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Coupling of molecular motions through non‐bonding interactions: 13 C NMR spin–lattice relaxation studies of a host–guest complex
Author(s) -
Hilmersson Göran,
Rebek Julius
Publication year - 1998
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199809)36:9<663::aid-omr350>3.0.co;2-1
Subject(s) - chemistry , coupling constant , spin–lattice relaxation , dipole , nuclear overhauser effect , j coupling , crystallography , magnetic dipole–dipole interaction , nuclear magnetic resonance , molecular dynamics , molecular physics , computational chemistry , nuclear magnetic resonance spectroscopy , chemical physics , stereochemistry , organic chemistry , physics , particle physics , nuclear quadrupole resonance
13 C NMR spin–lattice relaxation and 13 C–{ 1 H} nuclear Overhauser measurements were performed on the encapsulation complex between [2.2]paracyclophane and a dimeric capsule known as the hydroxy ‘softball.’ The data were analyzed using the formalism for an isotropically diffusing sphere. The binding constant for the complex is (3.5±0.5)×10 3 l mol ‐1 in CDCl 3 at 295 K. The average dipole–dipole relaxation time is 0.45±0.04 s for the CH vectors of the encapsulated [2.2]paracyclophane and 0.30±0.03 s for the skeleton of the hydroxy ‘softball.’ The correlation time for the skeleton of the hydroxy ‘softball’ is 2.7×10 ‐10 s. The corresponding correlation time for the encapsulated [2.2]paracyclophane is calculated to be 1.2×10 ‐10 s. This results in an average dynamic coupling constant, χ, of 0.47, indicating shape complementarity and correlated motion between the hydroxy ‘softball’ and the [2.2]paracyclophane. © 1998 John Wiley & Son Ltd.