Synthesis, Structure And Properties Of Rare Earth-Molybdenum Oxygen Clusters

In this paper,with the aim of researching microwave synthesis of rare earth-molybdate clusters,three series of rare earth-molybdenum oxygen cluster compounds are obtained by using ammonium molybdate,sodium molybdate,rare earth salts and organic ligands as raw materials through methods of microwave synthesis and conventi onal aqueous solution synthesis.Their crystal structures,infrared spectra,ultraviolet-visi ble spectra,X-ray powder diffractions?XRD?,thermal stability,fluorescence properties,photochromism and magnetic properties are characterized and studied.The catalytic p erformance of some compounds on the oxidation of thioethers is also preliminarily inv estigated.The main contents are as follows:1.Three isomorphous metal oxide clusters with[PMo₆O₂₁]^3-?{PMo₆}?as building blocks are synthesized by using ammonium molybdate and rare earth salts and org anic ligands as raw materials through microwave synthesis.These compounds are obtai ned through connecting two{PMo6}building blocks modified by two isonicotinic acid molecules to low-level building blocks.The two lower-level building blocks are furth er linked to one dimer by Ln³⁺ions.Both parts of the dimer are identical.Three com pounds show good catalytic properties for oxidation of thioethers and have luminescent properties of rare earth ions,and reversible photochromic effects under light irradiatio n.?NH₄?₇H₈{[(HPMo₆O₂₁)₂?C₆H₄NO₂?₅]₂Tm?H₂O?₆}?C₆H₅NO₂?·30H₂O?1??NH₄?₇H₈{[(HPMo₆O₂₁)₂?C₆H₄NO₂?₅]₂Er?H₂O?₆}?C₆H₅NO₂?·27H₂O?2??NH₄?₇H₈{[(HPMo₆O₂₁)₂?C₆H₄NO₂?₅]₂Ho?H₂O?₆}?C₆H₅NO₂?·24H₂O?3?2.Two isomorphous one-dimensional chain octamolybdenum oxide clusters-rare earth compounds are obtained by microwave synthesis.According to structures of co mpounds,[?-Mo₈O₂₈]^4-are bonded to one-dimensional chain through oxygen atoms,an d rare earth ions are coordinated to{MoO₆}octahedron.Compounds 4 and 5 both sh owe reversible photochromic effects under light irradiation,and luminescent properties of rare earth ions.The magnetic test results demonstrate that both compounds possess antiferromagnetic behavior.{[Tm₂?H₂O?₁₀](Mo₈O₂₇)}·8H₂O?4?{[Er₂?H₂O?₁₀](Mo₈O₂₇)}·8H₂O?5?3.One Silverton-type molybdenum oxide cluster-transition metal compound is obtained by conventional aqueous solution reaction at room temperature.Photolumines cence tests show that compound 6 has the red-emitting property.Magnetic test results indicate that the compound possesses antiferromagnetic behavior.NH₄{Mn₄[PrMo₁₂O₄₂]}·18H₂O?6?.