Luminophore with Multiple Emission Centers for Fluorescence/ Phosphorescence Dual Ratiometric Chemical Sensing in Aqueous Solution

Abstract Luminescent materials with multiple emission centers are attracting more and more attentions due to their potential applications in multicolor displays, polychromatic imaging, information encryption, and ratiometric chemical sensing. Organic molecules with phosphorescence behavior at room temperature (RTP) provide idea candidate for constructing luminescent materials with multiple emission centers, which show great potentials for application in ratiometric chemical sensing owing to its long‐lived emission and high signal‐to‐noise ratio. However, developing RTP materials with multiple emission centers and their application in aqueous solutions remains a huge challenge. Herein, two chromophore isomers (p‐N‐DPC·(PF 6 ) 2 and m‐N‐DPC·(PF 6 ) 2 ) based on carbazole and naphthalene units are prepared by using pyridine quaternary ammonium salt as link to improve their solubility in water and form electron deficient centers to facilitate charge transfer (CT). p‐N‐DPC·(PF 6 ) 2 displayed multiple emissions behavior, including monomer fluorescence, dimer fluorescence, monomer phosphorescence, dimer phosphorescence, and CT phosphorescence. Especially, p‐N‐DPC·(PF 6 ) 2 exhibits monomer fluorescence, dimer fluorescence, and CT phosphorescence in an aqueous solution, which is successfully applied as self‐calibrated dual ratio luminescent sensor for phosphate detection. This study not only provides a strategy to construct luminophore with multiple emissions but also develops a fluorescence/ phosphorescence dual ratio luminescent sensor in an aqueous solution.