title: Low-Percentage Ln3+Doping in a Tetranuclear Lanthanum Polyoxometalate Assembled from [Mo7O24]6-Polyanions Yielding Visible and Near-Infrared Luminescence.
abstract: A rare case of low-percentage trivalent lanthanide doping in multinuclear lanthanide polyoxometalates (LnPOMs) was investigated. The [La4(MoO4)(H2O)16(Mo7O24)4]14-polyanion was chosen as the host material for this study. In this polyanion the central [La4(MoO4)]10+core is coordinated by four heptamolybdate groups as well as 16 water molecules. The tetranuclear lanthanum POM was doped with 5% of Eu3+, Tb3+, Sm3+, Dy3+, Nd3+, Er3+, and Yb3+(according to synthesis), and the structures and luminescence properties of the x%Ln:LaPOMs were investigated. Additionally a series of tetranuclear lanthanide POMs built from [Mo7O24]6-heptamolybdate polyanions with Eu3+, Tb3+, Sm3+, Dy3+, and Nd3+instead of La3+were synthesized, and a detailed analysis revealed that the tetranuclear clusters formed monomers or dimers linked through oxygen bridges. The smaller lanthanide ions, namely, Er3+and Yb3+, did not form tetranuclear clusters, but instead mononuclear sandwich-type POMs were obtained. The obtained structures were shown to be lanthanide-specific, and not a result of different synthetic/crystallization conditions. The luminescence properties of the x%Ln:LaPOMs were compared with the luminescence properties of the LnPOMs.
authors.affiliation: L3-Luminescent Lanthanide Lab, Department of Inorganic and Physical Chemistry and ‡XStruct, Department of Inorganic and Physical Chemistry, Ghent University , Krijgslaan 281-S3, B-9000 Gent, Belgium.
authors.forename: Anna M
authors.identifier: http://orcid.org/0000-0001-5254-8762
authors.initials: AM
authors.lastname: Kaczmarek
authors.affiliation: L3-Luminescent Lanthanide Lab, Department of Inorganic and Physical Chemistry and ‡XStruct, Department of Inorganic and Physical Chemistry, Ghent University , Krijgslaan 281-S3, B-9000 Gent, Belgium.
authors.forename: Kristof
authors.initials: K
authors.lastname: Van Hecke
authors.affiliation: L3-Luminescent Lanthanide Lab, Department of Inorganic and Physical Chemistry and ‡XStruct, Department of Inorganic and Physical Chemistry, Ghent University , Krijgslaan 281-S3, B-9000 Gent, Belgium.
authors.forename: Rik
authors.identifier: http://orcid.org/0000-0001-7091-6864
authors.initials: R
authors.lastname: Van Deun