1 research outputs found
Ab Initio Study on an Excited-State Intramolecular Proton-Transfer Reaction in Ionic Liquid
An excited-state intramolecular proton
transfer (ESIPT) reaction
of 4′-<i>N</i>,<i>N</i>-dimethylamino-3-hydroxyflavone
in room temperature ionic liquid is theoretically investigated using
RISM-SCF-SEDD, which is a hybrid method of molecular liquid theory
and ab initio molecular orbital theory. The photo-excitation and proton-transfer
processes are computed by considering the solvent fluctuation. The
calculated absorption and emission energy are in good agreement with
the experiments. The changes in the dipole moment indicate that the
drastic solvation relaxation is accompanied by the excitation and
an ESIPT process, which is consistent with the remarkable dynamic
Stokes shift observed in the experiments. We calculated the nonequilibrium
free-energy contour as a function of the proton coordinate and the
solvation coordinate. We conclude that although immediately after
the excitation the barrier height of the ESIPT process is relatively
small, the barrier becomes larger as the solvation relaxation to the
excited normal state proceeds. The solvation relaxation process is
also investigated on the basis of microscopic solvation structure
obtained by RISM calculations