Highly effective detection of DNP and Fe3+ by designed coordination polymers containing electron rich linkers and azo functional groups

Three new coordination polymers, [Zn(BPTC)0.5(bphy)]⋅(DMF)3 (1), [Zn(HBTC)(azpd)0.5(H2O)]⋅H2O) (2), and [Cd(HBTC)(azpd)(H2O)]⋅(DMF)⋅(H2O)2 (3) (BPTC = biphenyl-3,3′,5,5′-tetracarboxylic acid, bphy = 1,2-bis(4-pyridyl)hydrazine, azpd = 4,4′-azopyridine and H3BTC = benzene-1,3,5-tricarboxylic acid), have been synthesized under solvothermal conditions. The CPs were structurally characterized by single crystal X-ray diffraction analyses and further characterized by powder X-ray diffraction (PXRD), Infrared spectra (IR), UV–visible, Thermogravimetric analysis (TGA), and Elemental analysis (EA). Complex 1 is constructed by 2D ladder chains and further extended through hydrogen bonds to generate a 3D supramolecular framework. Complex 2 and 3 are one-dimensional (1D) molecular chains and further extended via hydrogen bonding interactions to form 3D frameworks. The solid-state photoluminescence of complexes 1–3 was studied. Complex 1 exhibits strong fluorescence emission at 387 nm upon excitation at 310 nm. While complex 2 and 3 show strong emission peak at 403 and 393 nm upon excitation at 298 nm, respectively. Complexes 1–3 act as sensor for the detection of nitro compounds, especially dinitrophenol (DNP) and Fe3+ cation via quenching of their fluorescent intensity.