White Light and Color‐Tuning Long Persistent Luminescence from Metal Halide Based Metal‐Organic Frameworks

Abstract Room temperature phosphorescence (RTP) materials with long persistent luminescence (LPL) have raised particular attention among researchers for their potential uses in chemical sensing, optical recording devices, biological imaging, and security systems applications, due to the long‐lived triplet states. In this study, one‐pot method of reaction of appropriate ratio of crown ether ligand (15‐Crown‐5) and metallic salts (CdX 2 ) is utilized to yield three metal halide‐based complexes (namely 15‐5‐CdCl 2 , 15‐5‐CdBr 2 , and 15‐5‐CdI 2 ). In solid state, three complexes exhibit nearly standard white light emission with CIE coordinates of (0.28, 0.32), (0.31, 0.39), (0.30, 0.34) at room temperature under UV radiation of 340 nm. Meanwhile, they display the excitation‐dependent room temperature phosphorescence from blue/cyan to green/yellow, especially, 15‐5‐CdCl 2 and 15‐5‐CdBr 2 exhibit color‐tunable and visible LPL with time‐resolved luminescence lifetime as high as 1–2 s. Single‐crystal X‐ray diffraction analysis and theoretical calculations reveal that the bright LPL of 15‐5‐CdCl 2 and 15‐5‐CdBr 2 arise from the crown ether ligand and aggregation state induced by halogen‐bond. The thus obtained LPL provides potentials in lighting and displaying devices, optical recording devices, security systems and so on.