Experimental determination of orientations for the 17 O electric-field-gradient and chemical shielding tensors in L-alanine.
We have presented a solid-state 17 O NMR study of [13C, 17 O]-L-alanine. Using the experimental results for the 13C-17 O dipolar vector and Euler angles, the absolute orientations of 17 O chemical shielding (CS) and electric-field-gradient (EFG) tensors with respect to the molecular frame can be determined for L-alanine. The present results suggest that the intermediate EFG tensor components, VYY, lie in the carboxylate plane and parallel to the C-O bond directions, while the least shielded components, delta11, and the intermediate CS tensor components, delta22, roughly lie in the molecular plane and the direction of delta22 components are approximately 38 degrees and 25 degrees off the C-O bonds for O1 and O2, respectively. These results are in reasonable agreement with those of our quantum chemical calculations reported previously.
Yamada
Kazuhiko
K
Tsukuba Magnet Laboratory, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003, Japan. YAMADA.Kazuhiko@nims.go.jp
Shimizu
Tadashi
T
Asanuma
Miwako
M
Yamazaki
Toshio
T
Yokoyama
Shigeyuki
S
D000409:Alanine / Q000737:chemistry*; D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010103:Oxygen Isotopes; D012815:Signal Processing, Computer-Assisted
D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D000409:Alanine