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A DFT study on the standard electrode potentials of 2-substituted imidazoles

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Abstract

Extensive density functional theory, calculations, with optimization of geometries and estimation of substituent effects, have been performed to investigate the electrode potentials of dimer and protonated cation structures of 2-substituted imidazoles. The gas phase geometries of dimer, anion, protonated cation, and neutral structures of 2-substituted imidazoles have been optimized using Boese-Martin for kinetics (BMK) and the Minnesota 2005 (M05) hybrid functionals combined with the valence triple-ζ quality with polarization function (TZVP) basis set. The geometries in the presence of acetonitrile solvent have been optimized using the conductor-like polarizable continuum model model of solvation at the same levels of theory. Frequency calculations have been performed for all the structures and none of them is found to exhibit any imaginary frequency. N[BOND]H---H infrared harmonic frequencies have been calculated and compared with available experimental data. The substituent effects on the electrode potentials of imidazole have been investigated as electron donating [BOND]CH3, [BOND]OH, [BOND]NH2, [BOND]OCH3 and electron withdrawing [BOND]NO2, [BOND]Cl, [BOND]F, [BOND]Br groups, which are bonded to the second numbered carbon atom of the imidazole molecule. It has been found that electron donating substituents show more negative electrode potentials, whereas electron withdrawing substituents have the opposite effect. © 2012 Wiley Periodicals, Inc.

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