Effect of solvent medium on the photoreduction of cobalt(III) complexes

The photochemical behaviour at 365 nm of [Co(NH<SUB>3</SUB>)<SUB>5</SUB>(NO<SUB>2</SUB>)]<SUP>2+</SUP> and [Co(NH<SUB>3</SUB>)<SUB>5</SUB>(N<SUB>3</SUB>)]<SUP>2+</SUP> has been investigated in aqueous media containing added hydioxylic solvents to examine the role of solvent viscosity in determining the extent of radical breakdown, Φ(redox)(and also, in the case of the nitro-complex, linkage isomerization). In agreement with earlier findings, Φ(redox) decreases by &gt;30% on addition of glycerol or ethylene glycol, but to interpret this effect as purely due to changing viscosity is an oversimplification, for the addition of cyclohexanol to give the same relative viscosity leaves Φ(redox) unchanged. Evidently a more specific role exists for the added solvent. The effect of adding synthetic polymers to give high viscosities again leaves Φ(redox) unaffected, but this may simply reflect the heterogeneous nature of polymer solutions

Evaluation of DNA binding, antioxidant and cytotoxic activity of mononuclear Co(III) complexes of 2-oxo-1,2-dihydrobenzoh]quinoline-3-carbaldehyde thiosemicarbazones

Four new 2-oxo-1,2-dihydrobenzoh]quinoline-3-carbaldehyde N-substituted thiosemicarbazone ligands (H-2-LR, where R = H, Me, Et or Ph) and their corresponding new cobalt(III) complexes have been synthesized and characterized. The structures of the complexes 2 and 3 were determined by single crystal X-ray diffraction analysis. The interactions of the new complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNA via intercalation. Antioxidant studies of the new complexes showed that the significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of complexes 1-4 against A549 cell line was assayed which showed higher cytotoxic activity with lower IC50 values indicating their efficiency in killing the cancer cells even at very low concentrations. (C) 2012 Elsevier Masson SAS. All rights reserved

Synthesis, X-ray crystal structure, DNA binding, antioxidant and cytotoxicity studies of Ni(II) and Pd(II) thiosemicarbazone complexes

New complexes, [Ni(HL)(PPh3)]Cl (1), [Pd(L)(PPh3)](2), and [Pd(L)(AsPh3)](3), were synthesized from the reactions of 4-chloro-5-methyl-salicylaldehyde thiosemicarbazone [H2L] with [NiCl2(PPh3)(2)], [PdCl2(PPh3)(2)] and [PdCl2(AsPh3)(2)]. They were characterized by IR, electronic, H-1-NMR spectral data. Further, the structures of the complexes have been determined by single crystal X-ray diffraction. While the thiosemicarbazone coordinated as binegative tridentate (ONS) in complexes 2 and 3, it is coordinated as mono negative tridentate (ONS) in 1. The interactions of the new complexes with calf thymus DNA was examined by absorption and emission spectra, and viscosity measurements. Moreover, the antioxidant properties of the new complexes have also been tested against DPPH radical in which complex 1 exhibited better activity than that of the other two complexes 2 and 3. The in vitro cytotoxicity of complexes 1-3 against A549 and HepG2 cell lines was assayed, and the new complexes exhibited higher cytotoxic activity with lower IC50 values indicating their efficiency in killing the cancer cells even at very low concentrations