Improved Computational Prediction of the Electrochemical Reduction Potential of Twenty 3-Aryl-Quinoxaline-2-Carbonitrile 1,4-Di-N-Oxide Derivatives

Abstract

The ability of density functional theory (DFT) using the functional B3LYP with the cc-pVTZ basis set to accurately predict the electrochemical properties of 20 3-aryl-quinoxaline-2-carbonitrile 1,4-di-N-oxide derivatives in dimethylformamide (DMF) was investigated and compared to previous predictions from B3LYP/6-31G and B3LYP/lanl2dz. The B3LYP/cc-pVTZ method was an improvement over the B3LYP/6-31G and B3LYP/lanl2dz methods as it was able to predict the first reduction potential of the diazine ring (wave 1) for all of the 3-aryl-quinoxaline-2-carbonitrile 1,4-di-N-oxide derivatives accurately. The B3LYP/cc-pVTZ predicted electrochemical potentials had a strong correlation to experimental values for wave 1. None of the methods demonstrated the ability to predict the nitro wave reduction potential for derivatives containing a nitro group. B3LYP/cc-pVTZ predicted electrochemical potentials for the second reduction of the diazine ring (wave 2) had a low correlation to the experimental values for the derivatives without a nitro group and no correlation of the derivatives when the nitro group was included in the analysis.