A novel amino functionalized three-dimensional fluorescent Zn-MOF: The synthesis, structure and applications in the fluorescent sensing of organic water pollutants

Abstract

An amino functionalized three-dimensional (3D) Zn-MOF with molecular formula Zn(NH2bdc)(mbib) (complex 1) has been synthesized by using solvothermal method. The structure, purity, stability and morphology of complex 1 was fully characterized with single-crystal X-ray diffraction, PXRD, FT-IR, TGA, TEM, et al. The characterization results revealed that complex 1 crystallizes in the orthorhombic space group Pna21. In the structure of complex 1, each NH2bdc2− ligand connected to two Zn(II) to form a 1D zigzag chain which was further connected by the mbib ligands to give a fourfold interpenetration 3D framework. The single-crystal X-ray diffraction analysis indicated that the 3D framework of complex 1 was functionalized with free amino groups both on the surface and in the channels. Characteristic fluorescent emission centered at 430 nm which could be remarkably enhanced in water was observed, indicating complex 1 might be a promising candidate for the fluorescent sensing of water pollutants. The functionalized amino groups remarkably enhanced the selectivity and sensitivity of complex 1. Gradually fluorescence quenching of complex 1 was recorded in the fluorescent titration experiments with good quantitative relation after addition of acetone or picric acid in water samples. The experimental detection limits for acetone and picric acid were 0.03% (%V) and 340 nM, respectively. Plausible mechanisms for the fluorescent quenching sensing of acetone and picric acid were proposed.