Conformational Anisotropy of n-Alkanes Dissolved in a Nematic Solvent: A Rotational Isomeric State Analysis of Proton–Proton Dipolar Coupling and Deuterium Quadrupolar Splitting Data
Conformational Anisotropy of n-Alkanes Dissolved in a Nematic Solvent: A Rotational Isomeric State Analysis of Proton–Proton Dipolar Coupling and Deuterium Quadrupolar Splitting Data
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溶解在向列溶剂中的正构烷烃的构象各向异性：质子-质子偶极耦合和氘四极分裂数据的旋转异构态分析
DOI：
10.1295/polymj.23.117
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发表时间：
1991
期刊：
影响因子：
2.8
通讯作者：
A. Abe
中科院分区：
文献类型：
--
作者：
Yuji Sasanuma;A. Abe
研究了正构烷烃链在向列相环境中的构象各向异性。正己烷质子-质子偶极耦合的实验值[M.Gochin等人，Mol.Phys，69,671(1990)]和一系列n-CnD2n+2(n=5，6，7，8，10和16)的2H-核磁共振四极分裂[B.Janik等，J.Phys.化学，91,1842(1987)；D.J.Photinos等人，J.Phys.化学，94,4688(1990)]，根据以前在研究二聚体和聚合物主链液晶时采用的模型进行了分析。我们的处理过程如下：1.在RIS近似的框架内列举了自由分子的所有可能构型。2.对于每个构象，分子轴是沿着最长的惯性主轴定义的。3.根据单纯形法调整分配给各个键旋转的构象统计权重因子，以重现观测结果。通过可靠性因子来监测迭代的收敛情况。在所有的例子中，理论和实验之间的一致性都是令人满意的。由观测数据得到的键构象与自由态的估算结果进行了比较。在向列相介质中发现正构烷烃链具有高度的各向异性。
Conformational anisotropy of n-alkane chains incorporated in a nematic environment has been investigated. Experimental values of proton-proton dipolar couplings of n-hexane [M. Gochin et al., Mol. Phys., 69, 671 (1990)] and 2H-NMR quadrupolar splittings of a series of n-CnD2n+2 (n=5, 6, 7, 8, 10, and 16) [B. Janik et al., J. Phys. Chem., 91, 1842 (1987); D. J. Photinos et al., J. Phys. Chem., 94, 4688 (1990)] have been analyzed according to the model previously employed in the study of dimer and polymer main-chain liquid crystals. Our treatment proceeds as follows: 1. All possible configurations are enumerated for a free molecule within the framework of the RIS approximation. 2. For each conformer, the molecular axis is defined along the ‘longest’ principal axis of inertia. 3. Conformational statistical weight factors assigned to the individual bond rotations are adjusted according to the simplex method so as to reproduce the observations. The convergence of iteration was monitored by the reliability factor. The agreement between theory and experiment was found to be satisfactory in all examples. The bond conformations derived from the observed data were compared with those estimated for the free state. n-Alkane chains were found to be highly anisotropic in the nematic media.