Azo-Modified Luminescent Zn (II)-Organic Frameworks for Selective Detection of UO22+ and Antibiotics in Water

Uranium can cause irreversible reactions in the body if accidentally ingested by organisms, and when antibiotics exceed normal acceptable levels, they can cause serious illness, so detecting them is important but also challenging. In this work, new azo-imidazole ligands were formed by introducing different functional groups (biphenol, phenol) into the benzimidazole moiety (E)-4-((1H-benzo[d]imidazol-5-yl)diazenyl)-[1,1′-biphenyl]-2,2′-diol [L1]、(E)-3-((1H-benzo[d]imidazol-5-yl)diazenyl)phenol [L2]. Subsequently, under different high temperature, a series of water-stabilized Zn-based metal–organic frameworks (MOFs) [Zn(L1)(BDC)]·CH 3 OH·H 2 O ( MOF-1 ), [Zn 2 (L2) 4 (BDC) 2 ]·L2 ( MOF-2 ) and [Zn(L2)(1,3-BDC)]·H 2 O ( MOF-3 ) were obtained by using H 2 BDC and 1,3-H 2 BDC as auxiliary ligands. X-ray revealed that they were different 3D supramolecular framework. Outstanding fluorescent properties and structural stability of MOFs 1-3 making them potential luminescent sensors for UO 2 2+ ions and antibiotics in water. The results show that MOF-1 , MOF-2 , and MOF-3 exhibit high sensitivity for the detection of UO 2 2+ ions with detection limits of 3.00 × 10 −6 mol/L for MOF-1 , 2.58 × 10 −6 mol/L for MOF-2 , and 3.01 × 10 −6 mol/L for MOF-3 . Similarly, the strong emissions of MOF-1 , MOF-2 , and MOF-3 can be quenched efficiently by trace amount of NMs (metronidazole, MDZ; dimetridazole, DTZ) and NFs antibiotics (nitrofurazone, NZF; nitrofurantoin, NFT; furazolidone, FZD).