Phys Chem Chem Phys. 2018 Jan 31;20(5):3079-3091. doi: 10.1039/c7cp06127g.

Real-time observation of the photoionization-induced water rearrangement dynamics in the 5-hydroxyindole-water cluster by time-resolved IR spectroscopy.

Physical chemistry chemical physics : PCCP

Mitsuhiko Miyazaki, Ayumi Naito, Takamasa Ikeda, Johanna Klyne, Kenji Sakota, Hiroshi Sekiya, Otto Dopfer, Masaaki Fujii

PMID: 29143839 DOI: 10.1039/c7cp06127g

Abstract

Solvation plays an essential role in controlling the mechanism and dynamics of chemical reactions in solution. The present study reveals that changes in the local solute-solvent interaction have a great impact on the timescale of solvent rearrangement dynamics. Time-resolved IR spectroscopy has been applied to a hydration rearrangement reaction in the monohydrated 5-hydroxyindole-water cluster induced by photoionization of the solute molecule. The water molecule changes the stable hydration site from the indolic NH site to the substituent OH site, both of which provide a strongly attractive potential for hydration. The rearrangement time constant amounts to 8 ± 2 ns, and is further slowed down by a factor of more than five at lower excess energy. These rearrangement times are slower by about three orders of magnitude than those reported for related systems where the water molecule is repelled from a repulsive part of the interaction potential toward an attractive well. The excess energy dependence of the time constant is well reproduced by RRKM theory. Differences in the reaction mechanism are discussed on the basis of energy relaxation dynamics.

Publication Types

• Journal Article