The use of UV-C radiation as a germicidal agent has been employed in combating the global pandemic caused by the novel coronavirus (SARS-CoV-2), and the characterization of the structures generated from the interaction of biological material with radiation constitutes an important area of research. With this in mind, a theoretical study is presented, conducted through first principles computational methods, which aims to analyze the structural, electronic, and kinetic properties of systems composed of the nitrogenous bases that make up DNA or RNA (Thymine, Uracil, Guanine, Adenine, and Cytosine), with emphasis on pyrimidine dimers (Thymine and Uracil), which are one of the main photoproducts generated from the interaction of UV-C radiation with biological material. The dimers are formed due to the emergence of carbon-carbon (C-C) bonds different from those already identified in isolated bases. Our results for electronic properties show that the new C-C bonds are responsible for increasing the energy gap values and altering the valence band of the dimers. Reaction barrier calculations for Thymine dimers show that the desorption process is a barrierless event.
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