DFT studies on one-electron oxidation and one-electron reduction for 2- and 4-aminopyridinesReport as inadecuate




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Journal of Molecular Modeling

, Volume 18, Issue 9, pp 4367–4380

First Online: 15 May 2012Received: 27 January 2012Accepted: 23 April 2012

Abstract

Quantum-chemical calculations {DFTB3LYP-6-311+Gd,p} were performed for all possible tautomers aromatic and nonaromatic of neutral 2- and 4-aminopyridines and their oxidized and reduced forms. One-electron oxidation has no important effect on the tautomeric preference for 2-aminopyridine. The amine tautomer is favored. However, oxidation increases the stability of the imine NH tautomer, and its contribution in the tautomeric mixture cannot be neglected. In the case of 4-aminopyridine, one-electron oxidation increases the stability of both the amine and imine NH tautomers. Consequently, they possess very close energies. As major tautomers, they dictate the composition of the tautomeric mixture. The CH tautomers may be considered as very rare forms for both neutral and oxidized aminopyridines. A reverse situation takes place for the reduced forms of aminopyridines. One-electron reduction favors the C3 atom for the labile proton for both aminopyridines. This may partially explain the origin of the CH tautomers for the anionic states of nucleobases containing the exo NH2 group.

KeywordsAminopyridines DFT N-aza effects NH and CH tautomers One-electron oxidation One-electron reduction π-Electron delocalization  Download fulltext PDF



Author: Ewa D. Raczyńska - Tomasz M. Stępniewski - Katarzyna Kolczyńska

Source: https://link.springer.com/



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