Three-dimensional metal-organic frameworks based on functionalized tetracarboxylate linkers: synthesis, structures, and gas sorption studies.

New tetracarboxylate ligands with dihydroxy (L(1)) and crown ether functionalities (L(2)) have been synthesized and treated with Cu(II) and Zn(II) ions to generate three-dimensional (3D) metal-organic frameworks (MOFs) with the compositions of [Cu(2)(L(1))(H(2)O)(2)].14DMF.10H(2)O, 5, [Cu(2)(L(2))(H(2)O)(2)].12DMF, 6, [Zn(6)(mu(4)-O)(L(1))(2)(L(1)-H(2))].35DMF.27H(2)O, 7, and [Zn(3)Na(2)(L(2))(2)(DMF)(2)].7DMF.14H(2)O, 8. The four compounds show different framework structures with different connectivities. Compound 5 exhibits the PtS topology whereas compound 6 has a [6(4).8(2)](3)[6(6)] topology. Compound 7 adopts a new [4.6(5)][4(2).6(8)][4(4).6(2)][4(5).6][4(8).6(10).8(3)] topology while compound 8 exhibits the Flu topology. The porosity and H(2) uptake were studied by gas sorption experiments and grand canonical Monte Carlo (GCMC) simulations. Compound 5 shows a high H(2) uptake of up to 1.11 wt % at 77 K.