New Luminescent Three-Dimensional Zn(II)/Cd(II)-Based Metal Organic Frameworks Showing High H2 Uptake and CO2 Selectivity Capacity

Three new three-dimensional (3D) luminescent metal organic frameworks (MOFs), namely, [Zn-2(L)(2)]center dot 2DMA center dot 3H(2)O (1), [Zn-2(L)(2)]center dot H2O (2), and [Cd-2(L)(2)]center dot H2O (3) [H2L = 2-(imidazol-l-yl)terephthalic acid], have been solvothermally synthesized by using d(10) metal ions Zn(II)/Cd(II), and H2L in different solvent systems, which have been well characterized by elemental analysis, Fourier transform infrared spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. As influenced by the different solvents and metal ions, single-crystal X-ray diffraction shows that 1 is a three-dimensional (3D) microporous framework with one-dimensional (1D) pores (10.85 X 8.79 angstrom(2)) based on the [Zn-2(mu 2COO)(4)] secondary building units, and 2 and 3 are two 3D isostructural networks composed by 1D zigzag chains, which are further connected by L2- ligands into dense packing structures. Topology analyses reveal that 1 can be simplified as a binodal (6,3)-connected ant topological net with a point symbol of (4(4).6(3).8(3))(4(8).6(2)), and 2 and 3 show binodal (4,4) -connected nets with a point symbol of (4.6(3).8(2)). Gas sorption behaviors of 1 for N-2, H-2, CH4, and CO2 have been studied in detail at different temperatures, indicating that the high H-2 uptake and high selectivity for CO2 will make it as potential gas storage and separation materials. Moreover, the solid state luminescent properties of 1-3 have also been measured and studied at room temperature.