Urea-based flexible dicarboxylate linkers for three-dimensional metal-organic frameworks

[Display omitted] •First examples of 3D-MOFs with single urea-based ditopic dicarboxylate linker.•Isostructural 3D-MOFs of diamond (6,6), dia topology.•Fourfold interpenetrated MOFs, organized via H-bonds in the C(4)[R12(6)] motif.•Fourfold interpenetration still leaves 50% solvent-filled void volume. The metal-organic frameworks (MOFs) 3D-[Mn2(L1)2(DMF)]·2DMF (1), 3D-[Cd2(L2)2(DMF)3] (3), [Zn2(L2)2(DMF)3] (4) and 3D-[Mn2(L2)2(DMF)3] (5) are the first examples of three-dimensional metal-organic networks constructed from a single ditopic dicarboxylate linker (i.e., without bridging co-ligands) with an urea group in the linker axis (L12−=4,4′-(carbonylbis(azanediyl))dibenzoate; L22−=4,4′-(carbonylbis(azanediyl))bis(3-methylbenzoate), DMF=dimethylformamide). From Cd2+and L12− a 1D coordination polymer 1D-[Cd(L1)(DMF)3] (2) is formed. The urea group is engaged in hydrogen bonding with the C(4)[R12(6)] motif to an oxygen atom of a DMF solvent (in 1) or a metal-coordinated carboxylate group (in 3–5). Network 1 has infinite channels with parallelepiped cross sections and 30% solvent-filled volume. The 3D frameworks 3–5 are of diamond (6,6), dia topology with a single framework having large voids with 17.6Å and 19.7Å nodal separation. Thus, four symmetry-related nets interpenetrate, organized via H-bonds in the C(4)[R12(6)] motif, still leaving about 50% solvent-filled void volume in the fourfold interpenetrated structure.