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

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.     

Synthesis, Characterization and Biological Evaluation of Co(II), Cu(II), Ni(II) and Zn(II) Complexes With Cephradine

Some Co(II), Cu(II), Ni(II) and Zn(II) complexes of antibacterial drug cephradine have been prepared and characterized by their physical, spectral and analytical data. Cephradine acts as bidentate and the complexes have compositions, [M(L)(2)X(2)] where [M = Co(II), Ni(II) and Zn(II), L = cephradine and X = Cl(2)] showing octahedral geometry, and [M(L)(2)] where [M = Cu(II), L = cephradine] showing square planar geometry. In order to evaluate the effect of metal ions upon chelation, eephradine and its complexes have been screened for their antibacterial activity against bacterial strains, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa.     

Ni (II), Cu (II) and Zn (II) Metal Chelates With Some Thiazole Derived Schiff-Bases: Their Synthesis, Characterization and Bactericidal Properties

A number of thiazole derived tridentate Schiff-bases (LH) and its metal chelates of the type [M(L)(2)X] where M=Ni(II), Cu(II) and Zn(II), L=substituted salicylaldehyde (5-H, 5-CH(3), 5-OCH(3), 5-NO(2) and 5-Cl) and X=CI have been synthesized and characterized with the help of elemental analyses, conductivity measurements, magnetic moments, UV-Vis, IR and NMR spectral data. An octahedral structure for Ni(II) and Zn(II) and a distorted octahedral structure for Cu(II) chelates have been proposed. All the Schiff-bases and their metal chelates have been screened for their biological activity against Escherichia coli, Staphylococcus aureous , Pseudomonas aeruginosa and Klebsiella pneumonae and in comparison, the metal chelates have been shown to possess more antibacterial activity than the uncomplexed Schiff-bases.     

Synthesis, Characterization and Biological Properties of Anions of Bivalent Transition Metal [Co(II) and Ni(II)] Complexes With Acylhydrazine Derived ONO Donor Schiff Bases

Some acylhydrazine derived ONO donor Schiff bases and their Co(II) and Ni(II) complexes have been prepared having the same metal ion (cation) but different anions. These synthesized metal(II) complexes have been characterized on the basis of their elemental analyses, magnetic moment, molar conductance, and IR and electronic spectral data. All of the Schiff base ligands function as tridentates and the deprotonated enolic form is preferred for coordination. In order to evaluate the effect of anions on the bactericidal activity, these synthesized complexes, in comparison to the uncomplexed Schiff bases have been screened against bacterial species., Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and the results are reported.     

Spectroscopic Characterization and Biological Activity of Hesperetin Schiff Bases and Their Cu(II) Complexes

The three Schiff base ligands, derivatives of hesperetin, HHSB (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]isonicotinohydrazide), HIN (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]benzhydrazide) and HTSC (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]thiosemicarbazide) and their copper complexes, CuHHSB, CuHIN, and CuHTSC were designed, synthesized and analyzed in terms of their spectral characterization and the genotoxic activity. Their structures were established using several methods: elemental analysis, FT-IR, UV-Vis, EPR, and ESI-MS. Spectral data showed that in the acetate complexes the tested Schiff bases act as neutral tridentate ligand coordinating to the copper ion through two oxygen (or oxygen and sulphur) donor atoms and a nitrogen donor atom. EPR measurements indicate that in solution the complexes keep their structures with the ligands remaining bound to copper(II) in a tridentate fashion with (O^–, N, O_ket) or (O^–, N, S) donor set. The genotoxic activity of the compounds was tested against model tumour (HeLa and Caco-2) and normal (LLC-PK1) cell lines. In HeLa cells the genotoxicity for all tested compounds was noticed, for HHSB and CuHHSB was the highest, for HTSC and CuHTSC–the lowest. Generally, Cu complexes displayed lower genotoxicity to HeLa cells than ligands. In the case of Caco-2 cell line HHSB and HTSC induced the strongest breaks to DNA. On the other side, CuHHSB and CuHTSC induced the highest DNA damage against LLC-PK1.     

Symmetric 1,1'-Dimethylferrocene-Derived Amino Acids: Their Synthesis, Characterization, Ligational and Biological Properties With Cu(II), Co(II) and Ni(II) Ions

Some novel symmetric 1,1'-dimethylferrocene derived amino acids have been prepared by the reaction of 1,1'-ferrocenedimethyldichloride with amino acids (glycine, alanine, phenylalanine and tyrosine). Their Cu(II), Co(II) and Ni(II) complexes, of the type [M(L)] where [M = Cu(II) and L = L(1)-L(5)] and [M(L)Cl(2)] where [M-Co(II)and Ni(II), L = L(1)-L(5)] have been prepared. The dicarboxylic acids and their metal complexes were characterized by their physical, analytical and spectral data. The [M(L)] complexes showed a square planar geometry whereas an octahedral geometry was observed for [M(L)Cl(2)] complexes. The title dicarboxylic acids and their metal complexes have also been screened for their antibacterial activity.     

Synthesis, Ligational and Biological Properties of Cobalt(II), Copper(II), Nickel(II) and Zinc(II) Complexes With Pyrazinedicarboxaimide Derived Furanyl, Thienyl and Pyrrolyl Compounds

Preparation, ligational and biological properties of some pyrazinedicarboxaimide derived furanyl, thienyl and pyrrolyl compounds with Co(ll), Cu(ll), Ni(ll) and Zn(ll) metals are described. Magnetic moments, electronic, infrared, nuclear magnetic resonance spectra and elemental analysis data indicate that co-ordination of the ligands with the metal ions take place through the pyrazine ring nitrogen, azomethine nitrogen and heteroatom of heterocyclic ring system. The compounds are all novel and are proposed to possess an octahedral geometry for Co(ll) and Ni(ll), and a distorted octahedral geometry for Cu(ll) and Zn(ll) complexes. The comparative biological properties of the title ligands and their metal chelates against different bacterial species are also described.     

Structural and Biological Behaviour of Co(II), Cu(II) and Ni(II) Metal Complexes of Some Amino Acid Derived Schiff-Bases

Biologically active tridentate amino acid (Alanine, Glycine & Tyrosine) derived Schiff-bases and their Co(II), Cu(II) & Ni(II) complexes have been synthesised and characterised on the basis of their conductance and magnetic measurements, elemental analysis and (13)C-NMR, (1)H-NMR, IR and electronic spectral data. These Schiff-bases and their complexes have been evaluated for their antibacterial activity against bacterial species such as Staphylococcus aureus, Escherichia coli, Klebsiella pneumonae, Proteus vulgarus and Pseudomonas aeruginosa and this activity data show the metal complexes to be more antibacterial than the Schiff-bases against one or more bacterial species.     

Synthesis, characterization, and properties of polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II)

SUMMARY Polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II) metal ions are synthesized. These compounds are characterized by FT IR, UV-vis spectroscopy, and thermal analysis. The electrical conductivity measurements are carried out. These demonstrate that at temperature close to 130°C the electrical conductivity increased to values near to the semiconductor range. The PM3 calculations are also carried to study the geometry of the polychelates. Received: 1 November 2000/Revised version: 20 March 2001/Accepted: 21 March 2001     

Synthesis,Characterization and Properties of Four 3-D Supramolecular Architectures Assembled by Ni(II), Co(II), Zn(II), Cu(II) and 4-Nitro-1,3-benzenedicarboxylic Acid

Four new complexes M(NO₂–HBDC)₂(H₂O)₄·2H₂O [M = Ni (1), Co (2) and Zn (3)] and [Cu(NO₂–BDC)(H₂O)₃]₂ (4) (NO₂–H₂BDC = 4-nitro-1,3-benzenedicarboxylic acid) were prepared under hydrothermal conditions and were determined by single-crystal X-ray diffraction. X-ray structural analysis reveals that hydrogen bonds among the coordination water molecules and carboxyl oxygen atoms in complexes 1–3 bridge molecules forming an infinite chain, which is further interconnected to form a 3-D framework by a novel infinite 1-D metal–water chain containing the cyclic uudd water tetramer. In complex 4, Two five-coordinated Cu atoms are interlinked by NO₂–BDC ligands and coordinated water molecules to form a 3-D framework via hydrogen bonds and π···π stacking interactions. The elemental analysis, IR spectra, UV–vis and thermogravimetric analysis of complexes 1–4 were examined. The photoluminescence properties of complex 3 and temperature-dependent magnetic susceptibility for complex 4 were also studied.     

Synthesis and Catalytic Activities of Silica-Supported Multifunctional Azo-Containing Schiff Base Complexes with Cu(II), Co(II), Ni(II) and Mn(II)

A novel 4-((5-formyl-2,4-dihydroxyphenyl)diazenyl)benzylphosphonic acid (FPABP) ligand was synthesized and bound to silica-gel which was activated with 3-aminopropyltriethoxysilane (APTES). Cu(II), Co(II), Ni(II) and Mn(II) complexes of silica-supported ligand (FDPDABP) were synthesized. The ligand and its complexes were characterized by using NMR, FT-IR, elemental analysis, ICP-OES and scanning electron Microscope (SEM). Catalytic properties of the complexes were investigated for the selective oxidation of cyclohexane under microwave power. SiO₂-FDPDABP-Cu(II) complex showed good catalytic activitiy for the selective oxidation of cyclohexane to cyclohexanol with 35.61% yield and cyclohexanone with 7.74% yield.     

Polymer-metal complexes: Synthesis, characterization, and properties of poly(maleic acid) metal complexes with Cu(II), Co(II), Ni(II), and Zn(II)

SUMMARY Polymer metal complexes of poly(maleic acid) and Cu(II), Co(II), Ni(II), and Zn(II) were synthesized. Elemental analysis, as well as magnetic, spectral and thermal properties, in addition to electrical conductivities of the chelates were investigated, and possible structures have been assigned to the polychelates. Semi-empirical calculations at the PM3 level were carried out on the geometrical arrangement of the polychelates. Received: 19 November 1999/Revised version: 22 March 2000/Accepted: 31 March 2000     

Conductometric studies of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) tetrafluoroborates in N,N—dimethylacetamide solutions

Results are reported for the molar conductivities at 25°C of N,N—dimethylacetamide (DMA) solutions of Bu₄NBF₄ and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) tetrafluoroborates. The limiting molar conductivities of [M(DMA)₆]²⁺ (M  MN, Co, Ni, Cu, Zn) and BF^?₄, as well as association constants for Co(BF₄)₂ in DMA solutions have been calculated. The slight differences between conductometric curves of different metal ions are discussed.     

Physicochemical studies on square-planar Cu(II), Ni(II) and Co(II) chelate polymers

Chelate polymers of Cu(II), Ni(II) and Co(II) with bis-oxime of 5,5′-methylene bis(salicylaldehyde) have been prepared. The square-planar structure of the complexes was determined on the basis of infrared and electronic spectral measurements in conjunction with magnetic susceptibility measurements. The thermal stability of the chelates, obtained from the TG thermograms has the following order: Co(II) and Ni(II) chelates are found to increase their coordination number by interaction with pyridine at right angles to the plane of the parent molecule. The resulting complex is found to have octahedral structure. The ligand-field and nephelauxetic parameters have been determined from the spectra, using ligand-field theory of spin-allowed transitions which are found consistent with six-coordinate structure for these adducts.     

Synthesis,characterization of poly(allylamine)chelates with Cu(II), Co(II) and Ni(II)

Summary The parent polymer, poly(allylamine) as ligand polymer was employed to synthesize polychelates of heavy metal ions. The functional poly(allylamine) and its Ni(II), Co(II) and Cu(II) metal chelates were characterized by elemental analysis, FT-IR spectroscopy, TGA, and SEM. For the polychelates magnetic and conductivimetry studies were also carried out.     

Synthesis, Crystal Structure, Fluorescence and Thermostability of Ni(II), Zn(II), Cd(II) Complexes with Schiff Base 2-Acetylpyridine-d-tryptophan

Three novel transition metal coordination polymers, [Ni(C₁₈H₁₆N₃O₂)₂·2CH₃OH] _n (1), [Zn(C₁₈H₁₆N₃O₂)₂·4CH₃OH] _n (2) and [Cd(C₁₈H₁₆N₃O₂)₂·2CH₃OH] _n (3) (C₁₈H₁₆N₃O₂=2-acetylpyridine-d-tryptophan) were synthesized and characterized by elemental analysis, IR, UV, ¹H NMR and X-ray diffraction single crystal analysis. The analyses of the structures indicate that all three materials crystallize in the tetragonal crystal system, space group P4₁2₁2. They have similar structures; i.e., the Schiff base coordinates in its deprotonated form and behaves as a hexadentate (4N+2O) coordinated ligand to form a distorted octahedron geometry. On the other hand, as a result of the alternate arrangement of chains through N–H···O intermolecular hydrogen bonds interactions, 2-D layers are formed for the three complexes. Furthermore, the luminescent properties and thermal stabilities of the three complexes were investigated.     

Adsorption of Cr(III), Ni(II), Zn(II), Co(II) ions onto phenolated wood resin

In this study, phenolated wood resin was used an adsorbent for the removal of Cr(III), Ni(II), Zn(II), Co(II) ions by adsorption from aqueous solution. The adsorption of metal ions from solution was carried at different contact times, concentrations and pHs at room temperature (25°C). For individual metal ion, the amount of metal ions adsorbed per unit weight of phenolated wood resin at equilibrium time increased with increasing concentration and pH. Also, when the amounts of metal ions adsorbed are compared to each other, it was seen that this increase was order of Cr(III) > Ni(II) > Zn(II) > Co(II). This increase was order of Cr(III) > Ni(II) > Co(II) > Zn(II) for commercial phenol–formaldehyde resin. Kinetic studies showed that the adsorption process obeyed the intraparticle diffusion model. It was also determined that adsorption isotherm followed Langmuir and Freundlich models. Adsorption isotherm obtained for commercial phenol–formaldehyde resin was consistent with Freundlich model well. Adsorption capacities from Langmuir isotherm for commercial phenol–formaldehyde resin were higher than those of phenolated wood resin, in the case of individual metal ions. Original adsorption isotherm demonstrated the monolayer coverage of the surface of phenolated wood resin. Adsorption kinetic followed the intraparticle diffusion model. The positive values of ΔG° determined using the equilibrium constants showed that the adsorption was not of spontaneous nature. It was seen that values of distribution coefficient (K_D) decreasing with metal ion concentration in solution at equilibrium (C_e) indicated that the occupation of active surface sites of adsorbent increased with metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2838–2846, 2006     

Protolytic and complexing properties of microcrystalline chitosan with Co(II), Zn(II), and Cu(II) ions

It has been evidenced that microcrystalline chitosan (MCCh) with a determined (by the potentiometric method in nonaqueous medium) degree of deacetylation of 0.87 acts as a polymeric chelating agent with cobalt(II) and zinc(II). The predomination of hydrolytic reactions, in the case of copper(II) ions, has been attributed to a change in crystalline character of the ligand. The protolytic reactions have been studied using the Katchalsky–Spitnik equation. The pH profiles have been shown for Co(II)–MCCh and Zn(II)–MCCh systems and the corresponding equilibrium constants have been determined as well. Both the amino and hydroxyl groups are involved in Co²⁺ complexation, whereas for Zn²⁺, the complexes are formed only via amino nitrogen. © 1995 John Wiley & Sons, Inc.     

Biologically Active Transition Metal Chelates of Ni(II), Cu(II) and Zn(II) With 2-Aminothiazole-Derived Schiff-bases: Their Synthesis, Characterization and the Role of Anions (NO(3), SO(4), C(2)O(4)and CH(3)CO(2-)) on Their Antibacterial Properties

Biologically active nickel(ll), copper(ll) and zinc(ll) chelates with thiazole-derived nitro- and chlorosalicylaldehyde Schiff-bases having the same metal ion but different anions, e.g. nitrate, sulfate, oxalate and acetate have been synthesized and characterized on the basis of their physical, spectral and analytical data. In order to evaluate the possible participating role of anions on the antibacterial properties, these ligands and their synthesized metal chelates with various anions have been screened against bacterial species Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus.     

Polychelates of poly(acrylic acid-co-acrylamide)with Cu(II), Co(II), and Ni(II) Synthesis and properties

SUMMARY Polychelates were obtained by addition of an aqueous solution of the poly(acrylic acid-co-acrylamide) to an aqueous solution of Cu(II), Co(II), and Ni(II). All the polychelates were insoluble in water and in common organic solvents. The polychelates were characterized by elemental analysis, FT-IR spectroscopy thermogravimetry, and showed tetrahedral arrangement for Co(II) and Ni(II). Magnetic and conductivity studies for all the polychelates were also carried out. The poly(acrylic acid-co-acrylamide) behaved as semiconductor. Received: 25 July 1997/Revised version: 1 December 1997/Accepted: 5 December 1997