Cucurbit[8]uril-Induced Self-Sorting Heterodimer for Aqueous Red/NIR Delayed Emission

Abstract

Constructing red and near-infrared (NIR) delayed emission materials in water is challenging but holds significant potential for applications in bioimaging and so forth. Herein, a CB[8]-induced self-sorting heterodimer was constructed, avoiding complex molecular synthesis and purification processes and realizing red and NIR delayed emission from simple small molecules in an aqueous solution. Upon the addition of CB[8], the initially nonluminescent aqueous solution of BrMe (the target guest) exhibited red-shifted absorption at 475 nm and emitted red thermally activated delayed fluorescence (620 nm) and NIR phosphorescence (720 nm). Notably, unlike "one host and one/two guest" and "head-to-head" binding modes, BrMe-CB[8] were assembled in a "two hosts and two guests" and "head-to-tail" configuration, overcoming electrostatic repulsion, avoiding twisted intramolecular charge transfer, and facilitating through space charge transfer. Notably, the hydrogel formed by the further assembly of BrMe-CB[8] with nanoclay showed enhanced delayed emission. This study provides a simple supramolecular approach to achieving red/NIR aqueous-phase delayed emission and opportunities for further applications in biological imaging.