Cadmium Glutarate Coordination Polymers Containing Hydrogen-Bonding Capable Tethering Organodiimines: From Double Interpenetration to Supramolecular Cavities Containing an Unprecedented Water Tape Morphology

Two cadmium glutarate coordination polymers incorporating the hydrogen-bonding capable tethering organodiimines 4,4′-dipyridylamine (dpa) or bis(4-pyridylmethyl)piperazine (bpmp) have been prepared and structurally characterized. [Cd(glutarate)(dpa)]n (1) manifests a doubly interpenetrated decorated α-Po (pcu, 41263 topology) lattice, with octahedral coordination at cadmium. Compound 1 undergoes blue-violet luminescence upon UV irradiation. Use of the longer tethering organodiimine resulted in the formation of {[Cd(glutarate)(bpmp)(H2O)]·6H2O}n (2), which displays non-interpenetrated (4,4)-rhomboid grid coordination polymer layers. In contrast to 1, the cadmium ions in 2 adopt a pentagonal bipyramidal coordination geometry, with aqua ligands allowing construction of a hexagonal boron nitride (bnn, 4466 topology) supramolecular framework through interlayer hydrogen bonding. Unprecedented one-dimensional water molecule tapes with 2T5(2)7(2) classification occupy large ellipsoid channels coursing through the structure of 2, stabilizing the coordination polymer framework through hydrogen bonding. Upon partial dehydration the structure of 2 degrades irreversibly.