Development of pi-conjugated helical polymers bearing both molecular recognition sites and dynamically axial chirality in the main chain

合成了主链上以冠醚为分子识别中心的Poly(biphenyleneethynylene-alt-phenyleneethynylene)衍生物，并用圆二色谱(CD)研究了其与旋光活性氨基酸、胺的络合诱导手性及诱导螺旋构象的稳定性，以期构建新型的螺旋pi共轭聚合物。得到的聚合物在氯仿-乙腈(1/9)中与手性客体络合后折叠成优先手性螺旋构象。用非手性客体取代手性客体后，可以保持诱导的大分子螺旋性，并且聚合物在优先手螺旋和无规卷曲之间呈现可逆的构象变化，响应于溶剂的变化。这是第一个能够可逆构象变化的大分子螺旋度记忆的例子。

Poly(biphenyleneethynylene-alt-phenyleneethynylene) derivatives bearing crown ether moieties as molecular recognition sites in the main chains were synthesized, and chirality induction in the obtained polymers upon complexation with optically active amino acids and amines and the stability of the induced helical conformation were investigated by using circular dichroism (CD) spectroscopy in order to construct novel helical pi-conjugated polymers. The obtained polymers folded into a preferred-handed helical conformation in chloroform-acetonitrile (1/9) upon complexation with chiral guests. After replacement of the chiral guests with achiral guests, the induced macromolecular helicity could be maintained and the polymer showed a reversible conformational change between preferred-handed helix and random coil in response to change in solvents. This is the first example of macromolecular helicity memory capable of reversible conformational change.