Cobalt 5-bromoisophthalate coordination polymers containing bis(pyridyl)piperazine-type long spanning ligands and water molecule aggregations

Divalent cobalt coordination polymers containing long-spanning bis(pyridyl)piperazine and 5-bromoisophthalate (Brip) ligands have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. {[Co(H2O)2(4-bpmp)2](HBrip)2·14H2O}n (1, 4-bpmp = bis(4-pyridylmethyl)piperazine), and {[Co(Brip)(H2O)3(4-bpfp)]·6.5H2O}n (2, 4-bpfp = bis(4-pyridylformyl)piperazine) both show 1-D coordination polymer connectivity, but with different intriguing water molecule aggregations. An unprecedented T4(4)6(6)6(6)10(8) classification water tape is seen in 1, while a discrete 11-molecule water cluster is observed in 2. {[Co2(Brip)2(H2O)4(3-bpmp)]·4H2O}n (3, 3-bpmp = bis(3-pyridylmethyl)piperazine) manifests a 2D + 2D → 3D mutually inclined interpenetrated system of parallel sets of (4,4) rhomboid grids, with isolated water molecule pairs.