Bioexcimers as Precursors of Charge Transfer and Reactivity in Photobiology
- Institute de Ciencia Molecular, Universitat de Valencia Apartado de Correos 22085, ES-46071 Valencia (Spain)
- Fundacio General, Universitat de Valencia, Plaza del Patriarca, 4, 1, ES-46002 Valencia (Spain)
Accurate CASPT2//CASSCF calculations show that {pi}-stacked interactions in different biochromophores such as DNA nucleobases or porphyrin-quinone pairs yield excimer-like situations which behave as precursors of processes like charge transfer or photoreactivity. Examples are the transfer of charge between a reduced pheophytin and an accepting quinone molecule, process that trigger the sequence of electron transfer phenomena in photosynthetic photosystem II, the electron transfer between adjacent DNA nucleobases in a strand of oligonucleotides, and the photodimerization taking place in cytosine pairs leading to cyclobutanecytosine mutants. These processes take place through nonadiabatic photochemical mechanisms whose evolution is determined by the presence and accessibility of conical intersections and other surface crossings between different electronic states.
- OSTI ID:
- 21049423
- Journal Information:
- AIP Conference Proceedings, Vol. 963, Issue 1; Conference: ICCMSE 2007: International conference on computational methods in science and engineering, Corfu (Greece), 25-30 Sep 2007; Other Information: DOI: 10.1063/1.2827037; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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