期刊
MAGNETIC RESONANCE IN CHEMISTRY
卷 57, 期 11, 页码 961-967出版社
WILEY
DOI: 10.1002/mrc.4921
关键词
alignment; enantiodifferentiation; helicenes; NMR spectroscopy; residual dipolar couplings
Two functionalized [6]carbohelicenes, one of which was also available in its two enantiomeric pure forms, were oriented in stretched polystyrene in CDCl3, and in a recently introduced chiral thermoresponsive lyotropic polyaspartate (poly(benzyl)(0.5)(phenethyl)(0.5)-L-aspartate) in C2D2Cl4. From the resulting H-1,C-13 residual dipolar couplings, the helical pitch of a methylated [6]carbohelicene was determined and found to be in agreement with theoretical predictions and existing crystal structures (d(C2,C2 ') approximate to 4.3 angstrom). For a second [6]carbohelicene with para-methoxyphenyl substituents, a clear conformational preference of the substituents was observed. The orientational properties of the two helicene enantiomers in the chiral polyaspartate are very similar, but both drastically change around 306 K. We suggest this behavior is due to an unusual phase transition in the liquid crystal.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据