一种用于解析基于噻吩的向列相液晶重叠芳香族共振峰的二维固态核磁共振实验。

A 2D solid-state NMR experiment to resolve overlapping aromatic resonances of thiophene-based nematogens.

作者信息

Narasimhaswamy Tanneru, Lee Dong-Kuk, Yamamoto Kazutoshi, Somanathan Narayanasastri, Ramamoorthy Ayyalusamy

机构信息

Biophysics Research Division and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.

出版信息

J Am Chem Soc. 2005 May 18;127(19):6958-9. doi: 10.1021/ja051160j.

DOI:10.1021/ja051160j

PMID:15884932

Abstract

In this study, we demonstrate the feasibility of resolving overlapping 13C chemical shift spectral lines of aromatic rings in a thiophene-based nematogen in the mesophase using a 2D PITANSEMA solid-state NMR method. This technique provided the information about chemical shift values as well as dipolar couplings that are used for determining the orientational order parameter. Large C-H dipolar coupling values measured for thiophene in contrast to phenyl rings suggest that the heterocyclic ring is not part of the molecular axis. Using the order parameter, we determined the orientation of C-H vectors of the thiophene ring. We believe that the 2D solid-state NMR can be extended to other types of liquid crystalline materials such as the banana-based mesogens for determining the orientational order and bent angle.

摘要

在本研究中，我们证明了使用二维PITANSEMA固态核磁共振方法解析基于噻吩的向列相液晶中介相中芳环重叠的13C化学位移谱线的可行性。该技术提供了化学位移值以及用于确定取向序参数的偶极耦合信息。与苯环相比，噻吩测得的大C-H偶极耦合值表明杂环不是分子轴的一部分。利用序参数，我们确定了噻吩环C-H向量的取向。我们认为二维固态核磁共振可扩展到其他类型的液晶材料，如基于香蕉形的液晶，以确定取向序和弯曲角。