V) complex, [V2O3(o-van-val)2] (o-van-val = Schiff base derived from o-vanillin and L-valine), has been synthesized and structurally characterized. The crystal structure shows that both of the vanadium centers in the complex have a distorted octahedral coordination environment composed of tridentate Schiff base ligand. A V2O3 core in molecular structure adopts intermediate between cis and trans configuration with the O1dbnd V1⋯V1Adbnd O1A torsion angle 115.22 (28)° and the V1⋯V1A distance 3.455 Å. The binding properties of the complex with calf thymus DNA (CT-DNA) have been investigated by UV-vis absorption, fluorescence, CD spectra and viscosity measurement. The results indicate that the complex binds to CT-DNA in non-classical intercalative mode. Meanwhile, the interaction of the complex with bovine serum albumin (BSA) has been studied by UV-vis absorption, fluorescence and CD spectra. Results indicated that the complex can markedly quench the intrinsic fluorescence of BSA via a static quenching process, and cause its conformational change. The calculated apparent binding constant Kb was 1.05 × 106 M-1 and the binding site number n was 1.18.

Guo, Qiong; Li, Lianzhi; Dong, Jianfang; Liu, Hongyan; Xu, Tao; Li, Jinghong

2013-04-01

134

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

135

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

136

Synthesis and characterizations of NiO nanoparticles via solid-state thermal decomposition of nickel(II) Schiff base complexes  

NASA Astrophysics Data System (ADS)

To raise the need of new precursors in the synthesis of NiO nanoparticles, mononuclear nickel(II) Schiff base complexes, viz. Ni(salbn) and Ni(Me2-salpn), were employed as precursor in solid-state thermal decomposition. Structure, purity and morphology of these nanoparticles have been examined by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy (TEM). TEM analysis reveals that the synthesized nanoparticles have cubic particles with an average diameter of around 5-15 nm. This method is simple, less costly, and fast and safe for production of NiO nanoparticles in industrial applications.

Khalaji, Aliakbar Dehno; Das, Debasis

2014-08-01

137

Antifungal Activities of Biorelevant Complexes of Copper(II) with Biosensitive Macrocyclic Ligands.  

PubMed

Four copper(II) complexes have been prepared using macrocyclic ligands. The macrocyclic ligands have been synthesized by the condensation reaction of diethyl phthalate with Schiff bases derived from o-phenylene diamine and Knoevenagel condensed ?-ketoanilides (obtained by the condensation of acetoacetanilide and substituted benzaldehydes). The ligands and copper complexes have been characterized on the basis of Microanalytical, Mass, UV-Vis., IR and CV spectral studies, as well as conductivity data. On the basis of spectral studies, a square-planar geometry for the copper complexes has been proposed. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans. All the synthesized copper complexes showed stronger antifungal activities than free ligands. The minimum inhibitory concentrations (MIC) of the copper complexes were found in the range of 8~28 µg/ml. These compounds represent a novel class of metal-based antifungal agents which provide opportunities for a large number of synthetic variations for modulation of the activities. PMID:24039502

Raman, N; Joseph, J; Velan, A Senthil Kumara; Pothiraj, C

2006-12-01

138

Antifungal Activities of Biorelevant Complexes of Copper(II) with Biosensitive Macrocyclic Ligands  

PubMed Central

Four copper(II) complexes have been prepared using macrocyclic ligands. The macrocyclic ligands have been synthesized by the condensation reaction of diethyl phthalate with Schiff bases derived from o-phenylene diamine and Knoevenagel condensed ?-ketoanilides (obtained by the condensation of acetoacetanilide and substituted benzaldehydes). The ligands and copper complexes have been characterized on the basis of Microanalytical, Mass, UV-Vis., IR and CV spectral studies, as well as conductivity data. On the basis of spectral studies, a square-planar geometry for the copper complexes has been proposed. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans. All the synthesized copper complexes showed stronger antifungal activities than free ligands. The minimum inhibitory concentrations (MIC) of the copper complexes were found in the range of 8~28 µg/ml. These compounds represent a novel class of metal-based antifungal agents which provide opportunities for a large number of synthetic variations for modulation of the activities. PMID:24039502

Joseph, J.; Velan, A. Senthil Kumara; Pothiraj, C.

2006-01-01

139

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

NASA Astrophysics Data System (ADS)

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

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2007-07-01

140

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

141

Spectroscopic and biological activities studies of bivalent transition metal complexes of Schiff bases derived from condensation of 1,4-phenylenediamine and benzopyrone derivatives.  

PubMed

Many tools of analysis such as elemental analyses, infrared, ultraviolet-visible, electron spin resonance (ESR) and thermal analysis, as well as conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared Co(II), Ni(II) and Cu(II) complexes with Schiff bases derived from the condensation of 1,4-phenylenediamine with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzo-pyran-4-one (H2L) or 5,7-dihydroxy-6-formyl-2-methylbenzopyran-4-one (H4L). The data showed that all formed complexes are 1:1 or 2:2 (M:L) and non-electrolyte chelates. The Co(II) and Cu(II) complexes of the two Schiff bases were screened for antibacterial activities by the disk diffusion method. The antibacterial activity was screened using Escherichia coli and Staphylococcus capitis but the antifungal activity was examined by using Aspergillus flavus and Candida albicans. The Results showed that the tested complexes have antibacterial, except CuH4L, but not antifungal activities. PMID:24025671

Sherif, Omaima E; Abdel-Kader, Nora S

2014-01-01

142

Synthesis, spectroscopic and biological activities studies of acyclic and macrocyclic mono and binuclear metal complexes containing a hard-soft Schiff base  

NASA Astrophysics Data System (ADS)

Mono- and bi-nuclear acyclic and macrocyclic complexes with hard-soft Schiff base, H2L, ligand derived from the reaction of 4,6-diacetylresorcinol and thiocabohydrazide, in the molar ratio 1:2 have been prepared. The H2L ligand reacts with Co(II), Ni(II), Cu(II), Zn(II), Mn(II) and UO2(VI) nitrates, VO(IV) sulfate and Ru(III) chloride to get acyclic binuclear complexes except for VO(IV) and Ru(III) which gave acyclic mono-nuclear complexes. Reaction of the acyclic mono-nuclear VO(IV) and Ru(III) complexes with 4,6-diacetylresorcinol afforded the corresponding macrocyclic mono-nuclear VO(IV) and Ru(IIII) complexes. Template reactions of the 4,6-diacetylresorcinol and thiocarbohydrazide with either VO(IV) or Ru(III) salts afforded the macrocyclic binuclear VO(IV) and Ru(III) complexes. The Schiff base, H2L, ligand acts as dibasic with two NSO-tridentate sites and can coordinate with two metal ions to form binuclear complexes after the deprotonation of the hydrogen atoms of the phenolic groups in all the complexes, except in the case of the acyclic mononuclear Ru(III) and VO(IV) complexes, where the Schiff base behaves as neutral tetradentate chelate with N2S2 donor atoms. The ligands and the metal complexes were characterized by elemental analysis, IR, UV-vis 1H-NMR, thermal gravimetric analysis (TGA) and ESR, as well as the measurements of conductivity and magnetic moments at room temperature. Electronic spectra and magnetic moments of the complexes indicate the geometries of the metal centers are either tetrahedral, square planar or octahedral. Kinetic and thermodynamic parameters were calculated using Coats-Redfern equation, for the different thermal decomposition steps of the complexes. The ligands and the metal complexes were screened for their antimicrobial activity against Staphylococcus aureus as Gram-positive bacteria, and Pseudomonas fluorescens as Gram-negative bacteria in addition to Fusarium oxysporum fungus. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

Abou-Hussein, Azza A. A.; Linert, Wolfgang

143

Synthesis, characterization and catalytic oxidation of para-xylene by a manganese(III) Schiff base complex on functionalized multi-wall carbon nanotubes (MWNTs).  

PubMed

In the present study, hydroxyl functionalized manganese(III) Schiff-base; [Mn((OH)(2)-salophen)Cl] [(OH)(2)-salophen] = (N,N'-bis(4-hydroxysalicylidene)phenylene-1,2-diamine); has been covalently anchored on modified multi-wall carbon nanotubes (MWNTs); [Mn((OH)(2)-salophen)Cl]@MWNTs]. The new modified MWNTs have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), thermal analysis, FT-IR spectroscopy and elemental analysis. The results suggest that the symmetrical Schiff-base is a bivalent anion with tetradentate N(2)O(2) donors derived from the phenolic oxygen and azomethine nitrogen. 4-Hydroxy salophen; [(OH)(2)-salophen], complex of manganese, grafted on the walls of MWNTs have been investigated as catalysts for the aerobic oxidation of para-xylene in the absence of added halogen promoters and using tert-butylhydroperoxide (TBHP) as the initiator at low temperatures. The major products include toluic acid, toluyl aldehyde and toluyl alcohol. The MWNTs-grafted complex did not undergo any colour change during the reaction and could be easily separated and reused many times. In contrast, the neat complex, while they were active in the first cycle, was completely destroyed during the run and changed colour. They, however, gave lower conversions compared to the grafted catalyst. PMID:20601980

Salavati-Niasari, Masoud; Davar, Fatemeh; Bazarganipour, Mehdi

2010-08-21

144

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) 3·2H 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

145

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)2·H2O. 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

146

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

NASA Astrophysics Data System (ADS)

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)2·H2O. 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.

Ali, Omyma A. M.

2014-11-01

147

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

148

Synthesis and characterization of some new Schiff base complexes of group 13 elements, ab initio studies, cytotoxicity and reaction with hydrogen peroxide  

NASA Astrophysics Data System (ADS)

A novel tetradentate Schiff base, naphthabza-H2 = N,N'-bis(naphthylidene)-2-aminobenzylamine, and a series of aluminum(III), gallium(III), and indium(III) complexes with general formula, MLNO3, were synthesized and characterized by elemental analysis, 1H NMR, FT-IR, UV-Vis spectroscopy and thermogravimetric method. The product of the reaction of complexes with hydrogen peroxide was characterized by similar techniques. According to the ab initio calculations aluminum and gallium complexes have five-coordinated structures and indium complex is a six-coordinated one. Also, the growth inhibitory effects of the complexes toward K562 cancer cell line were measured and the results for these complexes are as follows: Al > Ga > In.

Asadi, Mozaffar; Savaripoor, Nooshin; Asadi, Zahra; Ghatee, Mohammad Hadi; Moosavi, Fatemeh; Yousefi, Reza; Jamshidi, Mehrnaz

2013-01-01

149

A cyclic voltammetry investigation of the complex formation between Cu 2+ and some Schiff bases in binary acetonitrile/dimethylformamide mixtures  

NASA Astrophysics Data System (ADS)

The complex formation between Cu 2+ ions and some Schiff base ligands was studied in binary solvent mixtures of acetonitrile (AN)/dimethylformamide (DMF) systems at 25 °C using the cyclic voltammetric technique. The stoichiometry and stability of the complexes were determined by monitoring the shift in the half-wave potential of the CV peaks of the copper against the ligands concentration. The stoichiometry of all the complexes was found to be 1:1 and the complexation constants increased with decreasing amounts of dimethylformamide in these binary systems. In all cases, the variation of the stability constant with composition of the solvents was monotonic and showed good correlation with the inherent solvation ability of the neat solvents which form the mixture.

Rahimi-Nasrabadi, M.; Ganjali, M. R.; Gholivand, M. B.; Ahmadi, F.; Norouzi, P.; Salavati-Niasari, M.

2008-08-01

150

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

151

Synthesis, characterization, equilibrium study and biological activity of Cu(II), Ni(II) and Co(II) complexes of polydentate Schiff base ligand  

NASA Astrophysics Data System (ADS)

Schiff base ligand, 1,4-bis[(2-hydroxybenzaldehyde)propyl]piperazine (BHPP), and its Cu(II), Ni(II) and Co(II) metal complexes were synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance and spectral (IR and UV-vis) studies. The ground state of BHPP ligand was investigated using the BUILDER module of MOE. Metal complexes are formed in the 1:1 (M:L) ratio as found from the elemental analysis and found to have the general formula [ML]·nH2O, where M = Co(II), Ni(II) and Cu(II), L = BHPP. In all the studied complexes, the (BHPP) ligand behaves as a hexadentate divalent anion with coordination involving the two azomethine nitrogen's, the two nitrogen atoms of piperazine ring and the two deprotonated phenolic OH-groups. The magnetic and spectral data indicates octahedral geometry of metal(II) complexes. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. They were found to be more active against Gram-positive than Gram-negative bacteria. Protonation constants of (BHPP) ligand and stability constants of its Cu2+, Co2+ and Ni2+ complexes were determined by potentiometric titration method in 50% DMSO-water solution at ionic strength of 0.1 M sodium nitrate. It has been observed that the protonated Schiff base ligand (BHPP) have four protonation constants. The divalent metal ions Cu2+, Ni2+ and Co2+ form 1:1 complexes.

El-Sherif, Ahmed A.; Shehata, Mohamed R.; Shoukry, Mohamed M.; Barakat, Mohammad H.

2012-10-01

152

Synthesis, characterization, equilibrium study and biological activity of Cu(II), Ni(II) and Co(II) complexes of polydentate Schiff base ligand.  

PubMed

Schiff base ligand, 1,4-bis[(2-hydroxybenzaldehyde)propyl]piperazine (BHPP), and its Cu(II), Ni(II) and Co(II) metal complexes were synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance and spectral (IR and UV-vis) studies. The ground state of BHPP ligand was investigated using the BUILDER module of MOE. Metal complexes are formed in the 1:1 (M:L) ratio as found from the elemental analysis and found to have the general formula [ML]·nH(2)O, where M=Co(II), Ni(II) and Cu(II), L=BHPP. In all the studied complexes, the (BHPP) ligand behaves as a hexadentate divalent anion with coordination involving the two azomethine nitrogen's, the two nitrogen atoms of piperazine ring and the two deprotonated phenolic OH-groups. The magnetic and spectral data indicates octahedral geometry of metal(II) complexes. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. They were found to be more active against Gram-positive than Gram-negative bacteria. Protonation constants of (BHPP) ligand and stability constants of its Cu(2+), Co(2+) and Ni(2+) complexes were determined by potentiometric titration method in 50% DMSO-water solution at ionic strength of 0.1 M sodium nitrate. It has been observed that the protonated Schiff base ligand (BHPP) have four protonation constants. The divalent metal ions Cu(2+), Ni(2+) and Co(2+) form 1:1 complexes. PMID:22935596

El-Sherif, Ahmed A; Shehata, Mohamed R; Shoukry, Mohamed M; Barakat, Mohammad H

2012-10-01

153

Synthesis, spectral, crystallography and thermal investigations of novel Schiff base complexes of manganese (III) derived from heterocyclic ?-diketone with aromatic and aliphatic diamine  

NASA Astrophysics Data System (ADS)

The Schiff base tetradentate ligands N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H 2L 1), N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H 2L 2), N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H 2L 3) and N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H 2L 4) were prepared from the reaction between 5-oxo-3-methyl-1-p-tolyl-1H-pyrazole-4-carbaldehyde or 4-(4-formyl-5-oxo-3-methyl-pyrazol-1-yl)-benzenesulfonic acid and o-phenylenediamine or ethylenediamine. And these are characterized by elemental analysis, FT-IR, 1H NMR and GC-MS. The corresponding Schiff base complexes of Mn(III) were prepared by condensation of [Mn 3(? 3-O)(OAc) 6(H 2O) 3]·3H 2O with ligands H 2L 1, H 2L 2, H 2L 3 and H 2L 4. All these complexes have been characterized by elemental analysis, magnetic susceptibility, X-ray crystallography, conductometry measurement, FT-IR, electronic spectra and mass (FAB) spectrometry. Thermal behaviour of the complexes has been studied by TGA, DTA and DSC. Electronic spectra and magnetic susceptibility measurements indicate octahedral stereochemistry of manganese (III) complexes, while non-electrolytic behaviour complexes indicate the absence of counter ion.

Surati, Kiran R.; Thaker, B. T.

2010-01-01

154

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

155

Syntheses, Crystal Structures and Kinetic Mechanisms of Thermal Decomposition of Rare Earth Complexes with Schiff Base Derived from o-Vanillin and p-Toluidine  

Microsoft Academic Search

Three complexes, [Pr(NO3)3(HL)2] (1), [Nd(NO3)3(HL)2] (2) and [Er(NO3)3(HL)2]·0.5H2O (3), were synthesized from the reaction of a Schiff base ligand 2-[(4-methylphenylimino) methyl]-6-methoxyphenol (C15H15NO2, HL) with Ln(NO3)3·6H2O (Ln = Pr, Nd, Er). Characterization by single-crystal X-ray diffraction technique, elemental analysis, molar conductance, FT-IR, UV-Vis, 1H NMR and thermal analysis shows the title complexes are neutral molecules where the central Ln(III) ion is

Guoliang Zhao; Yunlong Feng; Yihang Wen

2006-01-01

156

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

157

Syntheses, Characterizations, Crystal Structures and Antibacterial Activities of Two Zinc(II) Complexes with a Schiff Base Derived from o-Vanillin and p-Toluidine  

Microsoft Academic Search

Two new zinc(II) complexes, (Zn2L2Cl4)·2(ZnL(CH3OH)Cl2) 1 and (ZnL2(NO3)2) 2, were synthesized by reacting ZnX2·nH2O (X = Cl - , NO3 - ) and a Schiff base ligand 2-((4-me- thylphenylimino)methyl)-6-methoxyphenol (C15H15NO2, L) which was obtained by the condensation of o-vanillin (2-hydroxy-3-methoxybenzaldehyde) with p-toluidine. Both 1 and 2 were characterized by single-crystal X-ray diffraction technique, elemental analysis, molar conductance, FT-IR, UV-Vis, 1

YU Yu-Yea; ZHAO Guo-Liang; WEN Yi-Hang

158

Polymeric membrane sensors based on Cd(II) Schiff base complexes for selective iodide determination in environmental and medicinal samples.  

PubMed

The two cadmium chelates of schiff bases, N,N'-bis(salicylidene)-1,4-diaminobutane, (Cd-S(1)) and N,N'-bis(salicylidene)-3,4-diaminotoluene (Cd-S(2)), have been synthesized and explored as ionophores for preparing PVC-based membrane sensors selective to iodide(I) ion. Potentiometric investigations indicate high affinity of these receptors for iodide ion. Polyvinyl chloride (PVC)-based membranes of Cd-S(1) and Cd-S(2) using as hexadecyltrimethylammonium bromide (HTAB) cation discriminator and o-nitrophenyloctyl ether (o-NPOE), dibutylphthalate (DBP), acetophenone (AP) and tributylphosphate (TBP) as plasticizing solvent mediators were prepared and investigated as iodide-selective sensors. The best performance was shown by the membrane of composition (w/w) of (Cd-S(1)) (7%):PVC (31%):DBP (60%):HTAB (2%). The sensor works well over a wide concentration range 5.3x10(-7) to 1.0x10(-2)M with Nernstian compliance (59.2mVdecade(-1) of activity) within pH range 2.5-9.0 with a response time of 11s and showed good selectivity for iodide ion over a number of anions. The sensor exhibits adequate life (3 months) with good reproducibility (S.D.+/-0.24mV) and could be used successfully for the determination of iodide content in environmental water samples and mouth wash samples. PMID:18371713

Singh, Ashok Kumar; Mehtab, Sameena

2008-01-15

159

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  

NASA Astrophysics Data System (ADS)

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, 1H NMR, and 13C NMR. Particle sizes of synthesized compounds were measured with dynamic light scattering (DLS) analyser which indicates that particle diameter are of the range ca. 100-200 nm. 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.

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

2013-09-01

160

Synthesis, spectroscopic, photoluminescence properties and biological evaluation of novel Zn(II) and Al(III) complexes of NOON tetradentate Schiff bases  

NASA Astrophysics Data System (ADS)

Novel mononuclear Zn(II) and Al(III) complexes were synthesized from the reactions of Zn(OAc)2·2H2O and anhydrous AlCl3 with neutral N2O2 donor tetradentate Schiff bases; N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L1) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L2). The new complexes were fully characterized by using micro analyses (CHN), FT-IR, 1H NMR, UV-Vis spectra and thermal analysis. The analytical data have been showed that, the stoichiometry of the complexes is 1:1. Spectroscopic data suggested tetrahedral and square pyramidal geometries for Zn(II) and Al(III) complexes, respectively. The synthesized Zn(II), and Al(III) complexes exhibited intense fluorescence emission in the visible region upon UV-excitation in methylene chloride solution at ambient temperature. This high fluorescence emission was assigned to the strong coordination of the ligands to the small and the highly charged Zn(II) and Al(III) ions. Such strong coordination seems to extend the ?-conjugation of the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. As a potential application the biological activity (e.g., antimicrobial action) of the prepared ligands and complexes was assessed by in-vitro testing of their effect on the growth of various strains of bacteria and fungi.

Abdel Aziz, Ayman A.; Badr, Ibrahim H. A.; El-Sayed, Ibrahim S. A.

2012-11-01

161

Reactivity of nitrido complexes of ruthenium(VI), osmium(VI), and manganese(V) bearing Schiff base and simple anionic ligands.  

PubMed

Nitrido complexes (M?N) may be key intermediates in chemical and biological nitrogen fixation and serve as useful reagents for nitrogenation of organic compounds. Osmium(VI) nitrido complexes bearing 2,2':6',2?-terpyridine (terpy), 2,2'-bipyridine (bpy), or hydrotris(1-pyrazolyl)borate anion (Tp) ligands are highly electrophilic: they can react with a variety of nucleophiles to generate novel osmium(IV)/(V) complexes. This Account describes our recent results studying the reactivity of nitridocomplexes of ruthenium(VI), osmium(VI), and manganese(V) that bear Schiff bases and other simple anionic ligands. We demonstrate that these nitrido complexes exhibit rich chemical reactivity. They react with various nucleophiles, activate C-H bonds, undergo N···N coupling, catalyze the oxidation of organic compounds, and show anticancer activities. Ruthenium(VI) nitrido complexes bearing Schiff base ligands, such as [Ru(VI)(N)(salchda)(CH3OH)](+) (salchda = N,N'-bis(salicylidene)o-cyclohexyldiamine dianion), are highly electrophilic. This complex reacts readily at ambient conditions with a variety of nucleophiles at rates that are much faster than similar reactions using Os(VI)?N. This complex also carries out unique reactions, including the direct aziridination of alkenes, C-H bond activation of alkanes and C-N bond cleavage of anilines. The addition of ligands such as pyridine can enhance the reactivity of [Ru(VI)(N)(salchda)(CH3OH)](+). Therefore researchers can tune the reactivity of Ru?N by adding a ligand L trans to nitride: L-Ru?N. Moreover, the addition of various nucleophiles (Nu) to Ru(VI)?N initially generate the ruthenium(IV) imido species Ru(IV)-N(Nu), a new class of hydrogen-atom transfer (HAT) reagents. Nucleophiles also readily add to coordinated Schiff base ligands in Os(VI)?N and Ru(VI)?N complexes. These additions are often stereospecific, suggesting that the nitrido ligand has a directing effect on the incoming nucleophile. M?N is also a potential platform for the design of new oxidation catalysts. For example, [Os(VI)(N)Cl4](-) catalyzes the oxidation of alkanes by a variety of oxidants, and the addition of Lewis acids greatly accelerates these reactions. [Mn(V)(N)(CN)4]2(-) is another highly efficient oxidation catalyst, which facilitates the epoxidation of alkenes and the oxidation of alcohols to carbonyl compounds using H2O2. Finally, M?N can potentially bind to and exert various effects on biomolecules. For example, a number of Os(VI)?N complexes exhibit novel anticancer properties, which may be related to their ability to bind to DNA or other biomolecules. PMID:24047467

Man, Wai-Lun; Lam, William W Y; Lau, Tai-Chu

2014-02-18

162

Asymmetric synthesis of ?-amino acids via homologation of Ni(II) complexes of glycine Schiff bases; Part 1: alkyl halide alkylations.  

PubMed

Alkylations of chiral or achiral Ni(II) complexes of glycine Schiff bases constitute a landmark in the development of practical methodology for asymmetric synthesis of ?-amino acids. Straightforward, easy preparation as well as high reactivity of these Ni(II) complexes render them ready available and inexpensive glycine equivalents for preparing a wide variety of ?-amino acids, in particular on a relatively large scale. In the case of Ni(II) complexes containing benzylproline moiety as a chiral auxiliary, their alkylation proceeds with high thermodynamically controlled diastereoselectivity. Similar type of Ni(II) complexes derived from alanine can also be used for alkylation providing convenient access to quaternary, ?,?-disubstituted ?-amino acids. Achiral type of Ni(II) complexes can be prepared from picolinic acid or via recently developed modular approach using simple secondary or primary amines. These Ni(II) complexes can be easily mono/bis-alkylated under homogeneous or phase-transfer catalysis conditions. Origin of diastereo-/enantioselectivity in the alkylations reactions, aspects of practicality, generality and limitations of this methodology is critically discussed. PMID:23832533

Sorochinsky, Alexander E; Aceña, José Luis; Moriwaki, Hiroki; Sato, Tatsunori; Soloshonok, Vadim A

2013-10-01

163

Ligand influence over the formation of dinuclear [2+2] versus trinuclear [3+3] Cu(I) Schiff base macrocyclic complexes.  

PubMed

The preparation and characterization of three new macrocyclic ligands with pendant arms based on the [2+2] condensation of isophthalaldehyde and the corresponding triamine substituted at the central N-atom is reported. None of these new macrocyclic ligands undergo any equilibrium reaction, based on imine hydrolysis to generate [1+1] macrocyclic formation or higher oligomeric compounds, such as [3+3], [4+4], etc., at least within the time scale of days. This indicates the stability of the newly generated imine bond. In sharp contrast, the reaction of the [2+2] macrocyclic Schiff bases with Cu(I) generates the corresponding dinuclear Cu(I) complexes [Cu(2)(L(1))](2+), 1(2+); [Cu(2)(L(2))(CH(3)CN)(2)](2+), 2(2+); and [Cu(2)(L(3))(CH(3)CN)(2)](2+), 3(2+), together with their trinuclear Cu(I) homologues [Cu(3)(L(4))](3+), 4(3+); [Cu(3)(L(5))(CH(3)CN)(3)](3+), 5(3+); and [Cu(3)(L(6))(CH(3)CN)(3)](3+), 6(3+), where the [2+2] ligand has undergone an expansion to the corresponding [3+3] Schiff base that is denoted as L(4), L(5), or L(6). The conditions under which the dinuclear and trinuclear complexes are formed were analyzed in terms of solvent dependence and synthetic pathways. The new complexes are characterized in solution by NMR, UV-vis, and MS spectroscopy and in the solid state by X-ray diffraction analysis and IR spectroscopy. For the particular case of the L(2) ligand, MS spectroscopy is also used to monitor the metal assisted transformation where the dinuclear complex 2(2+) is transformed into the trinuclear complex 5(3+). The Cu(I) complexes described here, in general, react slowly (within the time scale of days) with molecular oxygen, except for the ones containing the phenolic ligands 2(2+) and 5(3+) that react a bit faster. PMID:21732585

Arbuse, Arnau; Mandal, Sukanta; Maji, Somnath; Martínez, Ma Angeles; Fontrodona, Xavier; Utz, Diana; Heinemann, Frank W; Kisslinger, Sandra; Schindler, Siegfried; Sala, Xavier; Llobet, Antoni

2011-08-01

164

Synthesis, spectral, electrochemical and biological studies of Co(II), Ni(II) and Cu(II) complexes with Schiff bases of 8-formyl-7-hydroxy-4-methyl coumarin  

Microsoft Academic Search

A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized with Schiff bases derived from 8-formyl-7-hydroxy-4-methyl coumarin and o-chloroaniline\\/o-toluidine. The structures of the complexes have been proposed from analytical, spectral (IR, UV-Vis, ESR and FAB-mass), magnetic, thermal and fluorescence studies. The complexes are soluble in DMF and DMSO and molar conductance values indicate the complexes are non-electrolytes. Elemental analyses

Ajaykumar Kulkarni; Prakash Gouda Avaji; Gangadhar B. Bagihalli; Sangamesh A. Patil; Prema S. Badami

2009-01-01

165

Reactivity of tris(acetylacetonato) iron(III) with tridentate [ONO] donor Schiff base as an access to newer mixed-ligand iron(III) complexes  

NASA Astrophysics Data System (ADS)

Two new mixed-ligand iron(III) complexes, [Fe(L n)(acac)(C 2H 5OH)] incorporating coordinated ethanol from the reaction solvent were accessed from the reaction of [Fe(acac) 3] with [ONO] donor dibasic tridentate unsymmetrical Schiff base ligands derived from condensation of 2-hydroxy-1-napthaldehyde with 2-aminophenol (H 2L 1) or 2-aminobenzoic acid (H 2L 2). The thermal study (TGA-DTA) provided evidence for weakly bound ethanol which is readily substituted by neutral N-donor molecule imidazole, benzimidazole or pyridine to produce an array of newer complexes, [Fe(L n)(acac)X] ( n = 1, 2; X = Im, Bim, Py). The compounds were characterized by elemental analyses, FT-IR, UV-vis, solution electrical conductivity, FAB mass, 1H and 13C NMR spectroscopy. Room temperature magnetic susceptibility measurements ( ?eff ˜ 5.8 B.M.) are consistent with spin-free octahedral iron(III) complexes. Cyclic voltammetry of ethanol complexes revealed a quasi-reversible one electron redox response (? Ep > 100 mV) for the Fe(III)/Fe(II) couple. Low half wave redox potential ( E1/2) values suggested easy redox susceptibility. The ground state geometries of the ethanol and imidazole complexes have been ascertained to be distorted octahedral by density functional theory using DMol3 program at BLYP/DNP level.

Bhattacharjee, Chira R.; Goswami, Pankaj; Pramanik, Harun A. R.; Paul, Pradip C.; Mondal, Paritosh

2011-05-01

166

Antioxidation and DNA-binding properties of binuclear lanthanide(III) complexes with a Schiff base ligand derived from 8-hydroxyquinoline-7-carboxaldehyde and benzoylhydrazine.  

PubMed

8-Hydroxyquinoline-7-carboxaldehyde (8-HQ-7-CA), Schiff-base ligand 8-hydroxyquinoline-7-carboxaldehyde benzoylhydrazone, and binuclear complexes [LnL(NO(3))(H(2)O)(2)](2) were prepared from the ligand and equivalent molar amounts of Ln(NO(3))·6H(2)O (Ln=La(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Dy(3+), Ho(3+), Er(3+), Yb(3+), resp.). Ligand acts as dibasic tetradentates, binding to Ln(III) through the phenolate O-atom, N-atom of quinolinato unit, and C=N and -O-C=N- groups of the benzoylhydrazine side chain. Dimerization of this monomeric unit occurs through the phenolate O-atoms leading to a central four-membered (LnO)(2) ring. Ligand and all of the Ln(III) complexes can strongly bind to CT-DNA through intercalation with the binding constants at 10(5)-10(6) M(-1). Moreover, ligand and all of the Ln(III) complexes have strong abilities of scavenging effects for hydroxyl (HO·) radicals. Both the antioxidation and DNA-binding properties of Ln(III) complexes are much better than that of ligand. PMID:22899614

Liu, Yongchun; Zhang, Kejun; Wu, Yun; Zhao, Junying; Liu, Jianning

2012-08-01

167

Effect of structure and composition of nickel(II) complexes with salicylidene Schiff base ligands on their DNA/protein interaction and cytotoxicity.  

PubMed

Three new salicylidene Schiff base nickel(II) complexes [Ni(L(1))(CH3COOH)2]2 (1), [Ni2(L(1))2(CH3OH)] (2), [Ni(L(2))2]·3H2O (3) {H2L(1)=N,N'-bis(salicylidene)-3,6-dioxa-1,8-diaminooctane, HL(2)=2-ethyl-2-(2-hydroxybenzylideneamino)propane-1,3-diol} were synthesized and characterized fully by structural, analytical, and spectral methods. The single-crystal X-ray structures of complexes 1 and 2 exhibit the symmetrical ligands coordinated to the nickel(II) ion in a tetradentate fashion via ONNO donor atoms, while the unsymmetrical ligand L(2) presented a ONO tridentate coordination mode in complex 3. The nickel(II) ions lie in the six-coordinated octahedral environment for the mononuclear complexes 1 and 3, along with dinuclear complex 2. The interaction of the complexes with calf thymus DNA (CT-DNA) has been explored by absorption and emission titration methods, which revealed that complexes 1-3 could interact with CT-DNA through intercalation. The interactions of the complexes with bovine serum albumin (BSA) were also investigated using UV-Vis, fluorescence and synchronous fluorescence spectroscopic methods. The results indicated that all of the complexes could quench the intrinsic fluorescence of BSA in a static quenching process. Further, the in vitro cytotoxic effect of the complexes examined on cancerous cell lines such as human lung carcinoma cell line (A549), human colon carcinoma cell lines (HCT-116), human promyelocytic leukemia cells (HL-60) and colonic cancer cell line Caco-2 showed that all three complexes exhibited substantial cytotoxic activity. PMID:24838006

Li, Peng; Niu, MeiJu; Hong, Min; Cheng, Shuang; Dou, JianMin

2014-08-01

168

Complexes of Schiff base of gossypol with 5-hydroxy-3-oxapentylamine and Ca 2+, Ba 2+ or Pb 2+ cations studied by NMR, FT-IR, ESI MS as well as PM5 semiempirical methods  

NASA Astrophysics Data System (ADS)

A new Schiff base of gossypol with 5-hydroxy-3-oxapentylamine (GSBH) has been found to complex bivalent metal cations, in particular Ca 2+, Ba 2+ and Pb 2+. This process of complex formation has been studied by ESI mass spectrometry, 1H, 13C NMR and FT-IR spectroscopy as well as by PM5 semiempirical method. It has been established that GSBH forms stable 1:1 complexes with all these cations. In all complexes the Schiff base of gossypol exists as the enamine-enamine tautomer. The Ca 2+, Ba 2+ cations are coordinated through oxygen atoms from the four hydroxyl groups, and Pb 2+ cation additionally also by two oxygen atoms from oxaalkyl chains. The structures of these complexes have been calculated by PM5 semiempirical method and discussed.

Przybylski, Piotr; Schroeder, Grzegorz; Brzezinski, Bogumil

2003-09-01

169

Cu(II), Co(II) and Ni(II) complexes of new Schiff base ligand: Synthesis, thermal and spectroscopic characterizations  

NASA Astrophysics Data System (ADS)

Cu(II), Co(II), and Ni(II) complexes were synthesized from 2-[(5-o-chlorophenylazo-2-hydroxybenzylidin)amino]-phenol Schiff base (H2L). Metal ions coordinate in a tetradentate or hexadentate features with these O2N donor ligand, which are characterized by elemental analyses, magnetic moments, infrared, Raman laser, electronic, and 1H NMR spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Reactions with Cu(II), Co(II) and Ni(II), resulted [Cu(H2L)(H2O)2(Cl)]Cl, [Co(H2L)(H2O)3]Cl2?3H2O and [Ni(H2L)(H2O)2]Cl2?6H2O. The thermal decomposition behavior of H2L complexes has been investigated by thermogravimetric analysis (TG/DTG) at a heating rate of 10 °C min-1 under nitrogen atmosphere. The brightness side in this study is to take advantage for the preparation and characterizations of single phases of CuO, CoO and NiO nanoparticles using H2L complexes as precursors via a solid-state decomposition procedure. The crystalline structures of products using X-ray diffractometer (XRD), morphology of particles by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) were investigated.

Refat, Moamen S.; El-Sayed, Mohamed Y.; Adam, Abdel Majid A.

2013-04-01

170

Four mu4-oxo-bridged copper(II) complexes: magnetic properties and catalytic applications in liquid phase partial oxidation reactions.  

PubMed

Four copper(II) complexes, [Cu(4)(O)(L(n))(2)(CH(3)COO)(4)] with N(2)O-donor Schiff-base ligands, where HL(1) = 4-methyl-2,6-bis(cyclohexylmethyliminomethyl)phenol for complex 1, HL(2) = 4-methyl-2,6-bis(phenylmethyliminomethyl)phenol for complex 2 x CH(3)CN, HL(3) = 4-methyl-2,6-bis(((3-tri-fluoromethyl)phenyl)methyliminomethyl)phenol for complex 3, HL(4) = 4-methyl-2,6-bis(((4-tri-fluoromethyl)phenyl)methyliminomethyl)phenol for complex 4, were synthesized and characterized by elemental analysis, FT-IR, UV-vis spectroscopy and finally by single crystal X-ray diffraction study. X-Ray analysis reveals that all of these are mu(4)-oxo-bridged tetrameric copper(II) complexes. Four copper atoms arrange themselves around an oxygen atom tetrahedrally. Magnetic susceptibility measurements show the existence of very strong antiferromagnetic coupling among these ions (J = -210.1 to -271.3 cm(-1)), mediated by the oxygen atoms. Catalysis of the epoxidation of cyclohexene, styrene, alpha-methylstyrene and trans-stilbene by these complexes has been carried out homogeneously as well as heterogeneously by immobilizing the metal complexes over 2D-hexagonal mesoporous silica. The results obtained in both the catalytic conditions show that the olefins are converted to the respective epoxides in good yield together with high selectivity. PMID:19859610

Roy, Partha; Nandi, Mahasweta; Manassero, Mario; Riccó, Mauro; Mazzani, Marcello; Bhaumik, Asim; Banerjee, Pradyot

2009-11-21

171

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

172

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

173

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

174

Interactions of Trivalent Lanthanide Cations with a New Hexadentate Di-Schiff Base: New Lanthanide(III) Complexes from (NE,N?E)-2,2?-(ethane-1,2-diylbis(oxy))bis(N-(pyridin-2-ylmethylene)ethanamine)  

PubMed Central

The novel lanthanide(III) complexes [Ln(NO3)2L](NO3)·3MeOH (Ln = La 1, Pr 2) and [Ln(NO3)3L](NO3)·2MeOH (Ln = Gd 3, Yb 4), where L = (NE,N?E)-2,2?-(ethane-1,2-diylbis(oxy))bis(N-(pyridin-2-ylmethylene)ethanamine), have been obtained by direct reaction of the Schiff base ligand and the corresponding hydrated lanthanide(III) nitrates in methanol. All complexes were characterized spectroscopically and thermogravimetrically. Complex 4 was also characterized with crystallographic studies: orthorhombic P212121, a = 10.6683(14), b = 13.4752(15), c = 19.3320(26) Å. In the molecular structure of 4, Yb(III) is surrounded by all donor atoms of the Schiff base (four nitrogen and two oxygen atoms) and four oxygen atoms belonging to two bidentate chelating nitrato ligands. PMID:20689704

Tsiouri, Mantha; Skorda, Konstantina; Papadimitriou, Christos; Li, Yang; Woollins, J. Derek; Plakatouras, John C.

2010-01-01

175

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

NASA Astrophysics Data System (ADS)

Two series of new binuclear complexes with Schiff base ligands, H 4L a or H 2L 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, 1H 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 4L a ligand behaves as a macrocyclic tetrabasic with two N 2O 2 sits, while the H 2L b ligand behaves as a dibasic with two N 2O sites. The H 4L a ligand is a compartmental ligand which hosts the two metal ions at the centers of two cis-N 2O 2 sites, while the metal complexes of H 2L b ligand are binuclear, where the ligand hosts two metal ions at the centers of two N 2O 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, 1H NMR, mass spectra, and thermal gravimetric analysis (TGA/DTA) as well as conductivity and magnetic moment measurements.

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

2006-07-01

176

Spectroscopic, thermal characterization and cytotoxic activity of bi-, tri- and tetra-nuclear Pd(II) and Pt(II) complexes with diSchiff base ligands  

NASA Astrophysics Data System (ADS)

In this paper; new di-, tri-, and tetra-nuclear Pd(II) and Pt(II) complexes of N,N?-bis(3,4-dihydroxybenzylidene)ethan-1,2-diamine (EDH4), N,N?-bis(3,4-dihydroxy-benzylidene)-benzene-1,2-diamine (PDH4) and N,N?-bis-(3,4-dihydroxybenzylidene)-4,5-dimethyl-1,2-diamine (MPDH4) ligands were synthesized by two different methods. The first method involve 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 Pd(II) or Pt(II) ions in the presence of 2,2?-dipyridyl (L) to form the di- and tri-nuclear metal complexes. The second method involve the condensation of the Pd complex LPd(II)L?, (L = 2,2?-dipyridyl, 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 PdCl2 to form di-, tri-, and tetra-nuclear palladium(II) complexes, respectively. Structures of ligands and metal complexes are characterized by physical properties, FT-IR spectra and nuclear magnetic resonance. The geometries of metal complexes are suggested according to elemental analysis, electronic absorption spectra, thermal analysis, atomic absorption, magnetic susceptibility and molar conductance. Cytotoxic activity against lung large cell carcinoma (H460), prostate carcinoma (DU145), breast adenocarcinoma (MCF-7), amelanotic melanoma (M-14), colon adenocarcinoma (HT-29), and chronic myelogenous leukemia (K562) is also reported.

Hegazy, Wael Hussein

2014-10-01

177

New poly-iron(II) complexes of N4O dinucleating Schiff bases and pseudohalides: syntheses, structures, and magnetic and Mössbauer properties.  

PubMed

Six dinuclear ferrous complexes including [Fe2(acpypentO)(O2CMe)(NCS)2] (1), [Fe2(acpypentO)(O2CMe)(NCSe)2] (2), [Fe2(acpypentO)(NCO)3] (3), ([Fe2(acpybutO)(O2CMe)(NCS)2] (5), [Fe2(acpybutO)(O2CMe)(NCO)2] (6), and [Fe2(acpybutO)(O2CMe)(N3)2] (7), one tetranuclear (bis-dinuclear) ferrous compound, [Fe4(acpypentO)2(N3)6] (4), and one mononuclear ferrous compound, [Fe(acpybutOH)(NCS)2] (8), have been prepared, and their structures and magnetic and Mössbauer properties have been studied (acpybutOH = 1,4-bis[[2-pyridyl(1-ethyl]imino)]butane-2-ol and acpypentOH = 1,5-bis[[2-pyridyl(1-ethyl]imino)]pentane-3-ol). The X-ray diffraction analyses yielded the following results: 1 (C23H26Fe2N6O3S2, monoclinic, P2(1)/n, a = 8.0380(7) A, b = 12.4495(8) A, c = 27.358(2) A, beta = 92.180(10) degrees, V = 2735.7(4) A(3), Z = 4) is a dinuclear species in which the unequivalent high-spin (HS) Fe(II) sites are bridged by the alkoxo oxygen atom of the symmetrical acpypentO- Schiff base and one syn-syn acetato anion; 3 (C22H23Fe2N7O4, triclinic, Ponemacr;, a = 8.4152(10) A, b = 9.1350(10) A, c = 17.666(2) A, alpha = 97.486(14) degrees, beta = 100.026(14) degrees, gamma = 113.510(13) degrees, V = 1195.9(2) A3, Z = 2) is a dinuclear species in which the unequivalent HS Fe(II) sites are bridged by the alkoxo oxygen atom of the symmetrical acpypentO- Schiff base and one end-on NCO anion; 4-MeOH (C39H50Fe4N26O3, triclinic, Ponemacr;, a = 9.1246(11) A, b = 10.2466(11) A, c = 14.928(2) A, alpha = 91.529(15) degrees, beta = 101.078(16) degrees, gamma = 106.341(14) degrees, V = 1309.6(3) A3, Z = 1) is a bis-dinuclear species in which the unequivalent HS Fe(II) sites are bridged by the alkoxo oxygen atom of the symmetrical acpypentO- Schiff base and one end-on N(3)(-) anion, and the symmetry related Fe(II) sites are bridged by two end-on N3- anions; 8-MeOH (C21H26FeN6O2S2, triclinic, Ponemacr;, a = 8.7674(9) A, b = 12.0938(13) A, c = 12.2634(14) A, alpha = 106.685(14) degrees, beta = 93.689(14) degrees, gamma = 108.508(13) degrees, V = 1163.7(2) A3, Z = 2) is a mononuclear species in which the octahedral low-spin (LS) Fe(II) site is in an N6 environment provided by the four N atoms of the protonated asymmetrical acpybutOH Schiff base and two thiocyanato anions. The Mössbauer spectra of all dinuclear species (1-3 and 5-7), and of the bis-dinuclear compound 4, evidence two distinct HS Fe(II) sites while the Mössbauer spectra of the mononuclear compound 8 evidence a LS Fe(II) site over the 80-300 K temperature range. The temperature dependence of the magnetic susceptibility was fitted with J = -13.7 cm(-1), D = -1.8 cm(-1), and g = 2.096 for 1; J = 3.0 cm(-1), D(1) = 1.6 cm(-1), E(1) = -0.35 cm(-1) (lambda(1) = 0.22), D2 = - 12.2 cm(-1), E2 = 1.1 cm(-1) (lambda2 = 0.09), and g = 2.136 for 3; and J(1) = - 0.09 cm(-1), J(2) = 15.9 cm(-1), D(1) = 5.7 cm(-1), D(2) = 12.1 cm(-1), and g = 1.915 for 4. The nature of the ground state in 3 and 4 was confirmed by simulation of the magnetization curves at 2 and 5 K. The intradinuclear interaction through the central O(alkoxo) of the acpypentO- ligand and one pseudohalide bridges is ferromagnetic in 3 (end-on cyanato) while it is very weakly antiferromagnetic in 4 (end-on azido). The interdinuclear interaction through two end-on azido bridges (4) is ferromagnetic as expected. In agreement with the symmetry of the two iron sites of complexes 3 and 4, the fits show that D2 (tetragonal pyramid) is larger than D1 (distorted trigonal bipyramid (3) or distorted octahedron (4)). PMID:14966997

Boudalis, Athanassios K; Clemente-Juan, Juan-Modesto; Dahan, Françoise; Tuchagues, Jean-Pierre

2004-02-23

178

Cellular and computational studies of proteasome inhibition and apoptosis induction in human cancer cells by amino acid Schiff base-copper complexes.  

PubMed

Proliferation and apoptosis pathways are tightly regulated in a cell by the ubiquitin-proteasome system (UPS) and alterations in the UPS may result in cellular transformation or other pathological conditions. Indeed, the proteasome is often found to be overactive in cancer cells. It has also been found that cancer cells are more sensitive to proteasome inhibition than normal cells, and therefore proteasome inhibitors are pursued as antitumor drugs. The use of the proteasome inhibitor Bortezomib for treatment of multiple myeloma and mantle cell lymphoma has proved this principle. Recent studies have suggested that copper complexes can inhibit proteasome activity and induce apoptosis in some human cancer cells. However, the involved molecular mechanism is unknown. In this study, we investigated the biological activities of four amino acid Schiff base-copper(II) complexes by using human breast (MDA-MB-231 and MCF-7) and prostate (PC-3) cancer cells. The complexes C1 and C3, but not their counterparts C2 and C4, inhibit the chymotrypsin-like activity of purified 20S proteasome and human cancer cellular 26S proteasome, cause accumulation of proteasome target proteins Bax and I?B-?, and induce growth inhibition and apoptosis in concentration- and time-dependent manners. Docking analysis shows that C1, but not C2 has hydrophobic, pi-pi, pi-cation and hydrogen bond interactions with the proteasomal chymotrypsin-like pocket and could stably fit into the S3 region, leading to specific inhibition. Our study has identified the mechanism of action of these copper complexes on inhibiting tumor cell proteasome and suggested their great potential as novel anticancer agents. PMID:23142973

Zuo, Jian; Bi, Caifeng; Fan, Yuhua; Buac, Daniela; Nardon, Chiara; Daniel, Kenyon G; Dou, Q Ping

2013-01-01

179

Pro-oxidant and antiproliferative effects of the 1,3,4-thiadiazole-based Schiff base and its metal complexes.  

PubMed

Adverse biological activities of Schiff base (SB) derivatives are well known. In this study, the ligand and its metal complexes have been synthesized and characterized by IR, (1)H-NMR spectra, elemental analyses, magnetic susceptibility, UV-Vis spectra, and thermogravimetry/differential thermal analysis. From the elemental analyses data, the complexes were proposed to have the general formula [Mn(L)(2)(H(2)O)(2)], [Co(L)(2)(H(2)O)(2)], and [Ni(2)(L)(H(2)O)(4)(Cl)(3)]. From the magnetic moment and UV-Vis spectra data, it was found that the geometrical structures of these complexes are octahedral. In the in vivo experiment, adult male rats were injected subcutaneously with a new SB (L) and its [Mn(L)(2)(H(2)O)(2)], [Co(L)(2)(H(2)O)(2)], and [Ni(2)(L)(H(2)O)(4)(Cl)(3)] complexes (25?mg/kg body weight) and were then sacrificed 16 days later. Effects of these compounds on serum antioxidant vitamins (i.e., vitamins A, E, and C) and malondialdehyde (MDA) levels were measured in blood serum, liver, and kidney tissues. In an in vitro experiment, antiproliferative effects of these compounds were assessed on the human breast carcinoma MCF-7 and murine leukemia L1210 cell lines. Serum MDA and vitamins A, E, and C levels did not change by the treatments. However, in the kidney and liver tissues, MDA levels were higher, whereas vitamin levels were lower in treatment groups, compared to the control group. All compounds inhibited cell proliferation of MCF-7 and L1210 cancer cell lines in a dose- and time-dependent manner. In conclusion, SB derivatives tested in the current study induced oxidative stress in vivo and exhibited anti-proliferative effects in an in vitro culture system. PMID:21714772

Turan, Nevin; Topçu, M Fatih; Ergin, Zuhal; Sandal, Suleyman; Tuzcu, Mehmet; Akpolat, Nusret; Yilmaz, Bayram; Sekerci, Memet; Karatepe, Mustafa

2011-10-01

180

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

181

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 Central

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.

Sun, Hao; Zhang, Haowei; Han, Jianlin

2014-01-01

182

Gastroprotection Studies of Schiff Base Zinc (II) Derivative Complex against Acute Superficial Hemorrhagic Mucosal Lesions in Rats  

PubMed Central

Background The study was carried out to assess the gastroprotective effect of the zinc (II) complex against ethanol-induced acute hemorrhagic lesions in rats. Methodology/Principal Finding The animals received their respective pre-treatments dissolved in tween 20 (5% v/v), orally. Ethanol (95% v/v) was orally administrated to induce superficial hemorrhagic mucosal lesions. Omeprazole (5.790×10?5 M/kg) was used as a reference medicine. The pre-treatment with the zinc (II) complex (2.181×10?5 and 4.362×10?5 M/kg) protected the gastric mucosa similar to the reference control. They significantly increased the activity levels of nitric oxide, catalase, superoxide dismutase, glutathione and prostaglandin E2, and decreased the level of malondialdehyde. The histology assessments confirmed the protection through remarkable reduction of mucosal lesions and increased the production of gastric mucosa. Immunohistochemistry and western blot analysis indicated that the complex might induced Hsp70 up-regulation and Bax down-regulation. The complex moderately increased the gastroprotectiveness in fine fettle. The acute toxicity approved the non-toxic characteristic of the complex (<87.241×10?5 M/kg). Conclusion/Significance The gastroprotective effect of the zinc (II) complex was mainly through its antioxidant activity, enzymatic stimulation of prostaglandins E2, and up-regulation of Hsp70. The gastric wall mucus was also a remarkable protective mechanism. PMID:24058648

Golbabapour, Shahram; Gwaram, Nura Suleiman; Hassandarvish, Pouya; Hajrezaie, Maryam; Kamalidehghan, Behnam; Abdulla, Mahmood Ameen; Ali, Hapipah Mohd; Hadi, A. Hamid A; Majid, Nazia Abdul

2013-01-01

183

Highly cytotoxic copper(II) complexes with modified paullone ligands.  

PubMed

The reaction of copper(II) chloride or copper(II) acetate with 6-N-(2-N',N'-dimethylaminoethylamino)-7,12-dihydroindolo-[3,2-d][1]benzazepine (HL(1)), 9-bromo-6-N-(2-N',N'-dimethylaminoethylamino)-7,12-dihydroindolo[3,2-d][1]benzazepine (HL(2)), N-(9-bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6(5H)-yliden-N'-(1-pyridin-2-yl-methylidene)azine (HL(3)), or N-(9-bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6(5H)-yliden-N'-(1-pyridin-2-yl-ethylidene)azine (HL(4)) in methanol affords the novel copper(II) complexes [Cu(HL(1))Cl(2)] (1), [Cu(HL(2))Cl(2)] (2), [Cu(HL(3))Cl(2)] (3), [Cu(HL(4))Cl(2)] (4), and [Cu(L(4))(CH(3)COO)(CH(3)OH)] (5). The new ligands (HL(2) and HL(3)) and the complexes 1-5 were characterized by (1)H and (13)C NMR, IR and electronic absorption spectroscopy, ESI mass spectrometry, and X-ray crystallography. Two ligands, HL(1) and HL(2), and complexes 1-4 were tested for cytotoxicity in three human cancer cell lines, namely, CH1 (ovarian carcinoma), A549 (non-small cell lung cancer), and SW480 (colon carcinoma). Additionally, complexes 1, 2, and 4 were assayed in an isogenic pair of ovarian cancer cell lines, one being sensitive to cisplatin (A2780) and the other having acquired cisplatin resistance (A2780cisR). All of the compounds evaluated are cytotoxic, with complexes 3 and 4 exhibiting IC(50) values in the nanomolar range. PMID:19968251

Primik, Michael F; Mühlgassner, Gerhard; Jakupec, Michael A; Zava, Olivier; Dyson, Paul J; Arion, Vladimir B; Keppler, Bernhard K

2010-01-01

184

Synthesis, spectroscopic characterization and thermal studies of some rare earth metal complexes of unsymmetrical tetradentate Schiff base ligand  

Microsoft Academic Search

The solid complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III) and Gd(III) with 4-hydroxy-3-(1-{2-(2-hydroxy-benzylidene)-aminophenylimino}-thyl)-6-methy-pyran-2-one (H2L) derived from o-phenylenediamine, 3-acetyl-6-methyl-(2H)pyran,2,4(3H)-dione (dehydroacetic acid or DHA) and salicylic aldehyde have been synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV–visible, FTIR, 1H NMR spectra, X-ray diffraction, and thermal analysis and screened for antimicrobial activity. The FTIR spectral data suggest that the ligand behaves

V. A. Shelke; S. M. Jadhav; V. R. Patharkar; S. G. Shankarwar; A. S. Munde; T. K. Chondhekar

185

Photochemical behaviour of iron(III) oxalato complexes with N, N?-ethylenebis(benzoylacetoneiminato) Schiff base derivatives  

Microsoft Academic Search

The complexes Na[Fe(4-R-benacen)(C2O4)], where 4-R-benacen2? are tetradentate chelating N,N’-ethylenebis(4-R-benzoylacetoneiminato) N2O2-ligands (R = H, Cl, Br, OCH3) are redox stable in the dark in methanolic solutions. Continuous irradiation of such solutions by ultraviolet and\\/or visible radiation leads to photophysical and photochemical deactivation processes yielding Fe(II) and CH2O as final products. However, the molar ratio of Fe(II): CH2O is much lower than

Mário Izakovi?; Jozef Šima; Vlasta Brezová

2004-01-01

186

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

187

Oxidation of heterocyclic thioureas to form benzothiazoles and their copper(II) complexes  

E-print Network

Oxidation of heterocyclic thioureas to form benzothiazoles and their copper(II) complexes Douglas X of the methoxy group on the aryl group. q 2002 Elsevier Science B.V. All rights reserved. Keywords: Thioureas(thiosemicarbazones). However, closely related heterocyclic thioureas are known to reduce copper(II) and form copper

Kaminsky, Werner

188

Syntheses, structures, and luminescence behavior of terephthalate bridged lead(II) complexes with tetradentate N-donor Schiff bases  

NASA Astrophysics Data System (ADS)

Three dinuclear compounds of the types [Pb2(L1)2(?-tp)](ClO4)2 (1) and [Pb2(L2)2(?-tp)](ClO4/PF6)2 (2/3) [L1 = N,N'-(bis-(pyridin-2-yl)formylidene)-1,2-ethanediamine; L2 = N,N'-(bis-(pyridin-2-yl)benzylidene)-1,2-ethanediamine and tp = terephthalate dianion] have been synthesized using one-pot reactions of 2:2:1:2 M ratio of Pb(OAc)2?3H2O, L1/L2, piperidinium terephthalate (ptp) and appropriate counter anions in MeOH at room temperature. Compounds 1-3 are characterized on the basis of microanalytical, spectroscopic, thermal and other physicochemical results. X-ray structural analyses of 1-3 reveal each six-coordinated lead(II) center with PbN4O2 chromophore to be bound by four N atoms of L1 in 1 and L2 in 2 and 3 and connected through O atoms of a bis(bidentate) tp bridge. The arrangements of L1/L2 ligand and the tp dianion suggest a void around the metal center presumably occupied by a stereoactive lone pair of electrons that reflect a hemidirected coordination around the metal center. The complexes exhibit reasonable thermal stabilities. In solid states, L1, L2, ptp and 1 display intraligand ? ? ?* fluorescence and 1-3 show ligand-to-metal charge transfer at room temperature.

Roy, Subhasis; Choubey, Somnath; Bhar, Kishalay; Khan, Sumitava; Mitra, Partha; Ghosh, Barindra Kumar

2013-11-01

189

Novel mixed ligand complexes of bioactive Schiff base (E)-4-(phenyl (phenylimino) methyl) benzene-1,3-diol and 2-aminophenol/2-aminobenzoic acid: synthesis, spectral characterization, antimicrobial and nuclease studies.  

PubMed

A novel bidentate Schiff base ligand has been synthesized using 2,4-dihydroxybenzophenone and aniline. Its mixed ligand complexes of MAB type [M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); HA=Schiff base and B=2-aminophenol/2-aminobenzoic acid] have been synthesized and characterized on the basis of spectral data UV-Vis, IR, (1)H NMR, FAB-Mass, EPR, SEM and magnetic studies. All the complexes were soluble in DMF and DMSO. Elemental analysis and molar conductance values indicate that the complexes are non-electrolytes. HA binds with M(II) ions through azomethine and deprotonated phenolic group and B binds through the primary amine group and deprotonated phenolic/carboxylic groups. Using FAB-Mass the cleavage pattern of the ligand (HA) has been established. All the complexes adopt octahedral geometry around the metal ions. It has been confirmed with the help of UV-Vis, IR, (1)H NMR and FAB-Mass spectral data. DNA binding activities of the complexes 1d and 2d are studied by UV-Vis spectroscopy and cleavage studies of Schiff base ligand and its complexes 1d and 2d have been by agarose gel electrophoresis method. In vitro biological activities of the free ligand (HA) and their metal complexes (1a-1e and 2a-2e) were screened against few bacteria, Escherichia coli, Staphylococcus saphyphiticus, Staphylococcus aureus, Pseudomonas aeruginosa and fungi Aspergillus niger, Enterobacter species, Candida albicans by well diffusion technique. PMID:23981416

Subbaraj, P; Ramu, A; Raman, N; Dharmaraja, J

2014-01-01

190

Spectral Characterization and 3D Molecular Modeling Studies of Metal Complexes Involving the O, N-Donor Environment of Quinazoline-4(3H)-one Schiff Base and Their Biological Studies  

PubMed Central

A simple condensation of 3-amino-2-methylquinazoline-4-one with 2-hydroxy-1-naphthaldehyde produced new tridentate ONO donor Schiff base ligand with efficient yield. The structural characterization of ligand and its Cu(II), Ni(II), Co(II), Mn(II), Zn(II), and Cd(II) complexes were achieved by the aid of elemental analysis, spectral characterization such as (UV-visible, IR, NMR, mass, and ESR), and magnetic data. The analytical and spectroscopic studies suggest the octahedral geometries of Cu(II), Co(II), Ni(II) and Mn(II) complexes and tetrahedral geometry of Zn(II) and Cd(II) complexes with the tridentate ONO Schiff base ligand. Furthermore, the conclusions drawn from these studies afford further support to the mode of bonding discussed on the basis of their 3D molecular modeling studies by considering different bond lengths, bond angles, and bond distance. The ligand and its metal complexes evaluated for their antimicrobial activity against Staphylococcus aureus (MTCC number 7443), Bacillus subtilis (MTCC number 9878), Escherichia coli (MTCC number 1698), Aspergillus niger (MTCC number 281), and Aspergillus flavus (MTCC number 277). The MIC of these compounds was found to be most active at 10??g/mL concentration in inhibiting the growth of the tested organisms. The DNA cleavage activity of all the complexes was studied by gel electrophoresis method. PMID:24678278

Siddappa, Kuruba; Mane, Sunilkumar B.

2014-01-01

191

Synthesis and spectroscopic studies of homo-binuclear, alkoxo bridged homo- and hetero-tetranuclear metal complexes of a bis-N2O4 Schiff base ligand derived from ethanolamine and macroacyclic tetranaphthaldehyde.  

PubMed

Three new homo-binuclear Ni(II), Cu(II), Zn(II) complexes (2-4), homo-tetranuclear Cu(II) complex (5), and hetero-tetranuclear Cu(II)-Ni(II) complex (6) of a macroacyclic potentially bis-hexadentate N2O4 Schiff base have been synthesized. The imino-alcohol ligand, H4L was obtained by the condensation of ethanolamine with 2,2'-[2,3-bis(1-formyl-2-naphthyloxymethyl)-but-2-ene-1,4-diyldioxy]bis(naphthalene-1-carbaldehyde). The structures of both the Schiff base and its complexes have been proposed by elemental analyses, spectroscopic data i.e. IR, 1H and 13C NMR, UV-vis, electrospray ionisation mass spectra, molar conductivities and magnetic susceptibility measurements. The ligand has two similar compartments to bind first primary two metal ions, and acts bi- or tetra-negative, bis-tetradentate forming five membered chelate ring. However, secondary two metal ions (either Cu2+ or Ni2+) are ligated with dianionic oxygen atoms of the alcohol groups and are linked to the 1,10-phenanthroline-nitrogen atoms in the tetranuclear complexes (5 and 6). PMID:21550297

Karao?lu, Kaan; Baran, Talat; De?irmencio?lu, Ismail; Serbest, Kerim

2011-09-01

192

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

193

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

194

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

195

A new trinuclear zinc(II) complex and a heptacoordinated mononuclear cadmium(II) complex with a pyrimidine derived Schiff base ligand: Syntheses, crystal structures, photoluminescence and DFT calculations  

NASA Astrophysics Data System (ADS)

The new N6 donor hexadentate Schiff base 2,4-bis [2-(pyridine-2-ylmethylidene) hydrazinyl] pyrimidine (L), its trinuclear Zn(II) complex, [Zn3(L)2Cl6] (1) and mononuclear heptacoordinate Cd(II) complex [Cd(L)(H2O)2](ClO4)2 (2) have been synthesised and characterised by crystallographically and spectroscopically. Complex 1 is featured by the triangular arrangement of three zinc atoms where the neighbouring Zn atoms are linked via half portion (N3 chromophore) of the same ligand molecule. In 1, the ligand molecules behave as hexadentate ones (employing both pyrimidine nitrogen atoms as active donor centres) to create the octahedral environment around Zn(II). The central and terminal Zn(II) atom has N6 and N3Cl3 chromophores respectively. In 2 the same ligand (L) behaves as pentadentate one (ignoring one pyrimidine nitrogen in the coordination process) to produce a pentagonal bipyramidal geometry with two apical water molecules. The geometries of both complexes were optimised in the singlet state by DFT method. The TDDFT calculations have been done on the optimised geometries to understand the electronic structure and spectral transition in the complexes. Complex 1 exhibits intraligand 1(? ? ?*) fluorescence in aqueous methanol solvent at room temperature.

Das, Kinsuk; Jana, Atanu; Konar, Saugata; Chatterjee, Sudipta; Mondal, Tapan Kumar; Barik, Anil Kumar; Kar, Susanta Kumar

2013-09-01

196

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 in vitro 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

197

Synthesis and X-ray structure analysis of a new binuclear Schiff base Co(II) complex with the ligand N,N'-bis(3-methoxysalicylidene)-1,4-butanediamine  

SciTech Connect

The title binuclear complex, tris[N,N-bis(3-methoxysalicylidene)-1,4-diaminobutane] dicobalt(II), C{sub 60}H{sub 70}Co{sub 2}N{sub 6}O{sub 15}, was prepared by the reaction of the tetradentate Schiff base ligand bis(3-methoxysalicylidene)-1,4-diaminobutane and Co(CH{sub 3}COO){sub 2} . 4H{sub 2}O in a ethanol solution and structurally characterized by single-crystal X-ray diffraction. This complex has a dinuclear structure where two Co(II) ions are bridged by one N{sup 0},N'-bis(3-methoxysalicylidene)-1,4-diaminobutane. The two Co(II) ions, have two distorted octahedral coordination involving two O and two N atoms.

Nasr-Esfahani, M., E-mail: m-nasresfahani@iaun.ac.ir [Islamic Azad University, Najafabad Branch, Department of Materials Science and Engineering (Iran, Islamic Republic of)

2009-12-15

198

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)2·2H2O] (1), [Cu2L2(N3)2·2H2O] (2), [Cu2L3(N3)2·2H2O] (3), [Cu2L4(N3)2·2H2O] (4) and [Cu2L5(N3)2·2H2O] (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

199

In vitro DNA binding, pBR322 plasmid cleavage and molecular modeling study of chiral benzothiazole Schiff-base-valine Cu(II) and Zn(II) complexes to evaluate their enantiomeric biological disposition for molecular target DNA  

NASA Astrophysics Data System (ADS)

Bicyclic heterocyclic compounds viz. benzothiazoles are key components of deoxyribonucleic acid (DNA) molecules and participate directly in the encoding of genetic information. Benzothiazoles, therefore, represent a potent and selective class of antitumor compounds. The design and synthesis of chiral antitumor chemotherapeutic agents of Cu(II) and Zn(II), L- and -D benzothiazole Schiff base-valine complexes 1a &b and 2a &b, respectively were carried out and thoroughly characterized by spectroscopic and analytical techniques. Interaction of 1a and b and 2a and b with CT DNA by employing UV-vis, florescence, circular dichroic methods and cleavage studies of 1a with pBR322 plasmid, molecular docking were done in order to demonstrate their enantiomeric disposition toward the molecular drug target DNA. Interestingly, these studies unambiguously demonstrated the greater potency of L-enantiomer in comparison to D-enantiomer.

Alizadeh, Rahman; Afzal, Mohd; Arjmand, Farukh

2014-10-01

200

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.  

PubMed

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 signals in 1H NMR and 13C NMR spectra indicated the presence of azomethine group as a result of condensation reaction. The stoichiometry, bonding and stereochemistries of complexes were ascertained on the basis of results of elemental analysis, magnetic susceptibility measurements, molar conductance and spectroscopic studies viz., FT-IR, 1H and 13C NMR, UV-vis and EPR. EPR, UV-vis and magnetic moment data revealed an octahedral geometry for complexes with distortion in Cu(II) complex and conductivity data show 1:2 electrolytic nature of complexes. Absoption and fluorescence spectroscopic studies supported that Schiff base ligand L and its Co(II), Ni(II) and Cu(II) complexes exhibited significant binding to calf thymus DNA. The complexes exhibited higher affinity to calf thymus DNA than the free Schiff base ligand L. PMID:21715221

Shakir, Mohammad; Abbasi, Ambreen; Azam, Mohammad; Khan, Asad U

2011-09-01

201

Solvent-ligated copper(II) complexes for the homopolymerization of 2-methylpropene.  

PubMed

Copper(II) complexes with weakly coordinating counter anions can be utilized as highly efficient catalysts for the synthesis of poly(2-methylpropene) ("polyisobutene") with a high content of terminal double bonds. These copper(II) compounds are significantly more active than the manganese(II) complexes described previously, can be applied in chlorine-free solvents such as toluene, are easily accessible, and can be handled at room temperature and in laboratory atmospheres for brief periods, but they are sensitive to excess water, thereby losing their catalytic activity. Replacing the acetonitrile ligands by benzonitrile ligands improves the solubility and catalytic activity in nonpolar and nonchlorinated solvents. However, the benzonitrile copper(II) compounds have lower thermal stability than their acetonitrile congeners. PMID:18637647

Li, Yang; Voon, Lih Ting; Yeong, Hui Yee; Hijazi, Ahmed K; Radhakrishnan, Narayanan; Köhler, Klaus; Voit, Brigitte; Nuyken, Oskar; Kühn, Fritz E

2008-01-01

202

Synthesis, structural characterization, thermal studies, catalytic efficiency and antimicrobial activity of some M(II) complexes with ONO tridentate Schiff base N-salicylidene-o-aminophenol (saphH2)  

NASA Astrophysics Data System (ADS)

The reactions of acetate salts of M(II) (M = Mn, Co, Ni, Cu and Zn) with N-salicylidene-o-aminophenol (saphH2) in ethyl alcohol afforded new four coordinated complexes with the general formula [M(II)(saph)(H2O)]. The complexes have been fully characterized by microanalysis, molar conductance, magnetic susceptibility, 1H NMR, IR, UV-Vis, ESR, mass spectra and thermogravimetric analysis (TGA). The experimental data have been shown that all complexes are mononuclear with the M(II) being coordinated by a dianionic tridentate Schiff base ligand, through the deprotonated two enolic oxygen and the azomethine nitrogen atoms. UV-Vis spectra and magnetic moments have been suggested square planar stereochemistry for Co(II) and Cu(II) complexes, and tetrahedral geometry has been suggested for Mn(II), Ni(II) and Zn(II) complexes. The new complexes have been tested for their abilities to catalyze aerial oxidation of benzaldehyde to benzoic acid. Finally, in view of the biological activity, antibacterial and antifungal tests of the ligand and its complexes have been carried out and the results were compared with some known antibiotics.

Abdel Aziz, Ayman A.; Salem, Abdel Naby M.; Sayed, Mostafa A.; Aboaly, Mohamed M.

2012-02-01

203

Complexation versus thiadiazole formation for reactions of thiosemicarbazides with copper(II).  

PubMed

The reactions of N,N-substituted thiosemicarbazides with copper salts have been investigated and either copper(II) thiosemicarbazide complexes, 1,3,4-thiadiazolium salts or 1,3,5-thiadiazoles are obtained depending on the Cu(II) salt and solvent used. PMID:17353950

López-Torres, Elena; Cowley, Andrew R; Dilworth, Jonathan R

2007-03-28

204

Evidence for Cu-O2 Intermediates in Superoxide Oxidations by Biomimetic Copper(II) Complexes  

E-print Network

Evidence for Cu-O2 Intermediates in Superoxide Oxidations by Biomimetic Copper(II) Complexes@jhu.edu Abstract: The mechanism by which [CuII (L)](OTf)2 and [CuII N3(L)](OTf) (L ) TEPA: tris(2-pyridylethyl geometries and redox potentials that span a 0.67 V range. The results are inconsistent with a mechanism

Roth, Justine P.

205

Synthesis, spectral characterization and antimicrobial studies of nano-sized oxovanadium(IV) complexes with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-thiadiazole and indoline-2,3-dione.  

PubMed

A new class of oxovanadium(IV) complexes with Schiff bases derived by the condensation of 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-thiadiazoles and indoline-2,3-dione have been prepared in ethanol in the presence of sodium acetate. Micro-analytical data, magnetic susceptibility, UV-Vis, IR, EPR and XRD spectral techniques were used to confirm the structures. Electronic absorption spectra of the complexes suggest a square-pyramidal geometry. The oxovanadium(IV) complexes have monoclinic crystal system and particle sizes were found to be in the range 18.0 nm to 24.0 nm (nano-size). In vitro antifungal activity of synthesized compounds was determined against fungi Aspergillus niger, Colletotrichum falcatum and Colletotrichum pallescence and in vitro antibacterial activity was determined by screening the compounds against Gram-negative (Escherichia coli and Salmonella typhi) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacterial strains. The oxovanadium(IV) complexes have higher antimicrobial effect than free ligands. PMID:24548812

Sahani, M K; Yadava, U; Pandey, O P; Sengupta, S K

2014-05-01

206

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

207

Synthesis, molecular structures and phase transition studies on benzothiazole-cored Schiff bases with their Cu(II) and Pd(II) complexes: Crystal structure of (E)-6-methoxy-2-(4-octyloxy-2-hydroxybenzylideneamino)benzothiazole  

NASA Astrophysics Data System (ADS)

Two new homologous series of Cu(II) and Pd(II) complexes with benzothiazole-cored Schiff bases have been synthesised with the aim to study the mesomorphic and thermal properties of ligands upon formation of metal complexes. The molecular structure of title compounds were elucidated with the employment of FT-IR, 1D and 2D FT-NMR spectroscopic techniques. Mesomorphic and thermal behaviour of title compounds have been investigated by differential scanning calorimetry and polarising optical microscope. All the ligands are nematogenic but the corresponding Cu(II) and Pd(II) complexes crystallised in ordinary solid. The conformation of 6-methoxy-2-(4-octyloxy-2-hydroxy-benzylideneamino)benzothiazole was determined by single crystal X-ray diffraction analysis of which the title compound favours more stable (E)-6-methoxy-2-(4-octyloxy-2-hydroxybenzylideneamino)benzothiazole. Crystal structure of the title compound also revealed that the bond length of Cdbnd N (1.303 Å) in the benzothiazole rings very close to that in the exocyclic Cdbnd N linkage (1.298 Å).

Yeap, Guan-Yeow; Heng, Boon-Teck; Faradiana, Nur; Zulkifly, Raihana; Ito, Masato M.; Tanabe, Makoto; Takeuchi, Daisuke

2012-03-01

208

Characterization, molecular modeling and antimicrobial activity of metal complexes of tridentate Schiff base derived from 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione and 2-aminophenol  

NASA Astrophysics Data System (ADS)

Metal complexes of Ni(II), Co(II), Cd(II), VO(IV) and UO2(VI) as well as several Cu(II) salts, including Cl,NO3-,AcO,ClO4- and SO4-2 with a tridentate O2N donor Schiff base ligand (H2L), synthesized by condensation of 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione with 2-aminophenol, were prepared and characterized on the basis of elemental analyses, spectral, magnetic, molar conductance and thermal gravimetric analysis. Square planar, tetrahedral and octahedral geometries have been assigned to the prepared complexes. Molecular parameters of the ligand and its metal complexes have been calculated and correlated with the experimental data, and the changes of bond lengths are linearly correlated with IR data. The antimicrobial activities of the synthesized compounds were tested in vitro against the sensitive organisms Staphylococcus aureus as Gram positive bacteria, Proteus vulgaris as Gram negative bacteria and Candida albicans as fungus strain, and the results are discussed.

Adly, Omima M. I.

209

Cd(II) and Zn(II) complexes of two new hexadentate Schiff base ligands derived from different aldehydes and ethanol amine; X-ray crystal structure, IR and NMR spectroscopy studies  

NASA Astrophysics Data System (ADS)

Four new [Cd(H2L1)(NO3)]ClO4 (1), [Zn(H2L1)](ClO4)2 (2), [Cd(H2L2)(NO3)]ClO4 (3), and [Zn(H2L2)](ClO4)2 (4), complexes were prepared by the reaction of two new Schiff base ligands and Cd(II) and Zn(II) metal ions in equimolar ratios. The ligands H2L1 and H2L2 were synthesized by reaction of 2-[2-(2-formyl phenoxy)ethoxy]benzaldehyde and/or 2-[2-(3-formyl phenoxy)propoxy]benzaldehyde and ethanol amine and characterized by IR, 1H and 13C NMR spectroscopy. All complexes were characterized by IR, 1H and 13C NMR, COSY, and elemental analysis. Also, the complex 1 was characterized by X-ray in addition to the above methods. The X-ray crystal structure of compound 1 showed that all nitrogen and oxygen atoms of ligand (N2O4) and a molecule of nitrate with two donor oxygen atom have been coordinated to the metal ion and the Cd(II) ion is in an eight-coordinate environment that is best described as a distorted dodecahedron geometry.

Golbedaghi, Reza; Rezaeivala, Majid; Albeheshti, Leila

2014-11-01

210

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; Antônio S Mangrich; Eva Rentschler; Bruno Szpoganicz; Erineu Schwingel

2001-01-01

211

Synthesis and structural features of U VI and V IV chelate complexes with (hhmmbH)Cl·H 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)Cl·H 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) 2·6H 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 Aurélio; de Oliveira, Gelson Manzoni

2009-10-01

212

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, Hernán; Palopoli, Claudia; Shova, Sergiu; De Gaudio, Mónica; Daier, Verónica; González-Sierra, Manuel; Tuchagues, Jean-Pierre; Signorella, Sandra

2006-10-01

213

Copper(II) complexes derived from tripodal tris[(2-ethyl-(1-pyrazolyl)]amine  

Microsoft Academic Search

Three mono-nuclear copper(II) complexes [Cu(tepza)X]ClO4 (X=Cl, 1; X=NCS, 2; X=dca, 3) and two dinuclear bridging complexes [Cu2(tepza)2(?-C4O4)](ClO4)2·H2O(4) and [Cu2(tepza)2(?-C5O5)](ClO4)2(5) where tepza=tris[2-ethyl(1-pyrazolyl)]amine, dca=dicyanamide, C4O42?=3,4-dihydroxycyclobut-3-ene-1,2-dionate (squarate dianion) and C5O52?=4,5-dihydroxycyclopent-4-ene-1,2,3-trionate (croconate dianion) were synthesized and structurally characterized by IR and UV–Vis spectroscopy as well as by single X-ray crystallography. In the solid state, the geometry of copper(II) centers in these complexes are as

Franz A. Mautner; Jörg H. Albering; Ramon Vicente; Febee R. Louka; August A. Gallo; Salah S. Massoud

2011-01-01

214

Influence of electron beam irradiation on spectral, thermal, morphological and catalytic properties of Co(II) complex immobilized on chitosan's Schiff base.  

PubMed

This study was carried out to investigate the effect of electron beam irradiation on the spectral and catalytic properties of chitosan supported (ONClCl) tetra coordinated Co(II) complex, [Co(OIAC)Cl2]. The complex was subjected to electron beam irradiation of 100 Gy, 1 kGy and 10 kGy doses. Chain scission of chitosan was observed on irradiation at 100 Gy and 10 kGy and chain linking at 1 kGy as evidenced by viscosity and FT-IR spectroscopic studies. This observation was also confirmed by thermo gravimetric and differential thermogravimetric (TG-DTG) analysis. It revealed that the thermal stability of the complex was increased at 1 kGy irradiation and decreased at 100 Gy and 10 kGy. In addition, the effect of electron beam irradiation on the surface morphology of the complex was studied by scanning electron microscopy. Catalytic abilities of both non-irradiated complex and irradiated complexes were determined and compared in the cyclohexane oxidation using hydrogen peroxide oxidant. The catalytic activity was found to increase after irradiation at all doses. Though the complex irradiated at 10 kGy showed highest conversion efficiency, irradiation at 1 kGy is suggested as the best dose due to the extensive reusability and adequate catalytic ability of the complex. PMID:24486862

Antony, R; Theodore David, S; Karuppasamy, K; Sanjeev, Ganesh; Balakumar, S

2014-04-24

215

An unexpected cobalt(III) complex containing a Schiff base ligand: Synthesis, crystal structure, spectroscopic behavior, electrochemical property and SOD-like activity  

NASA Astrophysics Data System (ADS)

An unexpected mononuclear Co(III) complex, [Co(L2)2·(CH3COO)]·CH3OH (HL2 = 1-(2-{[(E)-3,5-dichloro-2-hydroxybenzylidene]amino}phenyl)ethanone oxime), has been synthesized via complexation of Co(II) acetate tetrahydrate with HL1 originally. The plausible reaction mechanism for the formation of quinazoline-type ligand was proposed. HL1 and its corresponding Co(III) complex were characterized by IR, as well as by elemental analysis and UV-vis spectroscopy. The crystal structure of the complex has 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 properties of the cobalt(III) complex were studied by cyclic voltammetry and X-ray photoelectron spectrum (XPS). In addition, superoxide dismutase-like activities of HL1 and Co(III) complex were also investigated.

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

2014-10-01

216

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

217

Polystyrene-Anchored Palladium(II) Schiff Base Complex: A Reusable Catalyst for Phosphine-Free and Copper-Free Sonogashira Cross-Coupling Reaction in Aqueous Medium  

Microsoft Academic Search

A novel polystyrene-supported palladium(II) complex, an excellent and recyclable catalyst, was synthesized for Sonogashira reactions. The present complex shows high catalytic activity for Sonogashira cross-coupling reaction of aryl halides with phenylacetylene under phosphine-free and copper-free reaction conditions in aqueous (DMF–H2O) medium. The catalyst could be reused for at least six reaction cycles with almost unchanged catalytic properties.

Manirul Islam; P. Mondal; A. Singha Roy; K. Tuhina; S. Mondal; D. Hossain

2011-01-01

218

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

219

Synthesis, spectral characterization, molecular modeling and in vitro antibacterial activity of complexes designed from O2, NO and NO donor Schiff-base ligand.  

PubMed

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)O2(2+) 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)O2(2+) 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. PMID:25064507

El-Gammal, Ola A; Abu El-Reash, G; Ahmed, S F

2015-01-25

220

A novel tridentate Schiff base dioxo-molybdenum(VI) complex: Synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, 1H NMR and 13C NMR spectra  

NASA Astrophysics Data System (ADS)

A new dioxo-molybdenum(VI) complex [MoO2(L)(H2O)] has been synthesized, using 5-methoxy 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H2L) and MoO2(acac)2. The yellow crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FTIR), UV-visible, 1H NMR and 13C 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, 1H NMR and 13C 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 1H NMR shielding tensors computed at the B3LYP/DGDZVP level of theory is in agreement with experimental 1H NMR spectra. However, the 13C 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 13C 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.

Saheb, Vahid; Sheikhshoaie, Iran; Stoeckli-Evans, Helen

2012-09-01

221

Crystal structures, antioxidation and DNA binding properties of Eu(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxyaldehyde and three aroylhydrazines.  

PubMed

Eu(III) and every newly synthesized ligand can form a binuclear Eu(III) complex with a 1:1 metal to ligand stoichiometry and nine-coordinate at Eu(III) center. Every ligand acts as a dibasic tetradentate ligand, binding to Eu(III) through the phenolate oxygen atom, nitrogen atom of quinolinato unit, the C=N group (methylene) and (-)O-C=N- group (enolized and deprotonated from O=C-NH- group) of the aroylhydrazine side chain. One DMF (N,N-dimethylformamide) molecule is binding orthogonally to the ligand-plane from one side to the metal ion, while another DMF and a nitrate anion (bidentate) are binding from the other. Dimerization of the monomeric unit occurs through the phenolate oxygen atoms leading to a central planar four-membered (EuO)(2) ring. On the other hand, all the ligands and Eu(III) complexes may be used as potential anticancer drugs, binding to Calf thymus DNA through intercalations at the order of magnitude 10(5)-10(7) M(-1). All the ligands and Eu(III) complexes are strong scavengers of hydroxyl radicals and superoxide radicals, but Eu(III) complex containing active phenolic hydroxyl group shows stronger scavenging effects for hydroxyl radicals than others, and Eu(III) complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radicals than others. PMID:19481266

Liu, Yong-chun; Yang, Zheng-yin

2009-07-01

222

In-vitro antibacterial, antifungal activity of some transition metal complexes of thiosemicarbazone Schiff base (HL) derived from N4-(7'-chloroquinolin-4'-ylamino) thiosemicarbazide.  

PubMed

The synthetic, spectroscopic, and biological studies of Cu(II), Ni(II), Zn(II), Co(II), Mn(II), Fe(III) and Cr(III) complexes of N(4)-(7'-chloroquinolin-4'-ylamino)-N(1)-(2-hydroxy-benzylidene)thiosemicarbazone (HL) obtained by the reaction of N(4)-(7'-chloroquinolin-4'-ylamino)thiosemicarbazide with 2-hydroxybenzaldehyde. The structures of the complexes were determined on the basis of the elemental analyses, spectroscopic data (IR, electronic, (1)H and (13)C NMR and Mass spectra) along with magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses. Electrical conductance measurement revealed the non-electrolytic nature of the complexes. The resulting colored products are mononuclear in nature. On the basis of the above studies, only one ligand was suggested to be coordinated to each metal atom by thione sulfur, azomethine nitrogen and phenolic oxygen to form mononuclear complexes in which the thiosemicarbazone behaves as a monobasic tridendate ligand. The ligand and its metal complexes were tested against Gram + ve bacteria (Staphylococcus aureus), Gram - ve bacteria (Escherichia coli), fungi (Candida albicans) and (Fusarium solani). The tested compounds exhibited significant activity. PMID:18665996

Abou Melha, Khlood S

2008-08-01

223

Encapsulation of paramagnetic 3d1-vanadium(IV) in an antiferromagnetically coupled dodecanuclear copper(II) cage.  

PubMed

A mixed metal cluster [Cu12VO5L6] of a pentadentate Schiff base (H3L) containing vanadium(IV) in a dodecanuclear copper(I) cage is prepared by vanadyl templated self assembly of dicopper(II) precursor and the structurally characterized complex shows antiferromagnetic coupling involving copper(II) centers, which leads close to diamagnetism for the Cu(II) cage below 40 K in the presence of an encapsulated paramagnetic 3d1-V(IV) atom. PMID:14703816

Mukherjee, Arindam; Nethaji, Munirathinam; Chakravarty, Akhil R

2003-12-21

224

A potentiometric investigation of complex formation between some metal ions and biologically active quinazoline-4-3(H)-one Schiff's base  

NASA Astrophysics Data System (ADS)

The proton dissociation constant of the ligand and the stability of the complexes of Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Cu(II), Ba(II), Mg(II), Mn(II), Th(IV), and UO2(II) ions with 2-phenyl-3-(2'-hydroxy-5'-benzylidine)-quinazoline-4-(3H)-one [PBQ] were determined potentiometrically at 30 ± 0.1°C and ionic strengths of 0.025, 0.05, 0.10, 0.15 and 0.20 M NaNO3 in a 60:40 (v/v) ethanol-water medium. The proton-ligand and metal-ligand stability constants of the complexes were determined pH metrically by the Calvin-Bjerrum titration technique. The order of stability constants obeys the Irving-Rossotti rule. The negative values of ? G° suggest that the reactions are spontaneous.

Shivakumar, K.; Shashidhar, S.; Halli, M. B.

2007-10-01

225

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

226

Complexation of nitrogen and sulphur donor Schiff's base ligand to Cr(III) and Ni(II) metal ions: Synthesis, spectroscopic and antipathogenic studies  

NASA Astrophysics Data System (ADS)

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]X 2 and [Ni(L)X]X compositions (where L = ligand and X = NO 3-, Cl - and CH 3COO -) 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.

Sharma, Amit Kumar; Chandra, Sulekh

2011-01-01

227

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)]·4DMF·H(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 Mössbauer 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

228

Synthesis and characterization of binuclear [ONXO]-type amine-bis(phenolate) copper(II) complexes  

Microsoft Academic Search

Dimeric copper(II) complexes [CuII2L2] of a series of amine-bis(phenolate) ligands (H2L) bearing different non- or weakly coordinating side-arms such as ethyl (H2LEt), n-butyl (H2LBu), thiomethyl (H2LSMe) and hydroxyl (H2LOH) were synthesized. They were characterized by X-ray crystallography, UV–Vis, IR and magnetic susceptibility measurements. X-ray analysis revealed complexes in which Cu(II) centers are surrounded by three phenolate oxygen atoms, an amine

Elham Safaei; Maryam Rasouli; Thomas Weyhermüller; Eckhard Bill

2011-01-01

229

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

230

Magnetic exchange in binuclear copper(II) complexes with dissimilar bridging atoms  

NASA Astrophysics Data System (ADS)

Several copper(II) complexes have been prepared that use binucleating ligands to yield a coordinatively unsaturated product complex. These complexes will accept an exogenous ligand that binds to a bridging position. We have prepared two families of complexes from 5- or 7-coordinate binucleating ligands that exhibit similar magnetic effects as the exogenous bridging ligands are changed. Complexes of the 7-coordinate binucleating ligand are also especially useful as models of the active site of some binuclear copper proteins (e.g. hemocyanin). We report on our results covering a large series of complexes with exogenous bridging ligands B = Cl -, Br -, OH -, CH 3CO -2, 1,1-N -3, 1,3-N -3, ClO -4, etc. The magnetic exchange interaction for these complexes has not yet been observed to be ferromagnetic, but the magnitude of antiferromagnetic interactions range from Curie-Weiss paramagnetism (B = CH 3COO -) to diamagnetism (B = 1,3-N -3).

O'Connor, Charles J.; Sorrell, Thomas N.; Kahn, Olivier

1986-02-01

231

Olefin Metathesis Mediated By: - Schiff Base Ru-Alkylidenes -Ru-Alkylidenes Bearing Unsymmetrical NH Ligands  

NASA Astrophysics Data System (ADS)

The classic Grubbs second-generation complex 2 was modified through 1. The introduction of a bidentate Schiff base ligand 2. Changes in the amino side groups of the NHC ligand Representative olefin metathesis test reactions show the effects induced by the ligand modifications and demonstrate some interesting new properties of the described catalysts. catalysts.

Monsaert, Stijn; Voort, Pascal Van Der; Ledoux, Nele; Allaert, Bart; Drozdzak, Renata; Verpoort, Francis

232

Factors determining tautomeric equilibria in Schiff bases  

NASA Astrophysics Data System (ADS)

Schiff bases derived from o-hydroxyaldehydes present keto and enol tautomeric forms; the relative equilibrium between these two tautomers depending on the particular aldehyde the Schiff bases is derived from. Thus benzaldehyde produces a stable enol tautomer, while a naphthaldehyde produces a mixture of keto and enol tautomers. The energy difference between these tautomers is very small (˜5 kJ/mol) and therefore close to current precision limits of ab initio and DFT based quantum calculations. NMR spectroscopy results, which allows for the determination of the stable structure when one tautomer is prevalent, can be very difficult to interpret when both tautomers are present. We calculate energy differences between the tautomers and demonstrate that the precision of current DFT calculations is not sufficient to predict the most stable structure. On the other hand, DFT calculations of the NMR chemical shifts (using the GIAO technique) can properly interpret the spectroscopy results allowing the characterization of the experimentally present tautomers and the estimation of the relative abundance of each when both are present.

Flores-Leonar, Martha; Esturau-Escofet, Nuria; Méndez-Stivalet, José M.; Marín-Becerra, Armando; Amador-Bedolla, Carlos

2011-12-01

233

Characterization and biological activities of two copper(II) complexes with dipropylenetriamine and diamine as ligands.  

PubMed

Two new mixed-ligand copper(II) complexes, [Cu(dipn)(NN)]Br2(1-2) [dipn=dipropylenetriamine, NN=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). PMID:24632175

AL-Noaimi, Mousa; Choudhary, Mohammad I; Awwadi, Firas F; Talib, Wamidh H; Hadda, Taibi Ben; Yousuf, Sammer; Sawafta, Ashraf; Warad, Ismail

2014-06-01

234

Iron release from transferrin induced by mixed ligand complexes of copper(II).  

PubMed

Copper(II) complexes CuL1L2 with the ligand pairs 3-phosphoglycerate (PG)/ethylenediamine (en), phosphoserine (PS)/ethylenediamine, phosphoserine/malonate (mal) are shown to be effective in inducing the release of both iron atoms from di-ferric transferrin (Fe2Tf; human serum transferrin) at pH 7.3 in 1 M NaCl at 25 degrees C. Half-times of the reaction with Cu(PG)(en)- were less than 1 min at 0.02 M concentration. The iron(III) products are polynuclear hydroxo complexes. There is weaker interaction with Cu(PS)4-2 and virtually none with Cu(serine)(en) nor Cu(PS)(2,2'-bipyridyl)-, revealing crucial effects of the combined ligand sphere including the phosphomonoester group. The results suggest that the release of iron from Fe2Tf, or from either monoferric transferrins, occurred due to the breakdown of the stability of iron binding in conjunction with the expulsion of the synergistic anion carbonate (or oxalate). The active copper(II) complexes are postulated to be models of membrane components that could liberate iron from transferrin succeeding its uptake at the receptor sites of cells. PMID:2490073

Glaus, M; Schneider, W

1989-01-01

235

Monopicolinate cyclen and cyclam derivatives for stable copper(II) complexation.  

PubMed

The syntheses of a new 1,4,7,10-tetraazacyclododecane (cyclen) derivative bearing a picolinate pendant arm (HL1), and its 1,4,8,11-tetraazacyclotetradecane (cyclam) analogue HL2, were achieved by using two different selective-protection methods involving the preparation of cyclen-bisaminal or phosphoryl cyclam derivatives. The acid-base properties of both compounds were investigated as well as their coordination chemistry, especially with Cu(2+), in aqueous solution and in solid state. The copper(II) complexes were synthesized, and the single crystal X-ray diffraction structures of compounds of formula [Cu(HL)](ClO(4))(2)·H(2)O (L = L1 or L2), [CuL1](ClO(4)) and [CuL2]Cl·2H(2)O, were determined. These studies revealed that protonation of the complexes occurs on the carboxylate group of the picolinate moiety. Stability constants of the complexes were determined at 25.0 °C and ionic strength 0.10 M in KNO(3) using potentiometric titrations. Both ligands form complexes with Cu(2+) that are thermodynamically very stable. Additionally, both HL1 and HL2 exhibit an important selectivity for Cu(2+) over Zn(2+). The kinetic inertness in acidic medium of both complexes of Cu(2+) was evaluated by spectrophotometry revealing that [CuL2](+) is much more inert than [CuL1](+). The determined half-life values also demonstrate the very high kinetic inertness of [CuL2](+) when compared to a list of copper(II) complexes of other macrocyclic ligands. The coordination geometry of the copper center in the complexes was established in aqueous solution from UV-visible and electron paramagnetic resonance (EPR) spectroscopy, showing that the solution structures of both complexes are in excellent agreement with those of crystallographic data. Cyclic voltammetry experiments point to a good stability of the complexes with respect to metal ion dissociation upon reduction of the metal ion to Cu(+) at about neutral pH. Our results revealed that the cyclam-based ligand HL2 is a very attractive receptor for copper(II), presenting a fast complexation process, a high kinetic inertness, and important thermodynamic and electrochemical stability. PMID:22651379

Lima, Luís M P; Esteban-Gómez, David; Delgado, Rita; Platas-Iglesias, Carlos; Tripier, Raphaël

2012-06-18

236

Synthesis, characterization and antibacterial studies of a copper(II) levofloxacin ternary complex.  

PubMed

Solution behavior of levofloxacin (lvx) complexes with copper(II) in the presence and absence of phen was studied in aqueous solution, by potentiometry. The results obtained show that under physiological conditions (micromolar concentration range and pH 7.4) only copper(II):lvx:phen ternary complexes are stable. Hence, a novel copper(II) ternary complex of fluoroquinolone levofloxacin with nitrogen donor heterocyclic ligand phen was synthesized and characterized by means of UV-Visible and IR spectroscopy, elemental analysis and X-Ray crystallography. In the synthesized complex (1), [Cu(lvx)(phen)(H(2)O)](NO(3)).2H(2)O, levofloxacin acts as a bidentate ligand coordinating to the metal, in its anionic form, through the carbonyl and carboxyl oxygens and phen coordinates through two N-atoms forming the equatorial plane of a distorted square-pyramidal geometry. The fifth ligand of the penta-coordinated Cu(II) centre is occupied axially by an oxygen atom from a water molecule. Minimum inhibitory concentration (MIC) determinations of the complex and comparison with free levofloxacin in various E. coli strains indicated that the Cu-complex is as efficient an antimicrobial as the free antibiotic (both in the case of the dissolved synthesized complex and the complex formed following stoichiometric mixture of the individual components in solution). Moreover, results strongly suggest that the cell intake route of both species is different supporting, therefore, the complex's suitability as a candidate for further biological testing in fluoroquinolone-resistant microorganisms. PMID:22469700

Sousa, Isabel; Claro, Vasco; Pereira, João Lino; Amaral, Ana Luísa; Cunha-Silva, Luís; de Castro, Baltazar; Feio, Maria J; Pereira, Eulália; Gameiro, Paula

2012-05-01

237

An Anionic, Tetragonal Copper(II) Superoxide Complex  

PubMed Central

Insight into copper-oxygen species proposed as intermediates in oxidation catalysis is provided by the identification of a Cu(II)-superoxide complex supported by a sterically hindered, pyridinedicarboxamide ligand. A tetragonal, end-on superoxide structure is proposed based on DFT calculations and UV-vis, NMR, EPR, and resonance Raman spectroscopy. The complex yields a trans-1,2-peroxodicopper(II) species upon reaction with [(tmpa)Cu(CH3CN)]OTf, and, unlike other known Cu(II)-superoxide complexes, acts as a base rather than an electrophilic (H-atom abstracting) reagent in reactions with phenols. PMID:20977226

Donoghue, Patrick J.; Gupta, Aalo K.; Boyce, David W.; Cramer, Christopher J.; Tolman, William B.

2010-01-01

238

An anionic, tetragonal copper(II) superoxide complex.  

PubMed

Insight into copper-oxygen species proposed as intermediates in oxidation catalysis is provided by the identification of a Cu(II)-superoxide complex supported by a sterically hindered, pyridinedicarboxamide ligand. A tetragonal, end-on superoxide structure is proposed based on DFT calculations and UV-vis, NMR, EPR, and resonance Raman spectroscopy. The complex yields a trans-1,2-peroxodicopper(II) species upon reaction with [(tmpa)Cu(CH(3)CN)]OTf and, unlike other known Cu(II)-superoxide complexes, acts as a base rather than an electrophilic (H-atom abstracting) reagent in reactions with phenols. PMID:20977226

Donoghue, Patrick J; Gupta, Aalo K; Boyce, David W; Cramer, Christopher J; Tolman, William B

2010-11-17

239

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 mimetics.7,8 In the past few years, 1,2,3-triazole has also been recognized as a potent hydrogen-bond donor,2,3- triazole as a functionally versatile molecule. In conjunction with the synthetic prowess of the Cu

Weston, Ken

240

Preparation, characterization and pH-metric measurements of 4-hydroxysalicylidenechitosan Schiff-base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ru(III), Rh(III), Pd(II) and Au(III).  

PubMed

The 4-hydroxysalicylidenechitosan Schiff-base (2CS-Hdhba) was prepared by the condensation of 2,4-dihydroxybenzaldehyde with chitosan, and its metal complexes, [M(2CS-dhba)Cl(2)(H(2)O)(2)] (M(III)=Fe, Ru, Rh), [M'(2CS-dhba)(AcO)(H(2)O)(2)] (M'(II)=Co, Ni, Cu, Zn), [Pd(2CS-dhba)Cl(H(2)O)] and [Au(2CS-dhba)Cl(2)], are reported. These complexes were characterized by elemental analysis, by spectral data (FTIR, solid-phase (13)C NMR, UV-vis and ESR spectroscopy), by morphological observations (SEM and XRD), and by magnetic and thermal measurements. The Schiff base (2CS-Hdhba) behaves as a bidentate chelate with a single negative charge. The azomethine nitrogen and the deprotonated 2-hydroxy centres with the pendant glucosamine hydroxy functionality play no role in coordination. The dissociation constants of 2CS-Hdhba and the stability constants of some of its metal complexes have been determined pH-metrically. PMID:21392736

Anan, Neveen A; Hassan, Shawky M; Saad, Eman M; Butler, Ian S; Mostafa, Sahar I

2011-05-01

241

Dissociation of copper(II) ternary complexes containing cystine.  

PubMed

The collision-induced dissociations are reported for Cu(II) complexes containing 1,4,7-triazacyclononane (tacn) as the auxiliary ligand and a peptide containing one cystine residue. For six of the complexes examined, cleavage of the S-S bond in the peptide was the dominant fragmentation pathway. The exceptions were for complexes containing the largest peptides, (GlyCys'Gly)(2) and (GlyGlyCys')(2) (Cys' = NHCH(CH(2)S)CO, one half of the cystine residue; terminal H and OH are implicit), for which proton transfer to the auxiliary ligand was the major channel. Cleavage of the C-S bond was observed, but was a minor channel for all complexes. The radical cation (Cys')(2)(*+) was not observed although the complementary ion [Cu(I)(tacn)](+) was present in moderate abundance. Density functional calculations (at B3LYP/6-311++G(d,p)) gave low barriers to fragmentation of (Cys')(2)(*+) by homolytic fission of the C-S bond of the canonical ion (barrier 16.5 kcal mol(-1)) and of the structure at the global minimum, a captodative ion (barrier 17.2 kcal mol(-1)). Peptide radical cations (GlyCys')(2)(*+), (GlyCys'Gly)(2)(*+), (GlyGlyCys')(2)(*+) and (GlyCys'(Cys')Gly)(*+) were observed in low abundances; the first two of these ions dissociated predominantly by fragmentation of the S-S bond, while the other two preferentially cleaved at an amide bond. No cleavage of the C-S bond was observed for the peptide radical cations. Density functional calculations at B3LYP/6-31G(d) established that the cystine in [Cu(II)(tacn)(Cys')(2)](*2+) is bound as a zwitterion through the carboxylate anion with the proton on the distal amino group. The lowest energy complex containing a canonical cystine, coordinated through the carbonyl oxygen and the amino group of the same Cys', is 8.3 kcal mol(-1) higher in enthalpy. PMID:20539872

Ke, Yuyong; Zhao, Junfang; Siu, K W Michael; Hopkinson, Alan C

2010-08-21

242

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

243

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

NASA Astrophysics Data System (ADS)

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

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

2011-02-01

244

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.  

PubMed

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, (1)H, (13)C 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)A and 12.1667(4)A, b=8.0121(3)A and 10.4792(3)A, c=13.9625(4)A and 129.6616(3)A, V=1155.22(6)A(3) and 1155.22(6)A(3), D(x)=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. PMID:20047854

Unver, Hüseyin; Hayvali, Zeliha

2010-02-01

245

Monitoring cellular uptake and cytotoxicity of copper(II) complex using a fluorescent anthracene thiosemicarbazone ligand.  

PubMed

The thiosemicarbazone derivative of anthracene (ATSC, anthracene thiosemicarbazone 1) and its copper(II) complex (CuATSC, 2) were synthesized and characterized by spectroscopic, electrochemical, and crystallographic techniques. Interaction of 1 and 2 with calf thymus (CT) DNA was explored using absorption and emission spectral methods, and viscosity measurements reveal a partial-intercalation binding mode. Their protein binding ability was monitored by the quenching of tryptophan emission using bovine serum albumin (BSA) as a model protein. Furthermore, their cellular uptake, in vitro cytotoxicity testing on the HeLa cell line, and flow cytometric analysis were carried out to ascertain the mode of cell death. Cell cycle analysis indicated that 1 and 2 cause cell cycle arrest in sub-G1 phase. PMID:24328322

Kate, Anup N; Kumbhar, Anupa A; Khan, Ayesha A; Joshi, Pranaya V; Puranik, Vedavati G

2014-01-15

246

Absorption spectra and the symmetry of the environment of the copper(II) ion in aquoammine complexes  

Microsoft Academic Search

es with composition [Cu(H20)6_2nenn ]2+ (where n= 1-3) have not been investigated at all. The present work was devoted to investigation of the absorption spectra of the aquoammine and aquoethylenediam ine complexes of copper(II) for the purpose of determining the electronic structure of the central ion and the symmetry of its environment in these complexes. EXPERIMENTAL It is not possible

I. I. Volchenskova

1975-01-01

247

Role of ligand to control the mechanism of nitric oxide reduction of copper(II) complexes and ligand nitrosation.  

PubMed

The nitric oxide reactivity of two copper(II) complexes, 1 and 2 with ligands L(1) and L(2), respectively, [L(1) = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, L(2) = 5,5,7-trimethyl-[1,4]-diazepane] have been studied. The copper(II) center in complex 1 was found to be unreactive toward nitric oxide in pure acetonitrile; however, it displayed reduction in methanol solvent in presence of base. The copper(II) center in 2, in acetonitrile solvent, on exposure to nitric oxide has been found to be reduced to copper(I). The same reduction was observed in methanol, also, in case of complex 2. In case of complex 1, presumably, the attack of nitric oxide on the deprotonated amine is the first step, followed by electron transfer to the copper(II) center to afford the reduction. Alternatively, first NO coordination to the Cu(II) followed by NO(+) migration to the secondary amine is the most probable in case of complex 2. The observation of the transient intermediate in UV-visible and FT-IR spectroscopy prior to reduction in case of complex 2 also supports this possibility. In both cases, the reduction resulted into N-nitrosation; in 1, only mononitrosation was observed whereas complex 2 afforded dinitrosation as major product along with a minor amount of mononitrosation. Thus, it is evident from the present study that the macrocyclic ligands prefer the deprotonation pathway leading to mononitrosation; whereas nonmacrocyclic ones prefer the [Cu(II)-NO] intermediate pathway resulting into nitrosation at all the available sites of the ligand as major product. PMID:22040303

Kalita, Apurba; Kumar, Pankaj; Deka, Ramesh C; Mondal, Biplab

2011-12-01

248

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)]ClO4·H2O (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

249

Synthesis and crystal structure of a ternary copper(II) complex of 2,2?-bipyridine and picrate: Molecular docking, reactivity towards DNA and in vitro anticancer activity  

NASA Astrophysics Data System (ADS)

A new mononuclear ternary copper(II) complex with mixed ligands of 2,2?-bipyridine (bpy) and picrate (pic), namely [Cu(bpy)(pic)2], has been synthesized and characterized by elemental analysis, molar conductivity measurement, IR and electronic spectral studies, and single-crystal X-ray diffraction. The crystal structure analysis reveals the presence of two crystallographic independent molecules in an asymmetric unit. The copper(II) atoms are in elongated octahedral coordination geometries. A three-dimensional supermolecular network is formed through non-classical C-H⋯O hydrogen bonds. The DNA-binding properties of the copper(II) complex are investigated both theoretically and experimentally, revealing that the copper(II) complex can interact with HS-DNA in the mode of intercalation, and the molecular docking of the copper(II) complex with the self-complementary DNA duplex of sequence d(ACCGACGTCGGT)2 facilitates the binding events. The in vitro anticancer activities suggest that the copper(II) complex is active against the selected tumor cell lines.

Zheng, Kang; Jiang, Man; Li, Yan-Tuan; Wu, Zhi-Yong; Yan, Cui-Wei

2014-01-01

250

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, Luís M P; Halime, Zakaria; Marion, Ronan; Camus, Nathalie; Delgado, Rita; Platas-Iglesias, Carlos; Tripier, Raphaël

2014-05-19

251

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

252

Synthesis, characterization, DNA binding, cleavage activity and cytotoxicity of copper(II) complexes.  

PubMed

Three new mononuclear copper(II) complexes, [Cu(L2)](2+) (1), [Cu(acac)(L)](+) (2), and [Cu(acac-Cl)(L)](+) (3) (L = 2-(4-pyridine)oxazo[4,5-f]1,10-phenanthroline (4-PDOP); acac = acetylacetone; acac-Cl = 3-chloroacetylacetone), have been synthesized and characterized by elemental analysis, high resolution mass spectrometry (Q-TOF), and IR spectroscopy. Two of the complexes were structurally characterized by single-crystal X-ray diffraction techniques. Their interactions with DNA were studied by UV-vis absorption and emission spectra, viscosity, thermal melting, DNA unwinding assay and CD spectroscopy. The nucleolytic cleavage activity of the compounds was carried out on double stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment in the presence and absence of an oxidant (H2O2). Active oxygen intermediates such as hydroxyl radicals and hydrogen peroxide generated in the presence of L and complexes 1-3 may act as active species for the DNA scission. The cytotoxicity of the complexes against HepG2 cancer cells was also studied. PMID:24336842

Li, Mei-Jin; Lan, Tao-Yu; Cao, Xiu-Hui; Yang, Huang-Hao; Shi, Yupeng; Yi, Changqing; Chen, Guo-Nan

2014-02-21

253

3-Pyridylmethanol vs. N,N?-diethylnicotinamide in copper(II) complex formation - A comparative EPR study  

NASA Astrophysics Data System (ADS)

Copper(II) complexes, formed from 4-chlorosalicylic acid anion A (A = 4-Clsal-), different copper(II) salts (Cu(ac)2 or CuSO4) and different N-donor ligands B (B = 3-pyridylmethanol (ron) or N,N'-diethylnicotinamide (denia)) with varying N-donor ligand-to-metal ratio (x), were studied by EPR spectroscopy in the frozen water/methanol (1:3 v/v) solutions. The number of ligand B molecules coordinated to Cu(II) central ion was determined from the nitrogen perpendicular and parallel superhyperfine splitting multiplets of Cu(II) EPR spectra. It was found for both N-donor ligands: (i) At lower ligand B concentrations (x = 1, 2), [CuB] and/or [CuB2] species having one and/or two molecules of ligands B in equatorial position were dominant. The dominant ternary complex particles were [CuA2B2] species. (ii) At higher ligand B concentrations (x ? 4) the formation of [CuB3] and/or [CuB4] species having three and/or four molecules of ligands B in equatorial position was confirmed. Such information is not possible to get from Cu(II) EPR spectra of powdered samples of given copper(II) complexes.

Husáriková, L.; Repická, Z.; Valigura, D.; Valko, M.; Mazúr, M.

2013-10-01

254

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

255

Cu(II), Ni(II) and Fe(II) complexes with a new substituted [1,2,4] triazole Schiff base derived from 4-amino-5-(thien-2-yl ethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one and 2-hydroxy-1-naphthaldehyde: synthesis, characterization and a comparison of theoretical and experimental results by Ab inito calculation  

Microsoft Academic Search

The synthesis and structural properties of two novel compounds, 4-amino-5-(thien-2-yl ethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one\\u000a and 4-{[(2-hydroxy-1-naphthyl)methyl-ene]amino}-5-(thien-2-ylmethyl) ? 2,4-dihydro-3H-1,2,4-triazol-3-one have been described.\\u000a 4-Amino-5-(thien-2-ylmethyl)-2,4-dihydro-3H-1,2,4-triazol-3-one was synthesized by treating N-propionyl-2-thien-2-ylethane-hydrazonoate with hydrazine hydrate and the Schiff base was obtained from condensation of substituted\\u000a amine with 2-hydroxy-1-naphthaldehyde. The Cu(II), Ni(II) and Fe(II) complexes were prepared and characterized by elemental\\u000a analyses, IR, magnetic moment, UV–Vis, mass spectral data

Kemal Sancak; Mustafa Er; Yasemin Ünver; Melike Yildirim; Ismail Degirmencioglu; Kerim Serbest

2007-01-01

256

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

257

Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone  

SciTech Connect

The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate (I), bromo-(2-formylpyridinethiosemicarbazono)copper (II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate (III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I-III at a concentration of 10{sup -5} mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

Chumakov, Yu. M., E-mail: chumakov.xray@phys.asm.md [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Tsapkov, V. I. [State University of Moldova (Moldova, Republic of); Jeanneau, E. [Universite Claude Bernard, Laboratoire des Multimateriaux et Interfaces (France); Bairac, N. N. [State University of Moldova (Moldova, Republic of); Bocelli, G. [National Research Council (IMEM-CNR), Institute of Materials for Electronics and Magnetism (Italy); Poirier, D.; Roy, J. [Centre Hospitalier Universitaire de Quebec (CHUQ) (Canada); Gulea, A. P. [State University of Moldova (Moldova, Republic of)

2008-09-15

258

Metal-directed assembly of chiral bis-Zn(II) Schiff base structures.  

PubMed

Tetra-Schiff bases derived from (chiral) bis-salphen ligand scaffolds furnish, upon metalation with appropriate metal reagents, their multinuclear structures with associated Zn(OAc)(2) or Zn(OH)(2) fragments. The tendency of retaining these salts was investigated using four different (chiral) bis-salphen scaffolds. The presence of the additional Zn ions was supported by NMR studies, mass determinations and X-ray crystallography showing in two cases the possible mode of coordination within these multinuclear structures. In one case, dimerization of the Zn(3) complex leads to a unique hexanuclear Zn(6) complex being a mixture of diastereoisomeric complexes as revealed by NMR spectroscopy. PMID:22782074

Escárcega-Bobadilla, Martha V; Anselmo, Daniele; Wezenberg, Sander J; Escudero-Adán, Eduardo C; Martínez Belmonte, Marta; Martin, Eddy; Kleij, Arjan W

2012-08-28

259

Synthesis of novel bisindolylmethane Schiff bases and their antibacterial activity.  

PubMed

In an effort to develop new antibacterial drugs, some novel bisindolylmethane derivatives containing Schiff base moieties were prepared and screened for their antibacterial activity. The synthesis of the bisindolylmethane Schiff base derivatives 3-26 was carried out in three steps. First, the nitro group of 3,3'-((4-nitrophenyl)-methylene)bis(1H-indole) (1) was reduced to give the amino substituted bisindolylmethane 2 without affecting the unsaturation of the bisindolylmethane moiety using nickel boride in situ generated. Reduction of compound 1 using various catalysts showed that combination of sodium borohydride and nickel acetate provides the highest yield for compound 2. Bisindolylmethane Schiff base derivatives were synthesized by coupling various benzaldehydes with amino substituted bisindolylmethane 2. All synthesized compounds were characterized by various spectroscopic methods. The bisindolylmethane Schiff base derivatives were evaluated against selected Gram-positive and Gram-negative bacterial strains. Derivatives having halogen and nitro substituent display weak to moderate antibacterial activity against Salmonella typhi, S. paratyphi A and S. paratyphi B. PMID:25102118

Imran, Syahrul; Taha, Muhammad; Ismail, Nor Hadiani; Khan, Khalid Mohammed; Naz, Farzana; Hussain, Memona; Tauseef, Saima

2014-01-01

260

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

Çak?r, S.; Co?kun, E.; Naumov, P.; Biçer, E.; Bulut, ?.; ?çbudak, H.; Çak?r, O.

2002-08-01

261

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

262

Synthesis, Characterization, and Bioactivity of Schiff Bases and Their Cd2+, Zn2+, Cu2+, and Ni2+ Complexes Derived from Chloroacetophenone Isomers with S-Benzyldithiocarbazate and the X-Ray Crystal Structure of S-Benzyl-?-N-(4-chlorophenyl)methylenedithiocarbazate  

PubMed Central

Two bidentate Schiff base ligands having nitrogen sulphur donor sequence were derived from the condensation of S-benzyldithiocarbazate (SBDTC) with 2-chloroacetophenone and 4-chloroacetophenone to give S-benzyl-?-N-(2-chlorophenyl)methylenedithiocarbazate (NS2) and S-benzyl-?-N-(4-chlorophenyl)methylenedithiocarbazate (NS4) isomers. Each of the ligands was then chelated with Cd2+, Zn2+, Cu2+, and Ni2+. The compounds were characterized via IR spectroscopy and melting point while the structure of NS4 was revealed via X-ray crystallography. Finally, the compounds were screened for antimicrobial activity to investigate the effect that is brought by the introduction of the chlorine atom to the benzene ring. X-ray crystallographic analysis showed that the structure of NS4 is planar with a phenyl ring that is nearly perpendicular to the rest of the molecules. The qualitative antimicrobial assay results showed that NS4 and its complexes lacked antifungal activity while Gram-positive bacteria were generally inhibited more strongly than Gram-negative bacteria. Furthermore, NS4 metal complexes were inhibited more strongly than the ligand while the opposite was seen with NS2 ligand and its complexes due to the partial solubility in dimethyl sulfoxide (DMSO). It was concluded that generally NS2 derivatives have higher bioactivity than that of NS4 derivatives and that the Cd complexes of both ligands have pronounced activity specifically on K. rhizophila. PMID:24319401

Break, Mohammed Khaled bin; Tahir, M. Ibrahim M.; Crouse, Karen A.; Khoo, Teng-Jin

2013-01-01

263

Spectral and physico-chemical investigations of novel homo-dinuclear di-micro2-alkoxo bridged Schiff base complexes: 57Fe Mössbauer parameters of the Fe(III) complex.  

PubMed

Spectral and molecular model computations on homo-dinuclear complexes [M(2)L(2)(H(2)O)(2)Cl(2)] [L=1-(salicylaldeneamino)-3-hydroxypropane, M=Cr(3+), Mn(3+), Fe(3+), Co(3+), Ni(3+) or Cu(3+)] are consistent with a distorted hexa-coordinate geometry. X-band EPR spectral data indicated a rhombic distortion around Cu(II) ion. Magnetic moment and (57)Fe Mössbauer data confirmed a high-spin state electronic configuration (t(2g)(3)e(g)(2), S=5/2) and asymmetric ligand environment around Fe(III) with nuclear transitions Fe(+/-3/2-->1/2) exhibiting Kramer's double degeneracy. The neighboring Fe(III) nuclei in the homo-dinuclear species are antiferromagnetically coupled. PMID:20036186

Siddiqi, Zafar A; Khalid, Mohd; Kumar, Sarvendra; Shahid, M; Noor, Shabana

2010-02-01

264

Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity  

NASA Astrophysics Data System (ADS)

New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL1 and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL2 derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML(1-2)2 have been synthesized, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate ? coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mn < Zn < Cu < Co < Ni. The ligands and their complexes were tested for in vitro antibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu > Mn > Ni > Co > Zn.

Devi, Jai; Batra, Nisha; Malhotra, Rajesh

2012-11-01

265

N-benzoylated 1,4,8,11-tetraazacyclotetradecane and their copper(II) and nickel(II) complexes: spectral, magnetic, electrochemical, crystal structure, catalytic and antimicrobial studies.  

PubMed

A series of N-benzoylated cyclam ligands incorporating three different benzoyl groups 1,4,8,11-tetra-(benzoyl)-1,4,8,11-tetraazacyclotetradecane (L(1)), 1,4,8,11-tetra-(2-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L(2)) and 1,4,8,11-tetra-(4-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L(3)) and their nickel(II) and copper(II) complexes are described. Crystal structure of L(1) is also reported. The ligands and complexes were characterized by elemental analysis, electronic, IR, (1)H NMR and (13)C NMR spectral studies. N-benzoylation causes red shift in the lambda(max) values of the complexes. The cyclic voltammogram of the complexes of ligand L(1) show one-electron, quasi-reversible reduction wave in the region -1.00 to -1.04 V, whereas that of L(2) and L(3) show two quasi-reversible reduction peaks. Nickel complexes show one-electron quasi-reversible oxidation wave at a positive potential in the range +1.05 to +1.15 V. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment values mu(eff) 1.70-1.73 BM which is close to the spin-only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. All the ligands and their complexes were also screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi. PMID:20554242

Nirmala, G; Kalilur Rahiman, A; Sreedaran, S; Jegadeesh, R; Raaman, N; Narayanan, V

2010-09-15

266

N-benzoylated 1,4,8,11-tetraazacyclotetradecane and their copper(II) and nickel(II) complexes: Spectral, magnetic, electrochemical, crystal structure, catalytic and antimicrobial studies  

NASA Astrophysics Data System (ADS)

A series of N-benzoylated cyclam ligands incorporating three different benzoyl groups 1,4,8,11-tetra-(benzoyl)-1,4,8,11-tetraazacyclotetradecane (L 1), 1,4,8,11-tetra-(2-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L 2) and 1,4,8,11-tetra-(4-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L 3) and their nickel(II) and copper(II) complexes are described. Crystal structure of L 1 is also reported. The ligands and complexes were characterized by elemental analysis, electronic, IR, 1H NMR and 13C NMR spectral studies. N-benzoylation causes red shift in the ?max values of the complexes. The cyclic voltammogram of the complexes of ligand L 1 show one-electron, quasi-reversible reduction wave in the region -1.00 to -1.04 V, whereas that of L 2 and L 3 show two quasi-reversible reduction peaks. Nickel complexes show one-electron quasi-reversible oxidation wave at a positive potential in the range +1.05 to +1.15 V. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment values ?eff 1.70-1.73 BM which is close to the spin-only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. All the ligands and their complexes were also screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi.

Nirmala, G.; Rahiman, A. Kalilur; Sreedaran, S.; Jegadeesh, R.; Raaman, N.; Narayanan, V.

2010-09-01

267

Digital logic circuit based on a single molecular system of salicylidene Schiff base.  

PubMed

The salicylidene Schiff base N-3,5-dichloro-salicylidene-(S)-alpha-phenylethylamine (SPEA) has been synthesized and characterized. Stimulated by one optical input (UV light) and two chemical inputs (OH(-) and Zn(2+)), SPEA undergoes reactions of photochemistry, deprotonation, and complexation. Tailing these reactions by means of the UV-vis absorption spectra and fluorescence spectra, two obvious optical outputs, an absorption band at 323 nm and a fluorescent emission peak at 460 nm, have been obtained. On the basis of encoding binary digits in these inputs and outputs applying positive logic conventions, one monomolecular circuit, which integrates one OR, two NOT, and four AND gates, has been achieved. PMID:17134179

Zhao, Liyan; Sui, Dan; Chai, Jia; Wang, Yue; Jiang, Shimei

2006-12-01

268

A Schiff-based sensor with turn-on fluorescence for selective detection of Hg2+.  

PubMed

A simple Schiff-base colorimetric receptor 1 was prepared. It exhibits an ‘off–on-type’ mode with high sensitivity in the presence of Hg2+. The change in color is very easily observed by the naked eye in the presence of Hg2+, whereas other metal cations do not induce such a change. A Job plot indicated a 1 : 1 complexation stoichiometry between receptor 1 and Hg2+. The association constant for 1–Hg2+ in Tetrahydrofuran (THF) was determined to be 1.3 × 10(9)M-1 using a Hill plot. PMID:25337615

Wan, Chin-Feng; Lin, Hsiang-Yi; Chien, Cho; Wu, An-Tai

2014-09-01

269

Enantioselective Henry reaction catalyzed by "ship in a bottle" complexes.  

PubMed

Two chiral Schiff-base complexes of copper(II) have been successfully encapsulated inside the cavity of zeolite-NaY via a "ship in a bottle" synthesis method. The presence of the two complexes inside the cages of zeolite-Y has been confirmed based on various spectrochemical and physicochemical techniques, viz. FTIR, UV-vis/DRS, ESR, XPS, CV, EDX, SEM, and TGA. Zeolite-encapsulated chiral copper(II) Schiff-base complexes are found to give a high-enantioselective (84% ee, R conformation) nitro-aldol product at -20 °C. The encapsulated copper complexes are found to show higher catalytic efficiency than their homogeneous counterparts under identical conditions. Density functional theory (DFT) calculation has been implemented to understand the effect of the zeolite matrix on structural, electronic, and reactivity properties of the synthesized complexes. Theoretical calculation predicts that upon encapsulation into the zeolite matrix the Cu center becomes more susceptible to nucleophilic attack, favoring a nitro-aldol reaction. A plausible mechanism is suggested based on the experimental and theoretical results. The structures of reaction intermediates and transition state(s) involved in the catalytic cycle are derived using DFT. PMID:23848182

Bania, Kusum K; Karunakar, Galla V; Goutham, Kommuru; Deka, Ramesh C

2013-07-15

270

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 1×10(-2) to 1×10(-5) mol L(-1) with a detection limit (3?) of 1×10(-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

271

Synthesis, micellization behavior, antimicrobial and intercalative DNA binding of some novel surfactant copper(II) complexes containing modified phenanthroline ligands.  

PubMed

The novel surfactant copper(II) complexes, [Cu(ip)2DA](ClO4)21, [Cu(dpqc)2DA](ClO4)22, [Cu(dppn)2DA](ClO4)23, where ip=imidazo[4,5-f][1,10]phenanthroline, dpqc=dipyrido[3,2-a:2',4'-c](6,7,8,9-tetrahydro)phenazine, dppn=benzo[1]dipyrido[3,2-a':2',3'-c]phenazine and DA-dodecylamine, were synthesized and characterized by physico-chemical and spectroscopic methods. In these complexes 1-3, the geometry of copper metal ions was described as square pyramidal. The critical micelle concentration (CMC) value of these surfactant copper(II) complexes in aqueous solution was found out from conductance measurements. Specific conductivity data at different temperatures served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (?Gm°, ?Hm° and ?Sm°). The binding interaction of these complexes with DNA (calf thymus DNA) in Tris buffer was studied by physico-chemical techniques. In the presence of the DNA UV-vis spectrum of complexes showed red shift of the absorption band along with significant hypochromicity indicating intercalation of our complexes with nucleic acids. Competitive binding study with ethidium bromide (EB) shows that the complexes exhibit the ability to displace the nucleic acid-bound EB indicating that the complexes bind to nucleic acids in strong competition with EB for the intercalative binding site. Observed changes in the circular dichoric spectra of DNA in the presence of surfactant complexes support the strong binding of complexes with DNA. CV results also confirm this mode of binding. Some significant thermodynamic parameters of the binding of the titled complexes to DNA have also been determined. The results reveal that the extent of DNA binding of 3 was greater than that of 1 and 2. The antibacterial and antifungal screening tests of these complexes have shown good results compared to its precursor chloride complexes. PMID:25033435

Nagaraj, Karuppiah; Ambika, Subramanian; Rajasri, Shanmugasundaram; Sakthinathan, Subramanian; Arunachalam, Sankaralingam

2014-10-01

272

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

273

In vitro study of DNA interaction with a water-soluble dinitrogen schiff base.  

PubMed

The present study investigates the binding interaction between a water-soluble Schiff base, N,N'-bis{5-[(triphenylphosphonium chloride)-methyl]salicylidine}-o-phenylenediamine (SF), and calf thymus DNA (CT-DNA) using emission, absorption, circular dichroism, and viscosity studies. In fluorimetric studies, the dynamic enhancement constant (K(D)) and bimolecular enhancement constant (K(B)) were calculated at different temperatures and demonstrated that fluorescence enhancement is not initiated by a dynamic process, but instead by a static process that involves complex DNA formation in the ground state. Further, the enthalpy and entropy of the reaction between SF and CT-DNA showed that the reaction is exothermic and enthalpy-favored (DeltaH = -153.51 kJ mol(-1); DeltaS = -427.67 J mol(-1) K). In addition, detectable changes in the circular dichroism spectrum of CT-DNA in the presence of SF indicated deep conformational changes in the DNA double helix following interaction with SF. Further, the Schiff base at different concentrations is able to perform cleavage of pUC18 plasmid DNA. All these results prove that SF interacts with CT-DNA via an intercalative mode of binding. PMID:19732014

Shahabadi, Nahid; Kashanian, Soheila; Darabi, Farivash

2009-11-01

274

Synthesis of N4 donor macrocyclic Schiff base ligands and their Ru (II), Pd (II), Pt (II) metal complexes for biological studies and catalytic oxidation of didanosine in pharmaceuticals  

NASA Astrophysics Data System (ADS)

A series of tetraaza (N4 donor) macrocyclic ligands (L1-L4) were derived from the condensation of o-phthalaldehyde (OPA) with some substituted aromatic amines/azide, and subsequently used to synthesize the metal complexes of Ru(II), Pd(II) and Pt(II). The structures of macrocyclic ligands and their metal complexes were characterized by elemental analyses, IR, 1H &13C NMR, mass and electronic spectroscopy, thermal, magnetic and conductance measurements. Both the ligands and their complexes were screened for their antibacterial activities against Gram positive and Gram negative bacteria by MIC method. Besides, these macrocyclic complexes were investigated as catalysts in the oxidation of pharmaceutical drug didanosine. The oxidized products were further treated with sulphanilic acid to develop the colored products to determine by spectrophotometrically. The current oxidation method is an environmentally friendly, simple to set-up, requires short reaction time, produces high yields and does not require co-oxidant.

Ravi krishna, E.; Muralidhar Reddy, P.; Sarangapani, M.; Hanmanthu, G.; Geeta, B.; Shoba Rani, K.; Ravinder, V.

2012-11-01

275

Synthesis, spectroscopic characterization, molecular modeling and antimicrobial activities of Mn(II), Co(II), Ni(II), Cu(II) complexes containing the tetradentate aza Schiff base ligand  

NASA Astrophysics Data System (ADS)

Mn(II), Co(II), Ni(II), and Cu(II) complexes with a tetradentate macrocyclic ligand [1.2.5.6tetraoxo-3,4,7,8tetraaza-(1,2,3,4,5,6,7,8)tetrabenzene(L)] were synthesized and characterized by elemental analysis, molar conductance measurements, mass, nmr, i.r., electronic and e.p.r. spectral studies. All the complexes are non electrolytes in nature and may be formulated as [M(L)X2] [where, M = Mn(II), Co(II), Ni(II), Cu(II) and X = Cl-, CH3COO-]. On the basis of i.r., electronic and e.p.r. spectral studies a distorted octahedral geometry has been assigned for all complexes. The antimicrobial activities and LD50 values of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against two different species of bacteria and plant pathogenic fungi.

Chandra, Sulekh; Ruchi

2013-02-01

276

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

277

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.  

PubMed

A series of heteroleptic copper(II) complexes of the type [CuL(1-4)(diimine)](ClO4)2 (1-8) [L(1-4)=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 [Formula: see text] 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. PMID:24998685

Ravichandran, J; Gurumoorthy, P; Imran Musthafa, M A; Kalilur Rahiman, A

2014-12-10

278

Temperature-dependent self-assembly of near-infrared (NIR) luminescent Zn2Ln and Zn2Ln3 (Ln = Nd, Yb or Er) complexes from the flexible Salen-type Schiff-base ligand  

NASA Astrophysics Data System (ADS)

Through the self-assembly of the precursor [Zn(L)(MeCN)] (H2L = N,N?-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine) with LnCl3·6H2O (Ln = La, Nd, Yb, Er or Gd) and NaN3 in alcohol-containing solutions, two series of mixed anions-induced Zn2Ln-arrayed complexes [Zn2(L)2(MeOH)ClLn(N3)]·Cl (Ln = La, 1; Ln = Nd, 2; Ln = Yb, 3; Ln = Er, 4 or Ln = Gd, 5) and Zn2Ln3-arrayed complexes [Zn2(L)3Cl2(?2-OH)(?3-OH)2Ln3(N3)2] (Ln = La, 6; Ln = Nd, 7; Ln = Yb, 8; Ln = Er, 9 or Ln = Gd, 10) are obtained at room temperature or under reflux, respectively. In contrast to Zn2Ln-arrayed complexes with the two Zn2+ ions in the inner cis-N2O2 cores and one Ln3+ ion in the outer O2O2 moieties, the demetalation of partial precursors leads to the selective exchange of Zn2+ centers for the Ln3+ ions for the formation of novel heterometallic Zn2Ln3-arrayed complexes with the Ln3+ ions in both the inner cis-N2O2 core and the outer O2O2 moieties of the ligands. The result of their photophysical properties shows that the characteristic near-infrared (NIR) luminescence of Nd3+ or Yb3+ ion has been sensitized from the excited state (both 1LC and 3LC) of the ligand H2L, while relatively lower quantum yields for Zn2Ln3-arrayed complexes than those for Zn2Ln-arrayed complexes, correspondingly, should be due to the luminescent quenching with the involvement of OH- oscillators around the Ln3+ ions.

Miao, Tiezheng; Zhang, Zhao; Feng, Weixu; Su, Peiyang; Feng, Heini; Lü, Xingqiang; Fan, Daidi; Wong, Wai-Kwok; Jones, Richard A.; Su, Chengyong

2014-11-01

279

Synthesis, characterization, and catalase activity of a water-soluble diMn(III) complex of a sulphonato-substituted Schiff base ligand: an efficient catalyst for H2O2 disproportionation.  

PubMed

A new diMn(III) complex, Na[Mn(2)(3-Me-5-SO(3)-salpentO)(?-MeO)(?-AcO)(H(2)O)]·4H(2)O (1), where salpentOH = 1,5-bis(salicylidenamino) pentan-3-ol, was synthesized and structurally characterized. The complex possesses a bis(?-alkoxo)(?-acetato) triply bridged diMn(III) core, the structure of which is retained upon dissolution. Complex 1 is highly efficient to disproportionate H(2)O(2) in an aqueous solution of pH ? 8.5 or in DMF, with only a slight decrease of activity. Electrospray ionization mass spectrometry, EPR, and UV-vis spectroscopy used to monitor the H(2)O(2) disproportionation in buffered basic medium, suggest that the major active form of the catalyst during cycling occurs in the Mn(III)(2) oxidation state and that the starting complex retains the dinuclearity and composition during catalysis, with the acetate that moves from bridging to terminal ligand. UV-vis and Raman spectroscopy of H(2)O(2) + 1 + Bu(4)NOH mixtures in DMF suggest that the catalytic cycle involves Mn(III)(2)/Mn(IV)(2) oxidation levels. At pH 10.6 in an Et(3)N/Et(3)NH(+) buffer, complex 1 catalyzes dismutation of H(2)O(2) with saturation kinetics on the substrate, first order dependence on the catalyst, and k(cat)/K(M) = 16(1) × 10(2) s(-1) M(-1). During catalysis, the exogenous base contributes to retain the integrity of the bis(?-alkoxo) doubly bridged diMn core and favors the formation of the catalyst-peroxide adduct (low value of K(M)), rendering 1 a highly efficient catalyst for H(2)O(2) disproportionation. PMID:21859087

Palopoli, Claudia; Bruzzo, Natalia; Hureau, Christelle; Ladeira, Sonia; Murgida, Daniel; Signorella, Sandra

2011-09-19

280

Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity.  

PubMed

New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL(1) and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL(2) derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML((1-2)2) have been synthesized, where M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mncomplexes were tested for in vitro antibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu>Mn>Ni>Co>Zn. PMID:22813991

Devi, Jai; Batra, Nisha; Malhotra, Rajesh

2012-11-01

281

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 4.0eV 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

282

Synthesis and stereochemical assignments of diastereomeric Ni(II) complexes of glycine Schiff base with (R)-2-(N-{2-[N-alkyl-N-(1-phenylethyl)amino]acetyl}amino)benzophenone; a case of configurationally stable stereogenic nitrogen.  

PubMed

A family of chiral ligands derived from ?-phenylethylamine and 2-aminobenzophenone were prepared by alkylation of the nitrogen atom. Upon reaction with glycine and a Ni(II) salt, these ligands were transformed into diastereomeric complexes, as a result of the configurational stability of the stereogenic nitrogen atom. Different diastereomeric ratios were observed depending on the substituent R introduced in the starting ligand, and stereochemical assignments were based on X-ray analysis, along with NMR studies and optical rotation measurements. PMID:24605164

Moriwaki, Hiroki; Resch, Daniel; Li, Hengguang; Ojima, Iwao; Takeda, Ryosuke; Aceña, José Luis; Soloshonok, Vadim A

2014-01-01

283

Synthesis, characterization, structural analysis of metal(II) complexes of N'-[(E)-3-Bromo-5-Chloro-2-hydroxybenzidene]-4-hydroxybenzohydrazide-Multisubstituted Schiff base as a F(-) and Cu(2+) ions selective chemosensor.  

PubMed

New colorimetric chemosensor, N'-[(E)-3-Bromo-5-Chloro-2-hydroxybenzidene]-4-hydroxybenzohydrazide, containing OH and NH groups as binding sites have been synthesized and characterized by spectral UV, IR, NMR and ESR. The molecular structure of ligand is determined by X-ray crystallography and it has the monoclinic space group P21/c with cell parameters a=15.1058(6), b=14.3433(6), c=17.5800(8)Å and Z=8. The electronic spectral measurements show that Co(2+), Ni(2+) and Zn(2+) complexes have tetrahedral geometry, while Cu(2+) complex has square planar geometry. Magnetic measurements show that Cu(2+), Co(2+) and Ni(2+) complexes have paramagnetic behavior and Zn(2+) complex has diamagnetic behavior. Anion binding studies carried out using (1)H NMR and UV-visible spectrophotometric titrations revealed that these receptors exhibit selective recognition towards F(-) over other halide anions. The selectivity for F(-) among the halides is attributed mainly to the hydrogen-bond interaction of the receptor with F(-). Receptor (5 × 10(-5)M) shows color change from colorless to yellow in the presence of tetrabutylammonium fluoride (TBAF, 1.5 × 10(-3)M). Moreover, F(-)-induced color changes remain the same even in the presence of large excess of Cl(-), Br(-) and I(-). The binding constant is found to be higher towards F(-) ion and this may be due to presence of OH group, which offers extra binding site. Chromogenic receptor undergoes distinct color changes from colorless to green on gradual addition of Cu(2+) can be used as colorimetric probes for spectrophotometric and visual analysis of Cu(2+) in the presence of other transition metal ions such as Co(2+), Ni(2+) and Zn(2+). PMID:24759756

Sundar, A; Prabhu, M; Indra Gandhi, N; Marappan, M; Rajagopal, G

2014-08-14

284

Synthesis and stereochemical assignments of diastereomeric Ni(II) complexes of glycine Schiff base with (R)-2-(N-{2-[N-alkyl-N-(1-phenylethyl)amino]acetyl}amino)benzophenone; a case of configurationally stable stereogenic nitrogen  

PubMed Central

Summary A family of chiral ligands derived from ?-phenylethylamine and 2-aminobenzophenone were prepared by alkylation of the nitrogen atom. Upon reaction with glycine and a Ni(II) salt, these ligands were transformed into diastereomeric complexes, as a result of the configurational stability of the stereogenic nitrogen atom. Different diastereomeric ratios were observed depending on the substituent R introduced in the starting ligand, and stereochemical assignments were based on X-ray analysis, along with NMR studies and optical rotation measurements. PMID:24605164

Resch, Daniel; Li, Hengguang; Ojima, Iwao; Takeda, Ryosuke; Acena, Jose Luis

2014-01-01

285

Copper (II) and zinc (ii) metal-based salicyl-, furanyl-, thienyl- and pyrrolyl-derived ONNO, NNNO, ONNS & NNNS donor asymmetrically mixed schiff-bases with antibacterial and antifungal potentials.  

PubMed

A new series of asymmetric salicyl-, furanyl-, thienyl- and pyrrolyl-derived ONNO, NNNO, ONNS & NNNS donor antibacterial and antifungal Schiff-bases and their copper(II) and zinc(II) metal complexes have been synthesized and characterized. IR spectra indicated the ligands to act as quartdentate towards divalent metal ions via two azomethine-N, deprotonated-O of salicyl, furanyl-O, thienyl-S and/or pyrrolyl-N. The magnetic moments and electronic spectral data suggest octahedral geometry for Cu(II) and Zn(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against B. cereus, C. diphtheriae, E. coli, K. pneumoniae, P. mirabilis, P. aeruginosa, S. typhi, S. dysenteriae and S. aureus strains and for in-vitro antifungal activity against T. schoenleinii, C. glabrata, P. boydii, C. albicans, A. niger, M. canis and T. mentagrophytes. The results of these studies show the metal complexes to be more antibacterial/antifungal against one or more species as compared to the uncomplexed ligands. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties. Eight compounds, L(4), (1), (7), (8), (11), (17), (19) and (23) displayed potent cytotoxic activity with LD(50) = 1.445 x 10(- 3), 1.021 x 10(- 3), 7.478 x 10(- 4), 8.566 x 10(- 4), 1.028 x 10(- 3), 9.943 x 10(- 4), 8.730 x 10(- 4) and 1.124 x 10(- 3) M respectively, against Artemia salina. PMID:19005942

Chohan, Zahid H; Arif, M; Rashid, A

2008-12-01

286

Synthesis and characterisation of silver, zinc and cadmium compounds with an N 3O 2 Schiff base macrocycle: the crystal and molecular structures of the silver(I) and cadmium(II) complexes  

Microsoft Academic Search

The metal-templated cyclocondensation of 2,6-diformylpyridine and 1,4-bis(2-aminophenoxy)butane in the presence of silver(I), zinc(II) and cadmium(II) salts gave the following di-imine macrocyclic complexes: [AgL](ClO4) (1), [ZnL](ClO4)2·2H2O (2), [ZnL](NO3)2 (3), [CdL(H2O)2](ClO4)2 (4) and [CdL(NO3)(CH3OH)](NO3) (5) (L=macrocyclic ligand). All compounds have been characterised by microanalysis, IR, conductivity measurements, MS-FAB and 1H NMR spectroscopic studies. Compounds 1, 4 and 5 were also studied by

Laura Valencia; Harry Adams; Rufina Bastida; David E Fenton; Alejandro Mac??as

2001-01-01

287

X-ray absorption spectral studies of copper(II) mixed ligand complexes having ethylenediamine as one of the ligands  

NASA Astrophysics Data System (ADS)

X-ray absorption spectra of copper(II) mixed ligand complexes, having ethylenediamine (en) as one of the ligands, have been recorded at the K-edge of copper at the dispersive extended X- ray absorption fine structure (EXAFS) beamline (BL-8) at the 2.5 GeV INDUS-2 Synchrotron, RRCAT, Indore, India. The samples studied are: Cu(en)2(ClO4)2, Cu(en)2Br2.H2O and Cu(en)2SO4. The data obtained has been processed using EXAFS data analysis program Athena. The K-edge has been found to split in two edges K and K' in each of the complex. The energies of the edges K(EK) and K'(EK') and the principal absorption maximum A(EA) have been determined from the derivative spectra. The chemical shift has been utilized to determine the oxidation state of copper in the complexes and to estimate effective nuclear charge (ENC) on the absorbing atom. The EXAFS data has been used to determine the bond lengths in the complexes using three different graphical methods. The bond lengths, obtained from one of these methods and the Fourier transformation method, are comparable with each other, showing that both of these methods give phase uncorrected bond lengths.

Dwivedi, Shikha; Joshi, S. K.; Hinge, V. K.; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

2014-09-01

288

Synthesis, crystal structures and magnetic properties of one-and two-dimensional copper(II) complexes bridged by succinate q  

E-print Network

) Succinic acid (0.118 g, 1 mmol) was dissolved in a solution of NaOH (0.008 g, 2 mmol) in H2O (4 mSynthesis, crystal structures and magnetic properties of one- and two-dimensional copper(II) complexes bridged by succinate q Siau Gek Ang a,*, Bai Wang Sun a , Song Gao b a Department of Chemistry

Gao, Song

289

Study on the Phenolic Oxidation by H2O2 Using Metallomicelles Composed of Dinuclear Copper(II) Complex as Synthetic Peroxidases  

Microsoft Academic Search

A dinuclear copper(II) complex [Cu2(oxheel)] was synthesized and its structure was analyzed. This compound was then mixed with a surfactant (Brij35 or LSS) to form a metallomicelle, which would catalyze the phenol oxidation with the hydrogen peroxide (H2O2). The reaction mechanism and the mathematic model for the kinetics of this reaction were proposed, and the effect of the molar ratio

Hua Yan; Jun Li

2007-01-01

290

Discrete trinuclear copper(II) compounds as building blocks: the influence of the peripheral substituents on the magnetic coupling in oxamato-bridged complexes.  

PubMed

Two new trinuclear copper(ii) complexes without end-capping ligands, (Bu4N)2[Cu(dmso)2{Cu(dnopba)(dmso)}2] () and (Bu4N)2[Cu(dmso)2{Cu(dcopba)(dmso)}2] () [dnopba = 4,5-dinitro-ortho-phenylenebis(oxamate), dcopba = 4,5-dichloro-ortho-phenylenebis(oxamate), Bu4N(+) = tetra-n-butylammonium and dmso = dimethylsulfoxide], were synthesized and their structures were determined by single crystal X-ray diffraction. The crystal structures of and consist of two outer bis(oxamato)(dmso)cuprate(ii) units which act as bidentate ligands toward a trans-bis(dmso)copper(ii) inner entity leading to centrosymmetric tricopper(ii) complexes with copper-copper separations across the oxamate bridges of 5.1916(3) () and 5.1776(3) Å (). The peripheral copper(ii) ions in and are five-coordinate in somewhat distorted square pyramidal environments with a dmso molecule filling the apical position whereas the inner copper(ii) ion is six-coordinate in an elongated octahedral environment with two dmso molecules in the axial sites. The investigation of their magnetic properties in the temperature range 2.0-300 K shows the occurrence of a strong intramolecular antiferromagnetic coupling between the copper(ii) ions through the oxamate bridges [J1 = -296(1) () and -334(1) cm(-1) (), the Hamiltonian being defined as ? = -J1(?Cu2·?Cu1 + ?Cu2·?Cu1')], which leads to a low-lying spin doublet at low temperatures. Density functional theory calculations (DFT) have been used to substantiate these magnetic couplings and also to analyse the influence exerted on these interactions by the type of substituent at the 4,5-positions from the phenylene ring of the bis(oxamate) ligand. PMID:25135421

Barros, Wdeson P; da Silva, Beatriz C; Reis, Natália V; Pereira, Cynthia L M; Doriguetto, Antônio C; Cano, Joan; Pirota, Kleber R; Pedroso, Emerson F; Julve, Miguel; Stumpf, Humberto O

2014-10-21

291

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

PubMed

Structural properties of methocarbamol (Mcm) were extensively studied both experimentally and theoretically using FT IR, (1)H NMR, UV-Vis., geometry optimization, Mulliken charge, and molecular electrostatic potential. Stability arises from hyper-conjugative interactions, charge delocalization and H-bonding was analyzed using natural bond orbital (NBO) analysis. Mcm was decomposed in ethanol/water mixture at 80°C to guaifenesin [(RS)-3-(2-methoxyphenoxy)propane-1,2-diol] and carbamate ion [NH2COO(-)], where the degradation mechanism was explained by trapping the carbamate ion via the complexation with copper(II) ion. The structure of the isolated complex ([Cu(NH2COO)2(H2O)]?4H2O) was elucidated by spectral, thermal, and magnetic tools. Electronic spectra were discussed by TD-DFT and the descriptions of frontier molecular orbitals and the relocations of the electron density were determined. Calculated g-tensor values showed best agreement with experimental values from EPR when carried out using both the B3LYP and B3PW91 functional. PMID:24674917

Mansour, Ahmed M; Shehab, Ola R

2014-07-15

292

Copper(II) and gallium(III) complexes of trans-bis(2-hydroxybenzyl) cyclen derivatives: absence of a cross-bridge proves surprisingly more favorable.  

PubMed

Two cyclen (1,4,7,10-tetraazacyclododecane) derivatives bearing trans-bis(2-hydroxybenzyl) arms, the 1,7-(2-hydroxybenzyl)-1,4,7,10-tetraazacyclododecane (H2do2ph) and its cross-bridged counterpart (H2cb-do2ph), have been synthesized, aiming toward the possible use of their copper(II) and gallium(III) complexes in nuclear medicine. The protonation of both compounds was studied in aqueous solution as well as their complexes with Cu(2+) and Ga(3+) cations. The complexes of both ligands with Ca(2+) and Zn(2+) metal ions were also studied due to the abundance of these cations in biological media. In mild conditions the complexes of Ca(2+) and Ga(3+) with H2cb-do2ph did not form. The behavior of the two ligands and their complexes was compared by the values of the equilibrium constants, the data of varied spectroscopic techniques, the values of redox potentials of their copper(II) complexes, and the resistance of the complexes to acid dissociation. It was expected that, as found for related pairs of cyclen and cyclam (1,4,8,11-tetraazacyclotetradecane) derivatives, the cross-bridged macrocyclic derivative could be an excellent ligand for the complexation of copper(II). Additionally, the N-2-hydroxybenzyl groups were chosen due to their known ability to coordinate the gallium(III) cation. Due to the small size of the latter cation and its particular propensity to form hexacoordinate complexes, it was also expected that there would be a good ability of both ligands for the uptake of Ga(3+). Surprisingly, the results revealed that the cyclen derivative H2do2ph is the best ligand for the coordination of Cu(2+) and Ga(3+) cations, not only from their thermodynamic stability as expected but also from their kinetic inertness, when compared with its cross-bridged counterpart. PMID:24754354

Esteves, Catarina V; Madureira, Joana; Lima, Luís M P; Mateus, Pedro; Bento, Isabel; Delgado, Rita

2014-05-01

293

Design and synthesis of binucleating macrocyclic clefts derived from Schiff-base calixpyrroles.  

PubMed

The syntheses, characterisation and complexation reactions of a series of binucleating Schiff-base calixpyrrole macrocycles are described. The acid-templated [2+2] condensations between meso-disubstituted diformyldipyrromethanes and o-phenylenediamines generate the Schiff-base pyrrolic macrocycles H(4)L(1) to H(4)L(6) upon basic workup. The single-crystal X-ray structures of both H(4)L(3).2 EtOH and H(4)L(6).H2O confirm that [2+2] cyclisation has occurred, with either EtOH or H2O hydrogen-bonded within the macrocyclic cleft. A series of complexation reactions generate the dipalladium [Pd2(L)] (L=L(1) to L(5)), dinickel [Ni2(L(1))] and dicopper [Cu2(L)] (L=L(1) to L(3)) complexes. All of these complexes have been structurally characterised in the solid state and are found to adopt wedged structures that are enforced by the rigidity of the aryl backbone to give a cleft reminiscent of the structures of Pacman porphyrins. The binuclear nickel complexes [Ni2(mu-OMe)2Cl2(HOMe)2(H(4)L(1))] and [Ni2(mu-OH)2Cl2(HOMe)(H(4)L(5))] have also been prepared, although in these cases the solid-state structures show that the macrocyclic ligand remains protonated at the pyrrolic nitrogen atoms, and the Ni(II) cations are therefore co-ordinated by the imine nitrogen atoms only to give an open conformation for the complex. The dicopper complex [Cu2(L(3))] was crystallised in the presence of pyridine to form the adduct [Cu2(py)(L(3))], in which, in the solid state, the pyridine ligand is bound within the binuclear molecular cleft. Reaction between H(4)L(1) and [Mn(thf){N(SiMe(3))2}2] results in clean formation of the dimanganese complex [Mn2(L(1))], which, upon crystallisation, formed the mixed-valent complex [Mn2(mu-OH)(L(1))] in which the hydroxo ligand bridges the metal centres within the molecular cleft. PMID:17245783

Givaja, Gonzalo; Volpe, Manuel; Leeland, James W; Edwards, Michael A; Young, Thomas K; Darby, S Barnie; Reid, Stuart D; Blake, Alexander J; Wilson, Claire; Wolowska, Joanna; McInnes, Eric J L; Schröder, Martin; Love, Jason B

2007-01-01

294

Geometrical and optical benchmarking of copper(II) guanidine-quinoline complexes: Insights from TD-DFT and many-body perturbation theory (part II).  

PubMed

Ground- and excited-state properties of copper(II) charge-transfer systems have been investigated starting from density-functional calculations with particular emphasis on the role of (i) the exchange and correlation functional, (ii) the basis set, (iii) solvent effects, and (iv) the treatment of dispersive interactions. Furthermore (v), the applicability of TD-DFT to excitations of copper(II) bis(chelate) charge-transfer systems is explored by performing many-body perturbation theory (GW?+?BSE), independent-particle approximation and ?SCF calculations for a small model system that contains simple guanidine and imine groups. These results show that DFT and TD-DFT in particular in combination with hybrid functionals are well suited for the description of the structural and optical properties, respectively, of copper(II) bis(chelate) complexes. Furthermore, it is found an accurate theoretical geometrical description requires the use of dispersion correction with Becke-Johnson damping and triple-zeta basis sets while solvent effects are small. The hybrid functionals B3LYP and TPSSh yielded best performance. The optical description is best with B3LYP, whereby heavily mixed molecular transitions of MLCT and LLCT character are obtained which can be more easily understood using natural transition orbitals. An natural bond orbital analysis sheds light on the donor properties of the different donor functions and the intraguanidine stabilization during coordination to copper(I) and (II). © 2014 Wiley Periodicals, Inc. PMID:25255876

Hoffmann, Alexander; Rohrmüller, Martin; Jesser, Anton; Dos Santos Vieira, Ines; Schmidt, Wolf Gero; Herres-Pawlis, Sonja

2014-11-01

295

4-nitroacetophenone-derived thiosemicarbazones and their copper(II) complexes with significant in vitro anti-trypanosomal activity.  

PubMed

N(4)-methyl-4-nitroacetophenone thiosemicarbazone (H4NO(2)Ac4M, 1), N(4),N(4)-dimethyl-4-nitroacetophenone thiosemicarbazone (H4NO(2)Ac4DM, 2) and N(4)-piperidyl-4-nitroacetophenone thiosemicarbazone (H4NO(2)Ac4Pip, 3) and their copper(II) complexes [Cu(4NO(2)Ac4M)(2)] (4), [Cu(4NO(2)Ac4DM)(2)] (5) and [Cu(4NO(2)Ac4Pip)(2)] (6) were tested for their in vitro ability to inhibit the growth of Trypanosoma cruzi epimastigote forms. H4NO(2)Ac4DM (2), [Cu(4NO(2)Ac4M)(2)] (4) and [Cu(4NO(2)Ac4DM)(2)] (5) proved to be as active as the clinical reference drugs nifurtimox and benznidazol. Taking into consideration the serious side effects and the poor efficacy of the reference drugs, as well as the appearance of resistance during treatment, the studied compounds could constitute a new class of anti-trypanosomal drug candidates. PMID:17709156

Pérez-Rebolledo, Anayive; Teixeira, Letícia R; Batista, Alzir A; Mangrich, Antonio S; Aguirre, Gabriela; Cerecetto, Hugo; González, Mercedes; Hernández, Paola; Ferreira, Ana M; Speziali, Nivaldo L; Beraldo, Heloisa

2008-05-01

296

Tunable emissive lanthanidomesogen derived from a room-temperature liquid-crystalline Schiff-base ligand.  

PubMed

A novel photoluminescent room-temperature liquid-crystalline salicylaldimine Schiff base with a short alkoxy substituent and a series of lanthanide(III) complexes of the type [Ln(LH)3(NO3)3] (Ln = La, Pr, Sm, Gd, Tb, Dy; LH = (E)-5-(hexyloxy)-2-[{2-(2-hydroxyethylamino)ethylimino]methyl}phenol) have been synthesized and characterized by FTIR, (1)H and (13)C?NMR, UV/Vis, and FAB-MS analyses. The ligand coordinates to the metal ions in its zwitterionic form. The thermal behavior of the compounds was investigated by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The ligand exhibits an enantiotropic hexagonal columnar (Col(h)) mesophase at room temperature and the complexes show an enantiotropic lamellar columnar (Col(L)) phase at around 120?°C with high thermal stability. Based on XRD results, different space-filling models have been proposed for the ligand and complexes to account for the columnar mesomorphism. The ligand exhibits intense blue emission both in solution and in the condensed state. The most intense emissions were observed for the samarium and terbium complexes, with the samarium complex glowing with a bright-orange light (ca. 560-644?nm) and the terbium complex emitting green light (ca. 490-622?nm) upon UV irradiation. DFT calculations performed by using the DMol3 program at the BLYP/DNP level of theory revealed a nine-coordinate structure for the lanthanide complexes. PMID:23939837

Pramanik, Harun A R; Das, Gobinda; Bhattacharjee, Chira R; Paul, Pradip C; Mondal, Paritosh; Prasad, S Krishna; Rao, D S Shankar

2013-09-23

297

Interaction of Schiff base ligand with tin dioxide nanoparticles: optical studies.  

PubMed

Interaction between 1,4 Bis ((2-Methyl) thio) Phenylamino methyl benzene (BMTPMB) Schiff base with tin dioxide nanoparticles (SnO2 NPs) of various concentrations in methanol have been studied using UV-Visible and Fluorescence spectroscopic techniques. The low value of Stern-Volmer quenching constant and non-linear plot of Benesi-Hildebrand equation suggests the less affinity of SnO2 NPs towards the adsorption of BMTPMB Schiff base. The Scott equation has been employed to determine molar absorptivity of the Schiff base-NPs system. PMID:23770505

Rani, J Suvetha; Ramakrishnan, V

2013-10-01

298

Design, synthesis, and biological activities of aromatic gossypol schiff base derivatives.  

PubMed

A series of aromatic gossypol Schiff bases have been successfully synthesized via a feasible chemical modification. The antiviral activity against tobacco mosaic virus (TMV) of these gossypol Schiff bases has been tested for the first time. The bioassay studies indicated most of these derivatives exhibited excellent anti-TMV activity, in which o-trifluoromethylaniline Schiff base (19) displayed the best antiviral activities. Furthermore, compound 19 exhibited an eminent anti-TMV effect in the field and low toxicity to mice. These results suggest it is a promising candidate for the inhibitor of plant virus. PMID:25386768

Li, Ling; Li, Zheng; Wang, Kailiang; Zhao, Sheng; Feng, Jiming; Li, Jiarui; Yang, Peiwen; Liu, Yuxiu; Wang, Lizhong; Li, Yongqiang; Shang, Hui; Wang, Qingmin

2014-11-19

299

Equilibrium investigation of complex formation reactions involving copper(II), nitrilo-tris(methyl phosphonic acid) and amino acids, peptides or DNA constitutents. The kinetics, mechanism and correlation of rates with complex stability for metal ion promoted hydrolysis of glycine methyl ester  

Microsoft Academic Search

The complex formation reactions of [Cu(NTP)(OH2)] (NTP?=?nitrilo-tris(methyl phosphonic acid)) with some selected bio-relevant ligands containing different functional groups, are investigated. Stoichiometry and stability constants for the complexes formed are reported. The results show that the ternary complexes are formed in a stepwise mechanism whereby NTP binds to copper(II), followed by coordination of amino acid, peptide or DNA. Copper(II) is found

Ahmed A. El-Sherif; Mohamed M. Shoukry

2006-01-01

300

N, N?-disalicylidene-1,3-diaminopropane as a selective chelating titrant for copper(II)  

Microsoft Academic Search

This study was carried out to develop a new complexometric titration method for determination of copper. For this purpose, the standard solutions of copper(II) (10?3–10?5 M) were potentiometrically titrated using N,N?-disalicylidene-1,3-diaminopropane (Schiff base) as titrant and copper(II)-selective electrode for end-point indication in both ammonium acetate and ammonia\\/ammonium chloride buffer media. The stoichiometry of titration reaction and interference effects of some

Elif Kormal?; Esma K?liç

2002-01-01

301

Aryl-linked salicylaldoxime-based copper(II) helicates and "boxes": synthesis, X-ray analysis, and anion influence on complex structure.  

PubMed

The synthesis and spectroscopic analysis of both "metal-only" and anion encapsulated salicylaldoxime-based complexes utilizing a new 1,3-xylyl strap are described. X-ray crystallographic analysis reveals that the aromatic spacer restricts the confirmation flexibility of the resulting complexes leading to dicopper(II) double helicate and dicopper(II) 2 + 2 "box" structural forms. The choice of the structural motif is influenced by the anion present, with the copper(II) nitrate-containing complex [NO3?(Cu2L(3)2)](NO3)3, 4, adopting a double helicate form, whereas the analogous copper(II) bromide complexes [2Br?(Cu2L(3)2)](Br)2, 5, and [2Br?(Cu2L(3)2)](BF4)2, 6, both adopt 2 + 2 "box" structural configurations. Spectroscopic analysis has shown an enhancement in the binding strength of ClO4(-) over the anions SO4(2-) and NO3(-). The enhanced rigidity caused by the use of the 1,3-xylyl spacer in this series of complexes has favored the formation of the "double loaded" dibromide complex. PMID:23927604

Pannu, Ajay Pal Singh; Stevens, James R; Plieger, Paul G

2013-08-19

302

Schiff bases of 3-formylchromone as thymidine phosphorylase inhibitors.  

PubMed

3-Formylchromone (1), 3-methyl-7-hydroxychromone (2) and Schiff bases of 3-formylchromone 3-19 have been synthesized and their anti-thymidine phosphorylase inhibitory activity was evaluated. Compounds 1-19 showed a varying degree of thymidine phosphorylase inhibition with IC(50) values 19.77+/-3.25 to 480.21+/-2.34 microM. Their activity was compared with the standard 7-deazaxanthine (IC(50)=39.28+/-0.76 microM). Compound 12 showed an excellent thymidine phosphorylase inhibitory activity with an IC(50) value of 19.77+/-3.25 microM, better than the standard. Compound 4 also showed an excellent inhibitory activity (IC(50)=40.29+/-4.56 microM). The parent 3-formylchromone (1) and 3-methyl-7-hydroxychromone (2) were found to be inactive. The structures of the compounds were elucidated by using spectroscopic techniques, including (1)H NMR, EI MS, IR, UV and elemental analysis. PMID:19329330

Khan, Khalid Mohammed; Ambreen, Nida; Hussain, Sajjad; Perveen, Shahnaz; Choudhary, M Iqbal

2009-04-15

303

Deuterium isotope effects on 13C chemical shifts of lithium salts of Schiff bases amino acids  

NASA Astrophysics Data System (ADS)

The deuterium isotope effects on 13C chemical shift of Schiff bases lithium salts, derivatives of amino acids (glycine, L-alanine, L-phenylalanine, L-valine, L-leucine, L-isoleucine and L-methionine) and 2-hydroxynaphthaldehyde in D 2O as well as UV-vis spectra in different solvents have been measured. The results have shown that the lithium salts of the Schiff bases exist in the proton transferred NH form with intramolecular hydrogen bond in water.

Rozwadowski, Z.

2005-10-01

304

Synthesis, characterization and antibacterial activity of biodegradable films prepared from Schiff bases of zein.  

PubMed

Pure zein is known to be very hydrophobic, but is still inappropriate for coating and film applications because of their brittle nature. In an attempt to improve the flexibility and the antimicrobial activity of these coatings and films, Chemical modification of zein through forming Schiff bases with different phenolic aldhydes was tried. Influence of this modifications on mechanical, topographical, wetting properties and antimicrobial activity of zein films were evaluated. The chemical structure of the Schiff bases films were characterized by ATR-FTIR spectroscopy. The results indicate an improvement in mechanical properties with chemically modification of zein to form Schiff bases leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with slight influence on tensile strength. Plasticized zein films have similar initial contact angle (?40°). An increase in reaction temperature and time increases film's affinity towards water. As shown by contact angle measurements, a noticeable relation was found between film composition and the hydrophilicity. Surface topography also varied by forming Schiff bases, becoming rougher than zein-based films. The antibacterial activities of zein and Schiff bases of zein-based films were investigated against gram-positive bacteria (Listeria innocua, Listeria monocytogenes, Bacillus cereus and Clostridium sporogenes) and gram-negative bacteria (Escherichia coli, Yersinia enterocolitica and Salmonella enterica). It was found that the antibacterial activity of the Schiff bases-based films was more effective than that of zein-based films. PMID:25328181

Soliman, E A; Khalil, A A; Deraz, S F; El-Fawal, G; Elrahman, S Abd

2014-10-01

305

DNA-binding and cleavage studies of novel copper(II) complex with l-phenylalaninate and 1,4,8,9-tetra-aza-triphenylene ligands  

Microsoft Academic Search

DNA-binding properties of novel copper(II) complex [Cu(l-Phe)(TATP)(H2O)]+, where l-Phe=l-phenylalaninate and TATP=1,4,8,9-tetra-aza-triphenylene are investigated using electronic absorption spectroscopy, fluorescence spectroscopy, voltammetry and viscosity measurement. It is found that the presence of calf thymus DNA results in a hypochromism and red shift in the electronic absorption, a quenching effect on fluorescence nature of ethidium bromide–DNA system, an enhanced response on voltammograms of

Hong Li; Xue-Yi Le; Dai-Wen Pang; Hong Deng; Zheng-He Xu; Zhong-Hua Lin

2005-01-01

306

Oxidative cleavage of DNA by a dipyridoquinoxaline copper(II) complex in the presence of ascorbic acid.  

PubMed

Complex [Cu(dpq)(2)(H(2)O)](ClO(4))(2).H(2)O (1), where dpq is dipyrido-[3,2-D:2',3'-f]-quinoxaline, has been prepared by reacting copper(II) perchlorate hexahydrate with dpq in methanol and structurally characterized. The complex crystallizes in the triclinic space group P-1 with the unit cell parameters a=8.646(2) A, b=12.290(5) A, c=14.283(4) A, alpha=94.01(2) degrees, beta=91.69(2) degrees,gamma=101.60 (3) degrees, V=1481.7(8) A(3) and Z=2. The structure, refined to R=0.0505 and R(w)=0.1441 for 5212 reflections with I>2sigma (I) using 440 parameters, shows the presence of a CuN(4)O chromophore in an axially compressed distorted trigonal-bipyramidal structure. The Cu-N distances lie in the range 1.969(3)-2.103(3) A. The Cu-OH(2) distance is 2.145(3) A. The complex is one-electron paramagnetic and exhibits a visible spectral d-d band at 718 nm in MeCN. It shows a quasi-reversible cyclic voltammetric response at 0.091 V (DeltaE(p)=229 mV) at 50 mV s(-1) in MeCN-0.1 M TBAP for the Cu(II)/Cu(I) couple. In 50 mM Tris-HCl/0.1 M KCl buffer-DMF mixture (1:4 v/v, pH 7.2), the couple appears at 0.089 V versus SCE. The complex undergoes facile reduction with sodium ascorbate in an aqueous DMF mixture (4:1 v/v) to form an unstable brown Cu(I) species (lambda(max)=440 nm, epsilon=7480 M(-1) cm(-1)) which converts to 1 on exposure to air giving a turnover frequency of ca. 400. Binding studies revealed that 1 is an efficient binder to calf thymus DNA. Complex 1 on reaction with supercoiled (SC) DNA in presence of ascorbic acid in a 50 mM Tris-HCl/50 mM NaCl buffer (pH 7.2) shows nuclease activity which is 4.5 times greater than that of the phen analogue. PMID:12062122

Santra, Bidyut K; Reddy, Pattubala A N; Neelakanta, Girish; Mahadevan, Subramony; Nethaji, Munirathinam; Chakravarty, Akhil R

2002-04-28

307

The thioxotriazole copper(II) complex A0 induces endoplasmic reticulum stress and paraptotic death in human cancer cells.  

PubMed

The copper(II) complex A0 induces a type of non-apoptotic cell death also known as paraptosis. Paraptosis involves extensive endoplasmic reticulum vacuolization in the absence of caspase activation. A wide panel of human cancer cell lines was used to demonstrate differences in cytotoxicity by the paraptosis-inducing drug A0 and the metal-based pro-apoptotic drug cisplatin. Gene expression profiling of the human fibrosarcoma HT1080 cells showed that, while cisplatin induced p53 targets, A0 up-regulated genes involved in the unfolded protein response (UPR) and response to heavy metals. The cytotoxic effects of A0 were associated with inhibition of the ubiquitin-proteasome system and accumulation of ubiquitinylated proteins, in a manner dependent on protein synthesis. Cycloheximide inhibited the accumulation of ubiquitinylated proteins and hampered A0-induced cell death process. The occurrence of the UPR during A0-induced death process was shown by the increased abundance of spliced XBP1 mRNA, transient eIF2alpha phosphorylation, and a series of downstream events, including attenuation of global protein synthesis and increased expression of ATF4, CHOP, BIP, and GADD34. Mouse embryonic fibroblasts expressing a mutant eIF2alpha, which could not be phosphorylated, were more resistant to A0 than wild type cells, pointing to a pro-death role of eIF2alpha phosphorylation. A0 may thus represent the prototypical member of a new class of compounds that cause paraptotic cell death via mechanisms involving eIF2alpha phosphorylation and the UPR. PMID:19561079

Tardito, Saverio; Isella, Claudio; Medico, Enzo; Marchiò, Luciano; Bevilacqua, Elena; Hatzoglou, Maria; Bussolati, Ovidio; Franchi-Gazzola, Renata

2009-09-01

308

Selective chemosensor for copper ions based on fluorescence quenching of a Schiff-base fluorophore.  

PubMed

A Schiff base-based fluorescent chemosensor has been studied for divalent copper detection. The formation of 2-hydroxybenzaldehyde benzoylhydrazone-Cu(2+) complex induced a fluorescence quenching of this compound in a medium of water/ethanol (53% v/v) and 0.05 M phosphate buffer (pH 7.0). The continuous variations and mole-ratio plots of absorbance suggested a complex formation with a 1:1 metal-ligand stoichiometry. The conditional stability constant for the complex was evaluated to be 6 x 10(6) M(-1). A modified Stern-Volmer relationship was employed to obtain a linear calibration plot, obtaining a dynamic working range up to 157.4 microM. The detection limit of this system was found to be 5.6 microM and the relative standard deviation for five measurements of 78.7 microM concentration was 5.2%. This fluorescent chemosensor also showed a high selectivity for copper ions over other metal ions, such as Al(3+), Ca(2+), Cd(2+), Fe(2+), K(+), Mg(2+), Na(+), Pb(2+), or Zn(2+). The results of this investigation show a simple, rapid, low-cost, and selective method that can operate in neutral solutions and is useful for biological and environmental applications. PMID:20615285

Espada-Bellido, Estrella; Galindo-Riaño, Maria Dolores; García-Vargas, Manuel; Narayanaswamy, Ramaier

2010-07-01

309

A dinuclear copper(II) complex with adeninate bridge ligands and prominent DNA cleavage activity. Structural and spectroscopic characterization and magnetic properties.  

PubMed

A new dinuclear copper(II) complex has been synthesized and structurally characterized: [Cu(mu-ade)(tolSO3)(phen)]2.2H2O (Hade = adenine, tolSO3- = toluenesulfonate anion). Its magnetic properties and electronic paramagnetic resonance (EPR) spectra have been studied in detail. The compound has two metal centers bridged by two adeninate NCN groups. The coordination geometry of the copper(II) ions in the dinuclear entity is distorted square pyramidal, with the four equatorial positions occupied by two phenanthroline N atoms and two N atoms from different adenine molecules. The axial position is occupied by one sulfonate O atom. Magnetic susceptibility data show antiferromagnetic behavior with an estimated exchange constant of -2J = 65 cm-1. The EPR spectrum has been obtained at both X- and Q-band frequencies; a study at different temperatures has been carried out at the latter. Above 20 K, the Q-band spectra are characteristic of S = 1 species with a small zero-field splitting parameter (D = 0.0970 cm-1). A detailed study of the DNA-complex interaction has been performed. The title complex efficiently cleaves the pUC18 plasmid in the presence of reducing agents. Both the kinetics and the mechanism of the cleavage reaction are examined and described herein. PMID:17630687

García-Giménez, José Luis; Alzuet, Gloria; Gonzalez-Alvarez, Marta; Castiñeiras, Alfonso; Liu-Gonzalez, Malva; Borras, Joaquín

2007-08-20

310

Interaction of drug based copper(II) complexes with Herring Sperm DNA and their biological activities  

NASA Astrophysics Data System (ADS)

Square pyramidal Cu(II) complexes with NS donor ligand and ciprofloxacin have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using double dilution technique in terms of minimum inhibitory concentration (MIC) and colony forming unit (CFU). The DNA binding ability of the complexes with Sperm Herring DNA has been performed using absorption titration and viscosity measurement. The nuclease activity of complexes with plasmid DNA (pUC19) has been carried out using agarose gel electrophoresis technique. Synthesized complexes have been tested for their SOD mimic activity using NBT/NADH/PMS system. The cytotoxic properties of metal complexes have been evaluated using brine shrimp lethality bioassay.

Patel, Mohan N.; Patel, Chintan R.; Joshi, Hardik N.

2012-11-01

311

Interaction of drug based copper(II) complexes with Herring Sperm DNA and their biological activities.  

PubMed

Square pyramidal Cu(II) complexes with NS donor ligand and ciprofloxacin have been synthesized and characterized using analytical and spectral techniques. The synthesized complexes have been tested for their antimicrobial activity using double dilution technique in terms of minimum inhibitory concentration (MIC) and colony forming unit (CFU). The DNA binding ability of the complexes with Sperm Herring DNA has been performed using absorption titration and viscosity measurement. The nuclease activity of complexes with plasmid DNA (pUC19) has been carried out using agarose gel electrophoresis technique. Synthesized complexes have been tested for their SOD mimic activity using NBT/NADH/PMS system. The cytotoxic properties of metal complexes have been evaluated using brine shrimp lethality bioassay. PMID:22750339

Patel, Mohan N; Patel, Chintan R; Joshi, Hardik N

2012-11-01

312

Antitubercular and fluorescence studies of copper(II) complexes with quinolone family member, ciprofloxacin  

NASA Astrophysics Data System (ADS)

Four new mixed-ligand complexes of Cu(II) with ciprofloxacin (Cip) and uninegative bidentate ligands have been synthesized and characterized. The structure of mixed-ligand complexes was investigated using spectroscopic method, physicochemical and elemental analyses. The fluorescence spectra of complexes show red shift, which may be due to the chelation by the ligands to the metal ion. It enhances ligand ability to accept electrons and decreases the electron transition energy. Antimycobacterial screening of ligand and its copper compound against Mycobacterium tuberculosis shows clear enhancement in the antitubercular activity upon copper complexation.

Kharadi, G. J.

2011-09-01

313

A novel single pot synthesis of binuclear copper(II) complexes of macrocyclic and macroacyclic compartmental ligands: Structures and magnetic properties  

NASA Astrophysics Data System (ADS)

Two binuclear copper(II) complexes one (complex 1) with a macrocyclic ligand (H 2L1) and other (complex 2) with a macroacyclic (end-off type) compartmental ligand (HL2) have been synthesized from single pot template synthesis involving copper(II) nitrate, 1,2-diaminoethane, 4-methyl-2,6-diformylphenol, and sodium azide. Structure analysis of complex 1 reveals that there are actually two half molecules present in the asymmetric unit and so two complexes (molecule-I and molecule-II) are present in unit cell, although they show slight differences. The two Cu(II) centers are in distorted square pyramidal coordination environment with two endogenous phenoxo bridges provided by the phenolate of H 2L1 having Cu-Cu separations of 2.9133(10) Å and 2.9103(10) in the two molecules. In complex 2 the coordination environments around two Cu(II) centers are asymmetric, Cu1 is in distorted square pyramidal environment whereas, the coordination environment around Cu2 is distorted octahedral. The two Cu(II) centers in complex 2 are connected by two different kinds of bridges, one is endogenous phenoxo bridge provided by the phenolate of the ligand HL2 and the other is exogenous azido bridge (? -1,1 type) with Cu-Cu distance of 3.032(10) Å. Variable temperature magnetic studies show that two Cu(II) centers in both the complexes are strongly antiferromagnetically coupled with J = -625 ± 5 cm -1 and J = -188.6 ± 1 cm -1 for complex 1 and 2, respectively.

Chattopadhyay, Tanmay; Banu, Kazi Sabnam; Banerjee, Arpita; Ribas, Joan; Majee, Adinath; Nethaji, Munirathinam; Das, Debasis

2007-05-01

314

Synthesis, Spectral and Antibacterial Studies of Copper(II) Tetraaza Macrocyclic Complexes  

PubMed Central

A novel family of tetraaza macrocyclic Cu(II) complexes [CuLX2] (where L = N4 donor macrocyclic ligands) and (X = Cl?, NO3 ?) have been synthesized and characterized by elemental analysis, magnetic moments, IR, EPR, mass, electronic spectra and thermal studies. The magnetic moments and electronic spectral studies suggest square planar geometry for [Cu(DBACDT)]Cl2 and [Cu(DBACDT)](NO3)2 complexes and distorted octahedral geometry to the rest of the ten complexes. The biological activity of all these complexes against gram-positive and gram-negative bacteria was compared with the activity of existing commercial antibacterial compounds like Linezolid and Cefaclor. Six complexes out of twelve were found to be most potent against both gram-positive as well as gram-negative bacteria due to the presence of thio group in the coordinated ligands. PMID:22606024

Reddy, Puchakayala Muralidhar; Rohini, Rondla; Krishna, Edulla Ravi; Hu, Anren; Ravinder, Vadde

2012-01-01

315

EXAFS Studies of Some Copper(II) Mixed-Ligand Complexes  

NASA Astrophysics Data System (ADS)

X-ray K-absorption spectroscopic studies have been carried out on copper (II) mixed-ligand complexes with glutamic acid and aspartic acid as the primary ligands, where as water, pyridine, imidazole and benz-imidazole have been used as secondary ligands. Chemical shifts obtained from the X-ray absorption data have indicated that the glutamic acid complexes are more ionic as compared to their corresponding aspartic acid complexes having similar secondary ligands. Further, we have estimated the average metal-ligand bond distances from the from structure data. For the different complexes studied under the present investigation, the studies reveal that the bonding parameter ?1 decreases with the increase in the percentage covalency of the metal-ligand bond. Thus, the bonding parameter ?1 may be used for the estimation of percentage covalency of the metal-ligand bond in other similar complexes.

Joshi, S. K.; Katare, R. K.; Shrivastava, B. D.

2007-02-01

316

The catalytic mechanism of Fpg protein. Evidence for a Schiff base intermediate and amino terminus localization of the catalytic site.  

PubMed

Our recent structure-activity analysis of Fpg protein of Escherichia coli, using oligodeoxynucleotides containing various 8-oxopurine derivatives, has allowed us to postulate an enzyme mechanism involving protonation of 8-oxoguanine at O-6 and nucleophilic attack of the deoxyribose moiety at C-1' leading to the formation of an enzyme-substrate Schiff base intermediate (Tchou, J., Bodepudi, V., Shibutani, S., Antoshechkin, I., Miller, J., Grollman, A. P., and Johnson, F. (1994) J. Biol. Chem. 269, 15318-15324). In this paper, sodium cyanoborohydride has been used to convert the transient intermediate to a covalent enzyme-DNA complex. The location of the active site of Fpg protein is further delineated using two approaches. 1) A radiolabeled DNA substrate is used to tag the active site of Fpg protein, using sodium cyanoborohydride. The active site is mapped to the first 73 amino acid residue fragment by cyanogen bromide cleavage analysis. 2) A maltose-binding protein fusion system is used to generate amino-terminal modifications of Fpg protein to explore the role of the amino-terminal region in DNA binding and catalysis. Results support the conclusion that the active site of Fpg protein is located at or near the amino terminus. Thus, Fpg protein may act in a similar fashion as T4 endonuclease V, a DNA repair enzyme that uses its amino-terminal alpha-amino group of threonine to carry out catalysis via Schiff base formation (Dodson et al., 1993). PMID:7744806

Tchou, J; Grollman, A P

1995-05-12

317

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

E-print Network

Catechol oxidase, biomimetic, flow, heterogeneous catalysis, copper complex, diazonium salts, graphite felt, tyrosinase and catechol oxidase that use dioxygen to catalyze the oxidation of phenols and o- diphenols to o

Paris-Sud XI, Université de

318

Characterizing some gossypol and gossypolone Schiff's bases by studying their fragmentation patterns with electrospray ionization tandem mass spectra  

Microsoft Academic Search

To investigate the structural form of gossypol and gossypolone Schiff's bases, seven relevant Schiff's bases were synthesized and the electrospray ionization–tandem mass spectrometry (ESI–MS\\/MS) with low-energy collision-induced dissociation was used to analyze their fragmentations. A common fragmentation pathway with the loss of RNH2 from those schiff's bases quasi-molecular ions was observed and proposed on the basis of their MS\\/MS spectra

Long Zhang; Xing Xin Cao; Hai Xia Jiang; Biao Jiang; Yu Xin Cui

2009-01-01

319

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

PubMed

Some copper(II) complexes of the type [Cu(L1-3)(phen]·CH2Cl2 (1a-3a) and [Cu(L1-3) (bipy)]·CH2Cl2 (1b-3b) (where L1=N-(2-{[(2E)-2-(2-Hydroxy-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L2=N-(2-{[(2E)-2-(2-Hydroxy-(5-bromo)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L3=N-(2-{[(2E)-2-(2-Hydroxy-(5-methoxy)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide; phen=1,10-phenanthroline, bipy=2,2'-bipyridine) have been prepared and characterized on the basis of elemental analyses, IR, UV-Vis and EPR spectral studies. IR spectra indicate that the ligand L1-3 exists in the keto form in the solid state, while at the time of complexation, it tautomerises into enol form. The single crystal X-ray diffraction study of the representative complex [Cu(L1) (phen)]·CH2Cl2 (1a) reveals the distorted square pyramidal geometry around copper(II). Crystal data of (1a): space group=P21/n, a=11.5691(16) Å, b=11.0885(15) Å, c=24.890(4) Å, V=3166.2(8) Å(3), Z=4. The electrochemical behavior of all the complexes indicate that the phen complexes appears at more positive potential as compared to those for bipy complexes, as a consequence of its stronger ? acidic character. All the complexes exhibit blue-green emission as a result of the fluorescence from the intra-ligand (???(*)) emission excited state. PMID:24001977

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

2014-01-01

320

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

NASA Astrophysics Data System (ADS)

Some copper(II) complexes of the type [Cu(L1-3)(phen]?CH2Cl2 (1a-3a) and [Cu(L1-3) (bipy)]?CH2Cl2 (1b-3b) (where L1 = N-(2-{[(2E)-2-(2-Hydroxy-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L2 = N-(2-{[(2E)-2-(2-Hydroxy-(5-bromo)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide, L3 = N-(2-{[(2E)-2-(2-Hydroxy-(5-methoxy)-benzylidene)-hydrazino]carbonyl}phenyl)benzamide; phen = 1,10-phenanthroline, bipy = 2,2'-bipyridine) have been prepared and characterized on the basis of elemental analyses, IR, UV-Vis and EPR spectral studies. IR spectra indicate that the ligand L1-3 exists in the keto form in the solid state, while at the time of complexation, it tautomerises into enol form. The single crystal X-ray diffraction study of the representative complex [Cu(L1) (phen)]?CH2Cl2 (1a) reveals the distorted square pyramidal geometry around copper(II). Crystal data of (1a): space group = P21/n, a = 11.5691(16) Å, b = 11.0885(15) Å, c = 24.890(4) Å, V = 3166.2(8) Å3, Z = 4. The electrochemical behavior of all the complexes indicate that the phen complexes appears at more positive potential as compared to those for bipy complexes, as a consequence of its stronger ? acidic character. All the complexes exhibit blue-green emission as a result of the fluorescence from the intra-ligand (? ? ??) emission excited state.

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

2014-01-01

321

New d 10 heterometallic coordination polymers based on compartmental Schiff-base ligands. Synthesis, structure and luminescence  

Microsoft Academic Search

The self-assembly processes between binuclear [Zn2Ln]2+ complex cations and complex anions, [M(CN)2]? [M(I)=Ag(I), Au(I)], generate new one-dimensional (1-D) coordination polymers: 1?[{L1Zn2(?3-OH)}2(H2O){?-[Ag(CN)2]}](ClO4)3 THF 0.5MeOH 1, 1?[{L1Zn2(?3-OH)}2(H2O){?-[Au(CN)2]}](ClO4)3 THF H2O 2, 1?[{L2Zn2(?-OH)}{?-[Ag(CN)2]}][Ag(CN)2] H2O 3 (H2Ln are bicompartmental Schiff-base ligands resulting from condensation reactions between 2,6-diformyl-p-cresol with 2-aminomethyl-pyridine, and 2-aminoethyl-pyridine, respectively). The luminescence properties of the new heterometallic complexes have been investigated.

Gabriela Marinescu; Augustin M. Madalan; Carmen Tiseanu; Marius Andruh

2011-01-01

322

Coordination mode and reactivity of copper(II) complexes with kasugamycin.  

PubMed

Protonation and Cu(II) coordination of kasugamycin were studied by potentiometry, UV-vis, CD, EPR, 13C NMR, and 1H NMR. Mononuclear complexes with stoichiometries ranging from CuHL to CuH(-1)L were found. The aminoamidine moiety provides the coordination site in the CuHL species. The additional axial coordination of the amino nitrogen of the aminosugar ring is present in CuL. Finally, the CuH(-1)L complex is formed as a result of a deprotonation and coordination of the hydroxyl group of the inositol ring. The non-planar arrangement of the chelate rings results in the relative stabilization of a Cu(I) species. As a consequence, Cu(I) and superoxide radicals are involved in the redox mechanism of H(2)O(2) activation by the Cu(II) complex of kasugamycin. PMID:11410229

Jezowska-Bojczuk, M; Le?niak, W

2001-06-01

323

C{sub 2}-symmetric Copper(II) complexes as chiral Lewis acids  

SciTech Connect

Two new Cu(II)-derived Lewis acid catalysts 1 and 2 have been prepared and their utility as catalysts in the Diels-Alder reaction documented. While complex 1 is effective in catalyzing the cycloaddition of unsaturated aldehyde dienophiles with cyclopentadiene complex 2 is optimal for imide dienophiles. This study provides a rational basis for the design of Lewis acids based on the coordinating capacity of cationic Cu(II) complexes which possess sufficient Lewis acidity to catalyze a range of synthetically useful Diels-Alder reactions. In particular, documentation of the importance of counterion structure in the use of cationic metal centers as Lewis acids has been made for the first time.

Evans, D.A.; Murry, J.A.; Matt, P. von [Harvard Univ., Cambridge, MA (United States)] [and others

1995-12-01

324

Structure, spectroscopy, and theory calculations of mononuclear mixed-ligand copper(II) complex with malonate and 2-propylimidazole, [Cu(mal)(PIM) 2(H 2O)  

NASA Astrophysics Data System (ADS)

A mononuclear copper(II) complex, [Cu(mal)(PIM) 2(H 2O)] (1) [mal = malonate dianion, PIM = 2-propylimidazole] has been synthesized and characterized by elemental analysis, IR, UV-Vis, TG-DTA, and single crystal X-ray diffraction. The center Cu(II) atom in the complex has a distorted square-pyramidal geometry, being coordinated by two nitrogen atoms and three oxygen atoms. Density Functional Theory (DFT) with the B3LYP method and time-dependent DFT calculations were performed to provide insight into the structural, electronic, and electronic spectroscopic properties of the complex 1, and the UV-Vis spectrum of the title compound has been discussed on this basis. All the absorption bands in UV-Vis spectrum are mostly ?/( P, ?) ? d x2-y2 ligand-to-metal charge transfer (LMCT) transition, together with partial d ? d ligand field (LF) transition.

Peng, Xian; Cui, Guang-Hua; Li, De-Jie; Wu, Shang-Zhuo; Yu, Ya-Mei

2010-05-01

325

Development of pyridine-containing macrocyclic copper(II) complexes: potential role in the redox modulation of oxaliplatin toxicity in human breast cells.  

PubMed

The unique redox and catalytic chemistry of Cu has justified the development of novel Cu complexes for different therapeutic uses including cancer therapy. In this work, four pyridine-containing aza-macrocyclic copper(II) complexes were prepared (CuL1-CuL4) varying in ring size and/or substituents and their superoxide scavenging activity evaluated. CuL3, the most active superoxide scavenger, was further studied as a modulator of the cytotoxicity of oxaliplatin in epithelial breast MCF10A cells and in MCF7 breast cancer cells. Our results show that CuL3 enhances the therapeutic window of oxaliplatin, by both protecting non-tumour cells and increasing its cytotoxic effect in breast carcinoma cells. CuL3 is thus a promising complex to be further studied and to be used as a lead compound for the optimization of novel chemotherapy sensitizers. PMID:22612279

Fernandes, Ana S; Costa, Judite; Gaspar, Jorge; Rueff, José; Cabral, M Fátima; Cipriano, Madalena; Castro, Matilde; Oliveira, Nuno G

2012-09-01

326

Efficient plasmid DNA cleavage by a mononuclear copper(II) complex.  

PubMed

The Cu(II) complex of the ligand all-cis-2,4,6-triamino-1,3,5-trihydroxycyclohexane (TACI) is a very efficient catalyst of the cleavage of plasmid DNA in the absence of any added cofactor. The maximum rate of degradation of the supercoiled plasmid DNA form, obtained at pH 8.1 and 37 degrees C, in the presence of 48 microM TACI.Cu(II), is 2.3 x 10(-3) s(-1), corresponding to a half-life time of only 5 min for the cleavage of form I (supercoiled) to form II (relaxed circular). The dependence of the rate of plasmid DNA cleavage from the TACI.Cu(II) complex concentration follows an unusual and very narrow bell-like profile, which suggests an high DNA affinity of the complexes but also a great tendency to form unreactive dimers. The reactivity of the TACI.Cu(II) complexes is not affected by the presence of several scavengers for reactive oxygen species or when measured under anaerobic conditions. Moreover, no degradation of the radical reporter Rhodamine B is observed in the presence of such complexes. These results are consistent with the operation of a prevailing hydrolytic pathway under the normal conditions used, although the failure to obtain enzymatic religation of the linearized DNA does not allow one to rule out the occurrence of a nonhydrolytic oxygen-independent cleavage. A concurrent oxidative mechanism becomes competitive upon addition of reductants or in the presence of high levels of molecular oxygen: under such conditions, in fact, a remarkable increase in the rate of DNA cleavage is observed. PMID:15792466

Sissi, Claudia; Mancin, Fabrizio; Gatos, Maddalena; Palumbo, Manlio; Tecilla, Paolo; Tonellato, Umberto

2005-04-01

327

Metals in Anticancer Therapy: Copper(II) Complexes as Inhibitors of the 20S Proteasome  

PubMed Central

Selective 20S proteasomal inhibition and apoptosis induction were observed when several lines of cancer cells were treated with a series of copper complexes described as [Cu(LI)Cl] (1), [Cu(LI)OAc] (2), and [Cu(HLI)(LI)]OAc (3), where HLI is the ligand 2,4-diiodo-6-((pyridine-2-ylmethylamino)methyl)phenol. These complexes were synthesized, characterized by means of ESI spectrometry, infrared, UV-visible and EPR spectroscopies, and X-ray diffraction when possible. After full characterization species 1-3 were evaluated for their ability to function as proteasome inhibitors and apoptosis inducers in C4-2B and PC-3 human prostate cancer cells and MCF-10A normal cells. With distinct stoichiometries and protonation states, this series suggests the assignment of species [CuLI]+ as the minimal pharmacophore needed for proteasomal chymotryspin-like activity inhibition and permits some initial inference of mechanistic information. Three well characterized discrete copper complexes with asymmetric phenol-substituted ligands are able to inhibit the proteolytic activity of the 20s proteasome. Evidence for a minimal pharmacophore suggests a potential basis for new cancer therapies with tunable and cost-effective metallodrugs. PMID:19559507

Hindo, Sarmad Sahiel; Frezza, Michael; Tomco, Dajena; Heeg, Mary Jane; Hryhorczuk, Lew; McGarvey, Bruce R.; Dou, Q. Ping; Verani, Cláudio N.

2009-01-01

328

New copper(II) complexes with dopamine hydrochloride and vanillymandelic acid: Spectroscopic and thermal characterization  

NASA Astrophysics Data System (ADS)

The dopamine derivatives participate in the regulation of wide variety of physiological functions in the human body and in medication life. Increase and/or decrease in the concentration of dopamine in human body reflect an indication for diseases such as Schizophrenia and/or Parkinson diseases. The Cu(II) chelates with coupled products of dopamine hydrochloride (DO.HCl) and vanillymandelic acid (VMA) with 4-aminoantipyrine (4-AAP) are prepared and characterized. Different physico-chemical techniques namely IR, magnetic and UV-vis spectra are used to investigate the structure of these chelates. Cu(II) forms 1:1 (Cu:DO) and 1:2 (Cu:VMA) chelates. DO behave as a uninegative tridentate ligand in binding to the Cu(II) ion while VMA behaves as a uninegative bidentate ligand. IR spectra show that the DO is coordinated to the Cu(II) ion in a tridentate manner with ONO donor sites of the phenolic- OH, -NH and carbonyl- O, while VMA is coordinated with OO donor sites of the phenolic- OH and -NH. Magnetic moment measurements reveal the presence of Cu(II) chelates in octahedral and square planar geometries with DO and VMA, respectively. The thermal decomposition of Cu(II) complexes is studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the relative thermal stability of the complexes are discussed.

Mohamed, Gehad G.; Nour El-Dien, F. A.; El-Nahas, R. G.

2011-10-01

329

Mononuclear and polynuclear copper(II) complexes derived from pyridylalkylaminomethylphenol polypodal ligands.  

PubMed

Four mononuclear complexes [Cu(HL(1))Cl]PF(6).CH(3)OH (1), [Cu(HSL(1))Cl]PF(6).0.75H(2)O (2), [Cu(HL(2))Cl]PF(6).CH (3)OH (3), [Cu(HSL(2))Cl]PF(6).1.5CH(3)OH (4), and two polynuclear complexes [Cu (2)(SL(2))(2)](PF(6))(2).2CH(3)OH (5) and {Cu[Cu(SL(2))(Cl)](2)}(PF(6))(2) (6) (HL(1): 2-[(bis(2-pyridylmethyl)-amino)methyl]-4-methylphenol; HSL(1): 2-[(bis(2-pyridylmethyl)amino) methyl]-4-methyl-6-(methyl-thio)phenol; HL(2): 2-[(2-pyridylmethyl)(2'-pyridylethyl)-aminomethyl)]-4-methylphenol; HSL(2): 2-[(2-pyridylmethyl)(2'-pyridylethyl)amino-methyl]-4-methyl-6-(methylthio)phenol were obtained and characterized. The crystal structures of the mononuclear complexes 1-4 show the copper centers in a square-base pyramidal environment with the phenolic oxygen coordinated at the axial position. Dinuclear complex 5 has two copper centers with different geometry and bridged by phenoxo oxygens; one of the copper atoms is square pyramidal while the other can be described with a highly distorted octahedral geometry with a long Cu-S distance (2.867 A). Density functional theory calculations were used to obtain the reported structure of 6, since single crystals suitable for X-ray diffraction were not isolated. Magnetic studies done for 5 and 6 show an antiferromagnetic behavior for 5 (J = -134 cm(-1)) and a ferromagnetic behavior for 6 (J = +11.9 cm(-1)). Redox potentials for the mononuclear complexes were measured by cyclic voltammetry; the values show the effect of the chelating ring size (-213 mV and -142 mV for Cu-HL(1) and Cu-HL(2), respectively) and the presence of the thiomethyl substituent (-213 mV and -184 mV for Cu-HL(1) and Cu-HSL(1), respectively). PMID:19747001

Manzur, Jorge; Mora, Hector; Vega, Andrés; Venegas-Yazigi, Diego; Novak, Miguel A; Sabino, José Ricardo; Paredes-García, Verónica; Spodine, Evgenia

2009-09-21

330

Synthesis, spectroscopic characterization, thermal studies, catalytic epoxidation and biological activity of chromium and molybdenum hexacarbonyl bound to a novel N 2O 2 Schiff base  

Microsoft Academic Search

Complexes of M(CO)6 (M=Cr and Mo) with novel Schiff base N,N?-bis(salicylidene)4,5-dichloro-1,2-phenylenediamine (H2L) were prepared in benzene in two different conditions: (i) under reduced pressure resulting the dicarbonyl precursors [Cr(CO)2(H2L)] and [Mo(CO)2(L)] and (ii) in air resulting the oxo complex [Cr(O)(L)] and the dioxo complex [Mo(O)2(L)]. The complexes were characterized by elemental analysis, IR, 1H NMR, mass spectrometry, and magnetic measurement.

Ayman A. Abdel Aziz

2010-01-01

331

``Test kit'' for detection of biologically important anions: A salicylidene-hydrazine based Schiff base  

NASA Astrophysics Data System (ADS)

Test paper coated with Schiff base [(N,N/-bis(5-nitro-salicylidene)hydrazine] receptor 1 (host) can selectively detect fluoride and acetate ions (guest) by developing yellow color which can be detected by naked-eye both in aqueous-acetonitrile solution and in solid supported test kit. UV-vis spectral analysis shows that the absorption peaks at 288 and 345 nm of receptor 1 gradually decrease its initial intensity and new red shifted absorption bands at 397 nm and 455 nm gradually appear upon addition of increasing amount of F- and AcO- ions over several tested anions such as HPO4-, Cl, Br, I, NO3-, NO2-, HSO4-, HSO3-, and ClO4- in aqueous-acetonitrile solvent. The colorimetric test results and UV-vis spectral analysis are in well agreement with 1H NMR titration results in d6-DMSO solvent. The receptor 1 forms 1:2 stable complexes with F- and AcO- ions. However, similar kind of observation obtained from UV-vis titrations in presence of AcOH corresponds to 1:1 complexation ratio indicating the formation of H-bonding interaction between the receptor and anions (F- and AcO- ions). So, the observed 1:2 complexation ratio can only be explained on the basis of deprotonation (˜1 eqv.) and H-bonding (˜1 eqv.) interactions [1]. The ratiometric analysis of host-guest complexes corroborates well with the proposed theoretical model optimization at Density Functional Theory (DFT) level.

Dalapati, Sasanka; Alam, Md Akhtarul; Jana, Sankar; Karmakar, Saswati; Guchhait, Nikhil

2013-02-01

332

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

333

N,N'-disalicylidene-1,3-diaminopropane as a selective chelating titrant for copper(II).  

PubMed

This study was carried out to develop a new complexometric titration method for determination of copper. For this purpose, the standard solutions of copper(II) (10(-3)-10(-5) M) were potentiometrically titrated using N,N'-disalicylidene-1,3-diaminopropane (Schiff base) as titrant and copper(II)-selective electrode for end-point indication in both ammonium acetate and ammonia/ammonium chloride buffer media. The stoichiometry of titration reaction and interference effects of some metal ions on titration of copper were discussed. There was a good agreement between the results obtained by the proposed titration method and ethylenediaminetetraacetic acid (EDTA) titration method. The accuracy and precision of Schiff base method were tested by five replicate determinations both on the standard solution of copper(II) and standard reference materials. The results have indicated that the percentage of copper in alloys can be safely determined by using the Schiff base method without interference from many other metals in alloys. PMID:18968809

Kormal?, Elif; K?liç, Esma

2002-10-16

334

Rapid Photodynamics of Vitamin B6 Coenzyme Pyridoxal 5-Phosphate and Its Schiff Bases in Solution  

E-print Network

Rapid Photodynamics of Vitamin B6 Coenzyme Pyridoxal 5-Phosphate and Its Schiff Bases in Solution, 2007; In Final Form: February 4, 2008 The active form of vitamin B6, pyridoxal 5-phosphate (PLP (absorbing at 410 nm) tautomers in solution. 1. Introduction Pyridoxal 5-phosphate (PLP), one form of vitamin

Toney, Michael

335

Synthesis, antibacterial activities and molecular docking studies of peptide and Schiff bases as targeted antibiotics  

Microsoft Academic Search

A series of peptide and Schiff bases (PSB) were synthesized by reacting salicylic acid, primary diamines with salicylaldehyde or its derivatives, and 40 of which were newly reported. The inhibitory activities against Escherichia coli ?-ketoacyl-acyl carrier protein synthase III (ecKAS III) were investigated in vitro and molecular docking simulation also surveyed. Top 10 PSB compounds which posses both good inhibitory

Kui Cheng; Qing-Zhong Zheng; Yong Qian; Lei Shi; Jing Zhao; Hai-Liang Zhu

2009-01-01

336

Kinetic resonance Raman spectroscopy: dynamics of deprotonation of the Schiff base of bacteriorhodopsin.  

PubMed

We have developed a kinetic technique, combining resonance Raman spectroscopy and variable-speed continuous flow methods, to study molecular dynamics of isolated sites in macromolecules. Kinetic resonance Raman spectra of the retinylidence chromophore of bacteriorhodopsin have been obtained and the dynamics of the deprotonation of the Schiff base linkage is discussed. PMID:841330

Marcus, M A; Lewis, A

1977-03-25

337

Mechanism of the Schiff base forming fructose-1,6-bisphosphate aldolase: structural analysis of reaction intermediates.  

PubMed

The glycolytic enzyme fructose-1,6-bisphosphate aldolase (FBPA) catalyzes the reversible cleavage of fructose 1,6-bisphosphate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate. Catalysis of Schiff base forming class I FBPA relies on a number of intermediates covalently bound to the catalytic lysine. Using active site mutants of FBPA I from Thermoproteus tenax, we have solved the crystal structures of the enzyme covalently bound to the carbinolamine of the substrate fructose 1,6-bisphosphate and noncovalently bound to the cyclic form of the substrate. The structures, determined at a resolution of 1.9 A and refined to crystallographic R factors of 0.148 and 0.149, respectively, represent the first view of any FBPA I in these two stages of the reaction pathway and allow detailed analysis of the roles of active site residues in catalysis. The active site geometry of the Tyr146Phe FBPA variant with the carbinolamine intermediate supports the notion that in the archaeal FBPA I Tyr146 is the proton donor catalyzing the conversion between the carbinolamine and Schiff base. Our structural analysis furthermore indicates that Glu187 is the proton donor in the eukaryotic FBPA I, whereas an aspartic acid, conserved in all FBPA I enzymes, is in a perfect position to be the general base facilitating carbon-carbon cleavage. The crystal structure of the Trp144Glu, Tyr146Phe double-mutant substrate complex represents the first example where the cyclic form of beta-fructose 1,6-bisphosphate is noncovalently bound to FBPA I. The structure thus allows for the first time the catalytic mechanism of ring opening to be unraveled. PMID:15766250

Lorentzen, Esben; Siebers, Bettina; Hensel, Reinhard; Pohl, Ehmke

2005-03-22

338

Cocrystallization of Photosensitive Energetic Copper(II) Perchlorate Complexes with the Nitrogen-rich Ligand 1,2-Di(1H-tetrazol-5-yl)ethane.  

PubMed

Two recently introduced concepts in the design of new energetic materials, namely complexation and cocrystallization, have been applied in the synthesis and characterization of the energetic copper(II) compound "[Cu(dt-5-e)2(H2O)](ClO4)2," which consists of two different complex cations and can be described as a model energetic ionic cocrystal. The presence of both the N-rich 1,2-di(1H-tetrazol-5-yl)ethane ligand and oxidizing perchlorate counterion results in a new type of energetic material. The ionic complex cocrystal consists of a mononuclear and a trinuclear complex unit. It can be obtained by precipitation from perchloric acid or by dehydration of the related mononuclear coordination compound [Cu(dt-5-e)2(H2O)2](ClO4)2·2H2O at 70 °C in the solid state. The transformation starting at 60 °C was monitored by X-ray powder diffraction and thermal analysis. The energetic ionic cocrystal was shown to be a new primary explosive suitable for laser ignition. The different coordination spheres within the ionic cocrystal (octahedral and square pyramidal) were shown by UV/vis/NIR spectroscopy to result in excellent light absorption. PMID:25310513

Evers, Jürgen; Gospodinov, Ivan; Joas, Manuel; Klapötke, Thomas M; Stierstorfer, Jörg

2014-11-01

339

Synthesis, characterization and biological activity of some transition metals with Schiff base derived from 2-thiophene carboxaldehyde and aminobenzoic acid  

NASA Astrophysics Data System (ADS)

Metal complexes of Schiff base derived from 2-thiophene carboxaldehyde and 2-aminobenzoic acid (HL) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The ligand dissociation as well as the metal-ligand stability constants were calculated pH metrically at 25 °C and ionic strength ? = 0.1 (1 M NaCl). The complexes are found to have the formulae [M(HL) 2](X) n· yH 2O (where M = Fe(III) (X = Cl, n = 3, y = 3), Co(II) (X = Cl, n = 2, y = 1.5), Ni(II) (X = Cl, n = 2, y = 1) and UO 2(II) (X = NO 3, n = 2, y = 0)) and [M(L) 2] (where M = Cu(II) (X = Cl) and Zn(II) (X = AcO)). The molar conductance data reveal that Fe(III) and Co(II), Ni(II) and UO 2(II) chelates are ionic in nature and are of the type 3:1 and 2:1 electrolytes, respectively, while Cu(II) and Zn(II) complexes are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a terdentate manner with ONS donor sites of the carboxylate O, azomethine N and thiophene S. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ? H*, ? S* and ? G* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.

Mohamed, Gehad G.; Omar, M. M.; Hindy, Ahmed M. M.

2005-12-01

340

Metal based photosensitizers of tetradentate Schiff base: Promising role in anti-tumor activity through singlet oxygen generation mechanism  

NASA Astrophysics Data System (ADS)

In the present investigation, a Schiff base N?1,N?3-bis[(Z)-(2-hydroxynapthyl)methylidene]benzene-1,3-dicarbodihydrazide (L1) and its Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized as novel photosensitizing agents for photodynamic therapy (PDT). The interaction of these complexes with calf thymus DNA (CT DNA) has been explored using absorption, thermal denaturation and viscometric studies. The experimental results revealed that Co(II) and Ni(II) complexes on binding to CT DNA imply a covalent mode, most possibly involving guanine N7 nitrogen of DNA, with an intrinsic binding constant Kb of 4.5 × 104 M-1 and 4.2 × 104 M-1, respectively. However, interestingly, the Cu(II) complex is involved in the surface binding to minor groove via phosphate backbone of DNA double helix with an intrinsic binding constant Kb of 5.7 × 104 M-1. The Co(II), Ni(II) and Cu(II) complexes are active in cleaving supercoiled (SC) pUC19 DNA on photoexposure to UV-visible light of 365 nm, through 1O2 generation with quantum yields of 0.28, 0.25 and 0.30, respectively. Further, these complexes are cytotoxic in A549 lung cancer cells, showing an enhancement of cytotoxicity upon light irradiation.

Pradeepa, S. M.; Bhojya Naik, H. S.; Vinay Kumar, B.; Indira Priyadarsini, K.; Barik, Atanu; Ravikumar Naik, T. R.; Prabhakara, M. C.

2013-11-01

341

Proton transfer assisted charge transfer phenomena in photochromic Schiff bases and effect of -NEt2 groups to the anil Schiff bases.  

PubMed

Photochromic Schiff bases 5-diethylamino-2-[(4-diethylamino-benzylidene)-hydrazonomethyl]-phenol (DDBHP) and N,N'-bis(4-N,N-diethylaminosalisalidene) hydrazine (DEASH) with both the proton and charge transfer moieties have been synthesized, and their photophysical properties such as excited state intramolecular charge transfer (ICT) and proton transfer (ESIPT) processes have been reported on the basis of steady-state and time-resolved spectral measurement in various solvents. The ground-state six-membered intramolecular hydrogen bonding network at the proton transfer site accelerates the ESIPT process for these compounds. Both the compounds show large Stokes-shifted emission bands for proton transfer and charge transfer processes. The hydrogen bonding solvents play a crucial role in these photophysical processes. Excited-state dipole moment of DDBHP and DEASH calculated by the solvatochromic method supports the polar character of the charge transfer excited state. Introduction of -NEt(2) groups to the reported salicylaldehyde azine (SAA) Schiff base results an increase in fluorescence lifetime from femtosecond to picosecond time scale for the proton transfer process. PMID:23098054

Jana, Sankar; Dalapati, Sasanka; Guchhait, Nikhil

2012-11-15

342

DNA-binding and cleavage studies of novel copper(II) complex with L-phenylalaninate and 1,4,8,9-tetra-aza-triphenylene ligands.  

PubMed

DNA-binding properties of novel copper(II) complex [Cu(l-Phe)(TATP)(H(2)O)](+), where L-Phe=L-phenylalaninate and TATP=1,4,8,9-tetra-aza-triphenylene are investigated using electronic absorption spectroscopy, fluorescence spectroscopy, voltammetry and viscosity measurement. It is found that the presence of calf thymus DNA results in a hypochromism and red shift in the electronic absorption, a quenching effect on fluorescence nature of ethidium bromide-DNA system, an enhanced response on voltammograms of [Co(phen)(3)](3+/2+)-DNA system, and an obvious change in viscosity of DNA. From absorption titration, fluorescence analysis and voltammetric measurement, the binding constant of the complex with DNA is calculated. The latter two methods reveal the stronger binding of [Cu(l-Phe)(TATP)(H(2)O)](+) complex to double strand DNA by the moderate intercalation than [Co(phen)(3)](3+). Such a binding induces the cleavage of plasmid pBR322 DNA in the presence of H(2)O(2). PMID:16199091

Li, Hong; Le, Xue-Yi; Pang, Dai-Wen; Deng, Hong; Xu, Zheng-He; Lin, Zhong-Hua

2005-11-01

343

Chiral tetranuclear and dinuclear copper(ii) complexes for TEMPO-mediated aerobic oxidation of alcohols: are four metal centres better than two?  

PubMed

The one-pot reaction of 3,5-di-tert-butyl-2-hydroxybenzaldehyde, (R)-2-aminoglycinol and Cu(OAc)2·2H2O in a 1?:?1?:?1 ratio in the presence of triethylamine led to the isolation of X-ray quality crystals of the chiral complex (R)- in high yield. The single crystal structure of (R)- reveals a tetranuclear copper(ii) complex that contains a {Cu4(?-O)2(?3-O)2N4O4} core. A reaction using (1S,2R)-2-amino-1,2-diphenylethanol as precursor under the same conditions generated the chiral complex (S,R)-; its structure was determined by single crystal X-ray crystallography and was found to contain a {Cu2(?-O)2N2O2} core. Both (R)- and (S,R)- have been used for catalytic aerobic oxidation of benzylic alcohols in combination with the TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) radical. (R)- selectively catalyses the conversion of various aromatic primary alcohols to the corresponding aldehydes with high yields (99%) and TONs (770) in the air, while (S,R)- exhibits less promising catalytic performance under the same reaction conditions. The role of the cluster structures in (R)- and (S,R)- in controlling the reactivity towards aerobic oxidation reactions is discussed. PMID:24986135

Zhang, Guoqi; Proni, Gloria; Zhao, Sherry; Constable, Edwin C; Housecroft, Catherine E; Neuburger, Markus; Zampese, Jennifer A

2014-08-28

344

[Mn(III)(Schiff base)]?[Re(IV)(CN)?], highly anisotropic 3D coordination framework: synthesis, crystal structure, magnetic investigations, and theoretical analysis.  

PubMed

A new highly anisotropic coordination heterobimetallic polymer [Mn(III)(Schiff-base)]3[Re(IV)(CN)7] was synthesized and characterized structurally and magnetically. The single crystal X-ray analysis has revealed that this is the first framework among the complexes composed of homoleptic cyanometallate and Mn(III) complex of the tetradentate Schiff base ligand. A formation of 3D assembly is possible due to both the pentagonal bipyrimidal geometry of the cyanometallate unit and suitable size of constituents: [Re(CN)7](3-) and [Mn(III)(acacen)](+), where acacen = N,N'-ethylenebis(acetylacetoneiminato). The powder and crystal magnetic studies show that the compound undergoes an antiferromagnetic ordering of a complicated character below Neel temperature of 13 K, and exhibits a metamagnetic behavior and strong magnetic anisotropy similar to those observed in related 3D Mn(II)-[Mo(CN)7](4-) systems. Unusual magnetic properties of [Mn(III)(acacen)]3[Re(IV)(CN)7] (1) originate from an interplay of Re-Mn anisotropic spin coupling and ZFS effect of Mn(III) ions with a noncollinear orientation of the local magnetic axes in the cyano-bridged 3D network. A theoretical model of anisotropic spin coupling between orbitally degenerate [Re(IV)(CN)7](3-) complexes and Mn(III) ions is developed, and specific microscopic mechanisms of highly anisotropic spin coupling in Re(IV)-CN-Mn(III) linkages in complex 1 are analyzed in detail. PMID:25250555

Samsonenko, Denis G; Paulsen, Carley; Lhotel, Elsa; Mironov, Vladimir S; Vostrikova, Kira E

2014-10-01

345

Thermal lens technique to evaluate the fluorescence quantum yield of a schiff base  

NASA Astrophysics Data System (ADS)

The fluorescence spectrum of the schiff base obtained from salicylaldehyde and 2-aminophenol is studied using an argon-ion laser as the excitation source and its fluorescence quantum yield (Qf) is determined using a thermal lens method. This is a nondestructive technique that gives the absolute value of Qf without the need for a fluorescence standard. The quantum-yield values are calculated for various concentrations of the solution in chloroform and also for various excitation wavelengths. The value of Qf is relatively high, and is concentration dependent. The maximum value of Qf obtained is nearly 0.78. The high value of the fluorescence quantum yield will render the schiff base useful as a fluorescent marker for biological applications. Photostability and gain studies will assess its suitability as a laser dye.

Santhi, A.; Kala, U. L.; Nedumpara, R. J.; Kurian, A.; Kurup, M. R. P.; Radhakrishnan, P.; Nampoori, V. P. N.

2004-09-01

346

Synthesis, characterization, tautomerism and theoretical study of some new Schiff base derivatives  

NASA Astrophysics Data System (ADS)

New Schiff base derivatives were prepared by the condensation of 5-chloro and 5-bromo salicylaldehyde with bis( o-aminophenol)ethers. Five bis( o-nitrophenol)ether compounds were synthesized using some ditosylate, 1,3-dibromopropane and 1,4-dibromobuthane with o-nitrophenol. These compounds were reduced to bis( o-aminophenol)ethers. The products have been characterized by elemental analysis, FTIR, 1H, 13C NMR, HETCOR and HMBC spectroscopic techniques. The tautomerisms of all of the Schiff bases compounds were determined in DMSO, CHCl 3, C 2H 5OH and C 6H 12 solvents and in both acidic and basic media using the UV-vis spectrophotometric method. The heat of formation (? Hf), enthalpy (? H), entropy (? S), Gibbs free energy (? Gf and ? G), stable isomers, conformations and tautomers of the synthesized compounds are calculated using the MOPAC2009 (PM6) program.

Türko?lu, Gül?en; Berber, Halil; Dal, Hakan; Ö?retir, Cemil

2011-09-01

347

Spectroscopic and semiempirical studies of new Schiff base of gossypol with allylamine in solution  

NASA Astrophysics Data System (ADS)

The Schiff base of racemic gossypol with allylamine (GSBAL) has been studied by FT-IR, 1H and 13C NMR spectroscopy as well as by the PM5 semiempirical method. The spectroscopic methods have shown that GSBAL Schiff base exists in chloroform solution as enamine-enamine tautomer. The structure of GSBAL and the hydrogen bonds within this structure have been calculated to show that the allyl groups are out-of-planes of naphthalene rings. The strongest intramolecular hydrogen bond within the structure of GSBAL is formed between O 7⋯H-N 16 atoms and it belongs to the medium strong bonds. The other hydrogen bonds, although very weak, play a very important role in stabilising the GSBAL enamine-enamine structure.

Przybylski, Piotr; Ma?uszy?ska, Maria; Brzezinski, Bogumi?

2005-08-01

348

Photophysical properties of Schiff's bases from 3-(1,3-benzothiazol-2-yl)-2-hydroxy naphthalene-1-carbaldehyde  

NASA Astrophysics Data System (ADS)

A series of novel Schiff's bases have been synthesized from 3-(1,3-benzothiazol-2-yl)-2-hydroxynaphthalene-1-carbaldehyde. The presence of hydroxyl group ortho to the benzothiazolyl group as well as the imine linkage lead to the occurrence of excited state intramolecular proton transfer process. The computational strategy was used to study the ESIPT process of the synthesized Schiff's bases, which revealed surprisingly that the keto form predominantly exists in the ground state contradicting the ESIPT process. Density functional theory and time dependent density functional theory have been used to investigate the structural parameters and photophysical properties in different solvents of one of the Schiff's bases. The experimental results correlate well with the computed results. All Schiff's bases show good thermal stability.

Satam, Manjaree A.; Telore, Rahul D.; Sekar, Nagaiyan

2014-11-01

349

New 14-membered trans-di-substituted ‘tet-a’ macrocycles and their copper(II) and nickel(II) complexes: Spectral, magnetic, electrochemical, crystal structure, catalytic and antimicrobial studies  

NASA Astrophysics Data System (ADS)

Copper(II) and nickel(II) complexes of new trans-di-substituted macrocyclic ligands incorporating three different benzoyl groups, 1,8-bis-(benzoyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (L 1), 1,8-bis-(2-nitrobenzoyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (L 2), and 1,8-bis-(4-nitrobenzoyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (L 3) have been synthesized. The ligands and complexes were characterized by elemental and spectral analysis. Further, the X-ray crystal structure of one of the ligand, L 1, has been determined. N-benzoylation causes red shift in the ?max values of the complexes. The cyclic voltammogram of the complexes of ligand L 1 shows one-electron, quasi-reversible reduction wave in the region -0.94 to -1.00 V, whereas that of L 2 and L 3 show two quasi-reversible reduction peaks corresponding to ligand and metal. Nickel complexes show one electron quasi-reversible oxidation wave at a positive potential in the range +0.92 to +1.21 V. The Cu(II) complexes have a magnetic moment value close to the spin-only value with four hyperfine EPR signals. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and on the hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. The complexes containing electron-withdrawing group shows higher rate-constant values than that with no electron-withdrawing group. All the complexes were screened for antifungal and antibacterial activity.

Nirmala, G.; Kalilur Rahiman, A.; Sreedaran, S.; Jegadeesh, R.; Raaman, N.; Narayanan, V.

2011-03-01

350

Synthesis, X-ray Structure, Spectroscopic Properties and DFT Studies of a Novel Schiff Base  

PubMed Central

A series of Schiff bases, salicylideneaniline derivatives 1–4, was synthesized under mild conditions and characterized by 1H NMR, HRMS, UV-Vis and fluorescence spectra, and single-crystal X-ray diffraction. In solid and aprotic solvents 1–4 exist mainly as E conformers that possess an intramolecular six-membered-ring hydrogen bond. A weak intramolecular C–H···F hydrogen bond is also observed in fluoro-functionalized Schiff base 4, which generates another S(6) ring motif. The C–H···F hydrogen bond further stabilizes its structure and leads it to form a planar configuration. Compounds 1–3 exhibit solely a long-wavelength proton-transfer tautomer emission, while dipole-functionalized Schiff base 4 shows remarkable dual emission originated from the excited-state intramolecular charge transfer (ESICT) and excited-state intramolecular proton transfer (ESIPT) states. Furthermore, the geometric structures, frontier molecular orbitals (MOs) and the potential energy curves for 1–4 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT) and time-dependent DFT calculations. PMID:25329613

Chen, Kew-Yu; Tsai, Hsing-Yang

2014-01-01

351

Antioxidant properties of phenolic Schiff bases: structure-activity relationship and mechanism of action.  

PubMed

Phenolic Schiff bases are known for their diverse biological activities and ability to scavenge free radicals. To elucidate (1) the structure-antioxidant activity relationship of a series of thirty synthetic derivatives of 2-methoxybezohydrazide phenolic Schiff bases and (2) to determine the major mechanism involved in free radical scavenging, we used density functional theory calculations (B3P86/6-31+(d,p)) within polarizable continuum model. The results showed the importance of the bond dissociation enthalpies (BDEs) related to the first and second (BDEd) hydrogen atom transfer (intrinsic parameters) for rationalizing the antioxidant activity. In addition to the number of OH groups, the presence of a bromine substituent plays an interesting role in modulating the antioxidant activity. Theoretical thermodynamic and kinetic studies demonstrated that the free radical scavenging by these Schiff bases mainly proceeds through proton-coupled electron transfer rather than sequential proton loss electron transfer, the latter mechanism being only feasible at relatively high pH. PMID:24243063

Anouar, El Hassane; Raweh, Salwa; Bayach, Imene; Taha, Muhammad; Baharudin, Mohd Syukri; Di Meo, Florent; Hasan, Mizaton Hazizul; Adam, Aishah; Ismail, Nor Hadiani; Weber, Jean-Frédéric F; Trouillas, Patrick

2013-11-01

352

Innovation in acid pickling treatments of copper by characterizations of a new series of Schiff bases as corrosion inhibitors  

Microsoft Academic Search

Purpose – Aims to investigate the inhibitive effect of the new series of Schiff base molecules, namely, N, N?-ethylen-bis(salicylidenimine) [S1], N, N?-isopropylen-bis(salicylidenimine) [S2] and N, N?-Ortho-phenylen acetyl acetone imine, (2-hydroxy Benzophenone imine) [S3] on corrosion of copper during acid pickling treatment in 1 M HCl solution. Effects of concentration and temperature on the inhibition efficiencies of the selected Schiff bases

Maryam Ehteshamzadeh; Taghi Shahrabi; Mirghasem Hosseini

2006-01-01

353

Designing molecules for PDT: red light-induced DNA cleavage on disulfide bond activation in a dicopper(II) complex.  

PubMed

The binuclear copper(II) complex [Cu)(RSSR)2](1), where RSSR is a dianionic Schiff base derived from 2-(thioethyl)salicylaldimine having a disulfide bond is prepared, structurally characterized by X-ray crystallography and its photo-induced DNA cleavage activity studied. The Schiff base ligand H2RSSR is also structurally characterized. The crystal structure of shows the discrete dimeric nature of the complex with each metal showing square-planar geometry with a CuN2O2 coordination (Cu...Cu, 5.011(1)A). The tetradentate Schiff base RSSR acts as a linker of two copper centers. The sulfur atoms in the disulfide unit do not show any apparent interaction with the metal ion. Complex 1, which is cleavage inactive in the dark in the presence of reducing agents, shows significant cleavage of supercoiled pUC19 DNA on exposure to UV light of 312 nm or visible light of different wavelengths under aerobic conditions, in the absence of any additives. DNA cleavage data from control experiments reveal involvement of the disulfide unit as a photosensitizer undergoing photo-induced S-S bond cleavage on exposure to UV light and the resulting species activates molecular oxygen to form singlet oxygen (1O2) that causes DNA cleavage following a type-II process. Photo-induced DNA cleavage by 1 on red-light exposure using a CW laser of 632.8 nm or a pulsed ruby laser of 694 nm is proposed to involve sulfide radicals in a type-I process and hydroxyl radicals as the reactive species. PMID:15616724

Dhar, Shanta; Nethaji, Munirathinam; Chakravarty, Akhil R

2005-01-21

354

Halo-substituted thiosemicarbazones and their copper(II), nickel(II) complexes: Detailed spectroscopic characterization and study of antitumour activity against HepG2 human hepatoblastoma cells  

NASA Astrophysics Data System (ADS)

Copper(II) and nickel(II) complexes of two different halogen substituted thiosemicarbazone ligands were synthesized. The ligands 3,4-difluoroacetophenone thiosemicarbazone (1) and 2-bromo-4'-chloroacetophenone thiosemicarbazone (2) were characterized and confirmed spectroscopically by FT-IR, FT-Raman, UV-vis and fluorescence spectral analysis, while the respective copper(II) complexes [Cu(C9H9N3F2S)2Cl2] (1a), [Cu(C9H9N3ClBrS)2Cl2] (2a) and nickel(II) complexes [Ni(C9H9N3F2S)2] (1b), [Ni(C9H9N3ClBrS)2] (2b) were characterized by FT-IR, UV-vis and electron paramagnetic spectroscopy (EPR). The EPR spectra of the Cu(II) complexes provided the rhombic octahedral and axial symmetry of the complexes 1a and 2a respectively. For the complex 1a, the g values calculated as g1 = 2.1228, g2 = 2.0706 and g3 = 2.001 between 2900 and 3300 G. While for the complex 2a, a set of two resonance absorptions were observed. The synthesized compounds were tested for antitumor activity and showed that the ability to kill liver cancer cells significantly. Out of all the synthesized compounds, copper(II) complexes 1a and 2a showed high cytotoxic effect on liver cancer cells with 67.51% and 42.77% of cytotoxicity respectively at 100 ?M.

Jagadeesh, M.; Kalangi, Suresh K.; Sivarama Krishna, L.; Reddy, A. Varada

2014-01-01

355

Synthesis, structures, spectroscopy and antimicrobial properties of complexes of copper(II) with salicylaldehyde N-substituted thiosemicarbazones and 2,2'-bipyridine or 1,10-phenanthroline.  

PubMed

Among the biometals (Cu, Co, Ni-cofactors in many enzymes), copper derivatives of O, N, S-donor salicylaldehyde thiosemicarbazones have received considerable attention owing to their potential biological applications. Eight new complexes of salicylaldehyde-N-substituted thiosemicarbazones [5-MeO-2-HO-C?H?-C(2)(H)N(3)-N(2)H-C(1)(S)-N(1)HR; R = Me, H2L(1); Et, H?L(1), Ph, H?L(3), H, H?L(4)] with copper(II), namely, [Cu(?(3)-O,N,S-L)( ?(2)-N,N-L')] {(L)(2-) = (L(1))(2-), L' = bipy, 1, phen, 2; (L)(2-) = (L(2))(2-), L' = bipy, 3, phen, 4; (L)(2-) = (L(3))(2-), L' = bipy, 5, phen, 6; (L)(2-) = (L(4))(2-), L' = bipy, 7, phen, 8} have been isolated. Complexes have slightly distorted square pyramidal geometry around the metal center (? parameter = 0.243-0.357) and display weak to intense fluorescence in the region, 375-475 nm. These copper complexes have shown significant growth inhibitory activity (antimicrobial activity) against Staphylococcus aureus (MTCC740), methicillin resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae 1 (MTCC109), Shigella flexneri (MTCC1457), Pseudomonas aeruginosa (MTCC741) and Candida albicans (MTCC227). The activity against MRSA is an interesting observation as the commercially available gentamycin is found to be inactive against this bacterial strain. Specifically complex 5 formed by 5-methoxysalicylaldehyde-N-phenylthiosemicatbazone has shown novel antimicrobial activity against various bacteria and yeast investigated. PMID:24583354

Lobana, Tarlok S; Indoria, Shikha; Jassal, Amanpreet Kaur; Kaur, Harpreet; Arora, Daljit S; Jasinski, Jerry P

2014-04-01

356

Synthesis, crystal structure, magnetic property and oxidative DNA cleavage activity of an octanuclear copper(II) complex showing water-perchlorate helical network.  

PubMed

A new octanuclear copper(II) complex has been synthesized and structurally characterized by X-ray crystallography: [Cu(8)(HL)(4)(OH)(4)(H(2)O)(2)(ClO(4))(2)].(ClO(4))(2).2H(2)O (1) (H(3)L=2,6-bis(hydroxyethyliminoethyl)-4-methyl phenol). The complex is formed by the linkage of two terminal bimetallic cationic units and a tetranuclear mu(3)-hydroxo bridged dicubane core by a very short intramolecular hydrogen bond (O-H...O, 1.48(3)A and the angle 175 degrees). The coordination sphere of the terminal copper atoms is square pyramidal, the apical positions being occupied by water and a perchlorate ion. Complex 1 self-assembles to form a new type of water-perchlorate helical network [(H(2)O)(2)(ClO(4))](infinity) involving oxygen atoms of coordinated perchlorate ion and the two lattice water molecules through hydrogen-bonding interaction. The variable temperature-dependent susceptibility measurement (2-300K) of 1 reveals a strong antiferromagnetic coupling, J(1)=-220cm(-1) and J(2)=-98cm(-1) (J(1) and J(2) representing the exchange constant within [Cu(2+)](4) and [Cu(2+)](2) units, respectively). The complex binds to double-stranded supercoiled plasmid DNA giving a K(app) value of 1.2x10(7)M(-1) and displays efficient oxidative cleavage of supercoiled DNA in the presence of H(2)O(2) following a hydroxyl radical pathway. PMID:17045341

Dhara, Koushik; Ratha, Jagnyeswar; Manassero, Mario; Wang, Xin-Yi; Gao, Song; Banerjee, Pradyot

2007-01-01

357

Crystal structure of the schiff base intermediate prior to decarboxylation in the catalytic cycle of aspartate alpha-decarboxylase.  

PubMed

l-Aspartate alpha-decarboxylase (ADC), encoded by the panD gene, catalyzes the conversion of l-aspartate into beta-alanine. In the microorganisms, beta-alanine is required for the synthesis of pantothenate (vitamin B(5)), which is the precursor of 4'-phosphopantetheine and coenzyme A. We have determined the crystal structure of Helicobacter pylori ADC, a tetrameric enzyme, in two forms: the apo structure at 2.0 A resolution and the isoasparagine complex structure at 1.55 A resolution. All subunits of the tetramer are self-processed at the Gly24-Ser25 linkage, producing the smaller beta chain (residues 1-24) and the larger alpha chain (residues 25-117). Each subunit contains nine beta-strands and three alpha-helices; it is folded into the double-psi beta-barrel structure. In the apo structure, the new amino terminus of the alpha chain, Ser25, is converted into a pyruvoyl group. In the isoasparagine complex structure, the substrate analog is covalently attached to the pyruvoyl group. This structure represents the enzyme-substrate Schiff base intermediate that was proposed to form prior to the decarboxylation step in the catalytic cycle of ADC. Thus our study provides direct structural evidence for the reaction mechanism of ADC. PMID:15184017

Lee, Byung Il; Suh, Se Won

2004-06-25

358

Synthesis and antiproliferative activities of novel 5'-Schiff-base group substituted psoralen derivatives.  

PubMed

It was found that psoralen derivative could perform a Friedel-Crafts acylation smoothly with acetic anhydride to give 5'-acetylpsoralen in a 73% yield. In the presence of boron trifluoride etherate, 5'-acetylpsoralen reacted with both aromatic amines and aliphatic amine smoothly to afford 5'-Schiff-base group substituted psoralen derivatives in 72%-92% yields. The novel synthetic method has the advantages of cheap materials, mild reaction conditions, good yields and high regioselectivity in the Friedel-Crafts acylation. Cell viability assay by MTT demonstrates that some of the psoralen derivatives 6 have antiproliferative activities. PMID:21462896

Chen, Chao-Yue; Sun, Jian-Guo; Huang, Zhi-Zhen; Kwok, Tim-Tak; Fung, Kwok-Pui; Wu, Ping; Liu, Fei-Yan

2011-01-01

359

Model studies of pyridoxal Schiff's bases. Coplanarity and intramolecular hydrogen bonding.  

PubMed

The interactions between the pi cloud of the aromatic ring and the pi-electron pair of the imine double bond of aromatic oximes as model compounds of pyridoxal Schiff's bases have been studied by high-resolution carbon-13 magnetic resonance spectroscopy. The coplanarity and intramolecular hydrogen bonding have been determined by 13C-1H long range couplings. This detailed investigation of 13C-1H coupling also provides unambiguous proof of the existence of the "enol-imine" tautomers in chloroform and dimethyl sulfoxide solutions. The tautomerism between the "enol-imine" and "keto-enamine" is discussed. PMID:833823

Chang, C; Shieh, T L; Floss, H G

1977-01-01

360

A study on the versatility of metallacycles in host-guest chemistry: interactions in halide-centered hexanuclear copper(II) pyrazolate complexes.  

PubMed

Hexanuclear copper(II) pyrazolate complexes have shown the ability to encapsulate different halide ions, leading to [trans-Cu6{?-3,5-(CF3)2pz}6(?-OH)6X](-) (X = F, Cl, Br, I). They offer an interesting case study for variation in local properties at host binding sites, due to the presence of a six membered ring involving Cu(II) centers considered as the borderline Lewis acid according to the Pearson Hard and Soft Acids and Bases (HSAB) principle. Here, we describe the host-guest interactions via relativistic density functional calculations, involving the graphical description of local dipole and quadrupole moments, energy decomposition analysis, non-covalent indices, and magnetic behavior. The observed variation in the copper local dipole and quadrupole moments suggests that a metallacycle host offers great advantages in comparison to their organic counterparts, prompted by the versatility of the metallic centers to modulate the surrounding electron density accordingly. According to our results, the contribution of ion-dipole forces in the halide-centered series decreases from 95.0% to 77.0% from the fluoride to the iodide complex, whereas the contribution of higher order interactions such as quadrupole-dipole and quadrupole-quadrupole, goes from 5.0% to 23.0% towards a softer guest. In addition, the through-the-space magnetic response of trans-Cu6{?-3,5-(CF3)2pz}6(?-OH)6, reveals a noteworthy aromatic structure, which is driven by the superexchange through the ligands leading to a singlet ground state. PMID:24866754

Ponce-Vargas, Miguel; Muñoz-Castro, Alvaro

2014-07-14

361

Fluorescence of the Schiff bases of pyridoxal and pyridoxal 5'-phosphate withL-isoleucine in aqueous solutions.  

PubMed

The present study reports on the absorption and emission properties of the Schiff bases formed by pyridoxal and pyridoxal 5'-phosphate withL-isoleucine in aqueous solutions. Species protonated at the imine and ring nitrogen are the most fluorescent in both Schiff bases with a quantum yield of 0.02, i.e., 20-fold the value found for species in alkaline solutions. In agreement with other studies, species protonated at the imine nitrogen shows an emission around 500 nm upon excitation at 415 nm. In contrast to previous observations on other PLP Schiff bases, emissions at 560 nm (PL-Ile) and 540 nm (PLP-Ile) are observed upon excitation at 365 and 415 nm, respectively. The emission at 470 nm found in PLP-Ile Schiff base upon excitation at 355 nm is ascribed to a multipolar monoprotonated species. An estimation for the pK a of the imine in the excited state ( ? 8.5) for both Schiff bases is also reached. Our results suggest that fast protonation reactions on the excited state are responsible for the observed fluorescence. These effects, in which the hydrogen bond and the phosphate group seem to play a role, could be extended to understanding coenzyme environments in proteins. PMID:24226991

Cambrón, G; Sevilla, J M; Pineda, T; Blázquez, M

1996-03-01

362

Selective turn-on fluorescence for Zn(2+) and Zn(2+)+Cd(2+) metal ions by single Schiff base chemosensor.  

PubMed

Chemosensor based on Schiff base molecules (1, 2) were synthesized and demonstrated the selective fluoro/colorimetric sensing of multiple metal ions (Mn(2+), Zn(2+) and Cd(2+)) in acetonitrile-aqueous solution. Both 1 and 2 showed a highly selective naked-eye detectable colorimetric change for Mn(2+) ions at 10(-7)M. Fluorescence sensing studies of 1 and 2 exhibited a strong fluorescence enhancement (36 fold) selectively upon addition of Zn(2+) (10(-7)M, ?max=488nm). Fluorescence titration and single crystal X-ray analysis confirmed the formation of 1:1 molecular coordination complex between 1 and Zn(2+). Interestingly, a rare phenomenon of strong second turn-on fluorescence (190 fold, ?max=466nm) was observed by the addition of Cd(2+) (10(-7)M) into 1+Zn(2+) or Zn(2+) (10(-7)M) into 1+Cd(2+). Importantly both 1 and 2 exhibited different fluorescence ?max with clearly distinguishable color for both Zn(2+) and Cd(2+). PMID:25263119

Hariharan, P S; Anthony, Savarimuthu Philip

2014-10-27

363

Spectroscopic, electrochemical DNA binding and in vivo anti-inflammatory studies on newly synthesized Schiff bases of 4-aminophenazone.  

PubMed

4-Aminophenazone (Ap-1) Schiff bases i.e., 4-{(3,4,5-trimethoxybenzylidine) amino}phenazone (Ap-2), 4-{(2-chlorobenzylidine) amino}phenazone (Ap-3) and 4-{(4-chlorobenzylidine)amino} phenazone (Ap-4) were synthesized and characterized by different spectroscopic techniques. Interaction of these compounds with ds.DNA was investigated through UV-Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry at stomach (4.7) and blood (7.4) pH under 37 °C (human body temperature). Instrumental findings were further quantified both kinetically and thermodynamically. Results obtained through these techniques inferred intercalative mode of binding of all the compounds with DNA. The binding constant data, "Kb", and free energy change, ?G, indicated comparatively greater binding affinity and more spontaneity of binding of compounds with DNA at stomach pH (4.7), respectively. However, among these compounds, Ap-4 showed comparatively greater binding at both the pH. Formation of compound-DNA complex was further confirmed through the decrease in diffusion rates after the addition of DNA. The in vivo anti-inflammatory activity of the compounds was evaluated using the carrageenan-induced hind paw edema method. The results revealed that among all the compounds, Ap-4 showed greater percentage of edema inhibition compared to standard drug. PMID:25036662

Arshad, Nasima; Ahmad, Mukhtar; Ashraf, Muhammad Zaman; Nadeem, Humaira

2014-09-01

364

Spectroscopic and structural characterization of copper(II) and palladium(II) complexes of a lichen substance usnic acid and its derivatives. Possible forms of environmental metals retained in lichens  

Microsoft Academic Search

The metal binding properties of a phenolic lichen substance usnic acid (UA) and its acetyl and enamine derivatives 9-O-acetylusnic acid (MAUA), 7,9-di-O-acetylusnic acid (DAUA), ?2,11-enaminousnic acid (EUA), and N-substituted ?2,11-enaminousnic acids have been studied by synthetic and spectroscopic methods, and the structures of copper(II) and palladium(II) complexes have been established by the X-ray diffraction method. Cu(II) reacted with UA and

Masako Takani; Tatsuo Yajima; Hideki Masuda; Osamu Yamauchi

2002-01-01

365

Structural studies on copper(II) complex containing (Z)-2-(2-Aminothiazol-4-yl)- N-(2-hydroxyethyl)-2-(hydroxyimino) acetamide, A model compound for a cephalosporin antibiotic cefdinir  

Microsoft Academic Search

(Z)-2-(2-aminothiazol-4-yl)-N-(2-hydroxyethyl)-2-(hydroxyimino)acetamide (HL) has been employed as a model compound for an orally active cephalosporin antibiotic, Cefdinir (CFDN). A binuclear copper(II) complex Cu2L4 (1) has been obtained from an aqueous solution containing CuCl2 and HL, and its structure determined by means of X-ray crystallography: monoclinic, P2\\/c, a = 11.954(3) A?, b = 10.661(3) A?, c = 16.969(7) A?, ? = 108.13(3)°,

Shuhei Deguchi; Yayoi Shihahara; Marie T. Mooney; Kyoko Yamamoto; Toshiji Tada; Mamoru Fujioka; Yoshihiko Okamoto; Tsutomu Yasuda; Shinnichiro Suzuki

1997-01-01

366

DFT studies of structural and some spectral parameters of copper(II) complexes with N,N,N?,N?-tetrakis (2-hydroxyethyl/propyl) ethylenediamine and tris(2-hydroxyethyl)amine  

NASA Astrophysics Data System (ADS)

The structures and some spectral parameters of three copper(II) complexes; [Cu(THEEN)(H2O)](PIC)2 (1), [Cu(THPEN)] (PIC)2 C3H8O (2) and [Cu(TEAH3)(PIC)] (PIC)?(H2O) (3), previously synthesized and characterized by X-ray diffraction, are here computationally studied by using density functional theory (DFT) in its hybrid form B3LYP. In these complexes, THEEN is N,N,N?,N?-tetrakis(2-hydroxyethyl) ethylenediamine and THPEN is N,N,N?,N?-tetrakis(2-hydroxypropyl) ethylenediamine, tetrapodal ligands and TEAH3 is tris(2-hydroxyethyl)amine, a tripodal ligand. The primary coordination sphere of copper(II) ion in complexes (1), (2) and (3) are optimized, structural parameters are calculated, vibrational bands are assigned and energy gaps of frontier orbital (HOMO-LUMO) have been calculated with B3LYP/6-31G/LANL2DZ level of theory using DMSO as solvent. The calculated geometric and spectral results reproduced the experimental data with well agreement. Theoretical calculated molecular orbitals (HOMO-LUMO) and their energies have been calculated that suggest charge transfer occurs within the complexes.

Kumar, Rakesh; Obrai, Sangeeta; Mitra, Joyee; Sharma, Aparna

2013-11-01

367

Nonlinear optical analyses of organic N-(9-Anthrylmethylidene) methylamine Schiff base  

NASA Astrophysics Data System (ADS)

The organic NLO Schiff base of N-(9-Anthrylmethylidene) methylamine was synthesized by condensation process. The material was characterized through Powder XRD, FT-IR, and Raman techniques. The various planes of reflection are identified from the Powder XRD pattern. The formation of Schiff base is confirmed through FT-IR and Raman analysis. The intra molecular charge transfer interaction and the existence of the first-order molecular hyperpolarizability (?) are identified from the red shift of the UV-Vis analysis. The structure of the molecule was optimized by density functional theory (DFT) using B3LYP method with 6-31G basis set. The NBO analysis is used to interpret the delocalization. The dipole moment and first hyperpolarizability values were also computed by HF/6-31G. These values indicate that the compound is a good candidate with nonlinear optical properties. This is the first time report on the existence of a second harmonic generation (SHG), ?2, efficiency that has been identified by Powder Kurtz-Perry method.

Vijayalakshmi, S.; Kalyanaraman, S.; Krishnakumar, V.

2013-05-01

368

Synthesis, Characterization, and BSA Binding Studies of Some New Benzamides Related to Schiff Base  

PubMed Central

Condensation of amine 1 with aldehyde 2 gives Schiff base, N-(4-((benzofuran-2-ylmethylene) amino)phenyl)acetamide 3. Schiff base on N-acylation with different substituted acid chlorides in the presence of triethylamine gives the corresponding benzamides, N-acetyl-N-(4-((benzofuran-2-ylmethylene)amino)phenyl)substitutedbenzamide (NABP) 5a–j. The structures of newly synthesized compounds were characterized by elemental analysis, 1H NMR, 13C NMR FT-IR, and mass spectral studies. Compounds 3 and 5a–j have been screened for their antimicrobial activity using the disc diffusion and minimum inhibitory concentration (MIC) method against the selected bacterial and fungal strain. Compounds 5a, 5e, 5g, and 5h were found to be more active against all tested strains. The antioxidant properties were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radical scavenging methods. Compounds 5i and 5j showed predominant antioxidant activities among the synthesized analogues. The interaction between NABP and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopic techniques at 298?K under imitated physiological conditions. The results revealed that NABP caused the fluorescence quenching of BSA through a static quenching procedure. The binding constants and the number of binding sites were calculated. The binding distance between the donor (BSA) and acceptor (NABP) was determined based on Forster's theory. PMID:24052869

Prashanth, M. K.; Madaiah, M.; Revanasiddappa, H. D.; Amruthesh, K. N.

2013-01-01

369

Hydrogencyanamide-bridged one-dimensional polymers built on Mn(III)-Schiff base fragments: synthesis, structure, and magnetism.  

PubMed

The ability of NCNH(-) to construct transition metal coordination polymers and to transmit magnetic coupling was investigated. By introduction of various tetradentate Schiff base ligands (L) and different solvents (S), nine NCNH(-)-bridged manganese(III) coordination complexes were obtained. Their structures can be divided into three types: I) NCNH-bridged chains built on mononuclear [Mn(III)(L)] units, [Mn(III)(L)(mu(1,3)-NCNH)](n) (L=5-Brsalen (1), 5-Clsalen (2)); II) NCNH-bridged chains built on dinuclear [Mn(III) (2)(L)(2)] units, complexes 3-8, [Mn(III) (2)(L)(2)(mu(1,3)-NCNH)]ClO(4)S (L=salen, 5-Fsalen, 5-Clsalen, 5-OCH(3)salen; S=CH(3)OH or C(2)H(5)OH); III) NCNH-bridged Mn(III) dimers linked by hydrogen bonds into a 1D polymer, {[Mn(III)(3-OCH(3)salen)(H(2)O)](2)(mu(1,3)-NCNH)}ClO(4) x 0.5 H(2)O (9, salen=N,N'-bis(salicylidene)-1,2-diaminoethane). In these complexes, the N[triple chemical bond]C--NH(-) resonance structure dominates the bonding mode of the NCNH(-) ligand adopting the mu(1,3)-bridging mode. Magnetic characterization shows that the asymmetric NCNH(-) bridge transmits antiferromagnetic interaction between Mn(III) ions and often favors the weak ferromagnetism caused by spin canting in these one-dimensional chains. However, these complexes exhibit different magnetic behaviors at low temperatures. PMID:17171734

Yuan, Mei; Zhao, Fei; Zhang, Wen; Pan, Feng; Wang, Zhe-Ming; Gao, Song

2007-01-01

370

Synthesis, characterization, structural optimization using density functional theory and superoxide ion scavenging activity of some Schiff bases  

NASA Astrophysics Data System (ADS)

Four Schiff bases, 2-[(4-nitro-phenylimino)-methyl]-phenol (NPIMP-2), 4-[(4-nitro-phenylimino)-methyl]-phenol (NPIMP-4), (1 H-indol-3-ylmethylene)-(4-nitro-phenyl)-amine (IYNPA), (3-nitro-benzylidene)-(4-nitro-phenyl)-amine (NBNPA) with experimental clue of binding with superoxide ion have been synthesized by the condensation of p-nitroaniline with o-hydroxy benzaldehyde, p-hydroxybenzaldehyde, indole-3-carboxaldehyde and m-nitrobenzaldehyde respectively. These were characterized by IR, 1H NMR, CHN, mass spectroscopy and UV-visible spectroscopy. The Schiff bases thus synthesized exhibited evidence for their binding with superoxide ion in the form of a high intensity charge transfer band beyond 500 nm in their respective UV-vis spectra on the addition of two drops of N/10 NaOH to their respective 10 -2 M solutions in DMSO. On further addition of two drops of N/10 HCl solution, the charge transfer band vanished and the original spectral pattern of the Schiff bases in DMSO was observed. Out of the four Schiff bases, the binding of NPIMP-4 with O2- was observed to be reversible throughout both the cycles of measurements, but the remaining Schiff bases, namely NPIMP-2, IYNPA and NBNPA were found to show reversibility in only one cycle. The variable temperature 1H NMR (RT-175 °C) in DMSO- d6 revealed reversible intramolecular proton transfer in NPIMP-2 and NPIMP-4 leading to existence of several tautomeric structures. Besides these synthetic and spectroscopic studies, the density functional theory (DFT) calculations were performed for two Schiff bases i.e., NPIMP-2 and NPIMP-4. These calculations provided some important information about the relative stability of various tautomeric forms of NPIMP-2 and NPIMP-4.

Upadhyay, K. K.; Kumar, Ajit; Upadhyay, Shalini; Mishra, P. C.

2008-02-01

371

Interaction of two new mixed ligand copper(II) complexes with DNA probed by thermodynamic and spectroscopic studies.  

PubMed

The DNA binding behavior of [Cu(4,7-dmp)(phen-dione)Cl]Cl (1) and [Cu(2,9-dmp)(phen-dione)Cl]Cl (2) where dmp and phen-dion stand for dimethyl-1,10-phenanthroline and 1,10-phenanthroline-5,6-dion, respectively, was studied with a series of techniques including Viscometry, UV-Vis absorption, circular dichroism and fluorescence spectroscopy. Cytotoxicity effect was also investigated. Thermodynamic parameters, enthalpy and entropy changes were calculated according to Van't Hoff equation, which indicated that both reactions are predominantly enthalpically driven. However, these two complexes show different behavior in fluorescence, circular dichroism and viscometry methods which indicate the Cu(II) complexes interact with calf-thymus DNA by different mode of binding. These have further been verified by competition studies using Hoechst as a distinct groove binder. All these results indicate that these two complexes (1) and (2) interact with CT-DNA via groove binding and partially intercalative mode, respectively and the binding affinity of the complex 1 is higher than that of complex 2. Finally, our findings suggest that the type of ligands and structure of complexes have marked effect on the binding affinity of complexes involving CT-DNA. Also, these new complexes showed excellent antitumor activity against human T lymphocyte carcinoma-Jurkat cell line. PMID:24253899

Kashanian, Soheila; Khodaei, Mohammad Mehdi; Roshanfekr, Hamideh; Mansouri, Ghobad

2014-01-01

372

Selective recognition of sulfate anions in a 95% ethanol solvent with a simple neutral salicylaldehyde dansyl hydrazine Schiff base tuned by Brønsted-Lowry acid-base reaction.  

PubMed

A new Schiff base compound, 5-(dimethylamino)-N'-(2-hydroxybenzylidene)naphthalene-1-sulfonohydrazide (R), has been synthesized, characterized, and employed as a selective fluorescence receptor for the recognition of sulfate anions. UV-vis absorption, fluorescence emission, (1)H NMR spectra and DFT calculation studies on the system have been carried out to determine the nature of the interactions between R and anions. The results reveal that the deprotonation of the phenol without the need of a strong base leads to the formation of a hydrogen-bonding complex with a -SO2-NH- group, which is responsible for the spectra changes. The deprotonation process for the selectivity recognition of sulfate can be tuned by the Brønsted-Lowry acid-base reaction in nonaqueous solutions, revealing that suitable phenolic hydroxyl acidity is the key factor for anion recognition selectivity. PMID:24667421

Wei, Gao-Ning; Zhang, Jing-Li; Jia, Cang; Fan, Wei-Zhen; Lin, Li-Rong

2014-07-15

373

A computational study on the stability of the protonated Schiff base of retinal in rhodopsin  

NASA Astrophysics Data System (ADS)

We investigated the effect of amino acids in rhodopsin on the protonation state of the Schiff base (SB) retinal. We constructed a model system consisting of SB retinal, Glu113 (counterion), and eight residues. For this model, we considered two states of the SB retinal, namely, the protonated/deprotonated state. We then performed ab initio MO calculations at the RHF/6-31g* level. As a result, the protonated state was stabler than the deprotonated state. Interestingly, we observed an additive rule for the contribution to the stabilization energy due to each amino acid. Above all, it turned out that Ser186 and Cys187 play a significant role in the stability.

Yamada, A.; Kakitani, T.; Yamamoto, S.; Yamato, T.

2002-12-01

374

Some QSAR Studies for a Group of Sulfonamide Schiff Base as Carbonic Anhydrase CA II Inhibitors  

PubMed Central

In the present study, quantitative structure–activity-relationship (QSAR) study on a group of sulfonamide Schiff-base inhibitors of Carbonic Anhydrase (CA) enzyme has been carried out using Codessa Pro methodology and software. Linear regression QSAR models of the biological activity (Ki) of 38 inhibitors of carbonic anhydrase CA-II isozyme were established with 12 different molecular descriptors which were selected from more than hundreds of geometrical, topological, quantum-mechanical, and electronic types of descriptors and calculated using Codessa Pro software. Among the models presented in this study, statistically the most significant one is a five-parameter equation with correlation coefficient, R2 values of ca. 0.840, and the cross-validated correlation coefficient, R2 values of ca. 0.777. The obtained models allowed us to reveal some physicochemical and structural factors, which are strongly correlated with the biological activity of the compounds. PMID:19325742

Eroglu, Erol

2008-01-01

375

First X-ray structural characterization of isatin Schiff base derivative. NMR and theoretical conformational studies  

NASA Astrophysics Data System (ADS)

Isatin (1H-indole-2,3-dione) is an endogenous natural compound under intense development in medicinal chemistry. Here, we characterize isatin Schiff base derivative by X-ray crystallography. We describe a derivative that crystallizes E-isomer form in the triclinic space group P 1bar;a = 5.9580 (4) Å, b = 8.4184 (7) Å, c = 14.1801 (14) Å, ? = 73.962 (8)°, ? = 83.184 (7)°, ? = 81.143 (6)°. NMR data show that E-conformer interconverts to the Z-conformer when dissolved, this equilibrium weakly depends on the solvent type. The Z-isomer geometry and the energetics of ?EE-Z interconversion barriers were determined by quantum chemical calculations. The isomers are further characterized by means of FT-IR and UV-Vis spectroscopy.

Davidovich, Pavel; Novikova, Daria; Tribulovich, Vyacheslav; Smirnov, Sergey; Gurzhiy, Vlad; Melino, Gerry; Garabadzhiu, Alexander

2014-10-01

376

Phenol-quinone tautomerism in (arylazo)naphthols and the analogous Schiff bases: benchmark calculations.  

PubMed

Tautomerization energies of a series of isomeric [(4-R-phenyl)azo]naphthols and the analogous Schiff bases (R = N(CH3)2, OCH3, H, CN, NO2) are calculated by LPNO-CEPA/1-CBS using the def2-TZVPP and def2-QZVPP basis sets for extrapolation. The performance of various density functionals (B3LYP, M06-2X, PW6B95, B2PLYP, mPW2PLYP, PWPB95) as well as MP2 and SCS-MP2 is evaluated against these results. M06-2X and SCS-MP2 yield results close to the LPNO-CEPA/1-CBS values. Solvent effects (CCl4, CHCl3, CH3CN, and CH3OH) are treated by a variety of bulk solvation models (SM8, IEFPCM, COSMO, PBF, and SMD) as well as explicit solvation (Monte Carlo free energy perturbation using the OPLSAA force field). PMID:24417622

Ali, S Tahir; Antonov, Liudmil; Fabian, Walter M F

2014-01-30

377

Synthesis, characterization and spectroscopic investigation of a novel phenylhydrazone Schiff base with solvatochromism  

NASA Astrophysics Data System (ADS)

A novel Schiff base of 4,5-diazafluorene-9- p-nitrophenylhydrazone (DAFND) has been synthesized and characterized. The crystal structures of DAFND and its analogue 4,5-diazafluorene-9-phenylhydrazone (DAFPD) were determined by single crystal X-ray diffraction method. X-ray analyses reveal that DAFPD comprise of a nonplanar molecule and all atoms of DAFND are essentially coplanar. The color of DAFND changes from brown to blue when heated, so called thermochromism and the spectroscopic properties of the two compounds are investigated by electronic absorption spectra, showing DAFND possess solvatochromism, while DAFPD does not have thermochromic and solvatochromic properties. The ?max of DAFND within various pure solvents are different ranging from 370 nm in toluene to 614 nm in pyridine. The imaginable mechanisms of thermochromism and solvatochromism are proposed.

Li, Mingtian; Huang, Jun; Zhou, Xuan; Luo, Hong

2010-02-01

378

Synthesis, antibacterial activities and molecular docking studies of peptide and Schiff bases as targeted antibiotics.  

PubMed

A series of peptide and Schiff bases (PSB) were synthesized by reacting salicylic acid, primary diamines with salicylaldehyde or its derivatives, and 40 of which were newly reported. The inhibitory activities against Escherichia coli beta-ketoacyl-acyl carrier protein synthase III (ecKAS III) were investigated in vitro and molecular docking simulation also surveyed. Top 10 PSB compounds which possess both good inhibitory activity and well binding affinities were picked out, and their antibacterial activities against Gram-negative and Gram-positive bacterial strains were tested, expecting to exploit potent antibacterial agent with broad-spectrum antibiotics activity. The results demonstrate compound N-(3-(5-bromo-2-hydroxybenzylideneamino)propyl)-2-hydroxybenzamide (2d) can be as a potential antibiotics agent, displaying minimal inhibitory concentration values in the range of 0.39-3.13 microg/mL against various bacteria. PMID:19884012

Cheng, Kui; Zheng, Qing-Zhong; Qian, Yong; Shi, Lei; Zhao, Jing; Zhu, Hai-Liang

2009-12-01

379

Synthesis and anti-amoebic activity of gold(I), ruthenium(II), and copper(II) complexes of metronidazole.  

PubMed

A series of Au, Ru, and Cu complexes of metronidazole (= [1-(2-hydroxyethyl)-2-methyl-5-nitro-1H-imidazole; 1) were prepared as highly potent anti-amoebic drugs. The complexes [Au(PPh3)(1)]PF6 (2), [Ru(1)2(Cl)2(H2O)2] (3), and [Cu(1)2(mu-Cl)(H2O)]2Cl2 (4) were readily synthesized from [Au(PPh3)Cl], RuCl3 x 3 H2O, and CuCl2 x 2 H2O, respectively. All complexes were thoroughly characterized by IR, UV/VIS, 1H-NMR, FAB-MS, elemental and thermogravimetric analyses, and, in the case of 4, also by X-ray crystallography (Fig. 1). All complexes were evaluated in vitro as growth inhibitors of Entamoeba histolytica (HM1:IMSS strain). Their IC50 values were in the range of 0.10-0.51 microM (Table 2), which makes these drugs, especially the Cu(II) complex 4, considerably more potent than uncomplexed metronidazole (1; IC50 = 1.81 microM), the current standard drug for the worldwide treatment of amoebiasis. PMID:17191933

Athar, Fareeda; Husain, Kakul; Abid, Mohammad; Agarwal, Subhash M; Coles, Simon J; Hursthouse, Micheal B; Maurya, Mannar R; Azam, Amir

2005-10-01

380

Unsymmetrical salen-type ligands: high yield synthesis of salen-type Schiff bases containing two different benzaldehyde moieties  

Microsoft Academic Search

Salen-type Schiff base ligands incorporating two different benzylidene moieties and a diamine backbone were synthesized in high yield (80–90%) under mild conditions via a stepwise approach. In the first step, anhydrous hydrochloric acid was used to selectively protect one amino group of the vicinal diamine backbone. The resulting ammonium salt was added to a substituted benzaldehyde providing access to a

E. Joseph Campbell; SonBinh T Nguyen

2001-01-01

381

Understanding non-enzymatic aminophospholipid glycation and its inhibition. Polar head features affect the kinetics of Schiff base formation.  

PubMed

Non-enzymatic aminophospholipid glycation is an especially important process because it alters the stability of lipid bilayers and interferes with cell function and integrity as a result. However, the kinetic mechanism behind this process has scarcely been studied. As in protein glycation, the process has been suggested to involve the formation of a Schiff base as the initial, rate-determining step. In this work, we conducted a comparative kinetic study of Schiff base formation under physiological conditions in three low-molecular weight analogues of polar heads in the naturally occurring aminophospholipids O-phosphorylethanolamine (PEA), O-phospho-DL-serine (PSer) and 2-aminoethylphenethylphosphate (APP) with various glycating carbonyl compounds (glucose, arabinose and acetol) and the lipid glycation inhibitor pyridoxal 5'-phosphate (PLP). Based on the results, the presence of a phosphate group and a carboxyl group in ? position respect to the amino group decrease the formation constant for the Schiff base relative to amino acids. On the other hand, esterifying the phosphate group with a non-polar substituent in APP increases the stability of its Schiff base. The observed kinetic formation constants of aminophosphates with carbonyl groups were smaller than those for PLP. Our results constitute an important contribution to understanding the competitive inhibition effect of PLP on aminophospholipid glycation. PMID:21719301

Caldés, Catalina; Vilanova, Bartolomé; Adrover, Miquel; Muñoz, Francisco; Donoso, Josefa

2011-08-01

382

Synthesis of novel chiral tridentate schiff-base ligands and their applications in catalytic asymmetric Henry reaction.  

PubMed

A series of chiral tridentate Schiff-bases were prepared and used as ligands in the catalytic asymmetric Henry reaction. Under the optimal conditions, a variety of arylaldehydes were smoothly converted into corresponding adducts with high yields (up to 98%) and excellent enantioselectivities (up to 97% ee). Chirality 26: 780-783, 2014. © 2014 Wiley Periodicals, Inc. PMID:25318691

Qiang, Gen-Rong; Shen, Tian-Hua; Zhou, Xiao-Cong; An, Xiao-Xia; Song, Qing-Bao

2014-12-01

383

Spectral investigation of the intramolecular charge-transfer in some aminotriazole Schiff bases.  

PubMed

3-Amino-1,2,4-triazole Schiff bases were reported to contain intramolecular charge-transfer. The enhancing and depressing effects were remarkable as the substituent was changed from electron-donating to electron-withdrawing groups. The path of the resonating delocalization was reversed in the case of the p-NO2 group. To validate these results we effectively used Weinhold et al's natural bond orbital analysis to assess the UV and FT-IR spectrophotometric monitoring of the change reflected in this phenomenon when the substituent in the benzene ring is altered. The NBO analysis was simulated by ab inito computations at the HF/6-31G(d) level of theory, in order to properly detect any possible presence of a hydrogen bond association. The changes occurring in electron occupancies of double-centered bonds, antibonding orbitals and in lone-pair orbitals appraised the results, as did the s and p character listings of the two-centered bonds and the simultaneous changes occurring in the geometric parameters of the molecules in question. Contrary to its normal preference, in these molecules the nitrogen used sp2 hybrid orbitals for its interaction, housing its electron lone-pair in the third p hybrid orbital. Furthermore, NBO analysis reflected the presence of a very soft intramolecular hydrogen association (C-H??), labelled by UV and FT-IR assignments, between the benzene and triazole rings in all Schiff bases but p-N(Me)2. The n-?* stabilization energy decreased in the order: p-OH>p-OCH3>p-Cl>p-CH3>H>p-NO2>o-OH. The relation between the band position and Hammett substitution constant is interpreted in relation to the molecular structure. PMID:21640640

Issa, Y M; Hassib, H B; Abdelaal, H E; Kenawi, I M

2011-09-01