Crown‐Shaped Tungstogermanates as Solvent‐Controlled Dual Systems in the Formation of Vesicle‐Like Assemblies

Abstract

Reaction of early lanthanides, GeO2 , and Na2 WO4 in a NaOAc buffer results in large crown-shaped polyoxometalates based on [Ln2 GeW10 O38 ](6-) subunits. By using Ni(2+) as a crystallizing agent, [Na⊂Ln12 Ge6 W60 O228 (H2 O)24 ](35-) (Na⊂Ln12 ) hexamers formed by alternating β(1,5)/β(1,8) subunits were obtained for Ln=Pr, Nd. The addition of K(+) led to a similar anion for Ln=Sm, namely, [K⊂Sm12 Ge6 W60 O228 (H2 O)22 ](35-) (K⊂Sm12 ) and [K⊂K7 Ln24 Ge12 W120 O444 (OH)12 (H2 O)64 ](52-) (K⊂Ln24 ) dodecamers that consist of a central core identical to K⊂Sm12 decorated with six external γ(3,4) subunits for Ln=Pr, Nd. These anions dissociate in water into hexameric cores and monomeric entities, as shown by ESI mass spectrometry. The former self-assemble into spherical, hollow, and single-layered blackberry-type structures with radii of approximately 75 nm, as monitored by laser light scattering (LLS) and TEM techniques. Analogous studies performed for K⊂Nd24 in water/acetone mixtures show that the dodecamers remain stable and form in turn their own type of blackberries with sizes that increase from approximately 20 to 50 nm with increasing acetone content. This control over both the composition and size of the vesicle-like assemblies is achieved for the first time by modifying the architecture of the species that undergoes supramolecular association through the solvent polarity.

Acetate-Decorated Tri-Ln(III)-Containing Antimonotungstates with a Tetrahedral {WO4} Group as a Structure-Directing Template and Their Luminescence Properties

“…Previous research demonstrates that emission colors of Ln-AMTs can be tuned through switching variable excitation lights, which can realize the emission-tunable property. , In addition, W–O–Ln bond angles near 150° will result in dπ–pπ–fπ orbital mixing, which can lead to inactivity of ET from AMT segments to Ln 3+ ions. Fortunately, no W–O–Ln bond angles near 150° in 1–3 have been found, which suggests that ET cannot be inhibited by dπ–pπ–fπ orbital mixing. − In this work, excitation and emission spectra, decay lifetime curves, and time-resolved emission spectra (TRES) as measurement methods have been measured to analyze the PL properties of 1–3 .…”

Ln12‐Containing 60‐Tungstogermanates: Synthesis, Structure, Luminescence, and Magnetic Studies

“…Several examples of polyanions comprising dilacunary β‐Keggin units are known 6a. d, g, 10 Interestingly, the Ce 20 ‐containing 100‐tungsto‐10‐germanate contains the same dilacunary {β(4,11)‐GeW 10 } Keggin fragments as Eu 12 6a. Reinoso et al.…”

“…showed that {GeW 10 } fragments can also be formed in situ by direct reaction of Na 2 WO 4 , GeO 2 , and lanthanide sources in acetate buffer 6d. g, 10j…”

New Perspectives for Old Clusters: Anderson–Evans Anions as Building Blocks of Large Polyoxometalate Frameworks in a Series of Heterometallic 3 d–4 f Species

“…To systematically explore the reactivity of Krebs-type M 2 anions (M = Mn, Co, Ni, Zn) toward 4f metals,w ef irst selected the salt Na 10 [Co 2 ]a sarepresentative precursor and reacted it with the whole series of Ln ions (1:1 ratio) in hot NaOAc buffer (Method1). The reactivity differed considerably along the Ln series, as observed for other Ln/POMs ynthetic systems [14] (Scheme 1). Although attempts with late 4f metals (Tb to Lu) only affordedt he pristine Co 2 precursor back, crystalline batches obtained from larger early-to-mid Ln ions (La to Gd) contained an additional side product with as ubstantially different framework (Ln 3 Co 2 ), as inferred unequivocally from the IR spectra (see Figure S1 in the Supporting Information for acomparisono ft he spectra with that of Co 2 among other building blocks).…”