权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

THE ORIENTATION-DEPENDENT INTERACTION ENERGY AS STUDIED BY THE POLARIZABILITY ANISOTROPY ANALYSIS

极化率各向异性分析研究方向相关的相互作用能

基本信息

批准号：
61470098
负责人：
ABE AKIHIRO
金额：
$ 4.29万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

Molecular asymmetry is a feature common to all liquid crystalline substances. Soft-tails or spacers joined with a mesogenic core tend to take extended conformations along the director of the field. The polarizability anisotropy of molecules causes the intermolecular London attractions to be anisotropic, with the results the parallel intermolecular alignment is favored. For regid rods, we can elucidate the anisotropic part of the polarizability tensor from the depolarization Rayleigh scattering (DRS) measurements. The same technique cannot be used for the flexible chains which orient only under the anisotropic environment. The polarizability anisotropy of these flexible chains may be calculated by assuming the bond-additivity rule along the chain, provided that the conformations permitted in the anisotropic state are known. As we have demonstrated in a separate work, the latter information can be obtained by using the deuterium NMR technique.In fiscal 1986, a commercial DRS apparatus, modified slightly in the filtering system, was installed in our laboratory. In the following year, the optical anisotropy measurements were carried out for a series of dipeptides. The limit of thereliability of the apparatus was thus tested. Measurements were also performed for some typical mesogenic compounds such as PAA and MBBA. Finally, the polarizability anisotropy of nCB, a compound comprising cyanobiphenyl core and n-alkyl tail, was estimated according to the procedure described above. Contribution from the flexible tail was found to be substantial. The results obtained for the system with n=5 and 8 are consistent with the odd-even effect observed in various thermodynamic properties at the nematic-isotropic transition temperature. The mothodology we have abopted in this work was thus proved to be useful.

分子不对称性是所有液晶物质的共同特征。与介晶核连接的软尾或间隔区倾向于沿着场的指向矢采取延伸的构象。分子极化率的各向异性导致分子间伦敦引力的各向异性，从而有利于分子间的平行排列。对于regid棒，我们可以阐明各向异性部分的极化率张量从去极化瑞利散射（DRS）的测量。同样的技术不能用于仅在各向异性环境下定向的柔性链。这些柔性链的极化率各向异性可以通过假设沿链的键加性规则沿着来计算，只要各向异性状态下允许的构象是已知的。正如我们在另一项工作中所证明的，后者的信息可以通过使用氘NMR技术来获得。在1986财政年度，在我们的实验室中安装了一台商业DRS装置，在过滤系统中进行了轻微的修改。在接下来的一年中，光学各向异性的测量进行了一系列的二肽。从而检验了仪器的可靠性极限。对PAA、MBBA等典型介晶化合物也进行了测量。最后，根据上述程序估计了nCB（包含氰基联苯核和正烷基尾的化合物）的极化率各向异性。发现柔性尾翼的贡献很大。对于n=5和8的体系，所得到的结果与在向列相-各向同性转变温度的各种热力学性质中观察到的奇偶效应一致。因此，我们在这项工作中采用的方法是有用的。