Hydrogen-Deuterium Isotope Effects and Chiral Solvation in Polymer Solutions

聚合物溶液中的氢-氘同位素效应和手性溶剂化

• 批准号: 05044096
• 负责人: TERAMOTO Akio
• 金额: $ 1.28万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05044096/
• 关键词: Optical rotation; Cholesteric liquid crystal; Hydrogen-deuterium isotope effect; Chiral interaction; Polyisocyanate; Helical conformation; Helix reversal

1.Helical conformation of deuterium-substituted optically-active poly(hexyl isocyanate)s in dilute solutionThe optical rotation of poly(hexyl isocyanate)s with deuterium substituted on the alpha- or beta-carbon in the hexyl side chain was measured in dilute solution as a function of the molecular weight and temperature. The results were fitted by Lifson et al.'s statistical thermodynamic theory, where each monomer in the polyisocyanate chain was assumed to take one of three states, the left-handed helix, right-handed helix, and helix reversal. From the fitting, the free energy difference DELTAG_h between left- and right-handed helices per monomer was estimated to be a few cal/mol, while the free energy of the helix reversal more than 3000 cal/mol. The former value indicates a very small hydrogen-deuterium isotope effect on the monomer conformation. However the latter value demonstrates the difficulty in the occurrence of the helix reversal. This difficulty accumulates the small DELTAG_ … More h to provide a large disproportion of the left- and right-handed helical monomers in the chain.2.Helical conformation of polyisocyanates in liquid crystalline solutionOptically inactive poly(n-hexyl isocyanate)(PHIC) exists as a racemic mixture, and it's concentrated solution forms a nematic phase. When some optically active low-molar-mass substances or copolymers consisting of some optically active and inactive isocyanate monomers were added to the nematic solution of PHIC, the solution transformed from the nematic to cholesteric. This transformation indicates the disproportion of the left- and right-handed helical states in the PHIC chain due to an accumulated chiral interaction with the optically active substances.Although the optical rotation of the above copolymer in dilute solution depended on the monomer composition, the pitch of the induced cholesteric structure did not. This independence can be explained by the exclusion of the helix reversal state from the copolymer chain in the liquid crystalline solution. Less

1.氘取代的旋光聚异氰酸己酯在稀溶液中的螺旋构象研究了氘取代的聚异氰酸己酯在稀溶液中的旋光度随分子量和温度的变化。Lifson et al.的统计热力学理论，其中每个单体在多异氰酸酯链被假定采取三种状态之一，左手螺旋，右手螺旋，和螺旋反转。根据拟合，每个单体的左手螺旋和右手螺旋之间的自由能差DELTAG_h估计为几个cal/mol，而螺旋反转的自由能大于3000 cal/mol。前者的值表明一个非常小的氢氘同位素的单体构象的影响。然而，后一个值证明了螺旋逆转发生的困难。这个难度积累了小DELTAG-- ...更多信息 2.多异氰酸酯在液晶溶液中的螺旋构象旋光不活泼的聚异氰酸正己酯（PHIC）以外消旋混合物的形式存在，其浓溶液形成手性相。在PHIC的水溶液中加入一些光学活性的低摩尔质量物质或由一些光学活性和非光学活性的异氰酸酯单体组成的共聚物，溶液由水溶液转变为水溶液。这种转变表明PHIC链中由于与旋光活性物质的累积手性相互作用而导致左右手螺旋状态的不成比例。尽管上述共聚物在稀溶液中的旋光度依赖于单体组成，但诱导的螺旋结构的螺距不依赖于单体组成。这种独立性可以通过在液晶溶液中从共聚物链中排除螺旋反转状态来解释。少

项目成果

Hong Gu,Yo Nakamura,Akio Teramoto,Mark M.Green,and Shneior Lifson: "Molecular Weight Dependence of Optical Rotation of Chiral Polyisocyanates in Solution. 2.Poly((R)-2-deuterio-n-hexyl isocyanate)" Macromolecules. (発表予定).

Hong Gu、Yo Nakamura、Akio Teramoto、Mark M. Green 和 Shneior Lifson：“溶液中手性多异氰酸酯旋光的分子量依赖性。2.聚((R)-2-氘代正己基异氰酸酯)”大分子（即将公布）。

Takahiro Sato, Lionel Varichon, Akio Teramoto and Mark M.Green: "Statistical Thermodynamic Theory of a Helical Stiff-Chain Polymer Perturbed by a Dopant" Macromolecules. (to be submitted).

Takahiro Sato、Lionel Varichon、Akio Teramoto 和 Mark M.Green：“受掺杂剂扰动的螺旋硬链聚合物的统计热力学理论”大分子。

Hong Gu, Yo Nakamura, Akio Teramoto, Mark M.Green and Shneior Lifson: "Molecular Weight Dependence of Optical Rotation of Chiral Polyisocyanates in Solution. 2. Poly((R)-2-deuterio-n-hexyl isocyanate)" Macromolecules. (to be submitted).

Hong Gu、Yo Nakamura、Akio Teramoto、Mark M.Green 和 Shneior Lifson：“溶液中手性多异氰酸酯旋光的分子量依赖性。2. 聚((R)-2-氘代正己基异氰酸酯)”大分子。

Takahiro Sato,Yoshihiro Sato,Yoshimi Umemura,Akio Teramoto,Yoshikazu Nagamura,Jurgen Wagner,Dexi Weng,Yoshio Okamoto,Koichi Hatada,and Mark M.Green: "Polyisocyanates and the Interplay of Experiment and Theory in the Formation of Lyotropic Cholesteric Stat

Takahiro Sato、Yoshihiro Sato、Yoshimi Umemura、Akio Teramoto、Yoshikazu Nagamura、Jurgen Wagner、Dexi Weng、Yoshio Okamoto、Koichi Hatada 和 Mark M.Green：“多异氰酸酯以及实验与理论在溶致胆甾醇形成中的相互作用

Takahiro Sato,Lionel Varichon,Akio Teramoto,and Mark M.Green: "Statistical Thermodynamic Theory of a Helical Stiff-Chain Polymer Perturbed by a Dopant" Macromolecules. (発表予定).

Takahiro Sato、Lionel Varichon、Akio Teramoto 和 Mark M. Green：“受掺杂剂扰动的螺旋硬链聚合物的统计热力学理论”（待提交）。