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Published March 5, 1998 | public
Journal Article

Femtochemistry in Nanocavities: Reactions in Cyclodextrins


We present our first studies of the femtosecond dynamics of reactions in confined nanocavities in water solutions. Intramolecular proton transfer and isomerization dynamics of a hydrogen-bonded molecule (HPMO) in liquid solutions and encapsulated in the cavity formed by β-cyclodextrin (diameter ∼8 Å) is studied using the technique of fluorescence up-conversion. Our results suggest that the proton transfer in aprotic solvents occurs in much less than 300 fs while upon encapsulation this initial step is slowed to the subpicosecond time scale. Furthermore, in these aprotic solvents, HPMO undergoes a picosecond twisting motion around the interaromatic single bond, which is noticeably inhibited when the molecule is inside the nanocavity. Such studies of condensed-phase femtochemistry in nanocavities offer several promising extensions.

Additional Information

© 1998 American Chemical Society. Received: December 15, 1997; In Final Form: January 6, 1998. Publication Date (Web): February 14, 1998. This work was supported by the National Science Foundation. M.C. thanks the Swedish Foundation for International Cooperation in Research and Higher Education (STINT) for its generous fellowship. T.F. is grateful for financial support from the Deutsche Forschungsgemeinschaft. A.D. thanks Prof. A. H. Zewail and his group for their hospitality during his stay in Femtoland V. We thank Dr. W. Kühnle for his help with the HPLC.

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