Helix-Sense Controlled Polymerization of a Single Phenyl Isocyanide Enantiomer Leading to Diastereomeric Helical Polyisocyanides with Opposite Helix-Sense and Cholesteric Liquid Crystals with Opposite Twist-Sense

摘要

Optically active polymers with a controlled helix-sense have recently attracted considerable interest not only for mimicking biological helices,but also for developing novel chiral materials.Fully synthetic helical polymers have been prepared either by the polymerization of optically active monomers,such as isocyanates,silanes,acetylenes,or by the helix-sense selective polymerization of achiral methacrylates,isocyanides,and carbodiimides with bulky substituents by chiral catalysts or initiators.The former helical polymers are dynamic in nature,and the population of the interconverting right-and left-handed helices can be switched under certain conditions,while the helical conformations of the latter polymers are stable(static)in solution and their helical senses are kinetically determined during the polymerization.