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A solid‐state 17 O NMR study of L ‐phenylalanine and L ‐valine hydrochlorides
Author(s) -
Yamada Kazuhiko,
Shimizu Tadashi,
Ohki Shinobu,
Yamazaki Toshio
Publication year - 2008
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.2167
Subject(s) - chemistry , chemical shift , electric field gradient , molecule , magic angle spinning , phenylalanine , hydrogen bond , coupling constant , crystallography , stereochemistry , nuclear magnetic resonance spectroscopy , computational chemistry , quadrupole , amino acid , organic chemistry , biochemistry , physics , atomic physics , particle physics
We have presented an experimental investigation of the oxygen‐17 chemical shielding (CS) and electric‐field‐gradient (EFG) tensors for α‐COOH groups in polycrystalline amino acid hydrochlorides. The 17 O CS and EFG tensors including the relative orientations between the two NMR tensors are determined in [ 17 O]‐ L ‐phenylalanine hydrochloride and [ 17 O]‐ L ‐valine hydrochloride by the analysis of the 17 O magic‐angle‐spinning (MAS) and stationary NMR spectra obtained at 9.4, 11.7, 16.4, and 21.8 T. The quadrupole coupling constants ( C Q ) and the span of the CS tensors are found to be 8.41–8.55 MHz and 7.35–7.41MHz, and 548–570 ppm and 225–231 ppm, for carbonyl and hydroxyl oxygen atoms, respectively. Extensive quantum chemical calculations using density functional theory (DFT) have been also carried out for a hydrogen‐bonding model. It is demonstrated that the behavior of the dependence of hydrogen‐bond distances on 17 O NMR tensors for the halogen ions is different from those for the water molecule. Copyright © 2008 John Wiley & Sons, Ltd.