Multiple Stimuli-Responsive Supramolecular Organic Framework under Concomitant Emission Color Changes

A stimuli-responsive luminophore embedding an overcrowded bistricyclic aromatic ene structure with a heptagon=hexagon central ring, DCHA-TRZ, has been designed and synthesized. In a single-crystalline solid, DCHA-TRZ constructed a supramolecular organic framework (SOF) including n-hexane molecules as a guest molecule. The crystalline SOF (alpha phase) exhibited reversible crystalline (alpha)-to-amorphous-to-crystalline (alpha) solid-state phase transitions triggered by external stimuli of mechanical grinding and treatment with an n-hexane solvent, in which release and inclusion of the guest molecules played an important role. Moreover, the thermal annealing of the amorphous ground solid afforded a bluish-green-emitting solid with a different crystalline phase (beta). The combination of the three external stimuli of mechanical grinding, thermal annealing, and solvent treatment enables the reversible and cyclical phase transitions among three solid-state phases (crystalline alpha and beta and amorphous) under concomitant emission color changes.

Automated summary

A stimuli-responsive luminophore with a supramolecular organic framework structure has been designed and synthesized. It exhibits reversible and cyclical solid-state phase transitions triggered by external stimuli, such as mechanical grinding, thermal annealing, and solvent treatment, accompanied by color changes in emission.