Intramolecular Electron Transfer from Dipole-Bound to Valence Orbitals: Uracil and 5-Chlorouracil

Abstract

The electronic interaction between dipole-bound and valence anions of uracil and chlorouracil is investigated. In general, dipole-bound and valence states of an anion show very different electronic structures and the extra electron occupies completely different regions of space. Here, the coupling strength between the different attachment states is computed by fitting a simple diabatic model potential to a cut through the two adiabatic surfaces of the anions obtained from ab initio calculations. During these calculations, electron affinities of uracil and chlorouracil as well as resonance energies associated with vertical attachment into the valence orbitals of these molecules are obtained, and our results are compared with the available experimental and theoretical data. The estimated electronic coupling governs the intramolecular electron transfer from dipole-bound to valence orbitals, and the associated transfer rate has implications for the mechanism of electron attachment and electron-induced bond cl...