Synthesis, characterization, crystal structure, and biological studies of vanadium complexes with glycolic acid

• Published in: Journal of coordination chemistry 2009-05, Vol.62 (10), p.1561-1571
• Main Authors: R. Guilherme, Luciana, Massabni, Antonio C., Cuin, Alexandre, Oliveira, Luiz A.A., Castellano, Eduardo E., Heinrich, Tassiele A., Costa-Neto, Cláudio M.
• Format: Article
• Language: English
• Subjects: Complex; Crystal structure; Glycolate; Glycolic; Vanadium
• ISSN: 0095-8972; 1029-0389
• DOI: 10.1080/00958970802663555

Synthesis, characterization, crystal structure, and biological studies of two complexes with glycolic acid are described. The solid complexes were formulated as K 2 [VO(C 2 H 2 O 3 )(C 2 H 3 O 3 ) 2 ] · H 2 O (1) and K 2 [{VO 2 (C 2 H 2 O 3 )} 2 ] (2) and characterized by X-ray studies, Fourier transform infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and magnetic susceptibility. Conversion of 1 to 2 was studied in aqueous solution by UV-Vis spectroscopy and in the solid state by diffuse reflectance spectroscopy. Complex 2 contains dinuclear [{VO 2 (C 2 H 2 O 3 )} 2 ] 2− anions in which glycolate(2−) is a five-membered chelating ring formed by carboxylate and α-hydroxy groups. The geometry around the vanadium in 2 was interpreted as intermediate between a trigonal bipyramid and a square pyramid. Vanadium(IV) is pentacoordinate in 1 as a distorted square pyramid. Complex 1 contains a vanadyl group (V=O) surrounded by two oxygens from deprotonated carboxylate and hydroxy groups forming a five-membered ring. Two oxygens from different glycolates(1−) are bonded to the (V=O) also. Biological analysis for potential cytotoxic effects of 1 was performed using Human Cervix Adenocarcinoma (HeLa) cells, a human cervix adenocarcinoma-derived cell line. After incubation for 48 h, 1 causes 90 and 95% of HeLa cells death at 20 and 200 μmol L −1 , respectively.