Experimental and theoretical ab initio study of the influence of N-methylation on the dipole-bound electron affinities of thymine and uracil

The influence of N-methylation on the dipole-bound electron affinities of p yrimidine nucleic acid bases, uracil and thymine, has been investigated the oretically using ab initio quantum mechanical calculations, and experimenta lly using Rydberg electron transfer spectroscopy. Both experiment and theor y are consistent in showing that replacement of hydrogen atoms by methyl gr oups reduces electron affinities corresponding to formation of dipole-bound anions of these systems. Also, the distortion of the anion geometries with respect to the geometries of the neutral parents are reduced with the meth ylation. (C) 1999 American Institute of Physics. [S0021-9606(99)00124-5].