DFT study of vanadyl (IV) complexes with low molecular mass ligands: Picolinate, oxalate, malonate, and maltolate

Abstract

The insulin-mimetic activity of the VO 2þ complexes are much related to its chemical speciation in the blood serum. Low molecular mass ligands must have an important role in the mechanism of the VO 2þ biological activity affecting directly its absorption efficacy. In the present work, the chemical speciation of vanadyl (VO 2þ ) with malonate, maltolate, oxalate and picolinate ligands has been investigated by means of DFT/PCM calculations. Metal/Ligand 1:1 and 1:2 complexes have been calculated. All tautomers, conformations and the presence of water molecules acting as ligand fulfilling the coordination sphere of the metal center have been studied. The results showed that the 1:1 species prefer to have square pyramidal structure with two water molecules in the equatorial axis. The 1:2 species prefer the hexacoordinated structure with one water molecule in the available coordination site in the cis position with respect to the oxo group. The 6-membered ring malonate complex prefers to keep the square pyramidal structure without water molecule in the coordination sphere. The Gibbs free reaction energy for the formation of the 1:2 complexes from the interaction of the 1:1 complexes and the ligand was estimated. The error of the estimated values compared to the experimental data is not larger than 5 kcal mol À1 at the PBE/TZVP level of theory

As(III) immobilization on gibbsite: Investigation of the complexation mechanism by combining EXAFS analyses and DFT calculations

“…Indeed, it has been the subject of many studies (Abreu et al, 2006(Abreu et al, ,2008Guimarães et al, 2007b;Noronha et al, 2007;Rodrigues et al, 2011). However, in the case of the arsenous acid, at the pH range used at the experiments, the predominant species is fully protonated H 3 AsO 3 , (pKa $9).…”

Thermodynamic, spectroscopic and DFT description of oxidovanadium(IV) complexes with malate and tartrate in aqueous solution

“…The proposed speciation has been checked by means of a computational modelling. Various DFT studies concerning vanadyl coordinated by oxygenated ligands have been reported [16,33,34], and results were obtained by employing different hybrid functional and basis set. We have set up the computational method by examining the well-known aqua-vanadyl complex, both in the form of [VO(H 2 O) 5 ] 2+ , with four equatorial and one axial water ligand, and [VO(H 2 O) 4 ] 2+ system, with only equatorial ligands.…”

Oxidovanadium(IV) complexes involving dehydroacetic acid and β-diketones of bioinorganic and medicinal relevance: Their synthesis, characterization, thermal behavior and DFT aspects

“…In the recent past computational methods based on density functional theory (DFT) has been widely used. The results of many studies have indicated that density-functional theory (DFT) is a powerful method for predicting the geometry of vanadium compounds [37][38][39][40][41][42][43]. It is a useful method for the investigation of large molecules as well [44].…”