A multicolor room temperature phosphorescence (RTP) supramolecular photo‐switch encryption film is constructed by the coassembly of coumarin‐24‐crown‐8 (C24C8), diarylethene dicationic alkylammonium derivative (1), rhodamine B (RhB) and poly(vinyl alcohol) (PVA). Benefiting from the tightly binding of C24C8 and secondary alkylammonium ion, 1 formed noncovalent bridged bis(coumarin‐24‐crown‐8), which displayed photo‐switchable RTP with green afterglow (more than 5 s) after coassembly with PVA. Especially doping with RhB gave a photo‐switchable highly efficient phosphorescence‐harvesting system with multicolor through triplet‐to‐singlet Förster‐resonance energy transfer (TS‐FRET). The energy transfer efficiency and antenna effect of C24C8+RhB@PVA film reached 88.3% and 62.6 when the donor/acceptor ratio is 50:1, respectively. Therefore, diarylethene noncovalent bridged bis(coumarin‐24‐crown‐8) supramolecular assembly not only displays a multicolor photoluminescence‐switch, but also presents a phosphorescent photo‐switch with afterglow, which provides a simple and feasible way to construct smart RTP materials through host‐guest strategy.

Stokes shift, long lifetime, [1] and occurrence of cascade energy transfer from triplet states of phosphors to singlet states of dyes, [2] which has been successfully applied to photocatalysis [3] information security and anti-counterfeiting, [4] and biological imaging. [5] Although many researches have been carried out on the purely organic RTP cascade lightharvesting systems, the construction of these systems with long life time and high quantum yield in aqueous solutions still faces great challenges because of the strong quenching effect of water on excited state of luminescent materials and the free molecular motion during non-radiative decay, [6] thereby inevitably limiting their practical biological applications. Nowadays, methods of constructing the purely organic RTP materials are mainly divided into doping, [7] crystalline packing, [8] polymerization, [9] matrix rigidification, [10] host-guest interactions [11] and so on, in which supramolecular methodology based on host-guest complexation [12] has been proven to be an accessible method to obtain phosphorescence both in water and the solid phase. Recently, bromophenylpyridine, quinoline, or phthalimide derivatives with strong RTP confined by macrocycle cucurbit[n] urils (CB[n]s) were reported, [13] and further assembled into highly efficient phosphorescence energy transfer (PET) systems, which provides a strategy to construct materials with long lifetime near-infrared (NIR) emission. George and coworkers reported a highly effective RTP harvesting system by loading the phthalimide derivatives on the soluble inorganic silicate template to realize delayed fluorescence. [14] We reported purely organic RTP with a lifetime of 1.13 ms in aqueous solution through the secondary assembly of dibromophthalimide derivative, CB [7], and amphiphilic calixarene (SC4AD), and successfully constructed an effective cascade light-harvesting system. [15] In the process of constructing supramolecular phosphorescent materials, the photoreaction presented positive effects such as the anthrancene-modified bromophenylpyridine confined by CB[8] showing excellent organelle identification triggered by photo-oxidation. [16] It is well known that coumarin is a kind of fluorescent molecule with aromatic lactone and double bond Cascade energy capturers based on supramolecular assembly have recently generated great research interest in the field of luminescent materials. Herein is reported a cucurbit[8]uril (CB[8])-encapsulated coumarin-bridged phenylpyridinium salt (G) to form biaxial polypseudorotaxane (G⊂CB[8]), which not only induces the phosphorescence of the guest G, but also activates the photodimerization of coumarin functional group in the CB[8] cavity (G-dimer⊂CB[8]) to further boost its phosphorescence emission, extending the phosphorescence lifetime from 271.3 to 430.3 µs and the quantum yield from 5.1% to 25.7% in aqueous solution. After co-assembly with amphiphilic calixarene (SC4AD), the supramolecular biaxial polypseudorotaxane G-dimer⊂CB[8] is changed to the n...