Two porous three-dimensional (3D) metal-organic frameworks based on diverse metal clusters: selective sensing of Fe3+ and Cr2O72-

Two porous complexes, namely, {[H2N(Me)(2)](2)[Zn-5(L)(2)(OH)(2)]center dot 3DMF center dot 4H(2)O}(n) (1), and {[H2N(Me)(2)](4) [Cu-3(L)(2)(H2O)(2)]center dot 4DMF center dot 3H(2)O}(n) (2) were solvothermay constructed based on a symmetrical V-shaped rigid multicarboxylic acid ligand H5L (H5L = 3,5-di(2',5'-dicarboxylphenypbenzoic acid). Complexes 1 and 2 display 3D frameworks with various metal dusters. Complex 1 is a 3D porous framework with a (4,8)-connected topology featuring a 1D pore structure in the a-axis direction with a penta-nuclear duster [Zn-5(mu(2)-COO)(6)(mu(1)-COO)(4)(mu(3)-O)(2)]. By contrast, 2 displays a 3D (3,4)-connected net based on binuclear [Cu-2(COO)(4)] paddlewheel SBUs. Complex 1 reveals solid-state luminescent properties at ambient temperature, and the maximum emission peak was observed at similar to 443 nm (lambda(ex) = 339 nm). Meanwhile, 1 shows high selectivity and sensitivity not only for Fe3+ cations but also for Cr2O72- anions via the luminescence quenching effect with a low detection limit, which thus could be a potential crystalline material for detecting these substances. The mechanisms of the quenching effect and sensing properties of 1 were discussed in detail.