Sayaka Uchida

The states and dynamic behavior of acidic protons and water molecules in solid H3PW12O40·nH2O (0 < n < 6), which would be closely related to its pseudoliquid phase catalysis, were quantitatively elucidated by the comprehensive application of 31P, 1H, and 17O magic-angle spinning (MAS) NMR. 1H and 17O MAS NMR were sensitive to the local environment in the pseudoliquid phase (e.g., hydrogen bonding), and 31P MAS NMR was effective especially to quantify the states of the protons. At 173 K, several

Molecular sieving to take your breath away: The breathing ionic crystal 1 is synthesized by the complexation of Keggin-type [α-SiW12O40]4− (red) polyoxometalate with a macro cation [Cr3O(OOCH)6(H2O)3]+ (green and white). The water of crystallization is easily removed from 1 by evacuation to form a guest-free phase 2. Compound 2 reversibly adsorbs small alcohols and nitriles as well as water, while longer-chain alcohols and nitriles were excluded, which shows the novel molecular sieving of small

A polyoxometalate-macrocation ionic crystal of Cs5[Cr3O(OOCH)6(H2O)3][alpha-CoW12O40].7.5H2O (1a) was synthesized by the complexion of an inorganic metal-oxide cluster of [alpha-CoW12O40]6- and a macrocation of [Cr3O(OOCH)6(H2O)3]+. About 50% of the water of crystallization in 1a was desorbed by the evacuation to form phase 1b, and the crystallinity and crystal structure was essentially maintained by the transformation. 1b adsorbed water into the solid bulk but excluded larger alcohols. 1b was e

Ag2[Cr3O(OOCC2H5)6(H2O)3]2[alpha-SiW12O40] [1] is a nonporous flexible ionic crystal composed of 2D-layers of polyoxometalates ([alpha-SiW12O40](4-)) and macrocations ([Cr3O(OOCC2H5)6(H2O)3](+)) stacking along the b-axis. The silver ions are located in the vicinity of the oxygen atoms of the polyoxometalates. The sorption amounts of small unsaturated hydrocarbons such as ethylene, propylene, n-butene, acetylene, and methyl acetylene into 1 are comparable to or larger than 1.0 mol mol(-1) and lar

Cation-uptake and exchange has been an important topic in both basic and applied chemistry relevant to life and materials science. For example, living cells contain appreciable amounts of Na⁺ and K⁺, and their concentrations are regulated by the sodium-potassium pump. Solid-state cation-exchangers such as clays and zeolites both natural and synthetic have been used widely in water softening and purification, separation of metal ions and biomolecules, <i>etc.</i> Polyoxometa

Considerable efforts have been devoted to developing oxygen evolution reaction (OER) catalysts based on transition metal oxides. Polyoxometalates (POMs) can be regarded as model compounds of transition metal oxides, and cobalt-containing POMs (Co-POMs) have received significant interest as candidates. Nanocomposites based on Co-POMs have been reported to show high OER activities due to synergistic effects among the components; however, the role of each component is unclear due to its complex str

The complexation of Keggin-type polyoxometalates [alpha-XW12O40]n- (X = P, Si, B, Co), macrocation [Cr3O(OOCH)6(H2O)3]+, and alkali-metal ions forms ionic crystals of Na2[Cr3O(OOCH)6(H2O)3][alpha-PW12O40].16H2O (1a), K3[Cr3O(OOCH)6(H2O)3][alpha-SiW12O40].16H2O (2a), Rb4[Cr3O(OOCH)6(H2O)3][alpha-BW12O40].16H2O (3a), and Cs5[Cr3O(OOCH)6(H2O)3][alpha-CoW12O40].7.5H2O (4a). The space volumes of the ionic crystals decrease in the order of 1a > 2a > 3a > 4a. The water of crystallization in 1a-3a is co

A microstructured ionic crystal, K(3)[Cr(3)O(OOCH)(6)(H(2)O)(3)][alpha-SiW(12)O(40)].16 H(2)O (1) was synthesized by the complexation of the Keggin-type polyoxometalate of [alpha-SiW(12)O(40)](4-) with a macrocation of [Cr(3)O(OOCH)(6)(H(2)O)(3)](+). Compound 1 possessed a straight channel, with an opening of approximately 0.5x0.8 nm, which contained the water of crystallization. The use of the macrocation with large size (0.7 nm) and small charge (+1) reduced the anion-cation interaction and wa

The complexation of Dawson-type polyoxometalates of [α-P2W18O62]6-, [α2-P2W17V1O62]7-, and [α-P2W15V3O62]9- with the macrocation ([Cr3O(OOCH)6(H2O)3]+) forms ionic crystals of (NH4)4[Cr3O(OOCH)6(H2O)3]2[α-P2W18O62]·15H2O (1a), (NH4)5[Cr3O(OOCH)6(H2O)3]2[α2-P2W17V1O62]·15H2O (2a), and (NH4)7[Cr3O(OOCH)6(H2O)3]2[α-P2W15V3O62]·15H2O (3a), respectively. The compounds 1a−3a show the honeycomb packing and the symmetry of the constituent ions reflect on the crystal structures. The lengths of the a axes

Size-selective sorption is exhibited by a zeotype organic–inorganic ionic crystal with 1D channels: the guest-free phase sorbs water and methanol, while larger molecules are excluded. Moreover, K+ ions, which reside in the channels (see picture; O red, C black, H pink, N blue), can be exchanged with other alkali metal ions, and the guest sorption properties depend on the type of alkali metal ions.

The exploration of composition-structure-function relationship in proton-conducting solids remains a challenge in materials chemistry. Polyoxometalate-based compounds have been long considered as candidates for proton conductors; however, their low structural stability and a large decrease in conductivity under reduced relative humidity (RH) have limited their applications. To overcome such limitations, the hybridization of polyoxometalates with proton-conducting polymers has emerged as a promis

Cation adsorption and exchange has been an important topic in both basic and applied chemistry relevant to materials synthesis and chemical conversion, as well as purification and separation. Selective Cs(+) uptake from aqueous solutions is especially important because Cs(+) is expensive and is contained in radioactive wastes. However, the reported adsorbents incorporate Rb(+) as well as Cs(+) , and an adsorbent with high selectivity toward Cs(+) has not yet been reported. Highly selective uptak

The rational development of an anion templation strategy for the construction of macrocycles has been historically limited to small anions, but large polyoxoanions can offer unmatched structural diversity and ample binding sites. Here we report the formation of a {Mo₂₂ Fe₈ } macrocycle by using the Preyssler anion, [NaP₅ W₃₀ O₁₁₀ ]^14- ({P₅ W₃₀ }), as a supramolecular template. The {Mo₂₂ Fe<sub>8</s