Relaxation mechanisms of UV-photoexcited DNA and RNA nucleobases

0353300 - ÚOCHB 2011 RIV US eng J - Journal Article
Barbatti, M. - Aquino, A. J. A. - Szymczak, J. J. - Nachtigallová, Dana - Hobza, Pavel - Lischka, Hans
Relaxation mechanisms of UV-photoexcited DNA and RNA nucleobases.
Proceedings of the National Academy of Sciences of the United States of America. Roč. 107, č. 50 (2010), s. 21453-21458. ISSN 0027-8424. E-ISSN 1091-6490
R&D Projects: GA MŠMT LC512
Institutional research plan: CEZ:AV0Z40550506
Keywords : nonadiabatic photodynamical simulation * ultrafast photodeactivation * ab-initio multireference methods
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 9.771, year: 2010

Photodynamical ab initio simulations of the relaxation paths for adenine, guanine, cytosine, thymine, and uracil are reported. The simulations are based on a complete nonadiabatic surface-hopping approach using multiconfigurational wave functions. All bases share the basic conversion mechanisms with a different complexity of the photodynamics observed for purine and pyrimidine bases. Purines have the simpliest deactivation mechanism leading along a diabatic .pipi.* path directly and without barrier to the conical intersection with the ground state. For pyrimidines, the dynamics starts in flatt regions of the .pi.pi. surface due to coupling of several states prohibiting a clear formation of a single reaction path. Thus, their photodynamics is much richer and includes also .pi.pi. states. Implications of these findings are discussed for identifying possible singlet/triplet transitions and concerning the photodynamics of substituted pyrimidines as candidates for alternative nucleobases.
Permanent Link: http://hdl.handle.net/11104/0192584