Ultrafast Excited-State Deactivation of 8‑Hydroxy-2′-deoxyguanosine Studied by Femtosecond Fluorescence Spectroscopy and Quantum-Chemical Calculations

International audienceThe fluorescence properties of the 8-hydroxy-2′- deoxyguanosine (8-oxo-dG) in aqueous solution at pH 6.5 are studied by steady-state spectroscopy and femtosecond fluorescence up-conversion and compared with those of 2′-deoxyguanine (dG) and 2′-deoxyguanine monophosphate (dGMP). The steady-state fluorescence spectrum of 8-oxo-dG is composed of a broad band that peaks at 356 nm and extends over the entire visible spectral region, and its fluorescence quantum yield is twice that of dG/dGMP. After excitation at 267 nm, the initial fluorescence anisotropy at all wavelengths is lower than 0.1, giving evidence of an ultrafast internal conversion (