Solid state coordination chemistry of organodiphosphonates with copper(II) and auxilliary aromatic nitrogen heterocyclic ligands

The hydrothermal reactions of CuSO₄ · 5H₂O, a phosphonate ligand and an appropriate aromatic nitrogen heterocycle yield a series of materials of the Cu(II)/phosphonate/nitrogen ligand donor family. Two of the materials [Cu(2,2′-bpy)(HO₃PCH₂CH₂CH₂PO₃H)] (1) and [Cu(4,4′-bpy)(H₂O)₂(HO₃PCH₂CH₂CH₂CH₂PO₃H)] (2) are two-dimensional, while [{Cu(2,2′-bpy)}₂(O₃PC₆H₄PO₃)] · 8H₂O (3 · 8H₂O) is three-dimensional. When 1,3,5-benzenetricarboxylic acid is introduced as a reactant, the one-dimensional material [Cu(2,2′-bpy){OC₆H₂(CO₂H)₃}(HOPC₆H₅)] (4) is isolated. This is an example of an in situ hydrothermal ligand transformation in which the 1,3,5-benzene tricarboxylic acid is hydroxylated to give 1,3,5-benzene tricarboxylic acid-2-hydroxide. Compound 5 [Cu(terpy)(HO₃PC₆H₄PO₃H] is molecular.