Study of the interaction of Oxovanadium(IV) with a plant component (Caffeic acid). Synthesis and characterization of a solid compound.

PATRICIA A. M. WILLIAMS; ANA C. GONZÁLEZ BARÓ; EVELINA G. FERRER

POLYHEDRON

Año: 2002 vol. 21 p. 1979 - 1984

0277-5387

Abstract The interaction of caffeate (Caf) with vanadyl(IV) cation in aqueous solution has been investigated. Glass electrode potentiometry has been used to calculate the formation constants (298 K, I= 0.150 M) and to determine the speciation of the (ternary) system VO2+/Caf 3-/H+. Complexation starts at low pH value and the major species involve the simultaneous coordination of carboxylate and catechol groups or the chelation by the catecholate sites, depending on the experimental conditions. The model proposes the formation of six complex species in solution. UV-vis spectroscopy gave additional support to the results. The synthesis and characterization (diffuse reflectance, FTIR and thermal behavior) of the solid complex Na3[VOCaf(OH)2].3H2O is also reported.