Single-Luminophore Molecular Engineering for Rapidly Phototunable Solid-State Luminescence.

Smart materials enabling emission intensity or wavelength tuning by light stimulus have attracted attention in cutting-edge fields. However, due to the general limitation of the dense molecular stacking (in solid states, especially in crystals) on photoresponsivity, constructing rapidly phototunable solid-state luminescent systems remains challenging. Herein, we present a new luminophore that serves as both a photoresponsive and a luminous group with enhanced conformational freedom to attain this goal, namely, relying on photoexcitation-induced molecular conformational change of an ionized persulfurated arene based on weak intermolecular aliphatic C-H⋅⋅⋅π interaction. Together with the phosphorescence characteristic of the molecule itself, rapidly enhanced phosphorescence upon irradiation can be observed in a series of phase states, like solution state, crystal, and amorphous state, especially with a high photoresponsive rate of 0.033 s in crystal state that is superior to the relevant reported cases. Moreover, a rapidly phototunable afterglow effect is achieved by extending this molecule into some polymer-based doping systems, endowing the system with unique dynamic imaging and fast photopatterning capabilities. This single-luminophore molecular engineering and underlying mechanism have implications for building other condensed functional materials, principally for those with stimuli responses in solid states.