Two sulfone-functionalized Zn(II)-coordination polymers as luminescent sensors for sensitive and rapid detection of nitrofurans antibiotics

Through a dual-ligand strategy, two Zn(II) coordination polymers (CPs) including [Zn(L)(phen)]·0.5DMF (1) and [Zn₂(L)₂(4,4′-bipy)]·4DMF (2) have been synthesized from a sulfone-functionalized dicarboxylate (H₂L ​= ​2,2′-sulfone-4,4′-dicarboxylic acid) with the help of different N-donor co-ligands (phen ​= ​1,10-phenanthroline, 4,4′-bipy ​= ​4,4′-bipyridine). X-ray diffraction analyses reveal that the final structures are deeply influenced by the co-ligands. With chelate phen as the co-ligand, a double linear chain (1) is obtained. However, a 3D layer-pillared network (2) is generated with 4,4′-bipy as the co-ligand. Luminescence studies reveal that 1 and 2 show strong fluorescence in DMF, and they can serve as promising sensors for detection of trace amounts of nitrofurantoin (NFT) and nitrofurazone (NFZ) antibiotics via luminescence quenching. The K_SV values of 1 and 2 are 1.45 ​× ​10⁴ ​M⁻¹ and 1.30 ​× ​10⁴ ​M⁻¹ for NFZ, and 1.27 ​× ​10⁴ ​M⁻¹ and 1.14 ​× ​10⁴ ​M⁻¹ for NFT, respectively. Additionally, the possible mechanism for the luminescence quenching has been investigated.