A New Three‐Dimensional Cd(II) Metal‐Organic Framework for Highly Selective Sensing of Fe3+ as well as Nitroaromatic Compounds

A new three‐dimensional Cd(II)‐organic framework [Cd(H2BDDA)]n based on fluorescent ligand, 4,4’‐([2, 2’‐bipyridine]‐6,6’‐diylbis(oxy) diphthalic acid(H4BDDA), has been successfully achieved. The obtained [Cd(H2BDDA)]n contained both fluorescent ligands and cadmium ions, thus showing multi‐responsive photoluminescence sensing properties. It can be used to detect Fe3+ with a sensitivity of 2.69 ppm in aqueous solution. For the fluorescence responses of [Cd(H2BDDA)]n dispersed in water solution with gradually increased p‐nitroaniline(p‐NA) and N‐methyl‐4‐nitroaniline (N−M‐4‐NA) concentrations, photoluminescence quenching can be detected even at a very low concentration of 0.68 ppm for p‐NA and 0.80 ppm for N−M‐4‐NA, which indicated that [Cd(H2BDDA)]n has an extremely high sensitivity to p‐NA and N−M‐4‐NA. To our best knowledge, [Cd(H2BDDA)]n is the first example of Cd(II) MOF based on the fluorescent ligand H4BDDA, which can be used for the detection of Fe3+ ions and NACs, especially for p‐NA and N−M‐4‐NA. A new three‐dimensional Cd(II)‐organic framework(Cd‐HBDDA) has been synthesized under hydrothermal conditions, which exhibited excellent selectivity and highly sensitivity detective of Fe3+, p‐nitroaniline and N‐methyl‐4‐nitroaniline with a fluorescence quenching mechanism in water.