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Kufner, Corinna L.; Zinth, Wolfgang; Bucher, Dominik B. (2020): UV-Induced Charge-Transfer States in Short Guanosine-Containing DNA Oligonucleotides. In: Chembiochem, Vol. 21, No. 16: pp. 2306-2310
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Charge transfer has proven to be an important mechanism in DNA photochemistry. In particular, guanine (dG) plays a major role as an electron donor, but the photophysical dynamics of dG-containing charge-transfer states have not been extensively investigated so far. Here, we use UV pump (266 nm) and picosecond IR probe (similar to 5-7 mu m) spectroscopy to study ultrafast dynamics in dG-containing short oligonucleotides as a function of sequence and length. For the pure purine oligomers, we observed lifetimes for the charge-transfer states of the order of several hundreds of picoseconds, regardless of the oligonucleotide length. In contrast, pyrimidine-containing dinucleotides d(GT) and d(GC) show much faster relaxation dynamics in the 10 to 30 ps range. In all studied nucleotides, the charge-transfer states are formed with an efficiency of the order of similar to 50 %. These photophysical characteristics will lead to an improved understanding of DNA damage and repair processes.