Graphene oxide liquid crystals as a versatile and tunable alignment medium for the measurement of residual dipolar couplings in organic solvents.
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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DOI：
10.1021/ja506074a
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发表时间：
2014-08
影响因子：
15
通讯作者：
Xinxiang Lei;Zhen Xu;Han Sun;Shunchin C. Wang;C. Griesinger;Li-hua Peng;Chao Gao;R. Tan
中科院分区：
文献类型：
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作者：
Xinxiang Lei;Zhen Xu;Han Sun;Shunchin C. Wang;C. Griesinger;Li-hua Peng;Chao Gao;R. Tan
残余偶极耦合（RDC）已被证明是一个宝贵的各向异性NMR参数的复杂的生物聚合物和有机分子的结构解析。然而，限制有机和天然产物化学家更广泛使用的剩余瓶颈是缺乏一系列易于适用于各种有机溶剂的配向介质。在这项研究中，氧化石墨烯（GO）液晶（LC）的开发，以诱导有机分子的部分取向，允许RDC测量。这些LC被确定为维持在非常低的浓度（低至1 mg/mL，对应于四极（2）H分裂范围为2.8至30 Hz，并且对于CH 3COCH 3/水系统中的樟脑，最大（13）C-（1）H偶极耦合为20 Hz），并且是显著稳定的，并且与水性和有机溶剂（如二甲亚砜、CH 3COCH 3和CH 3CN）广泛相容。此外，与其他取向介质相比，由于GO分子的刚性和高分子量，在溶液中获得了非常干净和高质量的NMR光谱。开发的介质提供了一个通用的和强大的方法，RDC的测量，可以简化的RDC为基础的有机分子的结构测定。
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 (2)H splittings ranging from 2.8 to 30 Hz and maximum (13)C-(1)H 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.