Interaction Between the Low Molecular Mass Components of Blood Serum and the Vanadium(III)–2,2′-Bipyridine System

Abstract

The complex species formed between vanadium(III)–2,2′-bipyridine (Bipy) and the small blood serum bioligands lactic (HLac), oxalic (H2Ox), citric (H3Cit) and phosphoric (H3PO4) acids were studied in aqueous solution by means of electromotive forces measurements emf(H) at 25 °C and 3.0 mol⋅dm−3 KCl as the ionic medium. The data were analyzed using the least-squares computational program LETAGROP, taking into account the hydrolytic products of vanadium(III) and the binary complexes formed. Formation of the complexes [V(Bipy)(Lac)]2+, [V(Bipy)(Lac)2]+, [V(OH)2(Bipy)(Lac)] and [V2O(Bipy)2(Lac)2]− were observed in the vanadium(III)–Bipy–HLac system. Also, the species [V(Bipy)(HOx)]2+, [V(Bipy)(Ox)]+, [V(OH)(Bipy)(Ox)], [V(OH)2(Bipy)(Ox)]− and [V(OH)3(Bipy)(Ox)]2− were found in the vanadium(III)–Bipy–H2Ox system, the complexes [V(Bipy)(HCit)]+, [V(Bipy)(Cit)], [V(OH)(Bipy)(Cit)]− and [V(OH)2(Bipy)(Cit)]2− were found in the vanadium(III)–Bipy–H3Cit system, and the species [V(Bipy)(H2PO4)]2+ and [V(Bipy)(HPO4)]+ were detected in the vanadium(III)–Bipy–H3PO4 system. The stability constants of these complexes were determined.