Influence of the steric hindrance of organic amines on the supramolecular network based on polyoxovanadates

Abstract

Three new supramolecular architectures based on polyoxovanadates H₆V₁₀O₂₈·2HMTA·8H₂O(1), [Ni(enMe)₃]₂(V^IV₈V^V₇O₃₆Cl)·2H₃O (2) and [Co(en)₃]₂(V^IV₈V^V₇O₃₆Cl)·2H₃O (3) (HMTA = hexamethylenetetramine, enMe = 1,2′-propanediamine and en = ethylenediamine) have been prepared and characterized by elemental analyses, IR spectra, XPS spectra and single crystal X-ray diffraction structure analyses. Compound 1 displays a 3-D (4,8)-connected supramolecular host network, which is constructed of octamer water clusters and HMTA molecules, with 1-D channels occupied by the template [H₆V₁₀O₂₈] units. Compound 2 possesses a 2-D (3,6)-connected supramolecular layered structure formed by water molecules and [V₁₅O₃₆]³⁻ units showing honeycomb cavities occupied by the transition metal complexes (TMCs). Compound 3 exhibits a 3-D (4,6)-connected supramolecular host network built by the [V₁₅O₃₆]³⁻ units and the lattice water molecules with TMCs cations as the template. By a careful inspection of the structures of 1–3, it is believed that the steric hindrances of organonitrogen ligands are important for the formation of different supramolecular networks. Compound 1 exhibits intensive photoluminescence and compound 3 displays antiferromagnetic interactions.