Cartesian coordinates of optimiized geometries from Insights into the deactivation of 5-bromouracil after ultraviolet excitation
2017-02-08T14:53:15Z (GMT) by
5-Bromouracil is a nucleobase analogue that can replace thymine in DNA strands and acts as a strong radiosensitizer, with potential applications in molecular biology and cancer therapy. Here, the deactivation of 5-bromouracil after UV irradiation is investigated in the singlet and triplet manifold by accurate quantum chemistry calculations and non-adiabatic dynamics simulations. It is found that after irradiation to the bright ππ* state, three main relaxation pathways are, in principle, possible: relaxation back to the ground state, intersystem crossing (ISC) and C–Br photodissociation. Based on accurate MS-CASPT2 optimizations, we propose that ground-state relaxation should be the predominant deactivation pathway in gas phase. We then employ different electronic structure methods to assess their suitability to carry out excited-state dynamics simulations. MRCIS was used in surface hopping simulations to compute the ultrafast ISC dynamics, which mostly involves the <sup>1</sup>n<sub>O</sub>π* and <sup>3</sup>ππ* states.This article is part of the themed issue ‘Theoretical and computational studies of non-equilibrium and non-statistical dynamics in gas phase, condensed phase and interfaces’.