Three-Dimensional Metal-Organic Frameworks Based on Functionalized Tetracarboxylate Linkers: Synthesis, Strucures, and Gas Sorption Studies

New tetracarboxylate ligands with dihydroxy (L₁) and crown ether functionalities (L₂) 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 [Cu₂(L₁)(H₂O)₂]·14DMF·10H₂O, 5, [Cu₂(L₂)(H₂O)₂]·12DMF, 6, [Zn₆(μ₄-O)(L₁)₂(L₁-H₂)]·35DMF·27H₂O, 7, and [Zn₃Na₂(L₂)₂(DMF)₂]·7DMF·14H₂O, 8. The four compounds show different framework structures with different connectivities. Compound 5 exhibits the PtS topology whereas compound 6 has a [6⁴.8²]₃[6⁶] topology. Compound 7 adopts a new [4.6⁵][4².6⁸][4⁴.6²][4⁵.6][4⁸.6¹⁰.8³] topology while compound 8 exhibits the Flu topology. The porosity and H₂ uptake were studied by gas sorption experiments and grand canonical Monte Carlo (GCMC) simulations. Compound 5 shows a high H₂ uptake of up to 1.11 wt % at 77 K.