Self-assembled copper(II) coordination polymers derived from aminopolyalcohols and benzenepolycarboxylates: Structural and magnetic properties

Abstract

The new copper(II) or copper(II)/sodium(I) 1D coordination polymers [Cu2(Hmdea)2(μ-H2O)(μ2-tpa)] n·2nH2O (1), [Cu2(H2tipa) 2(μ2-ipa)]n·4nH2O (2), [Cu2(H2tea)2Na(H2O) 2(μ2-tma)]n-6nH2O (3), [Cu 2(H2tea)2(μ2-ipa)] n·nH2O (4a), and [Cu2(H 2tea)2{μ3-Na(H2O) 3}(μ3-ipa)]n(NO3) n·0.5nH2O (4b) have been prepared in aqueous medium by self-assembly from copper(II) nitrate, aminopolyalcohols [methyldiethanolamine (H2mdea), triisopropanolamine (H 3tipa), and triethanolamine (H3tea)] as main chelating ligands and benzenepolycarboxylic acids [terephthalic (H2tpa), isophthalic (H2ipa), and trimesic (H3tma) acid] as spacers. They have been characterized by IR spectroscopy, elemental and single-crystal X-ray diffraction analyses, the latter indicating the formation of unusual multinuclear metal cores interconnected by various benzenepolycarboxylate spacers, leading to distinct wavelike, zigzag, or linear 1D polymeric metal-organic chains. These are further extended to 2D or 3D hydrogen-bonded supramolecular networks via extensive interactions with the intercalated crystallization water molecules. The latter are associated, also with aqua ligands, by hydrogen bonds resulting in acyclic (H2O) 3 clusters in 1, (H2O)8 clusters in 2, infinite 1D water chains in 3, and disordered water-nitrate associates in 4b, all playing a key role in the structure stabilization and its extension to further dimensions. Variable-temperature magnetic susceptibility measurements have shown that 1-4 exhibit a moderately strong ferromagnetic coupling through the alkoxo bridge. The small Cu-O-Cu bridging angle and the large out-of-plane displacement of the carbon atom of the alkoxo group accounts for this behavior. The magnetic data have been analyzed by means of a dinuclear and a 1D chain model, and the magnetic parameters have been determined. The magnetic exchange coupling in 3, to our knowledge, is the highest found in alkoxobridged copper(II) complexes. © 2008 American Chemical Society.