Coordination Polymers Based on Copper(I) Iodide and <i>N</i> -Heteroaromatic Ligands for X-ray Scintillation and Imaging

Copper iodide-based coordination polymers (CPs) are promising candidates for X-ray scintillation and imaging due to low toxicity, earth abundance, excellent photoluminescence, and strong X-ray absorption stemming from iodine’s high atomic number, but their X-ray scintillation properties remain largely unexplored. In this work, we synthesized three bridging organic ligands by coupling pyridine with 1,2,4-triazole, imidazole, and benzimidazole and obtained three CuI-based CPs. The crystal structure and photo- and X-ray excited luminescence of the three CPs were studied. Among them, CP 3, constructed by {Cu2I2} rhombic binuclear units and (pyridin-4-yl)-benzimidazole, exhibited a photoluminescence quantum yield of 72.96%. The decomposition temperature of CP 3 exceeds 240 °C, and its photoluminescence was nearly unchanged after storage in air for 30 days, and then, it was immersed in water for 5 days. CP 3 showed a light yield of 9690 photons MeV–1 exited by X-ray, which is comparable to the commercial scintillator BGO (10,000 photons MeV–1). CP 3 was incorporated into a poly(dimethylsiloxane) film, forming a flexible composite film, which showed a spatial resolution up to 11 LP/mm for X-ray imaging, indicating good imaging capability.