氰基二苯乙烯基超分子聚合物的构筑与光响应行为

Construction and Photo-Responsiveness of Cyanostilbene-Based Supramolecular Polymers

通过在氰基二苯乙烯基元上引入氢键识别位点,驱使单体分子之间产生氢键与π-π堆积作用力的高效加合,构建了具有“成核-链增长”机制的超分子聚合物。通过获取组装热力学参数,揭示了酰胺及脲等不同氢键结构对于超分子聚合行为的影响规律。进一步利用超分子聚合态对于氰基二苯乙烯基元的限域效应,光照条件下特异性获得[2+2]环加成产物。与之相比,单体态时氰基二苯乙烯基元倾向于发生Z/E光异构化反应。这一研究结果可为多路径光化学反应的高效调控提供新的思路。

The nucleation-elongation cooperative mechanism,as widely adopted by natural systems such as microtubules and actin filaments,exhibits superior properties for supramolecular systems in comparison to the isodesmic mechanism by avoiding the formation of short-ranged oligomers.In this study,a novel type of artificial supramolecular polymers with the nucleation-elongation mechanism have been constructed by incorporating hydrogen bonding recognition motifs adjacent to the cyanostilbene core.It facilitates the combination of hydrogen bonds andπ-πstacking interactions between the neighboring monomers in a synergistic manner.The different hydrogen bonding units(urea versus amide)exert crucial impacts on the supramolecular polymerization behaviors,which can be qualified by the thermodynamic parameters of the self-assembly processes.Furthermore,supramolecular polymerization imparts confinement effect to the cyanostilbene unit,giving rise to the specific formation of[2+2]cycloaddition products under 430 nm photo-irradiation.It is in stark contrast to that in the monomeric state,which undergoes Z/E photoisomerization reactions under the same conditions.Overall,the current study provides new insights to modulate multi-path photochemical reactions in a precise manner.