Zhang Rong, Chen Yong, Liu Yu
College of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, P. R. China.
Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University, Tianjin, 300071, P. R. China.
Angew Chem Int Ed Engl. 2023 Dec 21;62(52):e202315749. doi: 10.1002/anie.202315749. Epub 2023 Nov 22.
Light-driven multicolor supramolecular systems mainly rely on the doping of dyes or a photo-reaction to produce unidirectional luminescence. Herein, we use visible light to drive the bidirectional reversible multicolor supramolecular shuttle from blue to green, white, yellow, up to orange by simple encapsulation of spiropyran-modified cyanostilbene (BCNMC) by the macrocyclic cucurbit[8]uril (CB[8]) monomer. The resultant host-guest complex displayed enhanced fluorescence properties, i.e. the multicolor fluorescence shuttle changed from blue to orange in the dark within 2 hours and reverted to the original state upon visible light irradiation for 30 s. Benefiting from the sensitivity of the spiropyran moiety to light, it can spontaneously isomerize from the ring-opened state to a ring-closed isomer in aqueous solution, and this photo-isomerization reaction is a reversible process under visible light irradiation, leading to the multicolor luminescence supramolecular shuttle as a result of intramolecular energy transfer. In addition, the light also drove the reversible conversion of the topological morphology of the host-guest complex from two-dimensional nanoplatelets to nanospheres. Different from the widely reported molecular rotaxane "shuttle", the spiropyran supramolecular shuttle confined in the macrocyclic host CB[8] not only modulated a reversible topological morphology by light but also exhibited multicolor luminescence, which was successfully applied in programmed and rewritable information encryption.
光驱动多色超分子体系主要依靠染料掺杂或光反应来产生单向发光。在此，我们通过用大环葫芦[8]脲（CB[8]）单体简单包封螺吡喃修饰的氰基芪（BCNMC），利用可见光驱动双向可逆多色超分子梭从蓝色转变为绿色、白色、黄色，直至橙色。所得的主客体复合物表现出增强的荧光特性，即多色荧光梭在黑暗中2小时内从蓝色变为橙色，并在可见光照射30秒后恢复到原始状态。得益于螺吡喃部分对光的敏感性，它在水溶液中能自发地从开环状态异构化为闭环异构体，并且这种光异构化反应在可见光照射下是一个可逆过程，由于分子内能量转移导致了多色发光超分子梭的产生。此外，光还驱动了主客体复合物的拓扑形态从二维纳米片可逆转变为纳米球。与广泛报道的分子轮烷“梭”不同，限制在大环主体CB[8]中的螺吡喃超分子梭不仅通过光调节了可逆的拓扑形态，还表现出多色发光，其成功应用于编程和可重写信息加密。
