“Turn-off” Cd-MOF fluorescence sensor for identification and detection of Fe3+, Cr6+ and antibiotics in aqueous solutions

A newly developed cadmium coordination polymer, [Cd(HEA)(L1)]_n (1), was prepared via a hydrothermal method and demonstrated to function as a multifunctional fluorescent probe for detecting heavy metal ions and antibiotics in aqueous solutions. The compound exhibits an unique two-dimensional layered structure that self-organizes into a robust three-dimensional framework, showcasing exceptional thermal stability and significant solvent tolerance. Fluorescence studies emphasized the outstanding metal ion detection capabilities of complex 1, which demonstrated a detection limit of 0.01434 μM for Fe³⁺ and 0.05949–0.06148 μM for Cr⁶⁺. Furthermore, the material exhibited selective fluorescence quenching towards specific antibiotics, with detection limits of 0.0369 μM for Ornidazole (ODZ) and 0.0687 μM for Nitrofurazone (NFZ). Notably, the material retained its fluorescent properties over five consecutive usage cycles. Comprehensive experimental studies and theoretical calculations show that the fluorescence quenching process involves the synergistic action of multiple mechanisms, mainly including: static quenching, dynamic quenching, competitive absorption, and light-induced electron transfer pathways. This work presents a promising strategy for sensing trace heavy metals and antibiotics in water systems, offering valuable contributions to the development of advanced environmental monitoring methodologies.