pH-metric, UV–Vis and 51V NMR study of vanadium(V) coordination to α-aminohydroxamic acids in aqueous solutions

Formation and structure in aqueous solution of complexes between vanadium(V) and aminohydroxamic acids that potentiates vanadium’s insulinomimetic activity: l-glutamic γ-hydroxamic and l-aspartic-β-hydroxamic acids

“…Since vanadium(V) ion does not exhibit any d-d transition in the visible spectrum, the color observed must be attributed to a strong oxygen to metal charge-transfer absorbance band in the ultraviolet [26,27] that extends into the visible range. This behavior was observed in our previous works about the vanadium(V) complexation by acetohydroxamic [11], b-alaninehydroxamic [13], glycinehydroxamic and a-aminohydroxamic acids [28]. In all these cases there is no consumption or release of protons, as observed now.…”

A thermodynamic model for vanadate in aqueous solution – equilibria and reaction enthalpies

“…1 Vanadates have been investigated for purposes as diverse as polymerisation catalysts, 2,3 nanofibres, 4,5 pH probes 6 and insulin mimetics. [7][8][9] In particular, the medicinal applications of vanadates have attracted a substantial amount of interest. In recent years, attention has been focused on vanadate complexes as insulin mimetics in the treatment of diabetes.…”

“…In recent years, attention has been focused on vanadate complexes as insulin mimetics in the treatment of diabetes. [7][8][9][10][11][12] Several vanadium chemistry reviews have been published in the last decade describing these investigations. [13][14][15][16] For the application and/or investigation of vanadates and vanadate complexes in aqueous solution, a thorough understanding of the solution chemistry is essential.…”

“…Currently the most commonly used speciation model (see for example ref. 7,8,14,[19][20][21] was first constructed as a result of rigorous investigations some thirty years ago using 51 V NMR measurements coupled with potentiometric titrations. 22,23 The postulated model included protonatable linear V 1 , V 2 and V 4 species, as well as cyclic, non-protonating V 4 , V 5 and V 6 species under neutral to basic conditions.…”

Carbonate complexes of vanadate

“…Indeed, vanadate and vanadate complexes have been found to both activate and inhibit phosphate metabolising enzymes [8]. In recent years, attention has been focused on the medicinal applications of vanadates [9], particularly their potential as insulin mimetics in the treatment of diabetes [10][11][12].…”