Synthesis and crystal structure of a Zn(II) metal-organic framework based on 1,3,5-benzenetricarboxylate and 4,4′-bis(1-imidazolyl)biphenyl ligands: selective sensing of Mn2+ and Fe3+ ions in aqueous solution

A new metal-organic framework (MOF), {[Zn-3(btc)(2)(bimb)(2)(H2O)(2)] (H2O)(3)}(n) (1), where H(3)btc = 1,3,5-benzenetricarboxylate and bimb = 4,4'-bis(1-imidazolyl)biphenyl, has been synthesized and characterized using single-crystal X-ray diffraction, IR spectroscopy, elemental, thermogravimetric, and photoluminescent analysis. X-ray diffraction crystallographic analyses indicate that 1 displays two types of Zn centers with a distorted pyramidal and a perfectly octahedral coordination sphere. The fully deprotonated btc(3-) ligand coordinates four Zn ions with two carboxylate groups having bidentate chelate modes and one binds mu(2)-eta(1):eta(1); bimb serves as a mu(2)-bridging ligand in 1, resulting in a new three-dimensional (3-D) metal-organic framework with an uncommon trinodal 4-connected network with a Schafli symbol of (6(5) 10)(2)(6(2) 8 10(3))(3)(7(3) 8 12) topology. In the crystal, a 3-D supramolecular architecture is further formed by O-H center dot center dot center dot O hydrogen bonds, C-H center dot center dot center dot O interactions, C-H center dot center dot center dot pi as well as pi center dot center dot center dot pi stacking. 1 shows intense fluorescence in the solid state and exhibits high selectivity for Mn2+ and Fe3+ ions through fluorescence enhancement and the quenching effect in aqueous solutions at room temperature, respectively. [GRAPHICS]