Parallel chain polyrotaxane, layer, and diamondoid divalent metal coordination polymers containing para aromatic dicarboxylate and bis(4-pyridylmethyl)piperazine ligands

Hydrothermal reaction of a closed-shell divalent metal salt, a para aromatic dicarboxylate precursor, and the long-spanning dipyridyl ligand bis(4-pyridylmethyl)piperazine (4-bpmp) afforded three new coordination polymers, which were structurally characterized by single-crystal X-ray diffraction. [Cd(tere)(4-bpmp)(H2O)]n (1, tere = terephthalate) exhibits a simple non-interpenetrated 66 diamondoid 3D network with pentagonal bipyramidally coordinated cadmium ions. [Zn2(tere)(4-bpmp)2Cl2]n (2), which possesses tetrahedrally coordinated zinc atoms, manifests an exceptionally rare 1D + 1D → 1D parallel interpenetrated threaded-loop polyrotaxane structure. Extension of the para aromatic dicarboxylate pendant arms by employing the 1,4-phenylenediacetate (1,4-phda) ligand generated [Zn(1,4-phda)(4-bpmp)(H2O)2]·2H2O}n (3), which shows a simple stacked (4,4) grid structure. Luminescent properties of these materials are also discussed.