Photoisomerization Dynamics of Candidate Molecules for Vibrational Control Experiments

Vibrational excitation prior to reaction can lead to efficient control of chemical reactions in isolated molecules. Extending vibrational control to the solution phase is complicated by frequent collisions between the molecule of interest and the surrounding solvent. We have shown that in the isomerization of trans-stilbene to cis-stilbene, we can preferentially promote vibrationally excited stilbene to the reactive electronic state. We find that excitation of the C-H stretch overtone and C-H stretch-bend combination band have no influence on the isomerization reaction.;Our results from the stilbene system teach us about isomerization systems that may be amenable to vibrational control. We have used transient absorption techniques to determine the photoisomerization dynamics of dMe-OMe-NAIP, a biomimetic photoswitch. We find that dMe-OMe-NAIP behaves very differently from other molecules in the NAIP class after excitation and determine that these differences are due to small changes in substitution near the reactive double bond.;We have also made the first measurements of the femtosecond and picosecond reaction dynamics of avobenzone, a common sunscreen component. Our measurements show the first direct evidence of a rotational isomer speculated to exist in microsecond-timescale experiments. Our experiments unify the well-studied microsecond and millisecond dynamics of avobenzone with the dynamics that occur immediately after excitation. Avobenzone is a promising candidate for vibrational control because its easily accessible C-H stretching motion may coincide with its enol to keto reaction coordinate.