Two bis-ligand-coordinated Zn(ii)-MOFs for luminescent sensing of ions, antibiotics and pesticides in aqueous solutions.

Two organometallic complexes with two and three-dimensional architectures were constructed by using multiple ligands and Zn(ii) ions: [Zn(BTC)(DTP)(HO)]·(HO) (Zn-1) (BTC = benzene-1,3,5-tricarboxylic acid and DTP = 3,5-di(1,2,4-triazol-1-yl)pyridine) and [Zn(NTD)(DTP)] (Zn-2) (NTD = 1,4-naphthalenedicarboxylic acid). The as-prepared complexes were characterized by single-crystal X-ray diffraction (SCXRD), elemental analysis, powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and fluorescence analysis. Fluorescence sensing tests revealed that the two complexes are effective, sensitive and selective toward cationic Fe and anionic MnO and CrO . During the antibiotic sensing process, cefixime (CFX) for Zn-1 and nitrofurantoin (NFT) for Zn-2 exhibited the highest quenching efficiencies. For sensing pesticides, the highest quenching efficiencies were exhibited by imidacloprid (IMI) toward Zn-1 and Zn-2. The fluorescence quenching of the complexes that was induced by antibiotics, pesticides and MnO was attributed to both the inner filter effect (IFE) and the fluorescence resonance energy transfer (FRET) effect.