An Imidazole-Based Halogen-Bonded Organic Framework for the High-Sensitive Detection of Nitrofuran Antibiotics

Abstract

Nitrofuran antibiotics threaten human health and the environment due to their toxicity and persistence. Their detection is challenging due to low concentrations and interference, while fluorescence sensing offers superior sensitivity and selectivity for effective monitoring. In this work, a novel halogen-bonded organic framework, XOF-TPEM, was introduced, constructed using an imidazole-based ligand AIE molecule, TPEM. The framework was successfully characterized by various techniques, including ¹H NMR, PXRD, XPS, FT-IR, HRTEM, SAED, SEM and EDS, confirming its excellent crystalline structure. As TPEM is an electron-donating AIE fluorophore, the fluorescent XOF-TPEM demonstrates potential as a selective sensor for electron-deficient nitrofuran antibiotics. Experimental results show that it exhibits high sensitivity and selectivity for detecting nitrofurans such as NFT, FZD, FLD, and NFZ, with LODs of 9.7 ppb, 11.0 ppb, 19.7 ppb, and 236.1 ppb, respectively. Mechanistic studies indicate that the outstanding fluorescence detection performance is attributed to the inner-filter effect occurring between XOF-TPEM and the nitrofuran antibiotics. Through comparison with the sensing performance of a pyridine-based XOF, the superiority of imidazole ligands in constructing XOFs is demonstrated. This study presents a novel luminescent halogen-bonded organic framework and highlights the superiority of imidazole-based halogen-bonded organic frameworks, underscoring their significant potential for expanding their functional applications.

Keywords

[N···I···N]⁺ halogen bond / Halogen-bonded organic framework / Nitrofuran antibiotics / Selective detection / Fluorescence quenching / Fluorescence sensing / Supramolecular chemistry / Molecular recognition

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