Interaction of H2@C60 and Nitroxide through Conformationally Constrained Peptide Bridges
Luca Garbuio, Yongjun Li, Sabrina Antonello, José A. Gascón, Ronald G. Lawler, Xuegong Lei, Yasujiro Murata, Nicholas J. Turro and Flavio Maran
Article first published online: 28 NOV 2013 | DOI: 10.1111/php.12191
We synthesized two molecular systems, in which a nitroxide and an endofullerene C60, incarcerating one hydrogen molecule (H2@C60), are connected by a folded 310-helical peptide. Despite the similar apparent distance r, reversing the orientation of the peptide bridge significantly affects the nuclear spin relaxation rate and the para → ortho conversion rate of the incarcerated hydrogen molecule. Overall, the results strengthen the outcome of previous investigations that while the conversion rates satisfactorily obey the Wigner's theory, the relaxation rates are in excellent agreement with the Solomon–Bloembergen equation.