Purely organic room-temperature phosphorescence (PORTP) supramolecular materials have been widely explored in bioimaging, but their relatively short excitation wavelength limits their further application. Herein, we reported a purely organic phosphorescence resonance energy transfer (PRET) assembly, which was constructed by purely organic upconversion phosphor 6-bromoisoquinolium-modified permethylated cyclodextrin (BQ-PCD), cucurbit[8]uril (CB[8]) and tetra(4-sulfonatophenyl)porphyrin (TPPS), displaying not only CB[8]-confinement enhanced PORTP, but also multi photon-mediated PRET achieving delayed deep-red luminescence for targeting cell imaging. Compared with BQ-PCD, BQ-PCD@CB[8] supramolecular assembly remarkably prolongs PORTP lifetime from 13.8 ns to 640 μs, which further assembles with TPPS through strong host-guest interaction between PCD and TPPS, achieving delayed deep-red luminescence with a lifetime of around 11 μs through high efficient PRET process (94.5%). Taking advantage of the 1:2 stoichiometric ratio, BQ-PCD@CB[8] efficient enhanced upconversion process compared with BQ-PCD@CB[7], leading to the delayed deep-red luminescence under multi photon excitation at 920 nm in TPPS@BQ-PCD@CB[8]. With the further cascade assembly with tumor-targeting hyaluronic acid (HA), the upconversion supramolecular nanoparticle could be successfully applied for targeting cell imaging through upconversion PRET process. This research offers a novel approach to fabricate long-lived deep-red fluorescence materials with upconversion properties via macrocyclic confinement assembly.
