Palladium(II), platinum(II) and platinum(IV) complexes of 2-mercapto-3-phenyl-4-quinazolinone: Reactions of palladium(II) chloride and platinum (IV) chloride with 2-mercapto-3-phenyl-4-quinazolinone in the presence and absence of variousN-heterocyclic bases

Summary Reactions of 2-mercapto-3-phenyl-4-quinazolinone (LH) with PdCl₂ · 2H₂O and PtCl₄ · 5H₂O lead to the formation of [ML₂ complexes (M = Pd^II or Pt^II). Reactions of PdCl₂ · 2H₂O with LH in the presence ofN-heterocyclic bases yield compounds of type [PdLClB], (B = py, 3-pic, (o-phen)_1/2, and (bipy)_1/2) or Pd(LH)Cl(imz). PtCl₄] · 5H₂O reacts with LH in the presence of variousN-heterocyclic bases to give [PtL₂B] compounds (B = py, 3-pic, (o-phen)_1/2 or (pyrm)_1/2) and [PtL₂BCl] (B = imz or pz). These complexes have been characterised on the basis of analytical, i.r. and electronic spectral and magnetic measurement studies, and tentative structures for them are proposed.     

Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

A series of mononuclear metal complexes of Co(III), Ni(II) and Cu(II) with 2‐(2,4‐dichlorobenzamido)‐N′‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide ( LH ₃ ) have been synthesized and characterized using various physico‐chemical, spectroscopic and single crystal X‐ray diffraction techniques. Structural studies of [Co( LH )( LH ₂ )]·H₂O ( 4 ) revealed the presence of both amido and imidol tautomeric forms of LH ₃ , resulting in a distorted octahedral geometry around the Co(III) ion. [Ni( LH )(H₂O)]·H₂O ( 5 ) and [Cu( LH )(H₂O)]·H₂O ( 6 ) are isomorphous structures and crystallize in the monoclinic P2₁/c space group. The crystal structures of 4 , 5 and 6 are stabilized by hydrogen bonds formed by the enclathrated water molecules, C‐H···π and π···π interactions. Complexes along with the ligand ( LH ₃ ) were screened for their in vivo anti‐inflammatory activity (carrageenan‐induced rat paw edema method) and in vitro antioxidant activity (DPPH free radical scavenging assay). Metal complexes have shown significant anti‐inflammatory and antioxidant potential.     

Tetradentate asymmetric Schiff bases and their Ni(II) and Fe(III) complexes

Three asymmetric Schiff-base tetradentate diimines H₂L¹, H₂L², and H₂L³ [(2-OH)C₆H₄N=CHC₆H₄2-N=CHC₆H₃(2-OH)(5-X), X?=?H, CH₃, Cl respectively] have been synthesized by a two step process. The reaction of 2-hydroxy aniline with 2-nitro-benzaldehyde in EtOH gave the starting Schiff base, 2-hydroxy-N-(2-nitrobenzylidene)aniline (SB-NO₂), which was reduced into the amino derivative (SB-NH₂) in solution. Reacting SB-NH₂ with 2-hydroxybenzaldehyde, 2-hydroxy-5-methylbenzaldehyde and 2-hydroxy-5-chlorobenzaldehyde gave the three new ligands H₂L¹, H₂L², and H₂L³ respectively. Their dimeric, binuclear metal complexes with Ni(II) and Fe(III) have also been synthesized. The ligands and their complexes were characterized by elemental analyses, LC–MS, IR, electronic, ¹H and ¹³C-NMR spectra, TGA, conductivity and magnetic measurements. All of the spectroscopic, analytical and other data indicate octahedral geometry M₂L₂(H₂O)X₂ (M: Ni,Co;X: Cl or H₂O), except for NiL² which is monomeric. Antimicrobial activities of the ligands and the complexes were evaluated against five bacteria. While the ligands and the Ni complexes are inactive towards Pseudomonas aeruginosa and Staphylococcus aureus, Fe complexes are active; only Fe complexes are inactive against Escherichia coli. All of the compounds have antimicrobial activities against Bacillus subtilis, and Yersinia enterecolitica.     

Substituted iron selenocarboxylate complexes CpFe(CO)(EPh3)SeCOR (E = P,As, Sb)

Photolytic substitutions of iron selenocarboxylate complexes CpFe(CO)₂SeCOR with triphenylphosphine, triphenylarsine or triphenylantimony (EPh₃) gave exclusively the monosubstituted complexes CpFe(CO)(EPh₃)SeCOR [R = 3,5-C₆H₃(NO₂)₂ (1), 4-C₆H₄NO₂ (2), Ph (3), 2-C₆H₄Me (4), and E = P (a), As (b), Sb (c)] in high yields.     

5-[2-(Methylthio)ethyl]-3-phenyl-2-thioxoimidazolidin-4-one and its complexes with transition metals (Co<Superscript>II</Superscript>, Ni<Superscript>II</Superscript>, and Cu<Superscript>II</Superscript>). Synthesis and electrochemical investigation

The reaction of 5-[2-(methylthio)ethyl]-3-phenyl-2-thioxoimidazolidin-4-one (LH) with salts MCl₂· xH₂O (M = Co, Ni, Cu; x = 2, 6) afforded the [M(L)Cl]_n complexes of Ni^II, Co^II, and Cu^II. The electrochemical behavior of the LH ligand and its complexes was studied using the cyclic voltammetry and rotating disk electrode techniques. The structures of the synthesized compounds were determined by the data of UV—Vis and IR spectroscopy, mass spectrometry, and electrochemical characteristics. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 339–343, February, 2007.     

2,6—二乙酰吡啶类双希夫碱配合物的研究——Ⅲ.Co(Ⅱ)、Ni(Ⅱ)、Zn(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)配合物的合成和表征

制备了由2,6—二乙酰吡啶和肼基硫代甲酸酯衍生的希夫碱C₅H₃N[CH=NNHC(S)XR]₂(X=S,R=CH₃、C₆H₅CH₂;X=O,R=C₆H₅CH₂).离析出类型为MC₅H₃N[CH=NN=C(S)XR]₂(M=Co²⁺、Ni²⁺、Zn²⁺、Pb²⁺和Cd²⁺)的希夫碱配合物.配合物为元素分析、红外、可见—紫外光谱以及磁化率测量所表征.结果指出:上述希夫碱均为N₃S₂型五齿配体.     

Fast atom bombardment mass spectrometry of neutral methanide and ionic carbene platinum(II) derivatives

The fast atom bombardment mass spectra of a series of neutral methanide and ionic carbene platinum(II) complexes of formula dPePtL₂ and [dPePt(LH)₂](BF₄)₂ (dPe = (C₆H₅)₂PCH₂CH₂P(C₆H₅)₂; L = ? C(OCH₃)-NCH₃, ? C(OCH₃) ? NC₆H₁₁, ? C(OCH₃) ? NC₆H₄p ? CH₃), respectively are reported. Glycerol, 3-mercapto-1,2-propanediol, bis (2-hydroxyethyl)sulphide, 3-nitrobenzyl alcohol, and 2,4-di-tert-pentylphenol have been used as matrices. Neutral and ionic derivatives containing the same ligand behave similarly and give the same quasi-molecular [dPePtL(L + H)]⁺ ion by different primary processes. Stepwise breakdown of the ligands L with retention or further loss of atoms or molecules of hydrogen is observed for all these complexes, followed by ejection of radicals from the dPe ligand. Elimination of CH₃OH from [dPePtL(L + H)]⁺ also occurs. The highest ionic yields of both neutral methanide and ionic carbene complexes are observed in 3-mercapto-1,2-propanediol, in bis(2-hydroxyethyl)sulphide, and in 3-nitrobenzyl alcohol with respect to glycerol. The [dPePt(LH)₂]²⁺ doubly charged ions are present in the spectra obtained with 3-nitrobenzyl alcohol and are rather strong when L is ? C(OCH₃) ? NCH₃ and ? C(OCH₃) ? NC₆H₄p ? CH₃. Substitution of ligands L with a molecule or with a fragment of a sulphur containing matrix takes place very seldom with this series of complexes.     

Manganese(III) Schiff-base complexes involving heterocyclic β-diketone and diethylene triamine

Synthesis, spectral, thermal and coordination aspects of pentadentate Schiff-base complexes of the type [Mn(L)(X)] · H₂O [where H₂L = N,N′–diethylamine bis(1-phenyl-3-methyl-4-acetylimino-2-pyrazoline-5-ol) and X=NCS, NO₃, ClO₄, CN or N₃] are reported. The Schiff-base ligand (H₂L) and metal complexes have been characterized by elemental analysis, FT-IR, ¹H-NMR, magnetic measurements, molar conductivity measurements, electronic spectra, cyclic voltammetric and thermal studies. Magnetic moment values are close to 4.9 B.M. indicating high spin complexes lacking exchange interaction. Infrared spectral data suggest coordination of the secondary amino group making the ligand pentadentate. All complexes are electrochemically inactive, indicating high stability. Thermal decomposition of the Schiff-base complexes indicates loss of water of hydration and decomposition of the ligand. Kinetic parameters such as order of reaction (n) and the energy of activation (E _a) are reported using the Horowitz–Metzger method, indicating first order kinetics and giving the activation entropy (ΔS*), the activation enthalpy (ΔH*) and the free energy of activation (ΔG*).     

Synthesis of (2-hydroxo-5-chlorophenylaminoisonitrosoacetyl)phenyl ligands and their complexes: Spectral,thermal and solvent-extraction studies

Four different types of new ligands Ar[COC(NOH)R] _n (Ar=biphenyl, n = 1 H₂L¹; Ar=biphenyl, n = 2 H₄L²; Ar=diphenylmethane, n = 1 H₂L³; Ar=diphenylmethane, n = 2 H₄L⁴; R=2-amino-4-chlorophenol in all ligands) have been obtained from 1 equivalent of chloroketooximes Ar[COC(NOH)Cl] _n (HL¹-H₂L⁴) and 1 equivalent of 2-amino-4-chlorophenol (for H₂L¹ and H₂L³) or 2 equivalent of 2-amino-4-chlorophenol (for H₄L² and H₄L⁴). (Mononuclear or binuclear cobalt(II), nickel(II), copper(II) and zinc(II) complexes were synthesized with these ligands.) These compounds have been characterized by elemental analyses, AAS, infra-red spectra and magnetic susceptibility measurements. The ligands have been further characterized by ¹H NMR. The results suggest that the dinuclear complexes of H₂L¹ and H₂L³ have a metal:ligand ratio of 1:2; the mononuclear complexes of H₄L² and H₄L⁴ have a metal:ligand ratio of 1:1 and dinuclear complexes H₄L² and H₄L⁴ have a metal:ligand ratio of 2:1. The binding properties of the ligands towards selected transition metal ions (Mn^II, Co^II, Ni^II, Cu^II, Zn^II, Pb^II, Cd^II, Hg^II) have been established by extraction experiments. The ligands show strong binding ability towards mercury(II) ion. In addition, the thermal decomposition of some complexes is studied in nitrogen atmosphere.     

Synthesis and characterization of oxovanadium(IV), vanadium(IV) and oxovanadium(V) complexes of tetradentate Schiff bases. Attempted preparation of vanadium-carbon bonded compounds through desilylation

Condensation of 1,3-diaminopropane-2-ol with diacetylmonoxime, acetylacetone, salicylaldehyde and orthohydroxyacetophenone yielded the tetradentate Schiff bases N,N′-(2-hydroxy)propylenebis{(2-imino-3-oximino)butane} (H₂dampnol), N,N′-(2-hydroxy)propylenebis(acetylacetoneimine) (H₂acacpnol), N,N′-(2-hydroxy)propylenebis-(salicyalaldimine) (H₂salpnol) and N,N′-(2-hydroxy)propylenebis(7-methylsalicylaldimine) (H₂ohacpnol), respectively. The ligands form complexes with oxovanadium(IV), vanadium(IV) and oxovanadium(V) salts. Some mixed ligand complexes involving σ-bonded phenyl and benzyl radical along with tetradentate ligand, H₂L (where, H₂L stands for H₂dampnol, H₂acacpnol, H₂salpnol or H₂ohacpnol) of the types [(L)V(C₆H₅)₂]CH₃OH and [(L)V(CH₂Ph)₂]CH₃OH have been synthesized, characterized and also provide the syntheses of some new organovanadium(IV) complexes. Silylation coupled with desilylation have been employed as a route to new organovanadium(IV) complexes. All the complexes have been characterized with the help of elemental analyses, molar conductance values, molecular weights, magnetic moments and spectroscopic (IR, UV-Vis, ESR) data.     

Synthesis,Characterization and Crystal Structures of new Coordination Polymers of Cerium(III) and Samarium(III) Containing 2,6‐Pyridinedicarboxylic Acid

The reaction of 2,6‐pyridinedicarboxylic acid ( 1 , LH₂) with CeCl₃·7H₂O and Sm(NO₃)₃·6H₂O in the presence of triethylamine led to the coordination polymer complexes [M(L)(LH)(H₂O)₂]·4H₂O [M = Ce ( 2 ) and Sm ( 3 )]. Both complexes were characterized by elemental analyses, IR spectroscopy and the crystal structures of 2 and 3 . Crystal data for 2 at ?80 °C: monoclinic, space group P2₁/c, a = 1404.6(1), b = 1122.1(1), c = 1296.1(1) pm, β = 102.09(1)°, Z = 4, R₁ = 0.0217 and for 3 at ?80 °C: monoclinic, space group P2₁/c, a = 1395.1(1), b = 1120.1(1), c = 1282.8(1) pm, β = 102.71(1)°, Z = 4, R₁ = 0.019.     

Synthesis,characterization and antimicrobial activity of cobalt(II), nickel(II)and copper(II) complexes with new asymmetrical Schiff base ligands derived from 7-formyanil-substituted diamine-sulphoxine and acetylacetone

Asymmetric 7-formyanil-substituted-imino-4-(4-methyl-2-butanone)-8-hydroxyquinoline-5-sulphonic acid (Schiff bases), react with Co^II, Ni^II and Cu^II ions to give 1:2, 1:1 and 2:1 complexes as established by conductometric titrations in 1:1 DMF:H₂O. The complexes were investigated by elemental analyses, molecular weight determinations, molar conductance, magnetic moments, thermal analysis, i.r., u.v.–vis. and e.s.r. spectra. The complexes have an octahedral crystal structure and general formula [ML·(OH₂)₂], where M^II = Co, Ni and Cu, and L = Na[7—X—HL], (—X— = (CH₂)₂, (CH₂)₃, p-C₆H₄, o-C₆H₄). Antimicrobial activity of these new ligands and their transition metal complexes has been screened in vitro on common fungi and bacteria.     

Synthesis,characterization, electrochemical and in-vitro antimicrobial studies of Co(II), Ni(II), and Cu(II) complexes with Schiff bases of formyl coumarin derivatives

A series of Co(II), Ni(II), and Cu(II) complexes have been synthesized with Schiff bases (H₂L^I and H₂L^II) derived from 8-formyl-7-hydroxy-4-methylcoumarin or 5-formyl-6-hydroxycoumarin and o-aminophenol. Structures have been proposed from elemental analyses, spectral (IR, UV-Vis, FAB-mass, and Fluorescence), magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Elemental analyses indicate ML · 3H₂O [M = Co(II), Ni(II), and Cu(II)] stoichiometry. Spectroscopic studies suggest coordination through azomethine nitrogen, phenolic oxygen of o-aminophenol, and the coumarin via deprotonation. The Schiff bases and their complexes have been screened for antibacterial (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, and Cladosporium) activities by minimum inhibitory concentration (MIC) method. The redox behavior of the complexes was investigated using cyclic voltammetry (CV).     

Synthesis and structural studies of (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}pyridin-2-yl)imino]butan-2-one oxime, ligand and its mono-, di- and trinuclear copper(II) complexes

A new dioxime ligand, (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}-pyridin-2-yl)imino]butan-2-one oxime, (H₂Pymdo) (3) has been synthesized in H₂O by reacting 2,3-butenedione monoxime (2) with 2,6-diaminopyridine. Mono-, di- and tri-nuclear copper(II) complexes of the dioxime ligand (H₂Pymdo) and/or 1,10-phenanthroline have been prepared. The dioxime ligand (H₂Pymdo) and its copper(II) complexes were characterized by ¹H-n.m.r., ¹³C-n.m.r. and elemental analyses, magnetic moments, i.r. and mass spectral studies. The mononuclear copper(II) complex of H₂Pymdo was found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). In the dinuclear complexes, in which the first Cu(II) ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu(II) ion is ligated with dianionic oxygen atoms of the oxime groups and are linked to the 1,10-phenanthroline nitrogen atoms. The trinuclear copper(II) complex (6) was formed by coordination of the third Cu(II) ion with dianionic oxygen atoms of each of two molecules of the mononuclear copper(II) complexes. The data support the proposed structure of H₂Pymdo and its Cu(II) complexes.     

Oxovanadium(IV) pyrazolyl carboxylic acid complexes: synthesis,crystal structures of [VO(pzH)(HMPA)2]2 · 4H2O (1) and VO(OH)(dmpzH)2(C6H5COO) (2) (H2MPA = 5-methyl-1H-pyrazole-3-carboxylic acid,pzH = pyrazole,dmpzH = 3,5-dimethyl pyrazole)

Two new monomeric complexes of oxovanadium(IV), [VO(pzH)(HMPA)₂]₂ · 4H₂O (1) and VO(OH)(dmpzH)₂(C₆H₅COO) (2) (H₂MPA = 5-methyl-1H-pyrazole-3-carboxylic acid, pzH = pyrazole, dmpzH = 3,5-dimethyl pyrazole), have been synthesized from reaction of VOSO₄ · nH₂O with respective ligands. The compounds were characterized by elemental analysis, IR spectra and X-ray diffraction. Structural analysis of 1 and 2 gave the following parameters: 1, monoclinic, P2(1)/n, a = 11.1729(13) Å, b = 23.965(3) Å, c = 13.5591(15) Å, β = 99.969(2)°, V = 3575.8(7) ų, Z = 4; 2, orthorhombic, Pbcn, a = 13.197(4) Å, b = 15.898(5) Å, c = 18.192(6) Å, V = 3817(2) ų, Z = 8. In each complex the vanadium is a distorted tetragonal bipyramid, which is typical for oxovanadium(IV) complexes. In both complexes, inter- and intra-molecular hydrogen bonds are also discussed. Complex 1 exists as an infinite chain along the b-axis by intermolecular hydrogen bonds. In addition, thermal analysis and quantum chemistry calculations were performed for analyzing the stability of the complexes.     

Synthesis, spectral characterization and redox properties of iron (II) complexes of 1-alkyl-2-(arylazo)imidazole

Iron (II) complexes of 1-alkyl-2-(arylazo)imidazoles (p-R-C₆H₄-N=N-C₃H₂NN-1-R′, R = H (a), Me (b), Cl (c) and R′ = Me (1/3), Et (2/4) have been synthesized and formulated astris-chelates Fe(RaaiR′) ₃ ²⁺ . They are characterized by microanalytical, conductance, UV-Vis, IR, magnetic (polycrystalline state) data. The complexes are low spin in character,t _2g ⁶ (Fe(II)) configurations.     

Syntheses,Structures, Magnetic Properties,and NIR Emission Properties of a Series of Novel 1, 2, 4, 5‐Cyclohexanetetracarboxylate‐bridged Lanthanide Complexes with 3D Framework Structures

Solvothermal combination of trivalent lanthanide metal precursors with 1, 2, 4, 5‐cyclohexanetetracarboxylic acid (L) ligand has afforded the preparation of a family of eight new coordination polymers [Ln₄(L)₃(H₂O)₁₀] · 7H₂O (Ln = Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb) ( 1 – 8 ). Structural analyses reveal that the 1, 2, 4, 5‐cyclohexanetetracarboxylic acid ligand with e,a,a,e (L^I) conformation displays a μ₄‐(κ³O, O, O⁵)(κ²O²,O²)(κ²O⁴,O⁴)‐bridging mode to generate 3D frameworks of complexes 1 – 8 and the α‐Po topology with the short Schläfli symbol {4¹².6³} could be observed in complexes 1 – 8 . The near‐infrared luminescence properties were studied, and the results have shown that the Ho^III, Er^III, and Yb^III complexes emit typical near‐infrared luminescence in the solid‐state. Variable‐temperature magnetic susceptibility measurements of complexes 2 – 7 have shown that complex 2 (Gd) shows the ferromagnetic coupling between magnetic centers, whereas the complexes 3 – 7 show the antiferromagnetic coupling between magnetic centers. Additionally, the thermogravimetric analyses were discussed.     

Oxomolybdenum(V) complexes of 2-benzothiazolyl hydrazones

Summary Oxomolybdenum(V) complexes of general formulae [Mo₂O₃L₂Cl₂]H₂O and [Mo₂O₃L₂(OH)₂(H₂O)₂] (LH = hydrazones derived from 2-hydrazinobenzothiazole with salicyladehyde, 5-methyl-, 5-chloro-, 5-bromo-, 3-methoxysalicyldehyde and 2-hydroxy-1-naphthaldehyde) have been prepared and characterized by elemental analysis, conductivities, magnetic moments, thermal studies, and i.r., u.v.-vis. and e.p.r. spectra. The data suggest that the complexes are non-electrolytes, paramagnetic and have distorted octahedral structures with possible metal-metal interactions via oxo bridging.     

SYNTHESIS AND CHARACTERIZATION OF TRIS(ALKYLISOCYANIDE) BIS(TRIARYL-PHOSPHINE)COBALT(II) COMPLEXES

Abstract

A series of complexes having the general formula, [Co(CNR)₃(PR₃)₂]X₂, X = ClO₄, BF₄ with CNR = CNCMe₃, CNCHMe₂, CNC₆H₁₁. CNCH₂Ph and PR₃ = PPh₃, P(C₆H₄Me-p)₃, P(C₆H₄OMe-p)₃ has been synthesized and characterized. Synthesis can be achieved by reaction of [Co(CNR)₄(AsPh₃)₂]X₂ complexes with controlled excess of PR₃ ligands, and by AgClO₄/AgBF₄ oxidation of the [Co(CNR)₃(PR₃)₂]X complexes. The latter procedure is preferable. Alternate syntheses of the [Co(CNR)₃(PR₃)₂]X complexes have also been employed. Five-coordinate Co(II) complexes have not been obtained using CNCMe₃ with P(C₆H₄Me-p)₃ ligands, CNCH₂Ph with P(C₆H₄OMe-p)₃ ligands, or CNC₄H_9-n with PPh₃ ligands. [Co(CNC-Me₃)₃{P(C₆H₄Cl-p)₃}₂]ClO₄ produced only [Co{CNCMe₃)₄H₂O](ClO₄)₂ upon forced oxidation with excess AgClO₄. [Co(CNR)₃(PR₃)₂]X₂ complexes appear to undergo varying degrees of distortion from regular (i.e., D _3h symmetry) axially-disubstituted trigonal bipyramidal coordination in the solid state, as evidenced by v(-N°C) IR patterns, but to assume regular trigonal bipyramidal coordination in solution. Effective magnetic moments indicate one-electron paramagnetism, and solution electronic spectra are compatible with trigonal bipyramidal coordination.     

Metal complexes of omeprazole. Preparation,spectroscopic and thermal characterization and biological activity

Metal complexes of omeprazole (OPZ) are prepared and characterized based on elemental analyses, IR, diffuse reflectance, magnetic moment, molar conductance and thermal analyses (TGA and DTA) techniques. From the elemental analyses, the complexes have the general formula [M(L)₂]X _n [where M = Cr(III) (X = Cl, n = 3), Ni(II) (X = ClO₄, n = 2) and Zn(II) (X = Cl, n = 2)], and [M(L)₂(H₂O)₂]X _n · yH₂O (where M = Fe(III) (X = Cl, n = 3, y = 0), Co(II) (X = Cl or ClO₄, n = 2, y = 0–4) and Ni(II) (X = Cl, n = 2, y = 4) and [Cu(L)₂]Cl₂ · H₂O. The molar conductance data reveal that all the metal chelates are 3 : 1 electrolytes (for Cr(III) and Fe(III) complexes) and 2 : 1 (for the remaining complexes). IR spectra show that OPZ coordinates to the metal ions as neutral bidentate with ON donor sites of the pyridine–N and sulphone-O. The magnetic and solid reflectance spectra indicate octahedral (FeCl₃, CoCl₂, CoClO₄ and NiCl₂), square planar [Cu(II)] and tetrahedral [Mn(II), Cr(III), NiClO₄ and Zn(II)] structures. The thermal behavior of these chelates using thermogravimetric and differential thermal analyses (TGA and DTA) techniques indicate the hydrated complexes lose water of hydration followed immediately by decomposition of the anions and ligand molecules in the successive overlapping OPZ and its metal complexes are screened for antibacterial activity against Escherichia coli, Staphylococcus aureus, Aspergillus flavus and fungi (Candida albicans). The activity data show the metal complexes to be more potent/antibacterial than the parent OPZ ligand against one or more bacterial species.