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Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using 13 C NMR in the solid state and solution along with single crystal X‐ray diffraction
Author(s) -
Steiner Emilie,
Mathew Renny,
Zimmermann Iwan,
Brotin Thierry,
Edén Mattias,
Kowalewski Jozef
Publication year - 2015
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/mrc.4265
Subject(s) - chemistry , dichloromethane , chloroform , magnetic dipole–dipole interaction , nuclear magnetic resonance spectroscopy , solid state nuclear magnetic resonance , chemical shift , molecule , crystallography , single crystal , crystal structure , dipole , stereochemistry , nuclear magnetic resonance , organic chemistry , physics , solvent
Host‐guest complexes between cryptophane‐A analogue with butoxy groups (cryptophane‐But) and chloromethanes (chloroform, dichloromethane) were investigated in the solid state by means of magic‐angle spinning 13 C NMR spectroscopy. The separated local fields method with 13 C‐ 1 H dipolar recoupling was used to determine the residual dipolar coupling for the guest molecules encaged in the host cavity. In the case of chloroform guest, the residual dipolar interaction was estimated to be about 19 kHz, consistent with a strongly restricted mobility of the guest in the cavity, while no residual interaction was observed for encaged dichloromethane. In order to rationalize this unexpected result, we performed single crystal X‐ray diffraction studies, which confirmed that both guest molecules indeed were present inside the cryptophane cavity, with a certain level of disorder. To improve the insight in the dynamics, we performed a 13 C NMR spin‐lattice relaxation study for the dichloromethane guest in solution. The system was characterized by chemical exchange, which was slow on the chemical shift time scale but fast with respect to the relaxation rates. Despite these disadvantageous conditions, we demonstrated that the data could be analyzed and that the results were consistent with an isotropic reorientation of dichloromethane within the cryptophane cavity. Copyright © 2015 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.