Functions and Preparation of Polymer LB Films having Chiral Discrimination

轴向手性联苯发色团(BN)可以作为N-烷基丙烯酰胺的共聚单体被引入到聚合物的Langmuir-Blodgett(LB)膜中，形成稳定的单分子膜和多层膜。通过表面压力-面积等温线的测定，研究了(S)-2-甲氧基-1，1‘-联萘-2’-甲基丙烯酸甲酯(S)或(S)-2-羟基-1，1‘-联萘-2’-甲基丙烯酸甲酯((S)-HOBM)与N-癸基(DA)、十二烷基(DDA)或十四烷基丙烯酰胺(TDA)的共聚物的铺展行为。等温线表明，当BN的摩尔分数小于20mol%时，共聚物，尤其是DDA共聚物在纯水中形成稳定的凝聚单分子层，轴向手性联苯发色团在水中均匀分散，具有自己的表面积。共聚物单分子膜可以通过朗缪尔-布洛杰特技术(Y型沉积)连续转移到固体载体上。观察到由正的第一和负的第二棉子效应组成的强圆二色谱，支持手性联萘发色团的(S)构型。用电化学电位法研究了手性共聚物LB膜对光学活性1-苯乙胺(PEA)的对映体选择性。经共聚物单分子膜修饰的电极对PEA的加入有非常灵敏的电位变化，S-HOBN共聚物单分子膜修饰的电极对R-和S-PEA有很大的手性分辨能力，而(S)-甲基溴氮共聚物电极对R-和S-PEA没有区别。可以清楚地揭示手性分子识别的机理。

Axially chiral binaphthalene chromophores (BN) can be incorporated into polymer Langmuir-Blodgett (LB) films as a comonomer of N -alkylacrylamides which have an excellent ability to form stable monolayrs and LB multilayrs. The spreading behavior of the copolymers of (S)-2-methoxy-1,1'-binaphthalene-2'-yl methacrylate ((S)-MeBn) or (S)-2-hydroxy-1,1'-binaphthalene-2'-yl methacrylate ((S)-HOBM) with N-decyl (DA), dodecyl (DDA), or tetradecyl acrylamide (TDA) was investigated by a measurement of the surface pressure-area isotherms. The isotherms show that the copolymers, especially DDA copolymers, form a stable condensed monolayr on pure water and the axially chiral binaphthalene chromophore is dispersed uniformly having its own surface area on water when the mole fraction of BN is less than ca. 20 mol%. The copolymer monolayrs could be transferred onto solid supports successively by the Langmuir-Blodgett technique (Y-type deposition). The strong CD (circular dichroism) spectra consisting of positive first and negative second Cotton effects were observed for the LB films, supporting the (S)-configuration of the chiral binaphthyl chromophore. The enantioselective response of the chiral copolymer LB films to optically active 1-phenylethylamine (PEA) was investigated by an electrochemical potentiometric method. The electrodes modified with the copolymer monolayrs induced a very sensitive potential change on addition of PEA.The electrode with (S)-HOBN copolymer monolayrs showed a large chiral discrimination to distinguish between R- and S-PEA, whereas the (S)-MeBN copolymers showed no discrimination. The mechanism for the chiral molecular recognition can be shown clearly.