Dual-state emission of anthracene and triphenylamine functionalized E-cyanostilbene derivative with mechanochromic property

In this work, an anthracene and triphenylamine functionalized E-cyanostilbene derivative (EN-TPA) was designed, synthesized and characterized. EN-TPA possessed excellent dual-state emission (DSE) property, possessing highly efficient emission both in solution and solid state. Meanwhile, the EN-TPA displayed obviously solvatochromic effect due to the intermolecular charge transfer, as confirmed by the Lippert–Mataga equation and quantum chemistry theoretical calculations. In aggregation state, EN-TPA was bright emissive with the solid fluorescence quantum yield (Φ_f) of 52.2%. Notably, the solid fluorescence of EN-TPA showed a 20 nm red shift after grinding, accompanied by a 4-fold decrease in Φ_f, attributed to the transition of crystalline to amorphous phase under grinding. Leveraging the reversible mechanochromic, the storage paper device of EN-TPA was fabricated and exhibited a distinct fluorescence change from green to yellow upon mechanical stimulation. Single-crystal X-ray diffraction analysis revealed that the twisted molecular structure of EN-TPA inhibited the π-π stacking and induced the molecule to form loose packing arrangements to achieve bright solid emission and stimulus response property. This work provides a new perspective for designing high-performing DSE molecules.

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