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NMR spectroscopic characterization of inclusion complexes comprising cyclodextrins and gallated catechins in aqueous solution: cavity size dependency
Author(s) -
Ishizu Takashi,
Tsutsumi Hiroyuki,
Yamamoto Hideji,
Harano Kazunobu
Publication year - 2009
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.2383
Subject(s) - chemistry , moiety , stereochemistry , proton nmr , ring (chemistry) , aqueous solution , inclusion (mineral) , crystallography , gallate , carbon 13 nmr , cyclodextrin , organic chemistry , nuclear chemistry , mineralogy
The structure of inclusion complexes of γ‐cyclodextrin (γ‐CD), (–)‐gallocatechin gallate (GCg), and (–)‐epigallocatechin gallate (EGCg) in D 2 O was investigated using several NMR techniques. GCg formed a 1:1 inclusion complex with γ‐CD in which the A and C rings of GCg were inserted deep at the head of the A ring into the γ‐CD cavity from the wide secondary hydroxyl group side. In the 1:1 inclusion complex with GCg and γ‐CD, the GCg moiety maintained a conformation in which the B and B′ rings of GCg took both pseudoequatorial positions with respect to the C ring. The structure of the inclusion complex of GCg and γ‐CD obtained from NMR experiments supported well that determined from PM6 semiempirical SCF MO calculations. However, 1 H NMR experiments suggested that EGCg did not form any inclusion complex with γ‐CD in D 2 O. The marked difference between GCg and EGCg in inclusion behavior toward γ‐CD may be explained in terms of the stabilization energy calculated with the PM6 method. Copyright © 2008 John Wiley & Sons, Ltd.