2A12 MHPOBCの¹³C-¹H二重共鳴における過渡的磁化振動 : キラル中心近傍の分子内運動の変化

抄録

Transient oscillation in ¹³C-¹H cross-polarization dynamics in NMR was studied for MHPOBC. Decay time of oscillation, which is determined by proton spin-diffusion, probes intramolecular motion. It was shown that chain conformational motions around the chiral center are different in the paraelectric smectic A (S_A) and antiferroelectric chiral smectic CA (S_CA^*) phases: A large-amplitude motion in S_A is frozen to a significant extent in S_CA^*, and hence enables a large transverse dipole moment of a molecule to come out.