Tetraphenyethylene-Fused Coumarin Compound Showing Highly Switchable Solid-State Luminescence

This paper explores high-contrast mechanoresponsive luminescence (MRL) turn-on materials by combining the features of the coumarin and typical aggregation-induced emission enhancement (AIEE) tetraphenyethylene groups. Therefore, fluorogen C3Ph is obtained by fusing triphenylvinyl and coumarin units, which exhibits typical AIEE characteristics with high solid-state photoluminance (PL) efficiency in the amorphous state. The formation of a unique two-dimensional hydrogen-bonded organic framework (HOF) is responsible for the crystalline-state PL quenching but guarantees the luminescence turn-on to the external stimuli. Furthermore, the reversible solid-state fluorescence on–off cycle for C3Ph can be achieved by alternate grinding and melting–solidifying. This work also offers a way to construct high-contrast MRL turn-on materials by using the HOF-involved molecules.