THE EFFECTS OF WATER SOLVATION OF DOUBLE PROTON TRANSFER REACTIONS

摘要

Femtosecond pump-probe studies are presented on water-solvated 7-azaindole dimers formed in a molecular beam. The 7-azaindole dimer has been studied for many years as a model system for the exploration of excited state proton transfer reactions in DNA. It has been demonstrated that the 7-azaindole dimer forms two conformational isomers in the gas phase, one that undergoes proton transfer, and one which does not. Contrary to steady state experiments, our dynamics studies reveal that the nonreactive isomer is actually induced to undergo a double proton transfer reaction when clustered with water. Reactive behavior has been seen with as little as one and as many as nine water molecules clustered along with the dimer. Moreover, in contrast to previous suggestions, we show that the addition of water to the reactive dimer does not prevent the occurrence of the proton transfer reaction.