Host–guest interaction-directed strategy for managing mechanochromic luminescence behavior by modulating molecular packing and conformation

Abstract

Developing a simple strategy to precisely modulate the mechanochromic luminescence (MCL) behavior of fluorophores is of great significance in understanding their structure–property relationship and promoting their potential application. Herein, we report a donor–acceptor (D–A) molecule 1-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)pyridin-4-one (NBDP), which shows a bathochromic shift of fluorescence upon grinding. Interestingly, when NBDP is absorbed by cucurbit[8]uril (CB[8]) solid, the formed NBDP@CB[8] complex exhibits an unexpected hypsochromic shift. Detailed spectroscopic and structural analyses suggest that molecular packing and conformation change induced by host–guest interactions are responsible for the distinct luminescence response. This strategy is both conceptually and synthetically simple and offers a promising approach for the construction of new MCL systems.