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

Three new supramolecular architectures based on polyoxovanadates H ₆V ₁₀O ₂₈·2HMTA·8H ₂O(1), [Ni(enMe) ₃] ₂(V ^IV ₈V ^V ₇O ₃₆Cl)·2H ₃O (2) and [Co(en) ₃] ₂(V ^IV ₈V ^V ₇O ₃₆Cl)·2H ₃O (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 [H ₆V ₁₀O ₂₈] units. Compound 2 possesses a 2-D (3,6)-connected supramolecular layered structure formed by water molecules and [V ₁₅O ₃₆] ^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 [V ₁₅O ₃₆] ^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.