Using photoexcited triplet states to probe small-molecule endohedral fullerenes by ESR

Vasileia Filidou; Salvatore Mamone; Alessandro Bagno; Federico Rastrelli; Yasujiro Murata; Koichi Komatsu; Xuegong Lei; Yongjun Li; Nicholas J. Turro; Malcolm H. Levitt; John J.L. Morton

Using photoexcited triplet states to probe small-molecule endohedral fullerenes by ESR

ORAL

Abstract

Ortho to para conversion of molecular hydrogen $\mbox{H}_{2} $ can be catalyzed by the use of a coupled paramagnet such as a fullerene in its triplet state. The recently synthesized endohedral fullerenes $\mbox{H}_{2} @\mbox{C}_{60} $ and $\mbox{H}_{2} @\mbox{C}_{70} $ were photoexcited to their long lived triplet state (S= 1) and probed by electron spin resonance (ESR) and electron nuclear double resonance (ENDOR) spectroscopic techniques. With these techniques we characterized both spin systems by extracting the hyperfine interaction the kinetic parameters of the triplet state and the spin relaxation times. The observed variations of the linewidths and the lineshape are discussed in the context of a dynamic Jahn-Teller effect. Irradiation of the $\mbox{H}_{2} @\mbox{C}_{70} $ at different temperatures reveals that the fullerene triplet state can serve as a spin catalyst for ortho to para interconversion while for the triplet $\mbox{H}_{2} @\mbox{C}_{60} $ no appreciable interconversion is observed

March 18, 2013, 10:12 AM – March 18, 2013, 10:24 AM

Authors

Vasileia Filidou
- London Centre for Nanotechnology, University College London, London WC1H, UK
Salvatore Mamone
- School of Chemistry, University of Southampton, SO17 1BJ, UK
Alessandro Bagno
- Dipartimento di Scienze Chimiche, Universita di Padova, via Marzolo, 1 -35131, Italy
Federico Rastrelli
- Dipartimento di Scienze Chimiche, Universita di Padova, via Marzolo, 1 -35131, Italy
Yasujiro Murata
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
Koichi Komatsu
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
Xuegong Lei
- Department of Chemistry, Columbia University, New York, New York 10027, US
Yongjun Li
- Department of Chemistry, Columbia University, New York, New York 10027, US
Nicholas J. Turro
- Department of Chemistry, Columbia University, New York, New York 10027, US
Malcolm H. Levitt
- School of Chemistry, University of Southampton, SO17 1BJ, UK
John J.L. Morton
- London Centre for Nanotechnology, University College London, London WC1H, UK