Dual-Color 2D Lead–Organic Framework with Two-Fold Interlocking Structures for the Detection of Nitrofuran Antibiotics and 2,6-Dichloro-4-nitroaniline

Abstract

The misuse of organic pollutants such as nitrofuran antibiotics (NFAs) and 2,6-dichloro-4-nitroaniline (DCN) has become a hot topic of global concern, and developing rapid, efficient, and accurate techniques for detecting NFAs and pesticides in water is a major challenge. Here, we designed a novel lead-based anion 2D metal-organic framework (MOF){[(CH₃)₂NH₂]₂[Pb(TCBPE)(H₂O)₂]}_<i>n</i> (<b>F3</b>) with interlocking structures, in which TCBPE stands for 1,1,2,2-tetra(4-carboxylbiphenyl)ethylene. Powder X-ray diffraction and thermogravimetric analysis revealed that <b>F3</b> has excellent chemical and solvent stability. It is worth noting that <b>F3</b> has a grinding discoloration effect. The solvent-protected grinding approach achieved <b>F3B</b> with a high quantum yield (QY = 73.77%) and blue fluorescence, while the direct grinding method produced <b>F3Y</b> with a high quantum yield (QY = 37.27%) and yellow-green fluorescence. Importantly, <b>F3B</b> can detect NFAs in water rapidly and sensitively while remaining unaffected by other antibiotics. <b>F3Y</b> can identify DCN in water quickly and selectively while remaining unchanged by other pesticides. <b>F3B</b> demonstrated high selectivity and rapid response to NFAs at a limit of detection (LOD) as low as 0.26 μM, while <b>F3Y</b> indicated high selectivity and responded quickly to DCN in water at an LOD as low as 0.14 μM. The method was successfully applied to detect NFAs in actual water samples of the fish tanks and ponds as well as the pesticide DCN in soil samples. The recovery rates were 97.0-105.15% and 102.2-106.48%, and the relative standard deviations were 0.63-1.45% and 0.29-1.69%, respectively. In addition, <b>F3B</b> and <b>F3Y</b> can be made into fluorescent test papers for the visual detection of NFAs and DCN, respectively. Combined with experiments and density functional theory calculations, the mechanism of fluorescence quenching of MOFs by target analytes was also revealed.