Low-cost, robust, and transportable devices based on Cu( <scp>i</scp> )–I cluster hybrid luminescent compounds as tetracycline sensors for contaminated waters

Submicron particles of [Cu₄I₆(pr-ted)₂] (pr-ted = 1-propyl-1,4-diazabicyclo[2.2.2]octan-1-ium) are easy to synthesize in one step under mild conditions. Additionally, they exhibit strong emission at 530 nm, high photoluminescence quantum yield, and excellent thermal (250 °C) and water stability (pH = 4-9). These properties make them a promising candidate for studying luminescence responses to external stimuli, potentially serving as a chemical sensor. Furthermore, their size and morphology make it possible to obtain stable suspensions in ethanol and water, which are extremely useful for subsequent processing. Indeed, submicrometric [Cu₄I₆(pr-ted)₂] particles in deionized water and real river water suspensions can be used to efficiently detect tetracycline (TC) <i>via</i> photoinduced electron transfer, resulting in a detectable fluorescence quenching. It features a low detection limit of 1.18 nM (0.52 ppb) and the reversible quenching of the emission demonstrates recyclability for over 30 cycles. The detection process is unaffected by other antibiotics, including sulfamethazine (SMZ), chloramphenicol (CAP), and ornidazole (ORN). Effective TC detection is supported by the theoretical computations of the energy bands of TC antibiotic and [Cu₄I₆(pr-ted)₂], indicating a good match between their energy bands, which aligns with the fluorescence quenching observed. As a proof of concept, the material has been further processed into various formats - such as pellets, paper strips, fiberglass, polylactic acid (PLA) composite films, and 3D-printed composite meshes using commercial photosensitive resins-for their practical application as robust, high sensitivity, rapid on-off response, and cost-effective tetracycline water sensor devices.