A Luminescent Cd(II) Metal-Organic Framework With Dual Fluorescence Response for Detection of Nitrofuran Antibiotics and Nitrophenolic Pesticides.

Antibiotics are extensively utilized for treating bacterial infections for human and animals. Similarly, pesticides are widely applied in modern agriculture to enhance crop yield. However, their excessive and inappropriate use often leads to contamination of water bodies and soil with their residues causing environmental pollution. Therefore, efficient detection of these contaminants is important. Luminescent metal-organic frameworks (MOFs) have been emerged as promising materials for sensing different types of organic pollutants through changes in fluorescence intensity and/or color. Herein, we report a novel luminescent organic linker, 5'-(bis(4-carboxybenzyl)amino)-[1,1':3',1''-terphenyl]-4,4''-dicarboxylic acid, which forms a 3D fluorescent Cd-MOF. The intense blue luminescence of the MOF was judiciously utilized in detection of different nitrofuran containing antibiotic molecules such as nitrofurazone (NFZ) and nitrofurantoin (NFT) with very low detection limits of ∼0.09 and ∼0.22 ppm, respectively. Furthermore, the MOF demonstrates remarkable emission color change from blue to green for nitrophenolic pesticides 4,6-dinitro-o-cresol (DNOC) and 2,4-dinitrophenol (DNP). Mechanistic investigation reveals that strong supramolecular interactions of nitrophenolic moiety with the MOF is responsible for the emission shift in case of DNOC and DNP. Notably, NFZ and DNOC could be selectively detected in presence of each other by judicious utilization of the dual sensing mode of the MOF.