Fluorescent metal-organic frameworks based on cadmium(II) coordinated by a mixture of ligands for sensitively sensing ions and pesticides

Two metal organic frameworks (MOFs) with 2D and 3D architectures were synthesized and characterized, namely: [Cd(DIN)(TPA)(H2O)](n) (DIN = 1,4-di(imidazol-1-yl)naphthalene, H(2)TPA = terephthalic acid) (Cd-1) and {[Cd(DIN)(FDC)(H2O)]center dot H2O}(n) (H2FDC = furan-2,5-dicarboxylic acid) (Cd-2). The structures and purities of Cd-1 and Cd-2 were revealed by elemental analyses, infrared spectra (IR), thermogravimetric analyses (TGA), single-crystal X-Ray diffraction analysis (SCXRD) and powder X-Ray diffraction (PXRD). Both two MOFs exhibited luminescence emission apexes around 350 nm upon relative incident light wavelengths of 230 and 290 nm. As a fluorescence sensor, Cd-1 shows a highly sensitive and selective ability towards I- (lambda(ex) = 230 nm) and Cr2O72- (lambda(ex) = 230 and 290 nm) during sensing of the ions. For sensing of the pesticides, the sensor shows a different performance. The sensor exhibits the highest quenching rates towards NTP and IMI upon excitation at 230 and 290 nm, respectively.