HIGH-RESOLUTION 13C NMR STUDY OF AN ANTIFERROELECTRIC LIQUID CRYSTAL : VERIFICATION OF THE BENT CHAIN STRUCTURE
HIGH-RESOLUTION 13C NMR STUDY OF AN ANTIFERROELECTRIC LIQUID CRYSTAL : VERIFICATION OF THE BENT CHAIN STRUCTURE
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反铁电液晶的高分辨率 13C NMR 研究：弯曲链结构的验证
DOI：
10.1021/jp9829952
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发表时间：
1999
影响因子：
3.3
通讯作者：
A. Fukuda
中科院分区：
文献类型：
--
作者：
T. Nakai;S. Miyajima;Y. Takanishi;Shohei Yoshida;A. Fukuda
本文报道了反铁电液晶MHPOBC的高分辨~（13）C NMR研究。两个烷基链的结构，手性和非手性链，分析了使用各向同性屏蔽常数，交叉极化效率，和场诱导位移。给出了一个全面的理论处理的闪烁引起的移位。结果表明，手性链的平均方向偏离分子长轴达43°（弯曲链结构），而非手性链的平均方向沿分子长轴沿着延伸.讨论了这种特殊形状的分子与分子双轴性的出现和反铁电性的发生的关系。
A high-resolution13C NMR study is reported on the antiferroelectric liquid crystal MHPOBC, 4-[(1-methylheptyloxy)carbonyl]phenyl 4-[4-(octyloxy)biphenyl]carboxylate. The structures of the two alkyl chains, the chiral and achiral chains, are analyzed using isotropic shielding constants, cross polarization efficiency, and the field alignment-induced shifts. A comprehensive theoretical treatment for the alignment-induced shift is given. It is shown that the average direction of the chiral chain deviates from the molecular long axis by as much as 43° (bent chain structure), while that of the achiral chain extends along the molecular long axis. The relationships of this particular shape of the molecule with the emergence of the molecular biaxiality and with the onset of antiferroelectricity are discussed.