Cucurbit[7]Uril‐Based Supramolecular Polymers With Dual Photochromism and Fluorescence: From Host‒Guest Design to Smart Applications
Long‐Jing Wu, Anqi Deng, Jing‐Xin Liu, Rui‐Lian Lin, Mang Ye, Guozheng Huang
Abstract
ABSTRACT The development and fabrication of cucurbit[7]uril (Q[7])‐based host‒guest supramolecular polymers remain challenging due to the limited cavity size of Q[7]. Herein, we designed and synthesized three thiophene‐pyridinium guests and investigated their binding interactions with Q[7]. NMR, ESI‐MS spectroscopy, and DFT calculations revealed that Q[7] can encapsulate one or two thiophene groups of the guests to form supramolecular complexes, including discrete inclusion complexes and supramolecular polymers. Importantly, all supramolecular complexes demonstrated reversible photochromism in the solid state, which is attributed to viologen radical generation, as confirmed by UV‐vis‐NIR, ESR, and DFT studies. Due to the aggregation caused quenching (ACQ) effect induced by the intermolecular π⋯π stacking interaction of thiophene groups within the Q[7] cavity, the Q[7]‐based supramolecular polymers remained fluorescence‐silent, whereas the discrete inclusion complexes showed enhanced fluorescence compared to their thiophene‐pyridinium guests. The dual photochromic and fluorescence properties of the Q[7]‐based supramolecular complexes render them suitable for applications in erasable inkless printing, multi‐level anti‐counterfeiting, and advanced information encryption. This study provides a strategy for constructing dual‐functional supramolecular polymers using Q[7]‐based host‒guest interactions.