Study Of Compounds With Multi-dimensional Structure Based On Lanthanide-substituted Keggin-type Polyoxometalates

Polyoxometalates (POMs), as early transition metal oxygen anions, not only are significant in theoretical study, but also possess potential practical values in various fields. In order to obtain multi-dimensional compounds and improve their practical properties, it is a commomly used way to introduce lanthanide cations or lanthanide-organic complex to POMs system.In this paper, by introducing lanthanide cations and organic ligands4-picolinic acid (Hpic) or3-pyridylacrylic acid (3-Hpya) to the monolacunary Keggin-type polyanions [a-SiW11O39]8-system, we synthesized a series of compounds with multi-dimensional structure under the routine conditions. And the compounds were characterized by elemental analysis, IR, UV, TG, PXRD and single-crystal X-ray diffraction. Furthermore, the photoluminescence properties, magnetic properties, and photocatalysis properties of some compounds have been investigated. This dissertation is divided into three parts.1. Three novel compounds1,2and3constructed by polyoxoanions [a-SiW11O39]8-and lanthanide cations, have been successfully synthesized. Compound1and2are isomorphic, displaying a3D structure with1D channels constructed by lanthanide cations and [{(H2O)4Ln(SiW11O39)}2]10-polyanions. When the Nd3+cation was utilized in place of La3+and Ce3+cations, compound3was obtained which possesses a different structure from1-2. Compound3displays a3D open framework composed of two kinds building blocks [{(H2O)4Nd(SiW11O39)}2]10-and [{(H2O)3Nd(SiW11O39)}2]10-polyoxoanions, thus obtaining two kinds of1D channels with different aperture in3.2. When Hpic was introduced to substitute the coordinated water molecules in1—3,3D hybrid compounds4-6were obtained. Compounds4-6are isomorphous and isostructural, constructed by [{(H2O)4Ln(SiW11O39)}2]10-polyoxoanions and{Ln(Hpic)(H2O)5} coordination complex moieties, displaying3D sturcuture with1D channels with larger aperture compared with that of compounds1-2.3. When3-Hpya was introduced to the system, compounds7-9were synthesized. Compounds7-8are isostructural, constructed by [Ln(SiW11O39)2]13-polyanions and {Ln(3-Hpya)n(H2O)m} coordination complex moieties, displaying2D sturcuture. When the Eu3+cation was utilized in stead of La3+and Ce3+cations, compound9was obtained which possesses a different structure from7-8. It displays a1D open framework constructed by [Eu(SiW11O39)2]13-polyanions and{Eu(3-Hpya)(H2O)5}.