Design and synthesis of deep-red dual-state emission triphenylamine derivatives for mechanochromism and H2S detection

Developing dual-state emission fluorogens (DSEgens) with highly efficient emission in both solution and solid state is an emerging research topic in the optical field. Especially, DSEgens with deep-red emission are particularly scarce. In this work, two donor–acceptor–donor (D-A-D) type triphenylamine derivatives (TBT-2CN and TBT-4CN) were designed, synthesized and characterized. The compounds possess highly efficient emission in both solution and aggregation states. The fluorescence of TBT-2CN and TBT-4CN solid emit deep-red fluorescence at 620 and 770 nm, respectively. Meanwhile, TBT-2CN and TBT-4CN exhibited reversible mechanochromism properties, in which the fluorescence spectra of the compounds were red-shifted by 9 and 67 nm after grinding. Moreover, the spectra reverted to the initial state after being fumed by dichloromethane for a few minutes. In addition, the compounds were sensitive to H₂S. The solutions and paper-based devices of the molecules could detect the H₂S in both solution and solid states.

Graphical abstract

Two novel triphenylamine derivatives with deep-red dual-state emission were designed and synthesized for reversible mechanochromism and H₂S detection.