A coordinated acetonitrile causing significant difference between two luminescent cuprous iodide hybrid materials based on dicationic DABCO ligands

Two new cuprous iodide hybrid materials, 1 and 2 , were synthesized at room temperature by the solvent evaporation method using two dicationic DABCO ligands, L 1 and L 2 . • Complex 1 exhibited severely quenched luminescence (Φ PL < 0.5%) attributed to nonradiative relaxation facilitated by coordinated acetonitrile. • Complex 2 displayed intense red luminescence with a high quantum yield of 70.50%. • The contrasting luminescence behavior provides a rational structure-property framework for understanding solvent-coordination-induced quenching in Cu(I)-iodide hybrid materials. Herein, two new cuprous iodide hybrid materials, (C₂₀H₂₆N₂)[CuI₃(CH₃CN)] ( 1 ) and (C₂₀H₂₄Cl₂N₂)[Cu₂I₄] ( 2 ), were synthesized using two dicationic DABCO-derived ligands L₁ and L₂ via a solvent evaporation method at room temperature. Both complexes exhibited broad phosphorescence bands, with emission maxima at 546 nm and 608 nm and lifetimes of 16.74 µs and 5.90 µs, respectively. Notably, complex 1 displayed severely quenched luminescence (Φ PL < 0.5%) attributed to nonradiative relaxation facilitated by the coordinated acetonitrile molecule. In contrast, complex 2 exhibited intense red emission with a high internal quantum yield (IQY) of 70.50%, enabled by the formation of a tetranuclear [Cu₄I₈]⁴⁻ chromophore and the introduction of a chlorine substituent on the benzyl ring of the ligand. Density functional theory (DFT) calculations revealed that halide-to-ligand charge transfer (XLCT) is the dominant emission mechanism in 2 . This study provides a rational structure-property framework for understanding solvent-coordination-induced luminescence quenching in cuprous iodide cluster materials.