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Although purely organic room‐temperature phosphorescence (RTP) has drawn widespread attention in recent years, regulatable phosphorescence resonance energy transfer (PRET) supramolecular switch is still rare. Herein, single molecular dual‐fold supramolecular light switches, which are constructed by phenylpyridinium salts modified diarylethene derivatives (DTE‐Cn, n = 3, 5) and cucurbit[8]uril (CB[8]) are reported. Significantly, biaxial [3]pseudorotaxane displayed efficiently reversible RTP after binding with CB[8] and the phosphorescence quenching efficiency is calculated up to be 99%. Furthermore, the binary supramolecular assembly can coassemble with Cy5 to form ternary supramolecular assembly showing efficiently PRET, which is successfully applied in switchable near infrared (NIR) mitochondria‐targeted cell imaging and photocontrolled data encryption. This supramolecular strategy involving energy transfer provides a convenient approach for phosphorescent application in biology and material fields., A switchable supramolecular phosphorescence resonance energy transfer system for NIR cell imaging and data encryption is reported. This supramolecular strategy involving energy transfer provides a convenient approach for phosphorescent application in biology and material fields.

Fluorescent single crystals that respond to multiple external stimuli are of great interest in molecular machines, sensors, and displays. The integration of photo- or acid-induced fluorescence enhancement and bending in one organic crystal, however, has not been reported yet. Herein, we report the interesting plastic photomechanical bending and switching on of the fluorescence of an azine crystal in a single-crystal transformation, due to extended π-conjugation and molecular slippage. Moreover, the fluorescent plastic bending driven by multiple volatile acid vapors was firstly observed, and attributed to the synergistic effect of push-pull electronic structure and hydrogen bonding. The single crystal also shows high elasticity under external force. In addition, reversible fluorescence switching can be triggered by grinding and solvent fuming, as well as by the adsorption and desorption of HCl vapor. The integration of plastic, elastic bending and switch-on fluorescence into one single crystal provides a new strategy for next-generation smart materials.

Research on photochromic molecules switched by visible light is of particular interest for their application in bioimaging and stimuli-responsive materials. Here, a photoswitchable supramolecular assembly comprised of monocharged bispyridinium-modified diarylethenes (DAEs) and cucurbit[8]uril (CB[8]) has been constructed, which exhibits reversible photochromic behaviour with visible light in both directions. The transformation of CB[8] not only prompts the DAEs to form charge-transfer complexes, but also restricts its intramolecular rotation to enhance fluorescence emission. In this CB[8]-containing supramolecular system, the π-conjugation is extended and its absorption is bathochromically shifted for visible light-driven cyclization of DAEs. Meanwhile, the fluorescence of the supramolecular assembly can also be reversibly modulated by visible light. These findings may furnish a new strategy for the development of visible light-driven fluorescent biomaterials and molecular machines.

Tunable photoluminescence nanomaterials have aroused increasing interest from researchers recently due to their application in bioimaging, photodynamic therapy, and energy conversion. Herein, an artificial ternary nanosystem comprised of dithienylethene-bridged bis(permethyl-β-CD)s, dodecyl-bearing porphyrin, and amphipathic near-infrared (NIR) cyanine fluorochrome is conveniently constructed by rationally designing the host/guest components, dimensions, and properties. In this system, an effective energy transfer (ET) from porphyrin to cyanine fluorochrome leads to the dramatic enhancement of NIR fluorescence intensity and more crucially, this process can be efficiently regulated by distinct light input, achieving photoswitching ET-NIR fluorescence in aqueous media.