The uracil dimer and trimer covalent anions: An ab initio study

In this work, we present new structures for both the uracil dimer anion (U-2(-)) and trimer anion (U-3(-)) calculated at the MP2/631++G** level of theory. In these systems, the excess electron is localized at only one uracil unit in a n-state and that molecule shows some off-plane distortion leading to higher anion stabilization. In both structures excess electron attachment leads to the formation of a stable covalent anion, with electron affinity values of 0.25, 0.05 eV for U-2 and U-3. respectively. Experimental implications in relation to the calculated data are also discussed. (c) 2005 Published by Elsevier B.V.