Synthesis,characterization, crystal structure and antiproliferative activity of platinum(II) complexes with 2-acetylpyridine-4-cyclohexyl-thiosemicarbazone

New platinum complexes have been synthesized by the reaction of Na₂PtCl₄ with 2-acetylpyridine-4-cyclohexyl-thiosemicarbazone, HAc4CyclHexyl (1). The new complexes [Pt(Ac4CyclHexyl)Cl] (2) and [Pt(Ac4CyclHexyl)₂] (3) have been characterized by elemental analyses and spectroscopic studies. The crystal structure of the complex [Pt(Ac4CyclHexyl)Cl] · DMF has been solved by single-crystal X-ray diffraction. The anion of Ac4CyclHexyl coordinates in a planar conformation to the central platinum(II) through the pyridyl N, azomethine N and thiolato S atoms. The crystal packing is determined by double intermolecular hydrogen interactions, π–π, Pt–C and Pt–π contacts. The cytotoxic activities of 1–3 have been evaluated for antiproliferative activity in vitro against the cells of three human cancer cell lines: MCF-7 (human breast cancer cell line), T24 (bladder cancer cell line), A-549 (non-small cell lung carcinoma) and a mouse L-929 (a fibroblast-like cell line cloned from strain L). The compounds 1–3 display IC₅₀ values in a μM range better than that of the antitumor drug cisplatin and are considered as agents with potential antitumor activity candidates for further stages of screening in vitro and/or in vivo.     

Organotin flufenamates: Synthesis, characterization and antiproliferative activity of organotin flufenamates

The organotin flufenamates [Me₂(flu)SnOSn(flu)Me₂]₂ (1), [Bu₂(flu)SnOSn(flu)Bu₂]₂ (2) and [Bu₂Sn(flu)₂] (3) have been prepared and structurally characterized by means of vibrational and NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy. The crystal structure of [Me₂(flu)SnOSn(flu)Me₂]₂ (1) has been determined by X-ray crystallography. Three distannoxane rings are present to the dimeric tetraorganodistannoxane of planar ladder arrangement. The structure is centro-symmetric and features a central rhombus Sn₂O₂ unit with two additional tin atoms linked at the O atoms. Six-coordinated tin centers are present in the dimer distannoxane. This structure is self-assembled via π → π and C-H → π stacking interactions. Flufenamic acid and flufenamates were evaluated for antiproliferative activity in vitro. Among the compounds tested [Bu₂(flu)SnOSn(flu)Bu₂]₂ (2) and [Bu₂Sn(flu)₂] (3) exhibited high cytotoxic activity against the cancer cell line A549 (non-small cell lung carcinoma).     

Synthesis,characterization, crystal structure and antiproliferative in vitro activity of long-chain aliphatic thiosemicarbazones and their Ni(II) complexes

In the course of a research on metal-based compounds active on white blood cell cancers (leukemia, lymphoma and myeloma) nine aliphatic thiosemicarbazones and their nickel complexes have been synthesized with the aim to test their effect on histiocytic lymphoma U937 cell proliferation. All compounds were characterized by elemental, IR and NMR spectra analyses and for five of the complexes also by X-ray crystallography diffraction analysis. Heptanal thiosemicarbazone and the corresponding nickel complex were chosen after a solubility/stability test to carry out preliminary experiments in vitro on human leukemia cell line U937. The complex possesses a remarkable biological activity in inhibiting cell growth and in inducing apoptosis.     

Synthesis,characterization, crystal structures, in vitro and in vivo antitumor activity of palladium(II) and zinc(II) complexes with 2-formyl and 2-acetyl pyridine N(4)-1-(2-pyridyl)-piperazinyl thiosemicarbazone

The present paper includes synthesis and spectral characterization of the novel prepared palladium(II) and zinc(II) complexes with 2-formyl pyridine N(4)-1-(2-pyridyl)-piperazinyl thiosemicarbazone, HFo4Npypipe, 1 and the 2-acetyl pyridine N(4)-1-(2-pyridyl)-piperazinyl thiosemicarbazone, HAc4Npypipe, 2. The Pd(II) complexes [PdCl(Fo4Npypipe)], 3, [PdCl(Ac4Npypipe)], 4 and the Zn(II) complexes [ZnCl₂(Fo4Npypipe)], 5 and [ZnCl₂(Ac4Npypipe)], 6 have been characterized by elemental analyses and spectroscopic studies. The crystal structure of the complexes [PdCl(Fo4Npippy)], 3 and [PdCl(Ac4Npippy)], 4, have been solved by single-crystal X-ray diffraction. The electronic, IR, UV/Vis, and NMR spectroscopic data of the complexes are reported. The results of the cytotoxic activity of 1–6 have been evaluated in vitro against the cells of three human cancer cell lines: MCF-7, T24, A-549 and a mouse L-929 (a fibroblast-like cell line cloned from strain L). For selected compounds 2 and 6 the acute toxicity and antitumor activity were evaluated on leukemia P388-bearing mice. The Zn(II) compounds 5 and 6 are considered as agents with potential antitumor activity, and can therefore be candidates for further stages of screening in vitro and/or in vivo.     

Synthesis,crystal structure,DNA interaction and anticancer evaluation of pyruvic acid derived hydrazone and its transition metal complexes

A novel tridentate chelating ligand, Ethyl 2‐(2‐(2‐chlorobenzoyl)hydrazono)propanoate and its late transition metal complexes were synthesized, characterized and evaluated for anticancer behavior. The structures were elucidated with the help of elemental analyses, spectral (vibrational, electronic, NMR and mass) and thermo‐gravimetric techniques. Single crystal X‐ray crystallographic studies of the ligand suggest an orthorhombic lattice structure with Pna21 space group. The interaction of ligand and complexes with DNA (CT‐DNA) has been extensively studied using absorption, emission, viscosity and thermal denaturation studies with E. coli DNA. The DNA cleavage ability of ligand and metal complexes was tested using plasmid pBR322 DNA by gel electrophoresis method. The ligand and its copper complex have been evaluated for their in vitro anticancer activity against human cancer cells of different origin such as KB (Oral), A431 (Skin), Mia‐Pa‐Ca (Pancreases), K‐549 (Lung), K‐562 (Leukemia), MCF‐7 (Breast) and VERO by MTT assay and the apoptosis assay was carried out with acridine orange/ethidium bromide (AO/EB) staining method. The studies suggest that ligand and copper complex exhibit significant cytotoxic activity on KB, MCF‐7, A‐431, Mia‐Pa‐Ca‐2 an d A‐549 cell lines compared to K‐562 and VERO cell lines.     

Synthesis and structural characterization of diorganotin(IV) esters with pyruvic acid isonicotinyl hydrazone and pyruvic acid salicylhydrazone Schiff bases

Eight diorganotin esters of Schiff base ligands formulated as [R₂SnLY]₂, where L₁ is 4-NC₅H₄CON₂C(CH₃) CO₂ with Y = H₂O, R = Ph (1), PhCH₂ (2), m-ClC₆H₄CH₂ (3), and L₂ is 2-HOC₆H₄CON₂C(CH₃) CO₂ with Y = CH₃OH, R = PhCH₂ (4), o-ClC₆H₄CH₂ (5), m-ClC₆H₄CH₂ (6), o-FC₆H₄CH₂ (7), p-FC₆H₄CH₂ (8) have been prepared and characterized by elemental analysis, IR, ¹H and ¹¹⁹Sn NMR spectra. The crystal structures of compounds 1, 2 and 4 have been determined by X-ray single crystal diffraction. Their structures show that the tin atoms of three compounds are all rendered seven-coordinated in distorted pentagonal bipyramid geometries with a planar SnO₄N unit and two apical aryl carbon atoms. A comparison of the IR spectra of the ligands with those of the corresponding compounds, reveals that the disappearance of the bands assigned to carbonyl unambiguously conforms that the ligands coordinate with tin in the enol form.     

Synthesis and crystal structure of diorganotin(IV) complexes with pyruvic acid benzoylhydrazone and pyruvic acid salicylhydrazone

Six diorganotin esters of Schiff-base ligands formulated as [R₂SnLY]₂, where L₁ is C₆H₅CON₂C(CH₃)CO₂ with Y?=?CH₃CH₂OH, R?=?mClC₆H₄CH₂ (1), oFC₆H₄CH₂ (2), pFC₆H₄CH₂ (3) and L₂ is 2-HOC₆H₄CON₂C(CH₃)CO₂ with Y?=?CH₃OH, R?=?oFC₆H₄CH₂ (4), pFC₆H₄CH₂ (5), mClC₆H₄CH₂ (6) have been prepared and characterized by elemental analysis, IR, ¹H and ¹¹⁹Sn NMR spectra. The crystal structures of complexes 1 and 4 have been determined by X-ray single crystal diffraction. The structure analyses reveal that the Sn atom in both 1 and 4 is seven-coordinate in distorted pentagonal bipyramid geometries with a planar SnO₄N unit and two apical aryl carbon atoms, thus forming a dimeric molecule, which sits on a crystallographic center of symmetry. Intramolecular or intradimeric hydrogen bonds contribute to the stability and compactness of the crystal structures.     

Diorganotin(IV) complexes with 2-benzoylpyridine and 2-acetylpyrazine N(4)-phenylthiosemicarbazones: Synthesis, crystal structures and biological activities

Four diorganotin(IV) complexes [(Me)₂Sn(L¹)(CH₃COO)]·CH₃CH₂OH (1), [(Ph)₂Sn(L¹)(CH₃COO)]·CH₃CH₂OH (2), [(Me)₂Sn(L²)Cl] (3) and [(Ph)₂Sn(L²)(CH₃COO)] (4) where HL¹ = 2-benzoylpyridine N(4)-phenylthiosemicarbazone and HL² = 2-acetylpyrazine N(4)-phenylthiosemicarbazone have been synthesized and characterized by elemental analysis, IR MS, ¹H NMR and single-crystal X-ray diffraction studies. Schiff bases in their deprotonated forms coordinate to tin(IV) via pyridine/pyrazine nitrogen atom and the nitrogen atom and sulfur atoms of the thiosemicarbazone moiety. The tin atom is seven-coordinated in 1, 2 and 4 containing one acetato group, respectively, and six-coordinated in 3 containing one chloride ion. Biological studies, carried out in vitro against selected bacteria and K562 leukaemia cells, respectively, have shown that different substituted groups attached at the thiosemicarbazone moieties and different diorganotin(IV) groups showed distinctive differences in the biological property.     

Synthesis,spectroscopic characterization,antimicrobial activity and crystal structure of silver and copper complexes of sulfamethazine

Silver(I) and copper(II) complexes of 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzenesulfonamide (smz) have been synthesized and characterized by elemental analysis and infrared (IR), ¹H NMR, and UV–vis spectroscopy. [Ag(smz)(pyridine)] (1) crystallizes in monoclinic system with space group P2₁/c and Z = 4, while [Cu(smz)₂(pyridine)₂]·H₂O (2) crystallizes in triclinic system with space group P-1 and Z = 2. X-ray analysis revealed that silver in 1 is four-coordinate exhibiting distorted tetrahedral geometry, while copper in 2 is coordinated to six nitrogens leading to a highly distorted octahedral geometry. The molecular structures of both 1 and 2 are stabilized by N–H?O and C–H?π intermolecular and C–H?O intramolecular interactions. Water plays a significant role in crystal packing by forming strong N–H?O_water intramolecular as well as O_water–H?N intermolecular interactions in 2. The results of IR, UV–vis, ¹H NMR spectral data and thermal analysis for 1 and 2 suggest that the binding of silver and copper to the sulfonamidic nitrogen is in agreement with the crystal structure determination. Antimicrobial activities of silver (1) and copper (2) complexes of sulfamethazine are studied by the dilution method against Staphylococcus aureus and Escherichia coli strains.     

Synthesis, structure and cytotoxicity of diorganotin(IV) complexes of 2,6-lutidine-α,3-diol (Lu): The crystal structures of Lu and [SnMe2(H2O)(Lu-2H)]

The reaction of dimethyl-, diethyl- and dibutyltin(IV) oxide with 2,6-lutidine-α²,3-diol (Lu) [2-(hydroxymethyl)-3-hydroxy-6-methylpyridine] in toluene/ethanol has been investigated. The compounds were isolated and characterized by IR, Raman and Mössbauer spectroscopy, EI and FAB mass spectrometry and ¹H and ¹¹⁹Sn NMR spectroscopy. The structures of Lu and [SnMe₂(H₂O)(Lu-2H)] were determined by X-ray diffraction. The crystal of [SnMe₂(H₂O)(Lu-2H)] contains dimeric [SnMe₂(H₂O)(Lu-2H)]₂ units, in which the tin atom is coordinated to the O atoms of the two deprotonated hydroxymethyl groups and one deprotonated phenolic hydroxyl group. The distorted octahedral coordination polyhedron of each tin atom is completed by a water molecule and two methyl C atoms. The butyl derivative exhibited significant in vitro antitumor activity against the human carcinoma cell lines HeLa-229, A2780 and A2780cis, although minor than that of the pyridoxine derivative prepared previously.     

Synthesis,spectroscopic characterization,crystal structure,and anti-bacterial activity of diorganotin(IV) complexes with 5-bromo-2-hydroxybenzaldehyde-N(4)-ethylthiosemicarbazone

Three new diorganotin(IV) complexes, [Me₂Sn(BDET] (2), [Bu₂Sn(BDET)] (3), and [Ph₂Sn(BDET)] (4), were synthesized by reacting R₂SnCl₂ (R = Me, Bu, and Ph) with 5-bromo-2-hydroxybenzaldehyde-N(4)-ethylthiosemicarbazone [H₂BDET, (1)] in the presence of KOH in absolute methanol. The newly synthesized complexes were characterized by elemental analysis, molar conductivity, UV–vis, FT-IR, ¹H, ¹³C, and ¹¹⁹Sn NMR spectroscopies. The molecular structure of 4 was confirmed by X-ray crystallography. X-ray crystallography revealed that the doubly deprotonated O,N,S-tridentate thiosemicarbazone coordinates to tin(IV), resulting in a distorted trigonal bipyramidal geometry. Their ¹H, ¹³C, and ¹¹⁹Sn NMR spectra support a five-coordinate tin(IV) in solution for all complexes, in accord with the solid-state X-ray structure determined for 4. Compounds 1–4 were evaluated for their antibacterial activities against Staphylococcus aureus, Enterobacter aerogenes, Escherichia coli, and Salmonella typhi. The results exhibited that 2–4 were active with comparable potency compared to the standard drug. Antibacterial studies also indicated that the complexes have potential for biological evaluation.     

Novel 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone and Zn(II), Cu(II), Ni(II) and Co(III) complexes: Synthesis,characterization, crystal structure,antioxidant, antimicrobial and antiproliferative activity

New zinc (II), copper (II), nickel (II) and cobalt (III) complexes, [Zn (HL)₂]I₂ (1) , [Cu (HL)Cl₂] (2) , [Cu (HL)Br₂] (3) , [Cu (HL)(H₂O)₂](ClO₄)₂ (4) , [Ni (HL)₂]I₂·H₂O (5) , [Co(L)₂]Cl (6) , [Co(L)₂]NO₃ (7) , [Co(L)₂]I·[Co(L)₂](I₃) (8) were obtained with 2-formylpyridine 4-allyl-S-methylisothiosemicarbazone ( HL ). The isothiosemicarbazone ligand was characterized by NMR (¹H and ¹³C), IR spectroscopy and X-ray diffraction. All the complexes were characterized by elemental analysis, IR, UV–Vis, ESI-MS spectroscopy, molar conductivity, magnetic susceptibility measurements. X-ray diffraction analysis on the monocrystal and powder elucidated the structure of the complexes 1 , 5 , 7 and 8 . The ligand and the complexes were tested for their antioxidant and antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida albicans. Also, the antiproliferative properties of these compounds on human leukemia HL-60, human cervical epithelial HeLa, human epithelial pancreatic adenocarcinoma BxPC-3, human muscle rhabdomyosarcoma spindle, large multinucleated RD cells and normal MDCK cells have been investigated. The nickel complex 5 and cobalt complexes 6 , 7 showed promising antiproliferative activity and low toxicity.     

Synthesis,characterization of diorganotin (IV) schiff base complexes and their in vitro antitumor activity

Six novel diorganotin(IV) complexes have been synthesized in good yields by the reaction of R₂SnCl₂ (R= methyl, phenyl) with the Schiff base derived from salicylaldehyde and substituted thiosemicarbazide. The complexes were characterized by elemental analysis, IR, ¹H NMR and MS spectra. The structure of 2f was confirmed by single crystal X‐ray diffraction. The crystal of 2f is triclinic, space group P‐1 with a = 0.84996(12), b = 1.1204(2), c = 1.27597(12) nm, β = 81.908(9)°, V=1.0904(2) nm³, Z = 2, D_c= 1.551 g/cm³. The final discrepancy factors are R = 0.0211 and R_w = 0.0536 for 3710 independent reflections. Tests of antitumor activities in vitro showed that the obtained complexes had relative inhibition interaction to the KB, HCT‐8 and BEL‐7402 tumor cell lines.     

Synthesis and structural characterizations of diorganotin(IV) complexes with 2-pyrazinecarboxylic acid

Two types of diorganotin(IV) complexes {[R₂Sn(O₂CC₄H₃N₂)]₂O}₂ (R = n-octyl 1, 2-ClC₆H₄CH₂3, 2-FC₆H₄CH₂5, 4-FC₆H₄CH₂7) and R₂Sn(O₂CC₄H₃N₂)₂ (R = n-octyl 2, 2-ClC₆H₄CH₂4, 2-FC₆H₄CH₂6, 4-FC₆H₄CH₂8) were prepared by reactions of diorganotin oxide with 2-pyrazinecarboxylic acid. The complexes 1-8 are characterized by elemental analysis, IR and NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopies. The complexes {[(n-C₈H₁₇)₂Sn(O₂CC₄H₃N₂)]₂O}₂ (1) and (n-C₈H₁₇)₂Sn(O₂CC₄H₃N₂)₂ (2) are also determined by X-ray single crystal diffraction, which reveal that the endo-cyclic tin atom of complex 1, is seven-coordinate, and the exo-cyclic tin atom is hexa-coordinated geometry, while the complex 2 is seven-coordinated geometry. The nitrogen atom of the aromatic ring participates in the interactions with the Sn atom.     

Synthesis,characterization and anti-bacterial activity of divalent transition metal complexes of hydrazine and trimesic acid

Transition metal complexes of trimesic acid and hydrazine mixed-ligands with a general formula M(Htma)(N₂H₄)₂, where, M = Mn, Co, Ni, Cu and Zn; H₃tma = trimesic acid, have been prepared and characterized by elemental, structural, spectral and thermal analyses. For the complexes, the carboxylate ν_asym and ν_sym stretchings are observed at about 1626 and 1367 cm^?1 respectively, with Δν between them of ～260 cm^?1, showing the unidentate coordination of each carboxylate group. The hydrazine moieties are present as bridging bidentates. Electronic and EPR spectral studies suggest an octahedral geometry for the complexes. All these complexes show three steps of decomposition in TGA/DTA. SEM images of CuO and MnO residues obtained from the complexes show nano-sized clusters suggesting that the complexes may be used as precursors for nano-CuO and nano-MnO preparation. The antimicrobial activities of the prepared complexes, against four bacteria have been evaluated.     

Synthesis and characterization of diorganotin(IV) complexes of tridentate Schiff bases: crystal structure of [N-(3-hydroxypyridine-2-yl)-5-chlorosalicylideneiminato]dimethyltin(IV)

Some five-coordinated dimethyltin(IV) complexes of the type Me₂SnL (where L is the anion of a bifunctional tridentate Schiff base) were synthesized. These Schiff bases are N-(3-hydroxypyridine-2-yl)-3-methoxysalicylideneimine, HOC₆H₃OCH₃CH=NC₅H₃NOH (1), N-(3-hydroxypyridine-2-yl)-3-ethoxysalicylideneimine, HOC₆H₃OC₂H₅CH=NC₅H₃NOH (2), N-(3-hydroxypyridine-2-yl)-5-chlorosalicylideneimine, HOC₆H₃ClCH=NC₅H₃NOH (3), and N-(3-hydroxypyridine-2-yl)-3-methoxy-5-bromosalicylideneimine, HOC₆H₂OCH₃BrCH=NC₅H₃NOH (4). Dimethyltin(IV) complex of 3 (3a) was characterized by single crystal X-ray diffraction method and a coordination geometry that is nearly halfway between trigonal–bipyramidal and square pyramidal arrangement was found. Dimethyltin complexes of (1), (2), and (4) were also prepared and characterized by the comparison of their elemental analysis and ¹H-NMR-, IR-, UV- and mass spectral data with those of (3a). For example, in the ¹H-NMR spectra, the ²J(¹¹⁹Sn-¹H) in the Sn-CH₃ moiety have values between 80 Hz and 90 Hz, typical of five-coordinated tin species. By using these values in Lockart’s Equations, H₃C–Sn–CH₃ angles in the complexes were estimated to lie between 130° and 145°. X-ray diffraction value for 3a, confirms this estimate within 3.4% relative deviation (129.7° exp. Vs. 134.9° estimate).     

Mononuclear diorganotin(IV) complexes with arylhydroxamates: syntheses,structures and assessment of in vitro cytotoxicity

Two series of diorganotin(IV) complexes with dihalogenobenzohydroxamate ligands (substituents = 2,4‐Cl₂, 2,4‐F₂, 3,4‐F₂, 2,5‐F₂, 2,6‐F₂), formulated as [R₂Sn(HL)₂] ( a ), and the arylhydroxamato/arylcarboxylato mixed‐ligand complexes [R₂Sn(HL)(L′)] ( b ), were prepared and characterized by FT‐IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopies, elemental analyses and melting point measurements. X‐ray diffraction analysis was also carried out for the complex [Me₂Sn{3,4‐F₂C₆H₃C(O)NHO}₂], 1a . These compounds exhibit in vitro cytotoxic activities towards human leukemic promyelocites HL‐60, BGC‐823, BEL‐7402 and KB cell lines which, in some cases, are identical to, or even higher than, that of cisplatin. The type, position and number of the X substituents in the phenyl ring play a role in the cytotoxic activity, and complex 8a , with its 2,6‐difluorobenzohydroxamato ligand, is highly active against all tumor cells. A tentative structure–activity relationship is also described. Copyright © 2007 John Wiley & Sons, Ltd.     

Cadmium iodide complexes with dimethylsulphoxide,and their crystal structures

The crystalline compounds [{CdI₂(dmso)}_n] ( 1 ,) and [Cd₂I₄(dmso)₄] ( 2 ,) provide a structural sequence illustrating the conversion of CdI₂ into the ionic derivatives [Cd(dmso)₆]²⁺ [Cd(dmso)I₃]₂^? · EtOH ( 3 ,) and [Cd(dmso)₆]²⁺ CdI₄^2? ( 4 ,), with increasing proportions of dmso. ( 1 ,) comprises polymeric chains with Cd centres linked by bridging iodide atoms, and alternately in four- and six-coordination. ( 2 ,) is a binuclear segment of the chains and can be seen as the structural forerunner of the ionic compounds ( 3 ,) and ( 4 ,). The ion packing in ( 3 ,) is loose, with lattice ethanol.     

Synthesis,crystal structures and spectroscopic studies of praseodymium(III) malonate complexes

Reactions of malonic acid (H₂mal) with PrCl₃·6H₂O afforded the known complex [Pr₂(mal)₃(H₂O)₆]_n (1), and compounds [Pr₂(mal)₃(H₂O)₆]_n·2nH₂O (2·2nH₂O), [PrCl(mal)(H₂O)₃]_n·0.5nH₂O (3·0.5nH₂O) and [Pr(mal)(Hmal)(H₂O)₃]_n·nH₂O (4·nH₂O) using various reaction ratios, reaction media (H₂O, MeOH) and pH values. Analogous reactions with CeCl₃·7H₂O afforded compounds [Ce₂(mal)₃(H₂O)₆]_n (5), [CeCl(mal)(H₂O)₃]_n·nH₂O (6·nH₂O) and [Ce(mal)(Hmal)(H₂O)₃]_n·nH₂O (7·nH₂O). Compounds 2·2nH₂O and 3·0.5nH₂O were characterized by X-ray crystallography, and 4–7 by microanalytical and spectroscopic data. The malonate(-2) ligand adopts three different coordination modes in the structures of 1–3, i.e., the μ₂-κO:κO′:κO″ and the μ₄-κ²O:κO′:κ²O″:κO? in 1 and 2 leading to a 3D network structure, and the μ₃-κ²O:κO′:κ²O″:κO? in 3 promoting an 1D structure. The thermal decomposition of 1 and 3·0.5nH₂O was monitored by TG/DTA and TG/DTG measurements. The structural features of 1–3 are discussed in terms of known malonato(-2) Ln^III and Ca^II complexes. The bioinorganic chemistry relevance of our results is discussed.     

Synthesis,characterization and antimicrobial activity of a bidentate NS Schiff base of S-benzyl dithiocarbazate and its divalent complexes

The reaction of S-benzyl dithiocarbazate (SBDTC) with 2,4,5-trimethoxybenzaldehyde afforded a bidentate NS Schiff base 1 (benzyl-3-N-(2,4,5-trimethoxyphenylmethylenehydrazine carbodithioate), which on further reaction with M(II) (where M(II) = nickel(II), zinc(II), palladium(II) and copper(II)) in ethanol under reflux yielded bis-chelated inner complexes [ML₂] 2–5 with deprotonated L. The ligand and its complexes were characterized by physicochemical techniques, viz., molar conductance, magnetic susceptibility measurement, IR, NMR, UV–Vis and mass spectroscopic techniques. The crystal structures of 1 and 5 were also determined by single-crystal X-ray crystallography. The crystal structure analysis showed that the ligand exists in its thione tautomeric form. In the complexes, each of the two deprotonated ligands chelated the metal ions through the β-nitrogen and the thione sulfur forming five-membered rings. The copper(II) complex (5) exhibited a square-planar geometry, where the two N₂S₂ chromophores are arranged trans. All the compounds showed strong antibacterial activity against S.-β-hemolyticus, Klebsiella pneumoni, and Escherichia coli. The compounds also showed strong antifungal activity against Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, and Candida albicans with the exception of the palladium(II) complex (4) which showed no activity, while all the compounds showed no activity against Fusarium vasinfectum.