Computational Study of Aqueous Solvation of Vanadium (V) Complexes

Abstract

Vanadium complexes are of great biological interest due to their antidiabetic and anticancer properties. Analyses of the aqueous solvation effects using explicit models in the octahydrated complexes of vanadium (V) linked to the tridentate ONO Schiff base (VL·(H2O)8), are performed. Here, L is the Schiff base 1-(((5-chloro-2-oxidophenyl)imine)methyl)naphthalen-2-olate. The complexes VL1, VL2, VL3 and VL4, include the functional groups –NH(CH3CH2)3, –CH2CH2CH3, and –CH2CH2CH2CH3, respectively. The explicit model is used to examine the effects of water molecules in the first solvation shell that surrounds the bis-peroxo-oxovanadate ion (two molecules per oxygen atom in the [VO(O2)2·(H2O)]−). Computational calculations are performed using density functional theory (DFT)/M06-2X. A complete basis set (CBS) using correlation-consistent Dunning basis sets from double-ξ to quadruple-ξ is used. The solvation energies are analyzed in order to propose possible complex structures as the most relevant species in biological-like systems. The results indicate that, by including explicit water molecules in the first solvation shell, a particular stabilization trend in the octahydrated complexes (VL1–VL4)·(H2O)8 is observed with VL1·(H2O)8 < VL3·(H2O)8 < VL4·(H2O)8 < VL2·(H2O)8. Our results indicate that the complex VL3·(H2O)8, substituted with –CH2CH2CH3, presents the most stable ΔGSolv and hence, it might represent the more likely species in biological-like environments.