Synthesis, characterization and luminescent properties of copper(I) halide 1D polymers with pyridoimidazole−derived bisphosphine ligand

One−dimensional (1D) copper(I) coordination polymers (Cu − CPs), labeled CP1 (X = I), CP2 (X = Br), and CP3 (X = Cl), were constructed using an unusual pyridoimidazole−based bisphosphine ligand (L) and CuX. Ligand L enforces rigidity around the Cu centers, and the Cu − CPs exhibit bright luminescence, with emission maxima at 640 nm (CP1), 633 nm (CP2), and 645 nm (CP3), respectively. Due to the strong SOC effect and Cu(I) stabilization imparted by I, CP1 achieves a high photoluminescence quantum yield (PLQY) of 39 % and an exceptionally short decay lifetime (τ) of 0.77 μs at room temperature, significantly outperforming CP2 (PLQY: 14 %, τ: 2.19 μs) and CP3 (PLQY: 6 %, τ: 2.28 μs). Theoretical and experimental investigations suggest that the room−temperature luminescence of CP1 arises from thermally activated delayed fluorescence (TADF). This work is expected to encourage further exploration of promising emitters based on Cu − CPs.