Engineering Coordination and Supramolecular Copper−Organic Networks by Aqueous Medium Self-Assembly with 1,3,5-Triaza-7-phosphaadamantane (PTA)

Abstract

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-N3)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 (H2O/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.