Eight chiral vinylterphenyl monomers, （＋）-2,5-bis{4＇-[（S）-1＂-methylpropyloxy]phenyl}styrene （Ia）, （＋）-2,5-bis{4＇-[（S）-2＂- methylbutyloxy]phenyl}styrene （Ib）, （＋）-2,5-bis{4＇-[（S）-3＂-methylpenty...Eight chiral vinylterphenyl monomers, （＋）-2,5-bis{4＇-[（S）-1＂-methylpropyloxy]phenyl}styrene （Ia）, （＋）-2,5-bis{4＇-[（S）-2＂- methylbutyloxy]phenyl}styrene （Ib）, （＋）-2,5-bis{4＇-[（S）-3＂-methylpentyloxy]phenyl}styrene （Ic）, （＋）-2,5-bis{4＇-[（S）-4＂- methylhexyloxy]phenyl}styrene （Id）, （-）-2,5-bis{4＇-[（R）-1＂-methylpropyloxy]phenyl}styrene （le）, （＋）-2-/4＇-[（S）-l＂-methyl- propyloxy]phenyl}-5-{4＇-[（R）-1＂-methylpropyloxy]phenyl}styrene （Ⅱa）, （-）-2-{4＇-[（R）-1＂-methylpropyloxy]phenyl}-5-{4＇- [（S）- 1 ＂-methylpropyloxy]phenyl } styrene （lib）, and （＋）-2- { 4＇-[（S）-2＂-methylbutyloxy]phenyl }-5- { 4＇-[（S）- 1＂-methylpropyl- oxy]phenyl}styrene （Ⅲ）, were synthesized and radically polymerized. These molecules were designed to further understand long-range chirality transfer in radical polymerization and to possibly tune the chiroptical properties of the polymers by varying the spatial configuration, position, and various combination of the stereogenic centers at the ends ofp-terphenyl pendants. The resultant polymers adopted helical conformations with a predominant screw sense. When the stereogenic centers ran away from the terphenyl group as in Ⅰb-d, the corresponding polymers changed the direction of optical rotation in an alternative way and showed no obvious stereomutation upon annealing in tetrahydrofuran. The two stereogenic centers of Ⅱa, Ⅱb, and Ⅲ acted concertedly in chiral induction, whereas those of la and Ie played a counteractive role. The five polymers derived from Ⅰa, Ⅰe, Ⅱa, Ⅱb, and Ⅲ underwent stereomutation when annealed in tetrahydrofuran. The polymers PIa-e had good thermal stability and high glass transition temperatures （Tgs）. They generated liquid crystalline phases at above Tgs that could be kept upon cooling, with the exception of Pie. This result was consistent with the extended helical structures.展开更多
基金supported by the National Natural Science Foundation of China(21274003)the Research Fund for Doctoral Program of Higher Education of Ministry of Education(20110001110084)
文摘Eight chiral vinylterphenyl monomers, （＋）-2,5-bis{4＇-[（S）-1＂-methylpropyloxy]phenyl}styrene （Ia）, （＋）-2,5-bis{4＇-[（S）-2＂- methylbutyloxy]phenyl}styrene （Ib）, （＋）-2,5-bis{4＇-[（S）-3＂-methylpentyloxy]phenyl}styrene （Ic）, （＋）-2,5-bis{4＇-[（S）-4＂- methylhexyloxy]phenyl}styrene （Id）, （-）-2,5-bis{4＇-[（R）-1＂-methylpropyloxy]phenyl}styrene （le）, （＋）-2-/4＇-[（S）-l＂-methyl- propyloxy]phenyl}-5-{4＇-[（R）-1＂-methylpropyloxy]phenyl}styrene （Ⅱa）, （-）-2-{4＇-[（R）-1＂-methylpropyloxy]phenyl}-5-{4＇- [（S）- 1 ＂-methylpropyloxy]phenyl } styrene （lib）, and （＋）-2- { 4＇-[（S）-2＂-methylbutyloxy]phenyl }-5- { 4＇-[（S）- 1＂-methylpropyl- oxy]phenyl}styrene （Ⅲ）, were synthesized and radically polymerized. These molecules were designed to further understand long-range chirality transfer in radical polymerization and to possibly tune the chiroptical properties of the polymers by varying the spatial configuration, position, and various combination of the stereogenic centers at the ends ofp-terphenyl pendants. The resultant polymers adopted helical conformations with a predominant screw sense. When the stereogenic centers ran away from the terphenyl group as in Ⅰb-d, the corresponding polymers changed the direction of optical rotation in an alternative way and showed no obvious stereomutation upon annealing in tetrahydrofuran. The two stereogenic centers of Ⅱa, Ⅱb, and Ⅲ acted concertedly in chiral induction, whereas those of la and Ie played a counteractive role. The five polymers derived from Ⅰa, Ⅰe, Ⅱa, Ⅱb, and Ⅲ underwent stereomutation when annealed in tetrahydrofuran. The polymers PIa-e had good thermal stability and high glass transition temperatures （Tgs）. They generated liquid crystalline phases at above Tgs that could be kept upon cooling, with the exception of Pie. This result was consistent with the extended helical structures.
