Zinc(II) and Copper(II) Metal-Organic Frameworks Constructed from a Terphenyl-4,4''-dicarboxylic Acid Derivative: Synthesis, Structure, and Catalytic Application in the Cyanosilylation of Aldehydes

Solvothermal reaction of zinc(II) and copper(II) salts with 3,3'''-dipropoxy-[1,1': 4', 1 ''-terphenyl]-4,4 ''-dicarboxylic acid (H2L) gave rise to the 1D and 2D metal-organic frameworks (MOFs) [Zn(L)(dmf)(2)](n) (1), [Zn-2(L)(NO3)(2)(4,4'-bipyridine)(2)](n) n(DMF) (2), [Cu(L)(H2O)(2)] n center dot 2n(H2O) (3), and [Cu-3(OH)(2)(L) 2](n)center dot n(H2O) (4), which were characterized by elemental analysis, FTIR spectroscopy, and X-ray single-crystal diffraction. MOFs 1 and 3 have zigzag- and linear-type 1D structures, respectively, whereas 2 and 4 possess rectangular grid-and layer-type 2D structures. In 2 and in 4, a dinuclear ZnII cluster (C2O4Zn2) and a trinuclear mu(3)-hydroxo-bridged CuII cluster [Cu-3(OH)(2)] n, respectively, act as building block units. These frameworks act as heterogeneous catalysts (the Zn-MOFs are more active than CuMOFs, and 1 is the most efficient) for the cyanosilylation of aldehydes with trimethylsilyl cyanide at room temperature. These MOF-based heterogeneous catalysts can be easily recovered and reused, at least over a few consecutive cycles, without losing activity.