Aqueous up-conversion organic phosphorescence and tunable dual emission in a single-molecular emitter

Materials exhibiting up-conversion room-temperature phosphorescence (RTP) with multi-emissive properties in aqueous solutions hold significant potential for optical imaging and sensing applications. However, achieving such photophysical materials within a molecular emitter remains a formidable challenge. Herein, we report a series of single-molecule chromophores demonstrating aqueous tunable up-conversion RTP and fluorescence dual emission. The RTP and fluorescence emission could be finely adjusted by manipulating the excitation wavelength within the visible and near-infrared range, enabling dynamic color modulation across the entire visible spectrum from blue to orange-red. Furthermore, we utilized the up-conversion RTP capability of a single-molecular emitter to achieve two-photon and time-resolved imaging. More importantly, through ratiometric regulation of phosphorescence by temperature combined with stable fluorescence as an internal reference, the RTP molecule enabled reliable temperature sensing in living cells. This study unveils a highly efficient strategy for fabricating intelligent organic RTP materials and sensors featuring dynamically controlled multi-emission.