Premium
Nuclear Magnetic Resonance of Hydrogen Molecules Trapped inside C 70 Fullerene Cages
Author(s) -
Mamone Salvatore,
Concistrè Maria,
Heinmaa Ivo,
Carravetta Marina,
Kuprov Ilya,
Wall Gary,
Denning Mark,
Lei Xuegong,
Chen Judy Y.C.,
Li Yongjun,
Murata Yasujiro,
Turro Nicholas J.,
Levitt Malcolm H.
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300269
Subject(s) - chemistry , anisotropy , molecule , nmr spectra database , j coupling , spectral line , dipole , chemical shift , solid state nuclear magnetic resonance , endohedral fullerene , fullerene , molecular physics , ground state , proton , degenerate energy levels , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , atomic physics , physics , stereochemistry , organic chemistry , quantum mechanics , astronomy
We present a solid‐state NMR study of H 2 molecules confined inside the cavity of C 70 fullerene cages over a wide range of temperatures (300 K to 4 K). The proton NMR spectra are consistent with a model in which the dipole–dipole coupling between the ortho ‐H 2 protons is averaged over the rotational/translational states of the confined quantum rotor, with an additional chemical shift anisotropy δ H CSA =10.1 ppm induced by the carbon cage. The magnitude of the chemical shift anisotropy is consistent with DFT estimates of the chemical shielding tensor field within the cage. The experimental NMR data indicate that the ground state of endohedral ortho ‐H 2 in C 70 is doubly degenerate and polarized transverse to the principal axis of the cage. The NMR spectra indicate significant magnetic alignment of the C 70 long axes along the magnetic field, at temperatures below ∼10 K.