Engineering coordination and supramolecular copper-organic networks by aqueous medium self-assembly with 1,3,5-triaza-7-phosphaadamantane (PTA)

The aqueous medium self-assembly reactions of copper(II) nitrate with 1,3,5-triaza-7-phosphaadamantane (PTA) as a main ligand and sodium azide or iodide as an auxiliary ligand lead to the new water-soluble Cu(I) coordination polymer [Cu(μ-N₃)(μ-PTA)]_n (1) and monomer [CuI(PTA)(PTAH)₂]I₂ · H₂O(2) (PTAH = N-protonated form of PTA), with the PTA cages exhibiting the rare P, N- or the conventional P-coordination mode, respectively. Another hydrosoluble P-bound PTA derivative [Cu(PTA)₄](NO₃) · 6H₂O(3) is furnished in the absence of any auxiliary ligand. The compounds have been characterized by IR and NMR spectroscopy, elemental and single crystal X-ray diffraction analyses which feature the formation of a unique one-dimensional (1D) coordination network in 1 composed of the {Cu₂(μ-N ₃)₂} cores and PTA spacers, as well as 1D (in 2) and three-dimensional (3D) (in 3) supramolecular structures built from multiple N-H ··· N (PTAH/PTA) and O-H ··· N(H ₂O/PTA) H-bonds, respectively. The study broadens the still limited use of PTA as a spacer or building block for crystal engineering of metal-organic coordination and supramolecular networks, their nature being also dependent on the type of auxiliary ligand. Compound 1 represents the first example of a copper coordination polymer with PTA.