期刊
COMPUTATIONAL AND THEORETICAL CHEMISTRY
卷 1077, 期 -, 页码 99-105出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.comptc.2015.11.002
关键词
Vanadium complexes; Antioxidant agents; Fenton reactions; Exchange-correlation functionals; Coupled-clusters; Multireference character
资金
- CONACYT, Mexico [154784, 155698, 155070, 265471, 29578]
The role of the ligand in vanadium IV and V complexes to produce reactive oxygen species (OH center dot and O-2(-center dot)) by Fenton and Haber-Weiss reactions is analyzed theoretically, in gas phase and considering solvated ions. By using reactivity indexes, we found that the presence of the oxo group induces the electron donating process over complexes that in first instance does not present it. Also, we show that the vanadyl ion promotes the production of OH center dot radicals, which is a contrary behavior presented by others vanadium complexes that may act as O-2(-center dot) producers or scavengers. For Haber-Weiss reactions, the analysis of the Gibbs free energy predict the following ordering: H2O > NH3 > Cl- > OH- > C2O42-, Cl- > C2O42-, NH3 > oxo, H2O > oxo, NH3 > oxo, Cl-, for ligands with vanadium V and IV in the formation of reactive oxygen species (ROS); which allow for the first time a criteria to predict ROS activity in vanadium complexes. All the results were obtained by using the Density Functional Theory, in its Kohn-Sham version, with four different exchange-correlation functionals (PBE, PBE0, B3LYP and M06-2X) coupled with the aug-cc-pVDZ basis set. It is well-known that transition metals sometimes exhibit a multireference character, for that reason several tests were considered over the vanadium complexes reported here. In particular, T1 test, multiconfiguration self-consistent field and coupled-clusters calculations were performed in order to test the feasibility of our results. In general, we can say that the M06-2X exchange-correlation functional exhibits the best performance to study theoretically vanadium complexes. (C) 2015 Elsevier B.V. All rights reserved.
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