Phenoxo-bridged symmetrical homobinuclear complexes derived from an “end-off” compartmental ligand, 2,6- bis [5′-chloro-3′-phenyl- 1H -indole-2′-carboxamidyliminomethyl]-4-methylphenol

A compartment ligand 2,6-bis[5′-chloro-3′-phenyl-1H-indole-2′-carboxamidyliminomethyl]-4-methylphenol was prepared and homobinuclear phenol-bridged Cu(II), Ni(II), Co(II), Zn(II), Cd(II), Hg(II), Fe(III), and Mn(II) complexes have been prepared by the template method using the precursors 2,6-diformyl-4-methylphenol, 5-chloro-3-phenylindole-2-carbohydrazide and metal chlorides in 1 : 2 : 2 ratio, respectively. The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility data, IR, NMR, FAB mass and ESR spectra, TGA, and powder XRD data. Cu(II), Co(II), Zn(II), Cd(II) and Hg(II) complexes exhibit square pyramidal geometry whereas Ni(II), Mn(II), and Fe(III) complexes are octahedral. Low magnetic moment values for Cu(II), Ni(II), Co(II), Fe(III), and Mn(II) complexes show antiferromagnetic spin-exchange interaction between two metal centers in binuclear complexes. The ligand and its complexes were tested for antibacterial activity against Escherichia coli and Staphyloccocus aureus, and antifungal activity against Aspergillus niger and Candida albicans.     

Template synthesis and spectral characterization of some Schiff base complexes derived from quinoxaline-2-carboxaldehyde and L-histidine

New Schiff base complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) were synthesized by template condensation of quinoxaline-2-carboxaldehyde, L-histidine, and the metal compound, and were characterized by elemental analysis, fourier transform infrared spectroscopy, electronic spectra, conductance measurements, magnetic susceptibility measurements, ESR spectra, and thermal analysis. In all the complexes, the Schiff base coordinates through azomethine nitrogen, quinoxaline nitrogen, and carboxylato oxygen. The physicochemical and spectroscopic measurements reveal square planar geometry for the copper(II) complex, tetrahedral geometry for the manganese(II), cobalt(II), and zinc(II) complexes, and octahedral geometry for the iron(III) and nickel(II) complexes.     

Synthesis,characterization and antimicrobial activity of homodinuclear complexes derived from 2,6- bis [3′-methyl- 2′-carboxamidyliminomethyl(6′,7′)benzindole]-4-methylphenol,an end-off compartmental ligand

End-off compartmental pentadentate Schiff base, 2,6-bis[3′-methyl-2′-carboxamidyliminomethyl(6′,7′)benzindole]-4-methylphenol is synthesized and characterized by 2D NMR experiments and mass spectral techniques. The homodinuclear phenalato bridged end-off compartmental Schiff-base complexes Cu(II), Co(II), Ni(II), Mn(II), Fe(III), VO(IV), Zn(II), Cd(II) and Hg(II) have been prepared by the template method using the precursors 2,6-diformyl-4-methylphenol, 3-methyl(6′,7′)-2-benzindolehydrazide and metal chlorides in 1?:?2?:?2 ratio. The complexes are characterized by IR, NMR, UV-vis, FAB-mass, ESR and TGA techniques. Ni(II), Mn(II) and Fe(III) complexes have octahedral geometry, whereas the Cu(II), Co(II), VO(IV), Zn(II), Cd(II) and Hg(II) complexes have square pyramidal geometry. Low magnetic moment values for Cu(II), Co(II), Ni(II), Mn(II), Fe(III) and VO(IV) complexes indicate antiferromagnetic spin-exchange interaction between two metal centers. The metal complexes have been screened for their antibacterial activity against Escherichia coli and Staphyloccocus aureus and antifungal activity against Aspergillus niger and Fusarium oxysporum.     

Synthesis,Spectroscopic and Magnetic Studies on Metal Complexes of 5-Methyl-3-(2-Hydroxyphenyl)Pyrazole

A tridentate ONN donor ligand, 5-methyl-3-(2-hydroxyphenyl)pyrazole; H₂L, was synthesized by reaction of 2-(3-ketobutanoyl)phenol with hydrazine hydrate. The ligand was characterized by IR, ¹H NMR and mass spectra. ¹H NMR spectra indicated the presence of the phenolic OH group and the imine NH group of the heterocyclic moiety. Different types of mononuclear metal complexes of the following formulae [(HL)₂M][sdot]xH₂O (M=VO, Co, Ni, Cu, Zn and Cd), [(HL)₂M(H₂O)₂] (M=Mn and UO₂) and [(HL)LFe(H₂O)₂] were obtained. The Fe(III) complex, [(HL)LFe(H₂O)₂] undergoes solvatochromism. Elemental analyses, IR, electronic and ESR spectra as well as thermal, conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. A square-pyramidal geometry is suggested for the VO(IV) complex, square-planar for the Cu(II), Co(II) and Ni(II) complexes, octahedral for the Fe(III) and Mn(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes, while the UO₂(VI) complex is eight-coordinate. Transmetallation of the UO₂(VI) ion in its mononuclear complex by Fe(III), Ni(II) or Cu(II) ions occurred and mononuclear Fe(III), Ni(II) and Cu(II) complexes were obtained. IR spectra of the products did not have the characteristic UO₂ absorption band and the electronic spectra showed absorption bands similar to those obtained for the corresponding mononuclear complexes. Also, transmetallation of the Ni(II) ion in its mononuclear complex by Fe(III) has occurred. The antifungal activity of the ligand and the mononuclear complexes were investigated.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Transition metal complexes of a Schiff base: synthesis,characterization, and antibacterial studies

Synthesis of a new Schiff base derived from 2-hydroxy-5-methylacetophenone and glycine and its coordination with compounds Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and UO₂(VI) are described. The ligand and complexes have been characterized on the basis of analytical, electrical conductance, infrared, ESR and electronic spectra, magnetic susceptibility measurements, and thermogravimetric analysis. The ligand is a dibasic tridentate (ONO) donor in all the complexes except Zn(II), where it is a monobasic bidentate (OO) donor. The solid state DC electrical conductivity of ligand and its complexes have been measured over 313–398 K, and the complexes were semiconducting. Antibacterial activities of ligand and its metal complexes have been determined by screening the compounds against various Gram (+) and Gram (?) bacterial strains.     

Potentiometric, spectroscopic and thermal studies on the metal chelates of 1-(2-thiazolylazo)-2-naphthalenol

The synthesis and characterization of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pd(II) and UO2(II) chelates of 1-(2-thiazolylazo)-2-naphthalenol (TAN) were reported. The dissociation constants of the ligand and the stability constants of the metal complexes were calculated pH-metrically at 25 degrees C and 0.1 M ionic strength. The solid complexes were characterized by elemental and thermal analyses, molar conductance, IR, magnetic and diffuse reflectance spectra. The complexes were found to have the formulae [M(L)2] for M = Mn(II), Co(II), Ni(II), Zn(II) and Cd(II); [M(L)X].nH2O for M = Cu(II) (X = AcO, n = 3), Pd(II) (X = Cl, n = 0) and UO2(II) (X = NO3, n = 0), and [Fe(L)Cl2(H2O)].2H2O. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the ligand is coordinated to the metal ions in a terdentate manner with ONN donor sites of the naphthyl OH, azo N and thiazole N. An octahedral structure is proposed for Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II) and UO2(II) complexes and a square planar structure for Cu(II) and Pd(II) complexes. The thermal behaviour of these chelates shows that water molecules (coordinated and hydrated) and anions are removed in two successive steps followed immediately by decomposition of the ligand molecule in the subsequent steps. The relative thermal stability of the chelates is evaluated. The final decomposition products are found to be the corresponding metal oxides. The thermodynamic activation parameters, such as E*, delta H*, delta S* and delta G* are calculated from the TG curves.     

Synthesis, Thermal, Electrical and Catalytic Studies of Some Transition Metal Polychelates of Bis-bidentate Schiff Base

Polychelates of Mn（Ⅱ）, Fe（Ⅱ）, Co（Ⅱ）, Ni（Ⅱ）, Cu（Ⅱ）, Zn（Ⅱ） and Cd（Ⅱ） with the bis salen-type ligand derived from 4,4＇-bis[（salicylaldehyde-5）azo]biphenyl and 1,4-diaminobutane have been synthesized. All the polychelalls have been characllrized by elemental analysis, magnetic susceptibility measurements, IR, electronic spectra and thennogravirncuic studies. All the complexes isolated in solid stall are dark coloured and insoluble in water and common organic solvents. The ligand behaves as a bis-bidentall molecule coordinating through the phenolic oxygen and azomethine nitrogen atoms. The thermal decomposition of these metal complexes was investigated by thermogravimetric analysis and data have been analyzed for kinetic parameters using Broido equation. The solid-state electrical conductivity of the ligand and its polychelalls in the form of compressed pellet was studied in the temperaturc range from 313 to 413 K All the polychelalls were found to show semiconducting nature. The Mn（Ⅱ）, Fe（Ⅱ）, Co（Ⅱ） and Ni（Ⅱ） polychelalls have been assessed for the catalytic epoxidation of styrene.     

Asymmetric Schiff Base (N 2 O 3 ) Complexes as Ligands Towards Mn(II), Fe(III) and Co(II), Synthesis and Characterization

Heterobi- and tri-nuclear complexes [LMM'Cl] and [(LM) 2 M'](M=Ni or Cu and M'=Mn, Fe or Co) have been synthesised. The heteronuclear complexes were prepared by stepwise reactions using two mononuclear Ni(II) and Cu(II) complexes of the general formula [HLM]·1/2H 2 O, as ligands towards the metal ions, Mn(II), Fe(III) and Co(II). The asymmetrical pentadentate (N 2 O 3 ) Schiff-base ligands used were prepared by condensing acetoacetylphenol and ethylenediamine, molar ratio 1 1, to yield a half-unit compound which was further condensed with either salicylaldehyde or naphthaldehyde to yield the ligands H 3 L 1 and H 3 L 2 which possess two dissimilar coordination sites, an inner four-coordinate N 2 O 2 donor set and an outer three-coordinated O 2 O set. 1 H NMR and IR spectra indicate that the Ni(II) and Cu(II) ions are bonded to the inner N 2 O 2 sites of the ligands leaving their outer O 2 O sites vacant for further coordination. Different types of products were obtained according to the type of metal ion. These products differ in stoichiometry according to the type of ligand in the parent compound. Electronic spectra and magnetic moments indicate that the structures of the parent Ni(II) and Cu(II) complexes are square-planar while the geometry around Fe(III), Mn(II) and Co(II) in their products are octahedral as elucidated from IR, UV-visible, ESR, 1 H NMR, mass spectrometry and magnetic moments.     

Synthesis and characterization of mixed ligand complexes of copper(II), nickel(II), cobalt(II) and zinc(II) with glycine and uracil or 2-thiouracil

Mixed ligand complexes of Cu(II), Ni(II), Co(II) and Zn(II) formed with glycine and uracil or 2-thiouracil have been synthesized and characterized by elemental analysis, conductance, spectral (IR and electronic spectra) and magnetochemical measurements. Results show that glycine is bidentate in all cases; uracil behaves as a bidentate ligand in Cu(II) complex, coordinating through its one carbonyl oxygen and nitrogen, whereas in other cases it is only monodentate, coordinating only through nitrogen. With thiouracil, coordination occurs from carbonyl oxygen and one nitrogen in Cu(II) and Ni(II) complexes, but in the Co(II) complex coordination occurs from thionyl sulphur and nitrogen. In the Zn(II) complex it shows tridentate behaviour, coordinating through oxygen, sulphur and one nitrogen. Mixed Cu(II), Co(II) and Zn(II) complexes of uracil and of Ni(II) and Zn(II) with thiouracil are octahedral, whereas the mixed Ni(II) complex with uracil shows distorted tetrahedral geometry, and the mixed Co(II)-thiouracil complex is square planar. The mixed Cu(II)-thiouracil complex has a binuclear structure, with square planar arrangement around each copper atom.     

Elaborated spectral,modeling, QSAR,docking, thermal,antimicrobial and anticancer activity studies for new nanosized metal ion complexes derived from sulfamerazine azodye

New azodye ligand (H₂L) and its relative Cr(III)-, Mn(II)-, Fe(III)-, Co(II)-, Ni(II)-, Cu(II)-, Zn(II)- and Cd(II)-nanosized complexes were prepared. A new synthesized compounds were characterized using spectral (mass, IR, UV–Vis, XRD, and ESR) and analytical (elemental, molar conductance, thermal and magnetic moment measurements) tools. Infrared spectra showed that the ligand behaves as a monobasic bidentate, coordinating with central atoms through carbonyl oxygen and α-hydroxyl group. The geometrical structures of Cr(III) and Fe(III) complexes were found to be in octahedral configuration, whereas Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes have tetrahedral forms. XRD patterns reflect an amorphous appearance of all investigated complexes. TEM images showed nanosized particles and identical distribution over the complex surface. Molecular modeling for the drug ligand and its metal ion complexes were performed using Gaussian09 program to assert on their structural formulae. Some essential parameters were extracted using HOMO and LUMO energies. AutoDock tools 4.2 was used to simulate the interaction process with infected cell proteins to expect the experimental pathway. The inhibition activity of drug ligand and its metal ion complexes was evaluated towards different types of bacteria and fungi through in vitro antimicrobial activities. The antitumor activities of all compounds are straightened towards human liver carcinoma (HEPG2) cell lines. Fe(III) and Co(II) complexes exhibited IC₅₀ of 2.90 and 4.23 µg mL^?1, respectively, which means they are more potent anticancer drug than the standard (doxorubicin, IC₅₀ = 4.73 µg mL^?1). Therefore, the two complexes may consider promising anticancer drugs.

     

Organic acid solutions in the chromatography of inorganic ions VIII. Cation-exchange of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media

Summary The cation-exchange behaviour of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media at various concentrations and pH, was studied with Dowex 50 WX8 resin (200–400 mesh) in the ammonium form. Separation of Fe(III)/Cu(II), Fe(III)/Cu(II)/Zn(II), Fe(III)/Co(II)/Mn(II), Cu(II)/Ni(II)/Mn(II), Fe(III)/Cu(II)/Co(II)/Mn(II), Fe(III)/Cu(II)/Ni(II)/Cd(II), Yb(III)/Eu(III), Sc(III)/Y(III),Sc(III)/Yb(III)/Dy(III) and Nb(V)/Yb(III)/Ho(III) has been achieved, among others.This work was supported by C.N.R. of Italy.     

Coordination "oligomers" in self-assembly reactions of some "tritopic" picolinic dihydrazone ligands-mononuclear, dinuclear, hexanuclear, heptanuclear, and nonanuclear examples

"Tritopic" picolinic dihydrazone ligands with tridentate coordination pockets are designed to produce homoleptic [3 x 3] nonanuclear square grid complexes on reaction with transition-metal salts, and many structurally documented examples have been obtained with Mn(II), Cu(II), and Zn(II) ions. However, other oligomeric complexes with smaller nuclearities have also been discovered and identified structurally in some reactions involving Fe(II), Co(II), Ni(II), and Cu(II), with certain tritopic ligands. This illustrates the dynamic nature of the metal-ligand interaction and the conformationally flexible nature of the ligands and points to the possible involvement of some of these species as intermediates in the [3 x 3] grid formation process. Examples of mononuclear, dinuclear, hexanuclear, heptanuclear, and nonanuclear species involving Fe(II), Co(II), Ni(II), and Cu(II) salts with a series of potentially heptadentate picolinic dihydrazone ligands with pyrazine, pyrimidine, and pyridine end groups are described in the present study. Iron and cobalt complexation reactions are complicated by redox processes, which lead to mixed-oxidation-state Co(II)/Co(III) systems when starting with Co(II) salts, and reduction of Fe(III) to Fe(II) when starting with Fe(III). Magnetic exchange within the polynuclear structural frameworks is discussed and related to the structural features.     

Synthesis,structural, and biological studies of some bivalent metal ion complexes with the tridentate Schiff base ligand

New complexes of a Schiff base derived from 2-hydroxy-5-chloroacetophenone and glycine with Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and UO₂(VI) have been synthesized. The ligand and the complexes have been characterized on the basis of analytical data, electrical conductance, IR, ESR, and electronic spectra, magnetic susceptibility measurements and thermogravimetric analysis. The ligand acts as a dibasic tridentate (ONO) donor molecule in all the complexes except the Zn(II) complex, where it acts as a monobasic bidentate (OO) donor. Antibacterial activities of the ligand and its metal complexes have been determined by screening the compounds against various Gram(+) and Gram(−) bacterial strains. The solid state d.c. electrical conductivity of the ligand and its complexes has been measured over 313–398 K and the complexes were found to be of semiconducting nature. The article is published in the original.     

Azo dye with nitrogen donor sets of atoms and its metal complexes: Synthesis,characterization, DFT,biological, anticancer and Molecular docking studies

An azo derivative was synthesized by coupling diazotized 2,6‐diaminopyridine with p‐dimethyl amino benzaldehyde and this new ligand formed a series of metal complexes with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) salts. These complexes were characterized on the basis of elemental analyses, molar conductance, infrared spectroscopy, UV–Vis, ¹H NMR, mass spectrometry, electronic spectra, magnetic susceptibility and ESR spectral studies, conductivity measurements, thermogravimetric analyses (TG‐DTG). The molecular and electronic structure of the azo ligand was optimized theoretically and the quantum chemical parameters were calculated. The ligand and its metal complexes were subjected to X‐ray powder diffraction study. The thermal stability of the ligand and its metal complexes was examined by thermogravimetry. The ligand and its complexes were tested for their in vitro antimicrobial activity, some of the complexes showed good antimicrobial activities against some selected bacterial and fungal strains. Anticancer activity of the ligand and its metal complexes are evaluated against human cancer (MCF‐7 cells viability). Molecular docking was used to predict the binding between azo ligand and the receptors of nucleoside diphosphate kinase of Staphylococcus aureus (3Q8U) and (3HB5) which is breast cancer mutant oxidoreductase. The docking study provided useful structural information for inhibition studies.     

Mononuclear and polynuclear chelates of picolinoyldithiocarbazate

Mononuclear and polynuclear chelates of potassium picolinoyldithiocarbazate (KHPcDC) with Mn(II), Fe(ll1), Fe(II), Co(Il), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II) and U(VI)O2 have been prepared and characterized by chemical and thermal (TG, DTG, DTA) analyses, molar conductivities, spectral (UV-Visible, IR, NMR, ESR) and magnetic moment measurements. The molar conductivities of the complexes lie in the non-electrolyte range whilst KHPcDC is a 1:1 electrolyte. Changes in selected vibrational absorption of the ligand upon coordination indicate that KHPcDC behaves as monoanionic and coordinates in a bidentate, tridentate and/or bridging tetradentate manner. Trans-form structure is proposed for [Pd(HPcDC)2] x 2H20 and [Cd(HPcDC)2] complexes on the basis of NMR data. An octahedral structure is proposed for Fe(III), Fe(II) and Ni(II) complexes, a square-planar structure for Co(II) and Pd(II) complexes and a tetragonally distorted octahedral structure for the Cu(II) chelate on the basis of spectroscopic and magnetic data. The ligand field parameters (B, Dq, beta) for the Fe(III) and Ni(II) chelates were calculated. TG, DTG and DTA studies support the different modes of chelation of KHPcDC. The solid metal acetate chelates have a unique decomposition exotherm profile which can be used as a rapid and sensitive tool for the detection of acetate-containing complexes.     

Spectroscopic investigations and physico-chemical characterization of newly synthesized mixed-ligand complexes of 2-methylbenzimidazole with metal ions

Some mixed ligand complexes containing 2-methylbenzimidazole and thiocyanate ion were synthesized. Free ligands and their metal complexes were characterized using elemental analysis, determination of metal, magnetic susceptibility, molar conductivity, infrared, UV-VIS, and (¹H, ¹³C) NMR spectra, and X-ray structure analysis. The results suggest that the Ag(I) complex has linear geometry, Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) have tetrahedral geometry, Pd(II) complex has square planar geometry, VO(IV) square pyramidal geometry, Pb(II) irregular tetrahedral geometry, and that the Cr(III) and Mn(II) complexes have octahedral geometry. The following general formulae were proposed for the prepared complexes: [AgBX], [CrB₃X₃], (HB)₂[MnB₂X₄] · 2B and [MB₂X₂], where B = 2-methylbenzimidazole, HB = 2-methylbenzimidazolium, X = thiocyanate ion, and M = VO(IV), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II), and Pb(II). Molar conductance of a 10⁻³ M solution in N,N-dimethyl formamide (DMF) indicates that all the complexes are non-electrolytes except the Mn(II) complex which is an electrolyte because the molar conductivity of its solution in DMF is high.     

Thermal and kinetic studies on solid complexes of 2-(2-benzimidazolylazo)-4-acetamidophenol with some transition metals

The preparation and characterization of 2-(2-benzimidazolylazo)-4-acetamidophenol (BIAAP) complexes are reported. Different physico-chemical methods like IR, Magnetic, solid reflectance spectra and molar conductance, were used to investigate the structure of BIAAP complexes. In particular, the thermal decomposition of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of BIAAP is studied in nitrogen atmosphere. All the complexes do not contain coordinated water molecules but contain (2-4) water molecules of crystallization. The water molecules were removed in a single step. The complexes of Co(II) and Ni(II) ions exhibited a phase transition and the decomposition or combustion of BIAAP occurred in the second and subsequent steps. The final decomposition products were identified by mass spectrometry as the corresponding metal oxides or carbonate. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes were evaluated and the stabilities of the thermal decomposition of the complexes are discussed. From the kinetic point of view, it is found that the thermal stability of the complexes follows the order Ni(II) > Cu(II) > Zn(II) > Fe(III) > Co(II) > Cd(II).     

Preparation,Characterization, Biological Activity and 3D Molecular Modeling of Mn(II), Co(II), Ni(II), Cu(II), Pd(II) and Ru(III) Complexes of Some Sulfadrug Schiff Bases

Mn(II), Co(II), Ni(II), Cu(II), Pd(II) and Ru(III) complexes of Schiff bases derived from the condensation of sulfaguanidine with 2,4‐dihydroxy benzaldehyde ( HL1 ), 2‐hydroxy‐1‐naphthaldehyde ( HL2 ) and salicylaldehyde ( HL3 ) have been synthesized. The structures of the prepared metal complexes were proposed based on elemental analysis, molar conductance, thermal analysis (TGA, DSC and DTG), magnetic susceptibility measurements and spectroscopic techniques (IR, UV‐Vis, and ESR). In all complexes, the ligand bonds to the metal ion through the azomethine nitrogen and α‐hydroxy oxygen atoms. The structures of Pd(II) complex 8 and Ru(III) complex 9 were found to be polynuclear. Two kinds of stereochemical geometries; distorted tetrahedral and distorted square pyramidal, have been realized for the Cu(II) complexes based on the results of UV‐Vis, magnetic susceptibility and ESR spectra whereas octahedral geometry was predicted for Co(II), Mn(II) and Ru(III) complexes. Ni(II) complexes were predicted to be square planar and tetrahedral and Pd(II) complexes were found to be square planar. The antimicrobial activity of the ligands and their metal complexes was also investigated against the gram‐positive bacteria Staphylococcus aures and Bacillus subtilis and gram‐negative bacteria, Escherichia coli and Pesudomonas aeruginosa, by using the agar dilution method. Chloramphenicol was used as standard compound. The obtained data revealed that the metal complexes are more or less, active than the parent ligand and standard. The X‐ray crystal structure of HL3 has been also reported.     

Synthesis,structural studies and bio-activity of some metal(II) complexes with glyoxal salicylaldehyde acyldihydrazones

Complexes of the type [M(gssdh)]Cl and [M(gspdh)]Cl, where M?=?Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), Hgssdh?=?glyoxal salicylaldehyde succinic acid dihydrazone and Hgspdh?=?glyoxal salicylaldehyde phthalic acid dihydrazone, have been synthesized and characterized by elemental analyses, molar conductance, magnetic moments, electronic, ESR and IR spectra and X-ray powder diffraction studies. The metal complexes are insoluble in common organic solvents and are 1?:?1 electrolytes. The magnetic moment values and electronic spectra indicate a spin–free octahedral geometry for all Co(II), Ni(II) and Cu(II) complexes. ESR spectral parameters of Cu(II) complexes suggest an elongated tetragonally–distorted octahedral stereochemistry around copper. Both ligands are monobasic hexadentate ligands coordinating through three >C=O, two >C=N– and a deprotonated phenolate group to the metal. X-ray powder diffraction parameters for three of the complexes correspond to an orthorhombic crystal lattice. The complexes show appreciable activity against various fungi and bacteria.