A Series Of Porous Interpenetrating Metal-Organic Frameworks Based On Fluorescent Ligands For Nitroaromatic Explosive Detection

Four porous interpenetrating metal-organic frameworks (MOFs), namely, [Cd-2(Tipb)(2)(btc)Cl]G(x) (1), [Cd(Tipb)(tdc)]G(x) (2), [Cd(Tipb)(fdc)]G(x) (3), and [Cd-5(Tipb)(4)(btc)(2)Cl-2(DMF)(2)(H2O)(5)]Cl(2)G(x) (4) (G = guest molecules, Tipb = 1,3,5-tris(p-imidazolylphenyl)benzene, btc = benzene-1,3,5-tricarboxylic acid, tdc = thiophene-2,5-dicarboxylic acid, fdc = furan-2,5-dicarboxylic acid, and DMF = N,N-dimethylformamide) have been assembled from -electron-rich ligands and cadmium salts. These four MOFs exhibit strong fluorescent emissions upon excitation at room temperature. Due to the presence of -electron-rich N-donor ligands, the sensing sensitivities of compounds 1-3 towards electron-deficient nitroaromatic explosives such as 2,4,6-trinitrophenol (TNP), 2,4-dinitrotoluene (2,4-DNT), 1,3-dinitrobenzene (1,3-DNB), and nitrobenzene (NB) have been studied by fluorescence quenching experiments. The results indicate that compounds 1-3 are highly sensitive to TNP owing to the electron and energy transfers between MOFs and TNP. Furthermore, compounds 1-3 remain stable after quenching and exhibit good recyclability. Moreover, the adsorption properties of 1-3 have also been investigated.