Quantum-chemical investigation of the photoproduct of the reaction of two 1-methylthymine molecules: The pyrimidine(6-4)pyrimidone adduct

Abstract

One of the products of the photochemical reaction induced by UV irradiation of the two 1-methylthymine molecules is pyrimidine(6-4)pyrimidone. Due to the low yield of this product, it is difficult to examine its geometry and vibrational spectrum. In this study, quantum chemical methods were used to characterize the structure of pyrimidine(6-4)pyrimidone. Its three conformers were optimized and their structures compared. Their vibrational frequencies in the harmonic approximation are discussed briefly. It was shown that the most significant changes in the infrared spectra arise from the formation of hydrogen bonds. All calculations were performed both in vacuum and in D2O. © 2012 Copyright (CC) SCS.