Covalent Anion of the Canonical Adenine−Thymine Base Pair. Ab Initio Study

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 104; no. 13; pp. 2994 - 2998
• Main Authors: Al-Jihad, Ismail, Smets, Johan, Adamowicz, Ludwik
• Format: Journal Article
• Language: English
• Published: American Chemical Society 06.04.2000
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp993975i

Theoretical ab initio calculations have been performed to determine the stability of the covalent anions of adenine and the adenine−thymine (AT) Watson−Crick base pair. The conclusions of this work are as follows:  (i) the covalent anion of adenine is predicted to be a stable system with respect to a vertical electron detachment, but unstable with respect to adiabatic detachment; (ii) the covalent anion of the adenine−thymine dimer (A−T-) has similar properties, although in this system the presence of the second base provides an additional stabilization to the excess electron; (iii) in A−T- the excess electron is localized at the thymine molecule, and this molecule's ring is puckered; (iv) no valence A−T anion was found in the calculations with the excess electron located at the adenine molecule; and (v) in view of the above results, we predict that the AT base pair is not an effective trap of excess electrons.