Synthesis and spectroscopic properties of copper(II) complexes derived from thiophene-2-carbaldehyde thiosemicarbazone. Structure and biological activity of [Cu(C6H6N3S2)(2)]

The synthesis, structure and spectroscopic properties on complexes with the formula [Cu(L-III)(2)] (1) and Cu(NO3)(2)(HLIII)(2) (2); where HLIII = thi ophene-2-carbaldehyde thiosemicarbazone, have been developed. The molecular structure of compound 1 consists of monomeric entities. The copper(II) ion s exhibit distorted square-planar geometry with both bidentate thiosemicarb azone ligands placed in a centrosymmetric way. Metal to ligand pi-backdonat ion is proposed to explain several structural and spectroscopic features in these complexes. The EPR spectra of compound 1 show an orthorhombic g tens or indicating the presence of weak magnetic exchange interactions. The reac tion of compound 1 with,glutathione causes the reduction of the metal ion a nd the substitution of the thiosemicarbazone ligand by the thiol ligand. Th is mechanism seems to be related to the cytotoxicity of this complex agains t Friend Erithroleukemia cells (FLC) and melanome B16F10 cells. (C) 1999 El sevier Science Inc. All rights reserved.