Helical chirality of pi-conjugated main-chain induced by polymerization of phenylacetylene with chiral bulky pinanyl groups: Effects of the flexible spacer and polymerization catalyst

摘要

Three optically;active phenylacetylene polymers with chiral bulky pinanyl groups, (-)-poly [4-(dimethylpinanylsilyl)phenylacetylene] [(-)-poly(PSPA)], (+)-poly{4-[3-(10-pinanyl)tetramethyldisiloxy]phenylacethylene} [(+)-poly(PDSPA)], and their copolymer [(-)-copoly(PSPA/PDSPA)], were synthesized. We observed high chirality in the main-chain chromophore of (-)-poly(PSPA), due to the presence of a chiral helix, with circular dichroism spectroscopy. In contrast, (+)-poly(PDSPA),with flexible SiOSi spacers between the chiral pinanyl group and the main chain, had lower chirality. (-)-Poly(PSPA), with large circular dichroism signals, was prepared by polymerization with a rhodium catalyst and had a highly stereoregular main chain (high cis-configuration percentage). However, (-)-poly(PSPA) prepared with a tungsten catalyst had lower chirality and lower stereoregularity in the main chain. A membrane from (-)-poly(PSPA) showed enantioselective permeability for tryptophan in an aqueous solution. (C) 2002 Wiley Periodicals, Inc. [References: 22]