A luminescent anionic Cadmium(II)-MOF for the detection of nitrophenol compounds and metal ions in an aqueous solution

An anionic MOF, namely, {(CH3)(2)NH2)(2)[Cd(mu(4)-PPTA)]center dot DMF center dot 7H(2)O n (1) was synthesized with 4,4',4",4"-(1,4-phenylenbis(pyridine-4,2,6-triyl))tetrabenzoic acid (H(4)PPTA) and characterized. X-ray results showed that 1 had a four-fold interpenetrating 3D framework with dia topology and the charged balance was provided by dimethylamine cations in the framework. Due to the high emission property and stability of 1 in water, the luminescence detections of nitroaromatic compounds and metal ions were performed with 1. 1 could detect the nitrophenol compounds and metal ions in water via luminescence quenching. The detection limits were 6.84 mu M for 4-nitrophenol (NP), 1.85 mu M for 2,4-dinitrophenol (DNP) and 2.76 mu M for 2,4,6-trinitrophenol (TNP) and 94.4 mu M for Al3+, 66 mu M for Cr3+, 18.3 mu M for Fe3+ and 27.6 mu M for Cu2+. The detections of the nitrophenol compounds by 1 were due to hydrogen bonding interaction and resonance energy transfer. Moreover, the detections of metal ions by 1 were assigned to competitive absorption and electrostatic interactions with the anionic framework.