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-螺旋型聚天冬氨酸的旋感反转行为（从左向右或相反）取决于侧链末端酯基的化学结构(X)。通过构建溶剂组成（TCE/TFA）和温度的函数相图，研究了聚合物（X=苄基、氯苯基和苯乙基）之间这种现象学差异的原因。用核磁共振方法研究了间甲酚中聚天冬氨酸（X=苄基和X=苯基）在高温下的螺旋型转变（一种正常型转变）。观察到的_χ1键旋转周围的^1H-^1H邻近耦合常数表明，在从左手态到随机线圈态的过渡区，随着温度的升高，g^-构象从~ 50%下降到~ 30%。研究了主链液晶的向列构象，以检验分子内氢键可能的掺入。光谱和热力学（PVT）分析得出结论，一组部分取向构象在整个向列态范围内持续存在。这是一个令人鼓舞的证据，为分子设计一类新的化学结构。

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.