ADVANCED ROTATIONAL ISOMERIC STATE SCHEME FOR MOLECULAR DESIGN OF ORGANIC AND POLMYERIC MATERIALS

在这个项目中，我们通过以下三个主题发展了一个先进的用于有机和聚合物材料分子设计的旋转异构态(RIS)方案。(1)制备了六种具有不同构型序列的聚环氧丙烷二聚体模型化合物，并用碳-13核磁共振对其进行了研究。RIS方案结合取代基效应很好地再现了观察到的碳原子的化学位移。理论和实验之间的一致性表明了计算中使用的构象能的有效性，分子内(C-H)…的存在用静态光散射和尺寸排斥层析-多通道激光光散射法研究了聚甲基正丙基硅烷、聚二丁基硅烷和聚二己基硅烷的无扰链尺寸。对于单个聚合物，通过分子动力学模拟确定了包括主链和侧链相互作用在内的构象能。利用所确定的构象能，RIS方案很好地再现了观测到的特征比。因此，我们发展了一种长侧链聚合物的构象分析方法。(3)研究了链状分子如正构烷烃、醚等在向列相溶剂中的构象和取向特征，以及两亲分子在六方、片状和反六方聚集体中的构象和取向特性。结合RIS格式和最大熵方法，模拟了质子核磁共振四极分裂和质子-质子偶极耦合。我们建立了一种在各向异性场中分析链分子构象的方法。

In this project, we have developed an advanced rotational isomeric state (RIS) scheme for molecular design of organic and polymeric materials through the following three subjects.(1) Six dimeric model compounds of poly (propylene oxide), having different configurational sequences, were prepared, and investigated by carbon-13 NMR.The observed chemical shifts, assigned experimentally to the component carbon atoms, were well reproduced by the RIS scheme combined with substituent effects. The agreement between theory and experiment shows the validity of the conformational energies used in the calculations, the presence of the intramolecular (C-H)…O attraction, and the applicability of the RIS scheme to chemical-shift evaluation.(2) Unperturbed chain dimensions of poly (methyl n-propylsilane), poly (di-n-butylsilane), and poly (di-n-hexylsilane) were evaluated by static light scattering and size-exclusion chromatography-multichannel laser light scattering. For individual polymers, conformational energies including interactions of both main and side chains were determined from molecular dynamics simulations. The observed characteristic ratios were well reproduced by the RIS scheme using the conformational energies thus determined. Thus, we have developed a method for conformational analysis of polymers with long side chains.(3) Conformational and orientational characteristics of chain molecules such as n-alkanes and ethers dissolved in nematic solvents and amphiphilic molecules incorporated in hexagonal, lamellar, and reversed hexagonal aggregates have been investigated. Deuterium NMR quadrupolar splittings and proton-proton dipolar couplings were simulated by a combined use of the RIS scheme and the maximum entropy method. We have established a methodology for conformational analysis of chain molecules in anisotropic fields.