NMR spectroscopic characterization of adinazolam mesylate: pH-dependent structure change in aqueous solution and active methylene.
The present study is to investigate structural changes of adinazolam mesylate in aqueous solution under various pH conditions by NMR spectroscopy. By plotting of the signal integration and chemical shifts of the side chain, pKa values for imine hydrolysis and the side chain amine were determined. Conformational analysis of the side chain was performed with deuterium-induced isotope effects on chemical shifts, nuclear Overhauser effects, relaxation times, and energy calculations. Hydrogen/deuterium exchange due to an active methylene at the 4-position under basic conditions was revealed.
Ogata
M
M
Tsukuba Research Laboratories, Upjohn Pharmaceuticals Limited, Ibaraki, Japan.
Tahara
T
T
Nishimura
T
T
D000928:Antidepressive Agents / Q000737:chemistry*; D001569:Benzodiazepines / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D006859:Hydrogen / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet
D000928:Antidepressive Agents; D012996:Solutions; D001569:Benzodiazepines; D006859:Hydrogen; C074080:adinazolam mesylate