A series of Dy Er-polyoxometalates (POMs) were successfully synthesized and characterized well by various physicochemical analysis. The structurally isolated compounds exhibit three characteristic emissions at 480 nm (blue, F → H transition), 573 nm (yellow, F → H transition), and 663 nm (red, F → H transition) whose luminescent color coordinates appear in the near-white area in the CIE 1931 chromaticity diagram. Time-resolved emission spectroscopy was used in Dy Er-POM to further authenticate energy transfer from the photoexcitation O → M ligand to the metal charge-transfer state of phosphotungstate components to active Dy/Er ions and energy transfer between Dy ion and Er ion via intramolecular energy transitions. The relative emission intensity of ∼32%, ∼53%, and ∼85% for Dy-POM, DyEr-POM, and DyEr-POM respectively, were obtained under 300 min of UV irradiation, which indicates better photostability of DyEr-POM. Furthermore, Dy Er-POM samples can emit macroscopic white light under blue irradiation.

Eight novel lanthanide-containing polyoxotantalates, Cs3[Ln­(H2O)6{H4(TaO2)6As4O24}]·7H2O (Ln = Sm (1), Eu (2), Tb (3), Dy (4), Er (5), Tm (6), Yb (7), Lu (8)), have been obtained via a one-pot reaction methodology. Each of these compounds is made up of the new type polyanion [(TaO2)6As4O24]10– with Ln3+ linkers, giving a one-dimensional chain. The compounds represent the first family of “pure” Ta-based polyoxometalate lanthanide derivatives. These architectures were characterized by various physicochemical analyses. Furthermore, the photoluminescence properties of compounds 2-Eu and 8-Lu were also explored, and meanwhile time-resolved emission spectroscopy indicated that the {As4Ta6} segment makes a contribution to the energy transfer of compound 2 from the polyoxotantalate to the EuIII center, which efficiently facilitates emissions of the Eu3+ center.

A 1-D infinite helical chain-like organic-inorganic hybrid arsenotungstate NaH[{Pr(HO)}{AsWO}{WO(mal)}]·24HO (mal = malate) (1) was prepared, which was characterized by elemental analyses, thermogravimetric (TG) analyses, IR spectroscopy, powder X-ray diffraction (PXRD) and X-ray single-crystal diffraction. Structural characterization revealed that 1 comprises the organo-functionalized [{AsWO}{WO(mal)}] polyanions hinged together by the Pr ions forming a 1-D infinite helical chain-like architecture. The malate ligand may play a vital role to stabilize the structure of 1 by the formation of the five-membered W-O-C-C-O chelate ring. Solid state photoluminescence reveals that 1 features excitation wavelength-dependent emission properties, achieving a reversible emission color switching simply via changing the excitation wavelength. Time-resolved emission spectroscopy (TRES) indicates that the photoexcitation O → M ligand to metal charge transfer (LMCT) of arsenotungstate fragments can sensitize the Pr ions through intramolecular energy transitions in 1.

Rare earth (RE) materials have been employed in almost every corner of modern industry, such as lighting application, defense technology, industrial catalysis and so on. Particularly, RE-based tungsten oxygen complexes...

The double-tartaric bridging Tm-substituted POM derivative [N(CH3)4]6K3H7[Tm(C4H2O6)(α-PW11O39)]2·27H2O (1) was successfully synthesized and well characterized by various physico-chemical analyses. Furthermore, the mixed Dy3+/Tm3+ ion-based POM derivatives [N(CH3)4]6K3H7[DyxTm1-x(C4H2O6)(α-PW11O39)]2·27H2O (3-8) were first synthesized and confirmed by PXRD and IR spectra, indicating compounds 3-8 are isomorphic with 1. The detailed analyses of Ln-O-W bond angle and coordinated aqua ligands around emitting Ln3+ ions have revealed that the mentioned negative factors do not effectively affect the luminescence of emitting Ln3+ ions in 1-8. Investigations of PL emissions reveal that 3-8 can display color-tunable PL properties, emitting color from blue to white to yellow. The study of time-resolved emission spectroscopy of 6 indicates the energy can transfer from the LMCT excited state of POM fragments to Tm3+ and/or Dy3+ ions. Furthermore, the decreased luminescent lifetime of Tm3+ ions in 3-8 reasonably verifies the energy transfer from Tm3+ to Dy3+ ions to efficiently facilitate emissions of the Dy3+ centre.