On the accessibility to conical intersections in purines: hypoxanthine and its singly protonated and deprotonated forms.

摘要: The dynamics following electronic excitation of hypoxanthine and its nucleoside inosine were studied by femtosecond fluorescence up-conversion. Our objective was to explore variants the purinic DNA bases in order determine molecular parameters that increase or reduce accessibility ground state conical intersections. From experiments water methanol solution we conclude both dominant neutral tautomers exhibit ultrashort excited lifetimes (τ < 0.2 ps), which are significantly shorter than related nucleobase guanine. This points a more accessible intersection for fluorescent upon removal amino group, present guanine but absent hypoxanthine. singly protonated also studied, showing biexponential decays with 1.1 ps component (5%) besides sub-0.2 ultrafast component. On other hand, S1 deprotonated forms show d...