Hydrothermal synthesis and characterization of a novel 3D open framework structure of mixed valence ethylenediamine–vanadium phosphate: [C2H10N2][(HVIVO3)(HVVO2) (PO4)]

A new three-dimensional open framework structure of mixed valence ethylenediamine–vanadium phosphate [C2H10N2][(HVIVO3)(HVVO2)(PO4)] (1), has been synthesized under mild hydrothermal conditions and characterized by elemental analyses, IR, fluorescent spectrum, TG-DTA and single crystal X-ray diffraction. Compound 1 exhibits a novel three-dimensional (3D) vanadium phosphate anion framework composed of vanadium, phosphate, and oxygen atoms through covalent bonds, with the diprotonated ethylenediamine [NH3CH2CH2NH3]2+ cations residing in the channels along c-axis. The organic diprotonated ethylenediamine cations interact with the O atoms in the inorganic network through hydrogen bonds. The electrochemical behavior of 1 has also been studied in detail by cyclic voltammograms, which is very important for practical applications in electrode modification. Furthermore, the strong photoluminescence property of compound 1 is also measured at room temperature.

The structure of 1 contains [(HVO3)(HVO2)(PO4)]2− framework separated by diprotonated ethylenediamine cations. One crystallographically distinct V(1)O5 tetragonal pyramids, V(2)O6 octahedron, and PO4 tetrahedron are connected by sharing oxygen atoms in the unit cell packing. Each V(2)O6 octahedron shares corners with one PO4 tetrahedron to form the infinite one-dimensional linear chain structure along c-axis. And the neighboring one-dimensional chains, are linked together in the corner sharing manner through adjacent V(1)O5 tetragonal pyramids, giving rise to the formation of two-dimensional layers parallel to the ac-plane. These two-dimensional layers stack along b-axis are linked together by bridging V(1)O5 tetragonal pyramids to further extend the structure to a three-dimensional framework.Figure optionsDownload as PowerPoint slide