Functionalization of decavanadate anion by coordination to cobalt(II): Binding to proteins, cytotoxicity, and water oxidation catalysis
Abstract
A series of five decavanadates (V(10)) using a simple, one-pot synthesis, adhering to the model template: transition metal ion - decavanadate - ligands:(Hnicotinamide)(2){[Co(H2O)(3)(nicotinamide)(2)](2)[μ-V10O28]} . 6H2O (1), {[Co(H2O)(4)(isonicotinamide)(2)](3)}V10O28 . 4H2O (2), {[Co(H2O)(4)](2)[Co(H2O)2(μ-pyrazinamide)2][μ-V10O28]} . 4H2O (3) {[Co(H2O)(4)(μ-pyrazinamide)](3).V10O28} . 4H2O (4), and (NH4)(2){[Ni(H2O)(4)(2-hydroxyethylpyridine)](2)}V10O28 . 2H2O (5) was synthesized. X-ray analysis reveals that 1 and 3 are decavanadato complexes, while 2, 4 and 5 are decavanadate complex salts.
Moreover, 3 is the first example of a polymeric decavanadato complex, employing direct coordination with the metal center and the organic ligand, in toto. From the solution studies using V-51 NMR spectroscopy, it was decoded that 1 and 3 stay stable in the model buffer solution and aqueous media.
Binding to model proteins, cytotoxicity and water oxidation catalysis (WOC) was studied primarily for 1 and 3 and concluded that neither 1 nor 3 have an interaction with the model proteins thaumatin, lysozyme and pro-teinase K, because of the presence of the organic ligands in the Co(II) center, any further interplay with the proteins was blocked. Cytotoxicity studies reveal that 1 is 40% less toxic (0.05 mM) and 26% less toxic (0.1 mM) than the uncoordinated V(10) with human cell lines A549 and HeLa respectively.
In WOC, 1 performed superior activity, by evolving 143.37 nmol of O2 which is 700% (9-fold) increase than the uncoordinated V(10).