Three New Metal Complexes with Imidazole-Containing Tripodal Ligands as Fluorophores for Nitroaromatics- and Ion-Selective Sensing.

Three new metal-organic complexes [Cd(TIPA)(suc)(NO)·1/2HO] (), [Ni(TIPA)(tda)(HO)·1/4HO] () and [Cd(TIPA)(tda)·11/2HO] () were synthesized via rigid tripodal ligand tris(4-(1H-imidazol-1-yl)phenyl)amine (TIPA) and three dicarboxylic acids; either succinic acid (Hsuc) or 2,5-thiophenedicarboxylic acid (Htda). Crystallographic data for - reveal three-dimensional (3D) networks and channels in the structures. The structure of is unique featuring an interpenetrating 2D network, 2D + 2D → 3D, with the two associated 2D networks existing in two opposite spiral channels. TGA plots exhibit a loss of mass corresponding to the loss of the solvated water molecules in the 100 - 200 °C temperature region and begin to lose additional fragments only at T > 300 °C revealing the robust nature of the 3D framework in the complexes. The metal-organic frameworks (MOFs) are screened for their potential application in the detection and removal of environmentally hazardous industrial pollutants. Fluorescence emission spectra for and show that the two MOFs are capable of sensing nitrobenzene (NB), with the nickel complex exhibiting significantly higher sensing ability. Powder XRD data measured for and and those of NB-treated and show significant differences in their patterns, providing further support for the strong interaction between the MOF complexes and NB. The fluorescence emission observed for is more effectively quenched by the presence of Fe than the series of 17 other metal ions investigated. Complex possesses some ability to adsorb inorganic pollutants.