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An Optically‐Pure Hemicryptophane as NMR and ECD Responsive Probe for Chloroform
Author(s) -
Brégier Frédérique,
Aubert Emmanuel,
Espinosa Enrique,
Chambron JeanClaude
Publication year - 2016
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201600312
Subject(s) - chemistry , cavitand , chloroform , solvent , circular dichroism , molecule , toluene , spectroscopy , nuclear magnetic resonance spectroscopy , proton nmr , derivative (finance) , benzene , chemical shift , crystallography , stereochemistry , organic chemistry , supramolecular chemistry , physics , quantum mechanics , financial economics , economics
An optically pure hemicryptophane cavitand, in which the primary side of permethylated α‐cyclodextrin (α‐CD) is capped with a C 3 ‐chiral cyclotribenzylene (CTB) derivative, responds to its solution environment, either by electronic circular dichroism or 1 H NMR spectroscopy. In particular, the primary methoxy (6′‐OMe) protons of the α‐CD component behave as solvent sensitive NMR probes. For example, they are more shielded in C 2 D 2 Cl 4 than in CDCl 3 , and their chemical shifts show opposite temperature dependence. A similar contrasted behavior was observed in benzene vs. toluene, suggesting that the observed effects are related to the size of the solvent molecule. Molecular Dynamics simulations indicated that C 2 H 2 Cl 4 and CHCl 3 were included in the α‐CD component of the hemicryptophane, but not in the CTB concavity, with binding energies of –21.1 kJ×mol –1 and –32.7 kJ×mol –1 , respectively.