Probing excited-state dynamics and intramolecular proton transfer in 1-acylaminoanthraquinones via the intermodular solvent response

Sarah J. Schmidtke, David F. Underwood, David A. Blank

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

The dynamics of a series of 1-acylaminoanthraquinones with varying degrees of excited-state intramolecular proton transfer are studied in acetonitrile and dichloromethane. Events are followed via changes in the third-order intermolecular Raman response as a function of time after resonant excitation of the chromophore. Compared to electronically resonant probes of the solute, measuring the ultrafast dynamics using the nonresonant solvent response offers a new and complementary perspective on the events that accompany excitation and proton transfer. Experimentally observed changes in the nuclear polarizability of the solvent follow dynamic changes in the solvent-solute interactions. Reorganization of the solvent in response to the significant changes in the intermolecular interactions upon proton transfer is found to play an important role in the reaction dynamics. With transfer of the proton taking place rapidly, the solvent controls the dynamics via the timedependent evolution of the free energy surface, even on subpicosecond time scales. In addition, the solvent response probes the effects of intermolecular energy transfer as energy released during the reactive event is rapidly transferred to the local solvent environment and then dissipates to the bulk solvent on about a 10 ps time scale. A brief initial account of a portion of this work has appeared previously, J. Am. Chem. Soc. 2004, 126, 8620-8621.

Original languageEnglish (US)
Pages (from-to)7033-7045
Number of pages13
JournalJournal of Physical Chemistry A
Volume109
Issue number32
DOIs
StatePublished - Aug 18 2005

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