Karuppannan Natarajan

Ruthenium(II) complexes containing bidentate Schiff bases and their antifungal activity

The reactions of ruthenium(II) complexes, [RuHCl(CO)(PPh3)2(B)] [B = PPh3, pyridine (py) or piperidine (pip)], with bidentate Schiff base ligands derived by condensing salicylaldehyde with aniline, o-, m- or p-toluidine have been carried out. The products were characterised by analytical, i.r., electronic, 1H-n.m.r. and 31P-n.m.r. spectral studies and are formulated as [RuCl(CO)(L)(PPh3)(B)] (L = Schiff base anion; B = PPh3, py or pip). An octahedral structure has been tentatively proposed for the new complexes. The Schiff bases and the new complexes were tested in vitro to evaluate their activity against the fungus Aspergillus flavus.

Biological evaluation of a novel water soluble sulphur bridged binuclear copper(II) thiosemicarbazone complex

The reaction of 2-oxo-1,2-dihydroquinoline-3-carbaldehyde 4(N,N)-dimethylthiosemicarbazone (HL) with copper(II) nitrate in methanol yielded water soluble [{Cu(L)(CH(3)OH)}(2)](NO(3))(2) · H(2)O. Structural analysis revealed that the complex consists of centrosymmetric binuclear entities containing square-pyramidal copper(II) ions bridged through the sulfur atoms. The spectroscopic experimental evidences strongly suggested that the ligand and complex could interact with calf thymus DNA (CT-DNA) through intercalation. A gel electrophoresis assay demonstrated the ability of the complex to cleave the pBR322 plasmid DNA. The complex also exhibited a strong binding to bovine serum albumin (BSA) over the ligand. Investigations of antioxidative properties showed that the complex has strong radical scavenging properties. Further, the cytotoxic effect of the complex was examined on HeLa, Hep G2, and HEp-2, which showed that the complex exhibited substantial cytotoxic specificity on HeLa over the other two.

Effect of N(4)-phenyl substitution in 2-oxo-1,2-dihydroquinoline-3-carbaldehyde semicarbazones on the structure, DNA/protein interaction, and antioxidative and cytotoxic activity of Cu(II) complexes.

A new ligand, 2-oxo-1,2-dihydroquinoline-3-carbaldehyde semicarbazone (OQsc-H) (1);, its N(4)-phenyl derivative (OQsc-Ph) (2); and their corresponding copper(II) complexes [CuCl(2)(OQsc-H)]·H(2)O·CH(3)OH (3), [CuCl(2)(OQsc-Ph)(H(2)O)]·CH(3)OH (4), and [CuNO(3)(OQsc-Ph)(H(2)O)]NO(3)·H(2)O·C(2)H(5)OH (5) have been synthesized and characterized by structural, analytical, and spectral methods, in order to investigate the influence of N(4)-phenyl substitution on structure and pharmacological properties. In all of the complexes, the ligands coordinated to the Cu(II) ion in a neutral fashion via ONO donor atoms. The single-crystal X-ray structures of neutral complex (3) and cationic complex (5) exhibit a slightly distorted square-pyramidal structure, while neutral complex (4) revealed an octahedral structure. The interaction of the compounds with calf thymus DNA (CT-DNA) has been explored by absorption and emission titration methods, which revealed that compounds 1-5 could interact with CT-DNA through intercalation. A gel electrophoresis pictogram demonstrated the ability of the complexes (3-5) to cleave the pBR322 plasmid DNA through a hydrolytic process. The interactions of the compounds with bovine serum albumin (BSA) were also investigated using UV-visible, fluorescence, and synchronous fluorescence spectroscopic methods. The results indicated that all of the compounds could quench the intrinsic fluorescence of BSA in a static quenching process. Investigations of antioxidative properties showed that all of the compounds have strong radical scavenging potencies against hydroxyl radicals, 2,2-diphenyl-1-picrylhydrazyl radicals, nitric oxide, and superoxide anion radicals. Further, the cytotoxic effect of the compounds examined on cancerous cell lines such as human cervical cancer cells (HeLa), human laryngeal epithelial carcinoma cells (HEp-2), human liver carcinoma cells (Hep G2), human skin cancer cells (A431), and noncancerous NIH 3T3 mouse embryonic fibroblasts cell lines showed that all three complexes exhibited substantial cytotoxic activity. Further, all of the pharmacological investigations support the fact that there exists a strong influence of N(4)-phenyl substitution in semicarbazone.

Ruthenium(II) carbonyl complexes with tridentate Schiff bases and their antibacterial activity

The products obtained by reacting ruthenium (II) complexes [RuHCl(CO)(PPh3)2(B)] [B = PPh3, pyridine (py) or piperidine (pip)] with tridentate Schiff base ligands derived by condensing salicylaldehyde or o-vanillin with o-aminophenol and o-aminothiophenol, have been characterised by analytical, i.r., electronic, 1H-n.m.r. and 31P-n.m.r. spectral studies and formulated as [Ru(L)(CO)(PPh3)(B)] (L = bifunctional tridentate Schiff base anion, B = PPh3, py or pip). An octahedral structure has been tentatively proposed for the new complexes. Some have been tested for the in vitro growth inhibitory activity against bacteria Escherichia coli, Bacillus sp. and Pseudomonas sp.

Synthesis, characterization and catalytic activities of ruthenium complexes containing triphenylphosphine/triphenylarsine and tetradentate Schiff bases

Abstract Ruthenium(II) complexes of the type [Ru(CO)(B)(L)] (B=AsPh3, pyridine, piperidine or morpholine; L=dianion of tetradentate Schiff bases) have been synthesized and characterized by physico-chemical methods. These complexes are found to be effective catalysts in the oxidation of primary and secondary alcohols using N-methylmorpholine-N-oxide as oxidant. The catalytic activity of these triphenylarsine complexes have been compared with that of triphenylphosphine complexes and with similar ruthenium(III) complexes. The formation of high valent Run+2O species as catalytic intermediate is proposed for the catalytic processes.

SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL ACTIVITIES OF RUTHENIUM(II) CARBONYL COMPLEXES CONTAINING BIFUNCTIONAL TRIDENTATE SCHIFF BASES

Ruthenium(II) carbonyl complexes have been synthesised by reacting [RuH2(CO)(PPh3)3] or [RuHCl(CO)(PPh3)2(Z)] (Z = PPh3, pyridine (py) or piperidine (pip)) with tridentate Schiff base ligands derived by condensing salicylaldehyde, o-vanillin or o-hydroxyacetophenone with N(4)-phenylsemicarbazide. These complexes have been characterised by analytical, IR, electronic, 1H NMR and 31P NMR spectral studies. The complexes of the general formula [Ru(L)(CO)(PPh3)(Z)] (L = Schiff base anion; Z = PPh3, py or pip) tentatively have been assigned an octahedral structure. Some of the complexes have been tested for in vitro growth inhibitory activity against the bacteria Escherichia coli, Bacillus sp. and Pseudomonas sp.

Synthesis, crystal structure and pharmacological evaluation of two new Cu(II) complexes of 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (benzoyl) hydrazone: a comparative investigation.

Two new copper(II) complexes have been synthesized by reacting 2-oxo-1,2-dihydroquinoline-3-carbaldehyde (benzoyl) hydrazone (H(2)L) with CuCl(2)·2H(2)O or Cu(NO(3))(2)·3H(2)O. The structures of the complexes have been determined by single crystal X-ray diffraction studies. Results obtained using spectroscopic methods strongly suggested that the ligand and its Cu(II) complexes could interact with calf thymus DNA through intercalation. In the case of protein binding, the obtained results indicated that all the three compounds could quench the intrinsic fluorescence of bovine serum albumin through static quenching process. In addition, antioxidant activity tests showed that H(2)L and its copper(II) complexes possess significant scavenging effect against free radicals. Further, the two copper(II) complexes exhibited effective cytotoxic activity against a panel of human cancer cell lines.

Synthesis and spectral studies of binuclear ruthenium(II) carbonyl complexes containing bis(β-diketone) and their applications

Abstract A series of new binuclear ruthenium(II) complexes of the type {[RuX(CO)(AsPh 3 ) 2 ] 2 L} (X=H or Cl; L=bis-β-diketone) have been synthesised by reacting [RuHX(CO)(AsPh 3 ) 3 ] (X=H or Cl) with various bis(β-diketones) of the general formula [(RCO)(R′CO)CHCH(R″)CH(COR)(COR′)] (R=CH 3 or C 6 H 5 ; R′=CH 3 or C 6 H 5 ; R″=H, C 6 H 5 , 4-(CH 3 )C 6 H 4 , 4-(OCH 3 )C 6 H 4 or 4-N(CH 3 ) 2 C 6 H 4 ) in 2:1 molar ratio in benzene. An octahedral structure has been tentatively proposed for all the new ligand bridged binuclear complexes. The new complexes have been subjected to the antibacterial and catalytic activity studies.

Synthetic, catalytic and biological studies of new binuclear ruthenium(II) complexes containing thiobis(β-diketones) and triphenylphosphine

Abstract A convenient synthesis of binuclear ruthenium(II) complexes of the type {[RuCl(CO)(PPh3)(B)]2(bis-β-dk)} (where B=PPh3, py, pip or mor; bis-β-dk=thiobis(β-diketonato ion) was accomplished by reacting [RuHCl(CO)(PPh3)2(B)] (where B=PPh3, py, pip or mor) with thiobis-β-diketones in benzene. The new compounds have been characterised by elemental analysis, IR, electronic, 1H and 31P NMR spectral data. The ruthenium(II) complexes were found to be efficient catalysts for the oxidation of primary alcohol to aldehyde in the presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant. The ligands and its ruthenium(II) complexes show growth inhibitory activity against the bacteria Escherichia coli, Bacillus sp. and Pseudomonas sp.

Role of Substitution at Terminal Nitrogen of 2-Oxo-1,2-dihydroquinoline-3-Carbaldehyde Thiosemicarbazones on the Coordination Behavior and Structure and Biological Properties of Their Palladium(II) Complexes

A series of four new palladium(II) complexes of 2-oxo-1,2-dihydroquinoline-3-carbaldehyde thiosemicarbazones with triphenylphosphine as coligand have been synthesized and characterized by the aid of various spectral techniques. The single-crystal X-ray diffraction studies revealed that the unsubstituted thiosemicarbazone ligand acted as monobasic tridentate (ONS(-)) in the cationic [Pd(H-Qtsc-H)(PPh(3))]Cl complex, whereas the monosubstituted thiosemicarbazone ligands acted as monobasic bidentate (NS(-)) in their respective complexes, [PdCl(H-Qtsc-R)(PPh(3))] (R = Me (2), Et (3), Ph (4)). To ascertain the potentials of the above Pd(II) complexes toward biomolecular interactions, additional experiments involving interaction with calf thymus DNA and bovine serum albumin were carried out. Moreover, all the palladium(II) complexes have been screened for their radical scavenging activity toward DPPH, O(2)(-), OH, and NO radicals. The efficiency of the complexes in arresting the growth of human cervical cancer cells (HeLa), human laryngeal epithelial carcinoma cells (HEp-2), human liver carcinoma cells (Hep G2), and human skin cancer cells (A431) has also been studied along with the cell viability test against the noncancerous NIH 3T3 mouse embryonic fibroblasts cell lines under in vitro conditions. All the in vitro pharmacological evaluation results clearly revealed the relationship between the structure and the activity of the new Pd(II) complexes.