Highly selective and sensitive detection of Fe3+, Al3+ and picric acid by a water-stable luminescent MOF

A novel luminescent metal-organic framework (MOF) {[Co3(phen)2(HL)2]·(H2O)2}n (1) (H4L = 3,3′,5,5′-azoxybenzenetetracarboxylic acid, phen = Phenanthroline) was successfully prepared under solvothermal conditions. Its structure has been identified by single-crystal X-ray diffraction, infrared spectroscopy, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. Additionally, the importance of the weak interactions to stabilize the structure of 1 has been discussed by Hirshfeld surfaces and the corresponding 2D fingerprint plots (FPs). Remarkably, 1 has high thermal stability up to 360 °C and excellent chemical stability in water with wide pH range of 2–11. Luminescence studies show 1 can recognize Fe3+ and Al3+ with high selectivity from mixed metal ions in aqueous solutions through the luminescence quenching and enhancement phenomenon, respectively. Furthermore, 1 can also detect PA with good selectivity and sensitivity among large common nitro-aromatic compounds (NACs).