Highly reversible photomodulated hydrosoluble stiff-stilbene supramolecular luminophor induced by cucurbituril

A photochromic molecular rotor based on stiff-stilbene(SSB-FMR)was handily prepared through coupled reaction,and further self-assembled with cucurbit[8]uril(CB[8])to form a 2:2 quaternary supramolecu-lar complex(SSB-FMR/CB[8]).Significantly,the intervention of CB[8]on SSB-FMR achieved dual functions that assembly-induced emission enhancement and assembly-induced improvement of photoisomerized performance(especially reversibility)of stiff-stilbene molecular photoswitch.The supramolecular strategy further facilitated the assembly as a photoresponsive fluorescence switch with outstanding fatigue resis-tance,which was expediently applied in high-security-level QR code anti-counterfeiting and controllable lysosome targeted imaging.The study unprecedentedly provides a supramolecular method for highly effi-ciently improving photoisomerized performance especially reversibility of molecular photoswitches based on stiff-stilbene,and is of vital significance for the construction of intelligent materials with excellent ca-pability.

Stiff-stilbene derivatives as new bright fluorophores with aggregation-induced emission

Stiff-stilbene derivatives have been widely explored as molecular rotors, molecular force probes and optical switches with excellent performance. However, their function as fluorophores is poorly understood. In the present work, we design three stiffstilbene derivatives and study their photophysical properties. These compounds exhibit very weak emission in solution but significantly enhanced monomer emission in viscous solvent, bright excimer emission in aggregates and at solid state. Detailed spectroscopic studies, single crystal structural analysis, powder X-ray diffraction(XRD) as well as effects of substituents have been carefully examined. They provide direct evidence that intermolecular interactions and molecular packing, which can restrict bond vibration and rotation, are responsible for the bright aggregation-induced emission.

Photoisomerization,assembling and fluorescence photoswitching behaviors of a water-soluble stiff-stilbene with cucurbit[7]uril

Photoresponsive supramolecular systems have merited extensive attention for their applications in materials science and life science.Here,we synthesized a water-soluble stiff-stilbene molecular photoswitch,exhibiting outstanding photoisomerization reaction between its(E)-and(Z)-configurations upon irradiation at distinct light.The photoswitch can assemble with cucurbit[7]uril(CB[7])to form a superior fluorescent supramolecular complex(compared to the only guest)with excellent water solubility,which manifested dramatic photoluminescence enhancement caused by restriction of intramolecular rotation and remained good photochromic characteristics.Furthermore,introduction of CB[7]influence photoreaction quantum yield(Φ)of the stiff-stilbene,leading to reduction ofΦ_(E→Z) and increase ofΦ_(Z→E) of the stiff-stilbene.Importantly,the photoadjustable supramolecular assembly can act as a fluorescence switch,and the phototunable guest further selectively modulate G-quadruplex structure of Tel22 upon light irradiation or with addition of CB[7].The study provides a new simple way for accurately regulating photochromic properties of molecular switches and developing smart materials with potential applications in controlled modulation of G-quadruplex,targeted biological imaging and so on.