Cyclic water clusters in tape-like and cage-like structures.

Controlling the ratio of 2,2'-bpy to benzene-1,3,5-tricarboxylic acid produces two interesting complexes, namely [Co(2,2'-bpy)₃]·(SO₄)·8.5H₂O (1) and [Cu₂(BTCA) (2,2'-bpy)₄] (OH)·(2,2'-bpy)₀.₅·14H₂O (2) (H₃BTCA = benzene-1,3,5-tricarboxylic acid, 2,2'-bpy = 2,2'-bipyridine). We report the structural evidence in the solid state of discrete lamellar water cluster conformations. These units are found to act as supramolecular glue in the aggregation of cobalt (II) or copper (II) complexes to give three dimensional cage-like networks through hydrogen-bonding. It is interesting that the structure of complex 1 contains a 3D negatively charged cage.