Studies on the Cooperativie Transformation of Hydrogen-Bonds During the Intramolecular First-Order Transitions of Polypeptides-An Application of ^2H NMR Analysis in the Liquid Crystalline State

1. α-螺旋聚碳酸酯的螺旋-有义反转行为（从左旋到右旋或反之亦然）根据侧链末端的酯基的化学结构（X）而显著不同。通过绘制相图，研究了聚合物（X=苄基、氯苄基和苯乙基）在不同温度下的相变。2.用核磁共振方法研究了聚合物（X=苄基和X=苯乙基）在间甲酚中的螺旋-线团相变（正常型相变）。在_χ1键旋转附近的^1H-^1H邻位耦合常数表明，在从左手态到无规卷曲态的过渡区，g^-构象随温度的升高从50%降低到30%。3.研究了主链液晶的顺式构象，以考察分子内氢键的可能掺入。光谱和热力学（PVT）分析得出的结论是，一组部分取向的构象持续在整个范围内的α-状态。这对于一类新的化学结构的分子设计是一个令人鼓舞的证据。

1.Screw-sense inversion behaviors (left- to right-handed or vice versa) of α-helical polyaspartates differ substantially depending on the chemical structure (X) of the ester group at the side-chain terminals. The cause of such phenomenological differences among polymers (X=benzyl, chlorobenzyl, and phenethyl) have been investigated by constructing the phase diagram as a function of solvent composition (TCE/TFA) and temperature.2.The helix-coil transition of polyaspartates (X=benzyl and X=phenethyl) in m-cresol at elevated temperature (a normal-type transition) has been studied by NMR methods. The observed ^1H-^1H vicinal coupling constant around the _χ1 bond rotation suggests that the g^- conformation decreases from 〜50% to 〜30% with increasing temperature in the transition region from the left-handed to random-coil state.3.The nematic conformation of main-chain liquid crystals has been studied to examine the possible incorporation of the intramolecular hydrogen-bond. The spectroscopic as well as thermodynamic (PVT) analyses led to a conclusion that a group of partially oriented conformation persists over the entire range of the nematic state. This is an encouraging evidence for the molecular design of a new class of chemical structures.