Phase transition of L-Ser monohydrate crystal studied by (13)C solid-state NMR.
We used gravimetric analysis (GA) and (13)C solid-state nuclear magnetic resonance (NMR) to study solid-phase transition from the transparent single crystal of L-serine (L-Ser) monohydrate to a turbid powder. We found that L-Ser monohydrate loses water molecules and transforms into an anhydrate, thus experimentally demonstrating Frey's assumption. Application of a handmade cross-polarization (CP) NMR probe with a saddle-type coil to the oriented crystal of the L-Ser monohydrate revealed the dehydration mechanism. Furthermore, the chemical shift tensor components of the carboxyl carbon in L-Ser monohydrate were determined. The difference in the tensor component of delta(22) between the monohydrate and anhydrate forms was more than 7 ppm, probably owing to differences in the hydrogen-bonding structure of each form.
Kameda
Tsunenori
T
National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan. kamedat@affrc.go.jp
Teramoto
Hidetoshi
H
D003460:Crystallization; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D012694:Serine / Q000737:chemistry*
D012694:Serine