Lanthanide-Incorporated Borotungstates Including Keggin-type [BW₁₁O₃₉]^9– Fragments and Their Luminescence Properties

Abstract

Three kinds of lanthanide (Ln)-substituted borotungstates including [BW11O39]9– segments KH2[Ce­(H2O)8]­[(α-BW11O39)­Ce­(H2O)3]·14H2O (1), K2Na2H2[(α-BW11O39)­Pr­(H2O)3]·15H2O (2), and Na3K8H­[W5O18]­Ln­[α-BW11O39]·22H2O [Ln = Eu3+ (3), Dy3+ (4), Ho3+ (5), Yb3+ (6)] were manufactured. Compound 1 adopts a one-dimensional (1-D) zigzag chain by fusing adjacent [Ce­(H2O)8]­[(α-BW11O39)­Ce­(H2O)3]3– polyoxoanions in the help of Ce3+ bridging. It is worth noting that adjoining chains can be interacted with each other by K+ cations and give birth to a fascinating two-dimensional sheet. In contrast, the polyoxoanion of 2 is assembled from a mono-PrIII embedded [(α-BW11O39)­Pr­(H2O)3]6– unit, which also propagates an analogical 1-D chain like 1 without hanging [Ln­(H2O)8]3+ cations. Compounds 3–6 display a typical mixed-POM dimeric assembly composed of monovacant Keggin [α-BW11O39)]9– and monovacant Lindqvist [W5O18]6– segments concatenated by an Ln cation. Luminescence performances of 3–5 were systematically probed at ambient temperature, exhibiting the featured emissions from f–f transitions of Ln ions. Meanwhile, energy transfer from borotungstate fragment to Ho3+ ion was observed in the emission process of 5.

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

“…5a). 79 Upon cooling, the χ M T value first decreases to 1.65 cm 3 K mol −1 in a strong linear trend, which may be due to the thermal depopulation of the excited crystal field sublevels. Then the χ M T value undergoes a sharp increase to some extent, owing to the intramolecular weak ferromagnetic coupling between the Nd III cations of 1 .…”

Preparations, Structures and Luminescence Properties of Penta‐rare‐earth Incorporated Tetravacant Dawson Selenotungstates and Their Ho3+/Tm3+ Co‐doped Derivatives

“…Meanwhile, by monitoring the emission at 664 nm, its excitation spectrum with three characteristic excitation peaks at 418, 454 and 486 nm were gathered, and three peaks correspond to 5 I 8 → 5 G 5 , 5 I 8 → 5 G 6 and 5 I 8 → 5 F 3 transitions of Ho 3+ ions, respectively (Figure b). To further understand the fluorescence lifetime of 1 , the decay time curve was gained based on monitoring the main emission peak at 664 nm –. The decay time curve of 1 was matched with a second‐order exponential function I = A 1 exp( t/τ 1 )+ A 2 exp( t/τ 2 ) (Figure c).…”

3-Pyridylacetic-Based Lanthanide Complexes Exhibiting Magnetic Entropy Changes, Single-Molecule Magnet, and Fluorescence

“…This lifetime value was consistent with those reported of the Eu III complex based on pyridinecarboxylic ligands. 74 As for 4, the characteristic emission spectra in the visible region were obtained upon excitation at 349 nm (Figure S10 in the SI), and they revealed four groups of characteristic single bands at 489, 545, 589, and 622 nm (Figure 8a), which can be assigned to 5 D 4 → 7 F 6 , 5 D 4 → 7 F 5 , 5 D 4 → 7 F 4 , and 5 D 4 → 7 F 3 electron transitions of the Tb III ion, respectively. Moreover, the fluorescence lifetime of 4 in the visible region was examined using the strongest emission (545 nm) and excitation (349 nm) with the decay curve (Figure 8b).…”