CHEMISTRY:
Unraveling the Molecular Mechanisms of Photoacidity
Wolfgang Domcke and Andrzej L. Sobolewski
Chemists have long sought to understand proton-transfer processes in aqueous solution at the molecular level. Studies of molecular clusters can provide important insights into these solution processes. In their Perspective, Domcke and Sobolewski highlight the report by Tanner et al., who have studied the photo-induced hydrogen transfer through a hydrogen-bonded molecular wire in a size-selected chromophore-solvent cluster. The reaction can be controlled by the excitation of ammonia-wire vibrations of the reactant and is detected via the fluorescence of the product. The results support a new paradigm of excited-state proton-transfer reactivity. In contrast to ground-state proton transfer, where an ion-pair is formed, the transfer of a hydrogen atom is the primary process in excited-state acid-base reactions.
W. Domcke is at the Institute of Physical and Theoretical Chemistry, Technical University of Munich, 85747 Garching, Germany. E-mail: domcke{at}ch.tum.de A. L. Sobolewski is at the Institute of Physics, Polish Academy of Sciences, 02668 Warsaw, Poland. E-mail: sobola{at}ifpan.edu.pl
