(+)-甲基丙烯酸{2,5-双[4′-((S)-2-甲基丁氧基)苯基]苯基}酯的合成及其螺旋选择性自由基聚合

Synthesis and helix-sense-selective free radical polymerization of (+)-{2,5-bis[4'-((S)-2-methylbutoxy)phenyl]phenyl}methacrylate

设计合成了手性单体(+)-甲基丙烯酸{2,5-双[4′-((S)-2-甲基丁氧基)苯基]苯基}酯,并进行了自由基溶液聚合.相比于单体,聚合物的比旋光度有显著的同向增长,且在其圆二色光谱上对应于三联苯侧基以及酯基的吸收区域呈现明显的Cotton效应,说明其主链可能采取某一旋向占优的螺旋构象.研究了聚合条件对聚合物旋光性质的影响.结果表明,采用极性大的芳香族溶剂或增加单体浓度有利于获得旋光度大的聚合物;随聚合温度增加,聚合物旋光度先增加后减小,在80℃时聚合达到最大值.该聚合物比甲基丙烯酸三芳基甲基酯类光学活性螺旋链聚合物具有更好的化学结构稳定性和立体结构稳定性.

A novel chiral monomer, （＋）-{2,5-bis[4＇-（（S）-2-methylbutoxy）phenyl]phenyl}methacrylate, was synthesized and polymerized via free radical polymerization in solution. Compared with the corresponding monomer, the specific optical rotation of polymer increased obviously in the same direction. In the UV-vis absorption regions of ester and p-terphenyl side-groups, the polymer gave strong Cotton effects, suggesting the formation of helical conformation with a dominant screw sense. The effect of polymerization conditions on polymer chiroptical property was investigated. It was found that polar aromatic solvent and high monomer concentration favor the generation of polymer with large optical rotation. With the increase of polymerization temperature, the specific optical rotation of polymer increased at first and reached a maximum value at 80℃. Further increasing polymerization temperature made the strength of polymer optical rotation decrease. The resultant polymer exhibited much better chemical structure and stereostructure stabilities than poly（triphenylmethyl methacrylate） and its analogous, which were the first commercialized optically active helical vinyl polymers with excellent chiral recognition ability. It might be widely used in chiral material and technology.