Engineering Morphology and Dimensionality in 1D and 2D Cu(I)-I Coordination Polymers for Enhanced Photocatalysis, Luminescence, and Selective Antibiotic Sensing

Copper(I) iodide coordination polymers (CPs) based on pyridine- and pyrazine-derived ligands are luminescent materials typically synthesized under solvothermal conditions using organic solvents. Herein, the archetypal compounds [CuI(4-methylpyridine)]n (CP1) and [Cu2I2(2-methylpyrazine)]n (CP2) were synthesized through one-step room-temperature methods, reducing the need for conventional high-temperature solvothermal procedures. Particle size modulation using polyvinylpyrrolidone and postsynthetic treatments, by sonication or grinding, enabled control over the morphology while preserving the crystal structure. Sonication additionally produced stable aqueous suspensions with enhanced dispersibility and processability. Both CPs exhibited size-dependent optical properties, with band gaps ranging from 2.1 to 3.2 eV for CP1 and from 2.2 to 2.4 eV for CP2. Reduced particle size and increased effective surface area led to enhanced photocatalytic activity toward methyl orange degradation, achieving complete degradation within 6 and 3 min, respectively, for the smallest particles. CP1 and CP2 displayed intense luminescence centered at 440 and 700 nm, respectively, and acted as luminescent sensors for tetracycline in water, with limits of detection (LODs) of 410 and 2800 nM, respectively. Furthermore, the improved processability of the sonicated materials enabled their incorporation into 3D-printed photopolymer composites and PLA films. These results highlight the potential of sustainable Cu(I)-iodide CPs for environmental remediation, antibiotic sensing, and portable functional devices.