Highly sensitive fluorescence detection of chlortetracycline and tetracycline residues in food samples based on a Zn(II) coordination polymer.

Residual Tetracycline-like analogs antibiotics, including Chlortetracycline (CTC) and Tetracycline (TC), in food pose a significant threat to public health. A 3D Zn(II) coordination polymer, designated as [Zn4(L)4(H2O)]·2(DMF)·4H2O (CP 1), was successfully synthesized via the solvothermal method, utilizing 4,4'-(quinoxaline-2,3-diyl)dibenzoic acid (H2L) as the organic ligand. This fluorescent material exhibits remarkable stability in maintaining its structure and fluorescence intensity across various aqueous environments and a broad pH range. Research on aqueous phase sensing indicates that CP 1 exhibits significant quenching efficiency for CTC and TC antibiotics (CTC: Ksv = 1.0478 × 105 M-1, TC: Ksv = 2.897 × 104 M-1) and low detection limits (CTC: 0.075 μM, TC: 0.27 μM). Notably, CP 1 exhibits superior anti-interference capabilities and excellent reusability in fluorescence sensing applications. When applied to the practical detection of CTC and TC in food samples (tap water, milk and honey), the recovery rates range from 90.0 % to 107.0 %, with relative standard deviations (RSD) falling within 0.5 % to 1.7 %. To further elucidate the underlying fluorescence quenching mechanism, a comprehensive analysis was conducted, combining experimental data, density functional theory (DFT) calculations, and Hirshfeld surfaces analysis. This comprehensive approach revealed that the fluorescence quenching observed during the sensing process is jointly attributed to fluorescence resonance energy transfer, internal filtration effect, photoinduced electron transfer, and hydrogen bonding interactions.