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.

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.