D–A–D structured triphenylamine fluorophore with bright dual-state emission for reversible mechanofluorochromism and trace water detection

Abstract

The design and development of materials showing bright dual-state emission (DSE) in both dilute solutions and the solid state have attracted great interest due to their potential in a wide variety of applications. The present work reports the synthesis of a novel donor–acceptor–donor (D–A–D) structured fluorophore, 2TPACHO, with DSE characteristics using triphenylamine as an electron donor and benzaldehyde as an electron acceptor. 2TPACHO possesses typical intramolecular charge transfer (ICT) characteristics and presents a highly twisted molecular conformation in the crystal structure with multiple weak interactions. As a result, 2TPACHO exhibits strong emission in solution and the solid state (Φ_THF = 0.43, Φ_solid = 0.62). As a DSE material, 2TPACHO shows clear mechanofluorochromism in response to external mechanical stimuli in its solid state and capabilities of sensing trace water in organic solvents as a fluorescent probe in the dissolved state. This work provides new insight into the design of DSE fluorophores that function in both solutions and the solid state.