Graphene Oxide Liquid Crystals as a Versatile and Tunable Alignment Medium for the Measurement of Residual Dipolar Couplings in Organic Solvents

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• 作者：Xinxiang Lei ; Zhen Xu ; Han Sun ; Shun Wang ; Christian Griesinger ; Li Peng ; Chao Gao ; Ren X. Tan
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：August 13, 2014
• 年：2014
• 卷：136
• 期：32
• 页码：11280-11283
• 全文大小：270K
• ISSN：1520-5126

文摘

Residual dipolar couplings (RDCs) have proven to be an invaluable anisotropic NMR parameter for the structural elucidation of complex biopolymers and organic molecules. However, a remaining bottleneck limiting its wider use by organic and natural product chemists is the lack of a range of easily applicable aligning media for diverse organic solvents. In this study, graphene oxide (GO) liquid crystals (LCs) were developed to induce partial orientation of organic molecules to allow RDC measurements. These LCs were determined to be maintainable at very low concentrations (as low as 1 mg/mL, corresponding to quadrupolar ²H splittings ranging from 2.8 to 30 Hz and maximum ¹³C鈥?sup>1H dipolar couplings of 20 Hz for camphor in a CH₃COCH₃/water system) and to be remarkably stable and broadly compatible with aqueous and organic solvents such as dimethyl sulfoxide, CH₃COCH₃, and CH₃CN. Moreover, compared with those for other alignment media, very clean and high-quality NMR spectra were acquired with the GO molecules in solution because of their rigidity and high molecular weight. The developed medium offers a versatile and robust method for RDC measurements that may routinize the RDC-based structure determination of organic molecules.