A new 3D Cd-MOF with 2fold interpenetrated as “turn-on/turn-off” fluorescent sensor for selective and sensitive detection of Cu2+, Al3+ and Fe3+ ions

The quantitative research with high sensitivity of metal ions has been increasingly important due to the influence to the environment and human health. In this work, a new luminescent Cd-MOF has successfully been constructed by one-dimensional spiral chain-shaped CdO6 clusters, H2O and 1-(4-carboxyphenyl)-5-methyl-4-oxo-1,4-dihydropyridazine-3-carboxylic acid ligands (H2(4-PDCA)), namely [Cd2(H2O)(4-PDCA)2]n (SNUT-19), which were further characterized by single crystal X-ray diffraction, PXRD, FT-IR and TGA. Single crystal X-ray analysis revealed that SNUT-19 exhibits unique 1D [Cd–O–Cd]∞ chain, further bridging by the ligand to form a three-dimensional (3D) structure with a 2-fold interpenetrated structure. SNUT-19 exhibits excellent water stability and good solid luminescence properties. In addition, the luminescence sensing experiments show that SNUT-19 as a fluorescent sensor for "turn on" and "turn off" luminescence sensitive detection of Cu2+, Al3+ and Fe3+ ions in aqueous media, which sensing mechanisms also have been investigated.