A water-stable zwitterionic Cd(II) coordination polymer as fluorescent sensor for the detection of oxo-anions and dimetridazole in milk

Abstract

Coordination polymers (CPs) constructed by zwitterionic ligands show obvious advantages in the fluorescence sensing of toxic pollutants due to the separated charge centers on the frameworks, where the construction of aqueous-phase stable and multifunctional complexes is crucial for practical applications in environmental or food safety detection. A Cd(II) 2D water-stable porous CPs {[CdL(H2O)2]·(ClO4)·3H2O} (1) (flexible H2LCl = 5-carboxy-1-(4-carboxybenzyl)-2-methylpyridin-1-ium chloride) was solvothermally synthesized from good fluorescent zwitterionic organic linkers and was further characterized by single-crystal X-ray diffraction, Hirshfeld surface analysis, powder X-ray diffraction (PXRD), IR spectra, elemental analysis, and thermogravimetric analysis (TG). Aqueous-phase sensing studies demonstrate that complex 1 can serve as a unique bifunctional luminescent probe for highly selective, quick responsive and multicyclic detection of three noxious high-valent oxo − anions Cr2O72−, CrO42−, MnO4− as well as dimetridazole (DTZ) antibiotic via remarkable fluorescence quenching with low limits of detection (LODs) (Cr2O72− 0.12 μM, CrO42− 0.16 μM, MnO4− 0.29 μM and DTZ 0.09 μM). Moreover, the sensor has a certain practical application potential. It obtains desirable recoveries (96.10–105.35 %) for the determination of oxo-anions and DTZ in milk, respectively. Mechanism for all the turn-off responses between the framework and analytes were elaborately explored by means of the electron transfer analytical methods and density functional theory (DFT) calculations.

Keywords

• Coordination polymers
• Zwitterionic ligands
• Luminescent probe
• High-valent oxo−anions sensing
• Dimetridazole sensing