文摘
The photophysical properties and tautomerization behavior of neutral lumazine were studied by fluorescence spectroscopy and density functional theory calculation. A quantitative estimation of the contributions from different solvatochromic parameters, like solvent polarizibility (¦Ð?), hydrogen bond donation (¦Á) and hydrogen bond accepting (¦Â) ability of the solvent, was made using linear free energy relationships based on the Kamlet-Taft equation. The analysis reveals that the hydrogen bond acceptance ability of the solvent is the most important parameter characterizing the excited state behavior of lumazine. Theoretical calculations result predict an extensive charge redistribution of lumazine upon excitation corresponding to the N3 and N1 proton dissociation sites by solvents in the ground and excited states, respectively. Comparison of S0 and S1 state potential energy curves constructed for several water mediated tautomerization processes by intrinsic reaction coordinate analysis of lumazine-H2O cluster shows that (3,2) and (1,8) hydrogen migrations are the most favorable processes upon excitation.
