Elucidating white light emissions in Tm³⁺/Dy³⁺ codoped polyoxometalates: a color tuning and energy transfer mechanism study

Abstract

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.

Double-Oxalate-Bridging Tetralanthanide Containing Divacant Lindqvist Isopolytungstates with an Energy Transfer Mechanism and Luminous Color Adjustablility Through Eu3+/Tb3+ Codoping

“…Ln-based heteropolyoxotungstate inorganic–organic hybrid materials (Ln-HPOTIOHMs) have been an active research area in the past decade . A large amount of work has been predominantly concentrated on di-, tri- and tetra-nuclear Ln- HPOTIOHMs with abundant structures and related properties. ,− However, very rare Ln-based isopolyoxotungstate inorganic–organic hybrid materials (Ln-IPOTIOHMs) have been reported (Figure S1). It is also worthy of considering that the construction of Ln-HPOTIOHMs often relies on mono-, di-, and trivacant Keggin-type heteropolyoxotungstate segments; similarly, it is worth considering whether multivacant isopolyoxotungstate units with more nucleophilic oxygen atoms at vacant sites exist?…”

Assembly of Lanthanide-Containing Polyoxotantalate Clusters with Efficient Photoluminescence Properties

“…Ln ion complexes have attracted significant attention because of their luminescence properties employed in lasers and luminescent materials. − In addition, the Ln 3+ ions emit different visible light with Eu 3+ being the most extensively studied because of hypersensitivity to the coordination environment, a narrow bandwidth, and a long lifetime. , Moreover, the energy transfer process and mechanism from POM to Eu 3+ ion has been previously documented, especially polyoxotungstate, whereas that of POTa has not. The diffuse reflectance spectra of compounds 2 and 8 were recorded at room temperature, which show intense broad bands of the O → Ta LMCT (ligand-to-metal charge transfer) absorptions of two compounds.…”

Oxalate-bridging NdIII-based arsenotungstate with multifunctional NIR-luminescence and magnetic properties

“…[11][12][13][14][15][16][17][18][19] In recent decades, lots of Ln-POM derivatives with attractive structures and novel physical and chemical properties have been reported. Nevertheless, most of these studies focus solely on the photoluminescence (PL) properties of Ln-POM derivatives, [20][21][22][23][24][25][26][27][28] although there are a few examples demonstrating SMM behaviors. [29][30][31][32][33][34] It is becoming widely accepted that the coordination environment of the Ln center has a great influence on the dynamic relaxation processes of Ln-SMMs.…”