Rational design of metallophosphors with tunable aggregation-induced phosphorescent emission and their promising applications in time-resolved luminescence assay and targeted luminescence imaging of cancer cells

Abstract

A series of Pt(II) complexes with different N⁁O ligands have been synthesized and characterized by NMR, mass spectroscopy, and X-ray diffraction studies. All complexes are non-emissive in dilute solution. Interestingly, they exhibit aggregation-induced phosphorescent emission (AIPE) with an absolute quantum efficiency of up to 38% in the crystal state. In addition, their AIPE properties can be tuned significantly by changing the chemical structures of N⁁O ligands. Furthermore, an AIPE mechanism of “restricted distortion of excited-state structure (RDES)” was proposed through experimental and theoretical investigations, which provided a rational design strategy for metallophosphors with tunable aggregation-induced phosphorescent emission. Considering their excellent emissive properties in aggregation state, the promising applications of these AIPE-active Pt(II) complexes in time-resolved luminescence assay utilizing the long emission lifetime of phosphorescent signal and targeted luminescence imaging of cancer cells have been demonstrated.