A luminescent zinc(II) coordination complex showing a sensitive, selective, and recyclable detecting for tetracycline in food samples

The overuse of tetracycline (TC) antibiotics has resulted in widespread residues in food products, posing serious threats to human health. Herein, we report the synthesis of a binuclear zinc(II) complex [Zn2(L)4(H2O)2] (1) by solvothermal reaction employing ZnCl2 and [(1-phenyl-1H-tetrazol-5-yl)sulfanyl]methyl}benzoic acid (HL) ligand. Complex 1 was characterized by single-crystal X-ray diffraction, FT-IR, PXRD and TGA. Structural analysis reveals that a 2D network architecture of 1 is constructed by binuclear molecules linked through intermolecular O-H···N hydrogen bonds. Luminescent studies demonstrate that 1 can serve as an “turn-off” luminescent sensor for the sensitive, selective, and recyclable detection of tetracycline (TC), with Ksv of 1.9 × 104 M−1 and LOD of 1.6 × 10−7 M. Mechanistic investigations using PXRD, UV-vis spectroscopy and DFT calculations confirm that the synergistic effect of inner filter effect (IFE) and photoinduced electron transfer (PET) dominates the luminescence quenching. It is noted that complex 1 enables reliable TC detection, with recoveries 99.70% ∼ 101.98% for milk samples and 99.73% ∼ 102.80% for egg samples, as well as relative standard deviations (RSD) of less than 1.65% for milk samples and less than 1.76% for egg samples, addressing the crucial need for on-site monitoring of antibiotic residues in real food samples.