1-Hydrazinophthalazine based hydrazones and their transition metal complexes: Structure and biological activity

Structure, tautomeric rearrangements, acid-base properties and complex formation ability of 1-hydrazinophthalazine hydrazones and their coordination compounds with transition metals are considered. The main factors influencing the structure and physicochemical properties of the complexes, biological activity of phthalazine hydrazones and their complexes are discussed.     

Synthesis,characterization and biological activity of triaminoxime and its metal complexes

Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of multifunctional triaminoxime have been synthesized and characterized by elemental analyses, IR, UV–Vis spectra, magnetic moments, ¹H- and ¹³C-NMR spectra for ligand and its Ni(II) complex, mass spectra, molar conductances, thermal analyses (DTA, DTG and TG) and ESR measurements. The IR spectral data show that the ligand is bi-basic or tri-basic tetradentate towards the metals. Molar conductances in DMF indicate that the complexes are non-electrolytes. The ESR spectra of solid copper(II) complexes [(HL)(Cu)₂(Cl)₂] · 2H₂O (2) and [(L)(Cu)₃(OH)₃(H₂O)₆] · 7H₂O (6) show axial symmetry of a d _{x²???y ²} ground state; however, [(HL)(Co)] (4) shows an axial type with d _Z ² ground state and manganese(II) complex [(L)(Mn)₃(OH)₃(H₂O)6] · 4H₂O (10) shows an isotropic type. The biological activity of the ligand and its metal complexes are discussed.     

Synthesis,characterization of Schiff base metal complexes and their biological investigation

A new Schiff base ligand named (E)‐2‐(((3‐aminophenyl)imino)methyl)phenol (HL) was prepared through condensation reaction of m‐phenylenediamine and 2‐hydroxybenzaldehyde in 1:1 molar ratio. The new ligand was characterized by elemental analysis and spectral techniques. The coordination behavior of a series of transition metal ions named Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) with the newly prepared Schiff base ligand (HL) is reported. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, IR, UV–Vis, ¹H NMR, mass, electronic spectra, magnetic susceptibility and conductivity measurements and further their thermal stability was confirmed by thermogravimetric analysis (TG). From IR spectra, it was observed that the ligand is a neutral tridentate ligand coordinates to the metal ions through protonated phenolic oxygen, azomethine nitrogen and nitrogen atom of NH₂ group. The existence, the number and the position of the water molecules was studied by thermal analysis. The molecular structures of the Schiff base ligand (HL) and its metal complexes were optimized theoretically and the quantum chemical parameters were calculated. The synthesized ligand and its complexes were screened for antimicrobial activities against bacterial species (Staphylococcus aureus and Bacillis subtilis, (gram positive bacteria)), (Salmonella SP., Escherichia coli and Pseudomonas aeruginosa, (gram negative bacteria)) and fungi (Aspergillus fumigatus and Candida albicans). The complexes were found to possess high biological activities against different organisms. Molecular docking was used to predict the efficiency of binding between Schiff base ligand (HL) and both receptors of Escherichia coli (3 T88) and Staphylococcus aureus (3Q8U). The receptor of Escherichia coli (3 T88) showed best interaction with Schiff base ligand (HL) compared to receptor of Staphylococcus aureu (3Q8U).     

Synthesis,characterization, and biological activity of metal complexes of azohydrazone ligand

A new azohydrazone, 2-hydroxy-N′-2-hydroxy-5-(phenyldiazenyl)benzohydrazide (H₃L) and its copper(II), nickel(II), cobalt(II), manganese(II), zinc(II), cadmium(II), mercury(II), vanadyl(II), uranyl(II), iron(III), and ruthenium(III) complexes have been prepared and characterized by elemental and thermal analyses as well as spectroscopic techniques (¹H-NMR, IR, UV-Vis, ESR), magnetic, and conductivity measurements. Spectral data showed a neutral bidentate, monobasic bidentate, monobasic tridentate, and dibasic tridentate bonding to metal ions via the carbonyl oxygen in ketonic or enolic form, azomethine nitrogen, and/or deprotonated phenolic hydroxyl oxygen. ESR spectra of solid vanadyl(II) complex (2), copper(II) complexes (3–5), and (7) and manganese(II) complex (10) at room temperature show isotropic spectra, while copper(II) complex (6) shows axial symmetry with covalent character. Biological results show that the ligand is biologically inactive but the complexes exhibit mild effect on Gram positive bacteria (Bacillus subtilis), some octahedral complexes exhibit moderate effect on Gram negative bacteria (Escherichia coli), and VO(II), Cd(II), UO(II), and Hg(II) complexes show higher effect on Fungus (Aspergillus niger). When compared to previous results, metal complexes of this hydrazone have a mild effect on microorganisms due to the presence of the azo group.     

Synthesis,characterization and biological properties of sulfonamide‐derived compounds and their transition metal complexes

Sulfonamide‐derived compounds and their first row d‐transition metal chelates [cobalt(II), copper(II), nickel(II) and zinc(II)] have been synthesized and characterized. The nature of bonding and structure of all the synthesized compounds have been proposed from magnetic susceptibility and conductivity measurements, IR, ¹H and ¹³C NMR, electron spectra, mass spectrometry and CHN analysis data. The structure of ligand, 4‐{[(E)‐(5‐chloro‐2‐hydroxyphenyl) methylidene] amino}‐N‐(4,6‐dimethyl pyrimidin‐2‐yl) benzene sulfonamide has also been determined by X‐ray diffraction method. An octahedral geometry has been suggested for all the complexes. The ligands and metal complexes have been screened for their in vitro antibacterial, antifungal and cytotoxic activity. The results of these studies revealed that all compounds showed moderate to significant antibacterial activity against one or more bacterial strains and good antifungal activity against various fungal strains. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,characterization, and biological evaluation of new polyester containing Schiff base metal complexes

The production of new biocidal polyester Schiff base metal complexes [PESB–M(II)] via polycondensation reaction between chelated Schiff base diol and adipoyl chloride is reported. The resulting polyesters were characterized by physico-chemical and spectroscopic methods. The analytical data of all the synthesized polyesters were found to be in good agreement with 1:1 molar ratio of chelated Schiff base diol to adipoyl chloride. Thermogravimetric analyses of synthesized polyesters were studied by TG in nitrogen atmosphere up to 1073 K and results indicate that Cu(II) polyester complex exhibited better heat resistant properties than the other polyesters complexes. Magnetic moment and UV–visible spectra were examined to explain the structure of all the polyesters which reveled that Mn(II), Co(II), Ni(II) have octahedral geometry while Cu(II) possess a distorted octahedral geometry. These newly developed polyesters were also tested for their antibacterial activity against several bacteria and fungi. Among all the tested compounds PESB–Cu(II) possess the highest bactericidal and fungicidal activity.     

Synthesis, characterization and biological activity of bis(phenylimine) Schiff base ligands and their metal complexes

Metal complexes derived from 2,6-pyridinedicarboxaldehydebis(p-hydroxyphenylimine); L1, 2,6-pyridinedicarboxaldehydebis (o-hydroxyphenylimine); L2, are reported and characterized based on elemental analyses, IR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The complexes are found to have the formulae [MX2(L1 or L2)] x nH2O, where M=Fe(II), Co(II), Ni(II), Cu(II) and Zn(II), X=Cl in case of Fe(II), Co(II), Ni(II), Cu(II) complexes and Br in case of Zn(II) complexes and n=0-2.5. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the Schiff bases are coordinated to the metal ions in a terdentate manner with NNN donor sites of the pyridine-N and two azomethine-N. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are trigonal bipyramidal (in case of Co(II), Ni(II), Cu(II) and Zn(II) complexes) and octahedral (in case of Fe(II) complexes). 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 coordinated water, anions and ligands (L1 and L2) in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the TG 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 aureus and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent organic ligands against one or more bacterial species.     

Synthesis, characterization and properties of some divalent metal(II) complexes: their electrochemical, catalytic, thermal and antimicrobial activity studies

In this study, we synthesized the amine compound 2-(2-aminoethyliminomethyl)phenol (H(3)A) as the starting material, and then we prepared the polydentate Schiff base ligands from the reactions of the amine compound (H(3)A) with phtaldialdehyde (H(2)L), 4-methyl-2,6-di-formlyphenol (H(3)L(1)) and 4-t-butyl-2,6-di-formylphenol (H(3)L(2)) in the ethanol solution. Moreover, the complexes Cd(II), Cu(II), Co(II), Ni(II), Zn(II) and Sn(II) of the ligands H(2)L, H(3)L(1) and H(3)L(2) have been prepared. All compounds have been characterized by the analytical and spectroscopic methods. In addition, the magnetic susceptibility and molar conductance measurements have been made. The catalytic properties of the mono- and binuclear Co(II) and Cu(II) complexes have been studied on the 3,5-di-tert-butylcatechol (3,5-DTBC) and ascorbic acid (aa) as a substrate. The oxidative C-C coupling properties of the Co(II) and Cu(II) complexes have been investigated on the sterically hindered 2,6-di-tert-butylphenol (dtbp). The antimicrobial activity properties of the ligands and their mono- and binuclear complexes have been studied against the bacteria and fungi. The results have been compared to the antibacterial and fungi drugs. The TGA curves show that the decomposition takes place in three steps for all complexes. Electrochemical properties of the complexes Cu(II) and Ni(II) have been investigated for the first time in acetonitrile by cyclic voltammetry.     

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

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*, ΔH*, ΔS* and ΔG* 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.     

Novel methacrylate copolymers with fluorine containing: Synthesis, characterization, reactivity ratios, thermal properties and biological activity

New methacrylate based monomers 2-(4-benzoylphenoxy)-2-oxoethyl-2-methylacrylate (BOEMA), 2-(4-acetylphenoxy)-2-oxoethyl-2-methylacrylate (AOEMA), and 2-[(4-fluorophenyl)amino]-2-oxoethyl-2-methylacrylate (FPAMA), were synthesized first time. The free-radical-initiated copolymerization of AOEMA and BOEMA with FPAMA were carried out in 1,4-dioxane solution at 65 °C using 2,2′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The monomers and copolymers were characterized by FTIR, ¹H NMR and ¹³C NMR spectral studies. The copolymer compositions were evaluated by nitrogen content in polymers. The reactivity ratios of the monomers were determined by the application of Fineman-Ross and Kelen-Tudos methods. The analysis of reactivity ratios revealed that BOEMA and AOEMA are less reactive than FPAMA, and copolymers formed are statistically in nature. The molecular weights ( and ) and polydispersity index of the polymers were determined using gel permeation chromatography. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increase in the mole fraction of FPAMA in the copolymers. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of FPAMA in the copolymers. The prepared homo and copolymers were tested for their antimicrobial activity against bacteria, fungi and yeast.     

Synthesis,characterization, thermal,and redox properties of a vic-dioxime and its metal complexes

A new vic-dioxime ligand containing benzophenone hydrazone units, N′-(benzophenone hydrazone)glyoxime [LH₂] has been prepared from benzophenone hydrazone and anti-chloroglyoxime in absolute ethanol. Mononuclear nickel(II), cobalt(II), copper(II), zinc(II), and cadmium(II) complexes were also synthesized. Ligand and complexes were characterized by elemental analyses, FT-IR, ¹H NMR, and ¹³C NMR spectroscopy, magnetic moments, and DTA/TG techniques. On the basis of the magnetic and spectral evidences a square-planar geometry for Ni(II) and Cu(II) complexes, tetrahedral for Cd(II) and Zn(II) complexes, and octahedral for Co(II) complex were proposed. Redox behaviors of ligand and its complexes were also investigated by cyclic voltammetry at the glassy carbon electrode.     

Synthesis and biological activity of metal chitosan complexes

A series of complexes of chitosans of various molecular weights (3000–150000) with copper, iron(II), and zinc sulfates were examined. Participation of amino groups of the polymer in coordination bonding with the metal was proved by IR spectroscopy. The affinity of chitosan for iron ions was enhanced by introducing phenolic fragments into the polymer.     

Synthesis, characterization and thermal properties of metal-containing polyurethane-ureas from hexadentate Schiff base metal complexes

Metal-containing polyurethane-ureas and copolyurethane-ureas have been synthesized by the reaction between hexadentate Schiff base metal complexes and isocyanate-terminated prepolymers. The metal complexes employed were MSal₂trien, where (M=Ni and Zn, Sal=salicylaldehyde and trien=triethylenetetramine). The NCO-terminated prepolymers used were tolylene 2,4-diisocyanate terminated poly(1,4-butanediol) (PB), tolylene 2,4-diisocyanate terminated poly(propylene glycol) (PP) prepolymers and the prepolymers synthesized from 4,4^′-diphenylmethane diisocyanate (MDI) and diols. The diols employed were polycaprolactone diol (PCL) and poly(tetramethylene oxide) (PTMO). Copolyurethane-ureas were synthesized by the reaction between MSal₂trien, PB or PP prepolymers and MDI. Characterizations of polymers were carried out using IR spectroscopy, elemental analysis, solubility and viscosity. Flammability of polymers was investigated by measuring limiting oxygen index (LOI) values and thermal stability was studied by thermogravimetric analysis (TGA).     

Synthesis, spectroscopic, thermal characterization, and antimicrobial activity of miconazole drug and its metal complexes

Metal complexes having the general composition [MCl₂(H₂O)₂(L)₂]·yH₂O (where y?=?1?C3, M?=?Mn(II), Cu(II), Co(II), Ni(II), and Zn(II) and L?=?miconazole drug?=?MCNZ) and [MCl₂(H₂O)₂(L)₂]Cl·3H₂O (where M?=?Cr(III) and Fe(III)) have been synthesized. All the synthesized complexes were identified and confirmed by elemental analyses, IR, diffused reflectance, and thermal analyses (TG and DTA) techniques as well as molar conductivity and magnetic moment measurements. The molar conductance data reveals that bivalent metal complexes are non-electrolytes while Cr(III) and Fe(III) complexes are electrolytes and of 1:1 type. IR spectral studies reveal that MCNZ is coordinated to the metal ions in a neutral unidentate manner with N donor site of the imidazole-N. On the basis of magnetic and solid reflectance spectral studies, an octahedral geometry has been assigned for the complexes. Detailed studies of the thermal properties of the complexes were investigated by thermogravimetry (TG) and differential thermal analyses (DTA) techniques and the activation thermodynamic parameters are calculated using Coats?CRedfern method. The free MCNZ drug and its complexes were also evaluated against bacterial species (P. aeruginosa, S. aureus, B. subtilis, E. Coli) and fungi (A. fumigatus, P. italicum, and C. albicans) in vitro. The activity data show that the metal complexes have higher biological activity than the parent MCNZ drug.     

Synthesis and characterization of norfloxacin-transition metal complexes (group 11, IB): spectroscopic, thermal, kinetic measurements and biological activity

The investigation of the new structures of Ag(I), Cu(II) and Au(III) complexes, [Ag(2)(Nor)(2)](NO(3))(2), [Cu(Nor)(2)(H(2)O)(2)]SO(4).5H(2)O and [Au(Nor)(2) (H(2)O)(2)]Cl(3) (where, Nor=norfloxacin) was done during the reaction of silver(I), copper(II) and gold(III) ions with norfloxacin drug ligand. Elemental analysis of CHN, infrared, electronic, (1)H NMR and mass spectra, as well as thermo gravimetric analysis (TG and DTG) and conductivity measurements have been used to characterize the isolated complexes. The powder XRD studies confirm the amorphous nature of the complexes. The norfloxacin ligand is coordinated to Ag(I) and Au(III) ions as a neutral monodentate chelating through the N atom of piperidyl ring, but the copper(II) complex is coordinated through the carbonyl oxygen atom (quinolone group) and the oxygen atom of the carboxylic group. The norfloxacin and their metal complexes have been biologically tested, which resulted in norfloxacin complexes showing moderate activity against the gram positive and gram negative bacteria as well as against fungi.     

Synthesis,characterization and biological applications of new copper(II) complexes of aryl hydrazones

On treatment of copper(II) acetate with aryl hydrazone ligands, four new solid derivatives of copper(II) were produced in appreciable yields. Various characterization techniques including infrared, UV–visible, NMR, electron paramagnetic resonance and mass spectroscopies, elemental analysis, scanning electron microscopy, powder X‐ray diffraction and thermogravimetric analysis revealed a tetra‐coordination in all the mononuclear crystalline complexes with high thermal stability. Further, significant interaction of these novel complexes with calf thymus DNA via intercalative mode of binding was revealed by electronic absorption spectroscopy. The chemical nuclease activity of the complexes on pBR322 DNA was investigated in the presence and absence of oxidizing agent (H₂O₂). A potent nuclease activity was observed only in the presence of H₂O₂. Further, antibacterial and antifungal studies of the new ligands and complexes revealed that the latter possessed comparatively better activity.     

Synthesis, characterization and biological activity of ternary copper(II) complexes containing polypyridyl ligands

Ternary copper(II) complexes involving polypyridyl ligands in the coordination sphere of composition [Cu(tpy)(phen)](ClO4)2 (1), [Cu(tpy)(bipy)](ClO4)2 (2), [Cu(tptz)(phen)](ClO4)2 (3) and [Cu(tptz)(bipy)](BF4)2 (4) where tpy = 2,2':6',2'-terpyridine, tptz = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine have been synthesized and characterized by elemental analysis, magnetic susceptibility, X-band e.p.r. spectroscopy and electronic spectroscopy. Single crystal X-ray of (1) has revealed the presence of a distorted square pyramidal geometry in the complex. Magnetic susceptibility measurements at room temperature were in the range of 1.77-1.81 BM. SOD and antimicrobial activities of these complexes were also measured. Crystal data of (1): P-1, a = 9.3010(7) A, b = 9.7900(6) A, c = 16.4620(6) A, Vc = 1342.73(14) A3, Z = 4. The bond distance of CuN in square base is 2+/-0.04 A.     

Synthesis,characterization and biological studies of ferrocenyl complexes containing thiophene moiety

A new ferrocenyl ligand was prepared from the condensation of 1,1′‐diacetylferrocene dihydrazone with 2‐thiophenealdehyde. The ligand, 1,1′‐bis[(2‐thienylmethylidene)hydrazono‐1‐ethyl]ferrocene, forms 1:1 complexes with cobalt(II), nickel(II), copper(II) and zinc(II) in good yield. Characterization of the ligand and complexes was carried out using IR, ¹H NMR, electronic absorption and elemental analysis. Biological activity of the ligand and its complexes was assessed against Bacillus subtilis (+ve), Staphylococcus aureus (+ve), Candida albicans (yeast), Esherichia coli (?ve), Salmonella typhi (?ve), Aspergillus niger (fungi), and Fusarium solani (fungi). The biological results indicated that the complexes prepared are more active than the ligand. Copyright © 2005 John Wiley & Sons, Ltd.