Tunable multimode emission induced by charge transfer and multiple resonance effect

Single-component luminescent materials with dual emission properties show great promise in material and life science. Here, we report a novel thermally activated delayed fluorescence (TADF) emitter BO-PST based on a rigid B-embedded dioxygen-bridged acceptor (A) and flexible phenothiazine donor (D). The flexibility of D unit contributes to different charge transfer characteristic and interesting multimode emission in various environment, including D-A-type TADF emission, multi-resonant (MR) fluorescence emission and MR induced afterglow with long lifetime of 1.55 s. Single-crystal structures and theoretical calculations prove that dual emission originates from the quasi-equatorial and quasi-axial conformers of the phenothiazine unit, respectively. The dynamic multicolor properties demonstrate the potential of the novel BO-PST molecule in the volatile organic compounds (VOCs) detection and the stimulus-responsive application.