A highly sensitive and selective Cd-MOF fluorescent probe for the detection of His, NB, TC and PTH and its applications in real samples.

A novel metal-organic framework (MOF) with the formula of [Cd(CIA)(4,4'-BB)·HO]·HO (Cd-MOF) (HCIA = 5-methoxyisophthalic acid, 4,4'-BB: 4,4'-bis((1H-imidazol-1-yl)methyl)-1,1'-biphenyl) has been designed and synthesized through solvothermal reaction. The structure was characterized by TG, IR, PXRD, elemental analysis, single-crystal X-ray diffraction and XPS. The coordination pattern of the fully deprotonated ligand (CIA) in Cd-MOF is μ-к: к: к. The complex is found to be a three-dimensional reticular material with good thermal stability. Further study revealed that Cd-MOF has good fluorescence performance and can be used as a fluorescent probe for sensitive detection of histidine (His), nitrobenzene (NB), tetracycline (TC) and pyrimethanil (PTH) in water. Four cycles experiments can be achieved with a low detection limit. The detection limits were 0.3 µM (His), 0.05 µM (NB), 0.2 µM (TC) and 0.01 µM (PTH), respectively. To verify the feasibility of detecting PTH in real samples, we further explored it in water samples and apple peels. The spiked recoveries were 95.3-99.4 % and 97.2-101.2 %, respectively. Finally, the fluorescence quenching mechanism of Cd-MOF in His, NB, TC and PTH detection is discussed in detail.