Predicting the paramagnet-enhanced NMR relaxation of H₂ encapsulated in endofullerene nitroxides by density-functional theory calculations.

TitlePredicting the paramagnet-enhanced NMR relaxation of H₂ encapsulated in endofullerene nitroxides by density-functional theory calculations.
Publication TypeJournal Article
Year of Publication2013
AuthorsRastrelli F, Frezzato D, Lawler RG, Li Y, Turro NJ, Bagno A
JournalPhilosophical transactions. Series A, Mathematical, physical, and engineering sciences
Volume371
Issue1998
Pagination20110634
Date Published2013 Sep 13
Abstract

We have investigated the structure and nuclear magnetic resonance (NMR) spectroscopic properties of some dihydrogen endofullerene nitroxides by means of density-functional theory (DFT) calculations. Quantum versus classical roto-translational dynamics of H₂ have been characterized and compared. Geometrical parameters and hyperfine couplings calculated by DFT have been input to the Solomon-Bloembergen equations to predict the enhancement of the NMR longitudinal relaxation of H₂ due to coupling with the unpaired electron. Estimating the rotational correlation time via computed molecular volumes leads to a fair agreement with experiment for the simplest derivative; the estimate is considerably improved by recourse to the calculation of the diffusion tensor. For the other more flexible congeners, the agreement is less good, which may be due to an insufficient sampling of the conformational space. In all cases, relaxation by Fermi contact and Curie mechanisms is predicted to be negligible.

DOI10.1093/jxb/ert178
Alternate JournalPhilos Trans A Math Phys Eng Sci