Optically Active Polymers And Supramolecular Assemblies:Controlled Fabrication,Properties And Applications

Chiral substances are ubiquitous in nature.Optically active materials play an important role in chemistry,materials science,nanoscience,physics owing to their broad applications in chiral recognition,enantioselective separation,chiral optics,chiroptical switch and asymmetric catalysis.Controllable construction of optically active polymers or supramolecular assemblies and further studying their unique properties and applications have been attracting growing research interests.Light-induced thiol-ene/yne asymmetric polymerization and diacetylene topological polymerization are efficient methods for the preparation of optically active polymers.However,the exact mechanism of chiral manipulation is still not fully understood.We have designed and synthesized a series of optically active hyperbranched/linear polymers and helical polydiacetylene induced by light irradiation and the applications in asymmetric catalysis are studied.Besides,we have successfully constructed variety of chiral supramolecular assemblies and investigated their detailed physical and chemical properties,also the applications in asymmetric catalysis and electricity to contact a preliminary exploration.1.Controllable construction of various optically active polymers.We have developed a series of polymerization methods for optically active hyperbranched/linear polymers and helical polydiacetylene induced by light irradiation.Different optically active hyperbranched polymers could be easily synthesized via thiol-yne click reaction by varying the mixing ratio of L-or D-monomer in the reactant monomers.Optically active linear polymers could be fabricated by 980 nm circularly polarized near-infrared light irradiation in the presence of upconversion particles.Helical polydiacetylene could be fabricated through topological polymerization by combining a magnetic field and linearly polarized ultraviolet light irradiation.2.Optically active hyperbranched polymers use as chiral host platform for asymmetric Michael addition reactions in aqueous environments.We successfully prepared amphiphilic optically active HBPs,which were used as microenvironments as well as scaffolds for immobilization of quinine to promote the asymmetric Michael addition reactions in an aqueous environment.The chiral cavities within the HBPs provide a three-dimensional chiral microenvironment for the asymmetric Michael addition reaction and highly influence their enantioselectivity.The D-HBPs and quinine work together in a synergistic way,which leads to an enhancement in the catalytic stereoselectivity.However,for the L-HBPs,the quinine are very likely to be shielded by the polymer chains,leading to a decline in the catalytic efficiency.This work not only provides a catalyst scaffold to achieve high yield(89%)and satisfactory enantioselectivity for the asymmetric Michael addition in aqueous environments,but also is of great fundamental value for the rational design of artificial synthetic materials in other types of asymmetric catalysis reactions.3.Fabrication and properties of π-conjugated supramolecular chiral gel.A series of triphenylene derivatives were synthesized and lucubrated the necessary conditions for gel formation by adjusting the molecular structures of the polarity of the organic solvent.Optically active supramolecular gels were formed from achiral triphenylene derivative by introducing limonene as the chiral source.Owing to the well-ordered supramolecular packing,the homochiral supramolecular gels(pure P-or M-helix)exhibited the greater mechanical strength as well as the higher conductivity,compared to those of heterochiral architectures(equal amount of P-and M-helix).The smaller π－planar intervals and shorter neighboring π-π stacked column distances of homochiral supramolecular assemblies corresponded well to their better mechanical strength and conductivity.