Hydrogen bonding to Coumarin-102 in ground and electronically excited states

CHED 1408

Kerri J. Grove and Rollin A. King, rking@bethel.edu. Department of Chemistry, Bethel University, 3900 Bethel Dr, St. Paul, MN 55112-6999
Following electronic excitation of the dye Coumarin-102 (C102), infrared laser pulses tuned to its carbonyl stretch reveal an impulsive cleavage of a hydrogen bond formed with phenol, chloroform or aniline molecules within 200 fs of excitation, with reformation of the hydrogen-bond taking 30 ps. This computational project is an attempt to determine the nature of the hydrogen-bond to C102 in its excited electronic state, and the explanation of the apparent bond-breaking. We report ab initio, density functional, and molecular dynamics computations. Both before and after electronic excitation, the dipole moment of C102, the strength and extent of hydrogen bonding in solution, and the experimentally observed third-order Raman effect are of particular interest.