通过 13C NMR 光谱和 DFT 计算相结合研究两种氟代和异硫氰酸酯取代的向列相介晶的取向有序性。
Orientational order of two fluoro- and isothiocyanate-substituted nematogens by combination of 13C NMR spectroscopy and DFT calculations.
机构信息
Istituto di Chimica dei Composti OrganoMetallici, Consiglio Nazionale delle Ricerche - CNR , via G. Moruzzi 1, 56124 Pisa, Italy.
出版信息
J Phys Chem B. 2014 Mar 27;118(12):3469-77. doi: 10.1021/jp412565s. Epub 2014 Mar 18.
Orientational order properties of two nematogens containing a fluoro- and isothiocyanate-substituted biphenyl moiety have been investigated by means of (13)C NMR spectroscopy. (13)C NMR spectra acquired on static samples under high-power (1)H-decoupling allowed both (13)C chemical shift anisotropies and (13)C-(19)F couplings to be measured. These data were used to determine the local principal order parameter and biaxiality for the different rigid fragments of the molecules. To this aim, advanced DFT methods for the calculation of geometrical parameters and chemical shift tensors were used. The orientational order parameters obtained by NMR have been critically compared with those obtained by dielectric spectroscopy. Trends of order parameters with temperature have been analyzed in terms of both mean field theory and the empirical Haller equation.
通过（13）C NMR 光谱研究了两种含有氟代和异硫氰酸酯取代联苯部分的向列相液晶的取向序性质。在高功率（1）H 去耦下采集静态样品的（13）C NMR 谱，允许测量（13）C 化学位移各向异性和（13）C-（19）F 耦合。这些数据用于确定分子不同刚性片段的局部主序参数和双轴性。为此，使用了先进的 DFT 方法来计算几何参数和化学位移张量。通过 NMR 获得的取向序参数与通过介电光谱获得的参数进行了严格比较。根据平均场理论和经验 Haller 方程分析了温度对序参数的影响。
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