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The POM capsule functions as a redox-active inorganic crown ether. Specifically, Cs+ ions are captured in the crown-ether-like pores {Mo3Fe3O6}, which exist on the surface of the capsule, and electrons are stored in the Mo atoms of the capsule.

Pore structure of (NH4)4SiW12O40 sponge crystal was successfully elucidated by means of Ar adsorption isotherm analysis combined with molecular probe method and molecular modeling. The pores consis...

Selenosugars are interesting targets of organic synthesis as they would possess potential biological activities. However, 4-selenotherofuranose derivatives, which have trans configuration for the two dihydroxy substituents at the 2,3-positions and a glycoside bond at the anomeric position, are not available in the current selenosugar library. In this study, racemic 4-selenothreofuranose derivatives were synthesized from trans-3,4-dioxygenated tetrahydroselenophenes in 77-99% yields with the α/β selectivity about 7:3 via oxidation and subsequent seleno-Pummerer rearrangement. The acetoxy group introduced at the anomeric position was then substituted with various nucleophiles, including activated 6-chloropurine, which afforded 4'-selenothreonucleoside derivatives, in the presence of BF3·OEt2 or TMSOTf. The stereochemistry of the selenosugar products was established by 1H NMR spectroscopy as well as X-ray analysis. The similar α/β selectivity observed in the latter glycosylation reaction to that in the former seleno-Pummerer rearrangement suggested the mediation of a common selenonium intermediate (-Se+=C

A polymerizable ionic-liquid cation having methacryl group and imidazolium moieties (denoted as MAImC1) was successfully hybridized with octamolybdate (Mo8O264−, Mo8) to obtain inorganic–organic hybrid crystals containing monovalent metal cations. The hybrid crystals were initially prepared as sodium ion-containing hybrid crystal of MAImC1–Na–Mo8. The sodium cations in MAImC1–Na–Mo8 were exchangeable to other monovalent metal cations such as silver or potassium to form hybrid crystals of MAImC1–Ag–Mo8 or MAImC1–K–Mo8. Their molecular and crystal structures were clearly revealed by single crystal X-ray analyses. The MAImC1–Na–Mo8 hybrid crystal worked as the hybrid monomer, and was found polymerizable by a radical polymerization using AIBN as an initiator to obtain inorganic–organic polymers (P-MAImC1–Na–Mo8). The conductivities of the hybrid monomer and polymer consisting of MAImC1–Na–Mo8 were investigated.

Polyoxovanadate–surfactant hybrid layered crystals were successfully synthesized as single crystals by employing a primary alkylammonium cation, octylammonium ([C8H17NH3]+, C8NH3). Two types of hybrid crystals with the formulae [C8H17NH3]6[V10O28]·2H2O (C8NH3–V10) and [C8H17NH3]4Li2[V10O28]·4C2H5OH·6H2O (C8NH3–Li–V10) were obtained by different synthetic procedures. Changing the synthetic conditions enabled the precise introduction of lithium cations into the polyoxovanadate–surfactant hybrid crystals according to compositional control. C8NH3–V10 contained a discrete [V10O28]6− anion, while C8NH3–Li–V10 was composed of a [V10O28]6− anion associated with two lithium cations formulated as {[Li(H2O)3]2[V10O28]}4−. The conductivities of C8NH3–V10 and C8NH3–Li–V10 were investigated under anhydrous conditions at intermediate temperatures.

The crystallinity and porosity of all-inorganic dodecatungstophosphate M3PW12O40 (M = Cs, NH4, Ag, denoted as MPW) particles are controlled by the changes in the synthetic temperatures and countercations. The MPW particles can be classified into three groups by the crystallinity and porosity: (i) mesoporous “disordered” aggregates, (ii) microporous “self-organized” aggregates, and (iii) nonporous single crystals. The formation and growth mechanism of MPW particles is expressed by three steps: formation of nanocrystallites, assembly of the nanocrystallites to form aggregates, and the growth of aggregates by the attachment of nanocrystallites. The time courses of the turbidity of the synthetic solution, the concentration of the nanocrystallites, and the average particle sizes of MPW particles are well reproduced by the calculation based on the mechanism.

A two-dimensional array of polyoxomolybdate nanoball ([MoVI72MoV60O372(CH3COO)30(H2O)72]42-, Mo132) was successfully constructed by a Langmuir−Blodgett (LB) semiamphiphilic method by using Mo132 aqueous solution as a subphase and dimethyldioctadecylammonium (DODA) as a cationic amphiphile. Conservation of molecular structure of the Mo132 nanoball in the built-up LB film was confirmed by ultraviolet−visible (UV−vis) and infrared (IR) spectroscopy. Specular X-ray reflectivity (SXR) measurements combined with UV−vis spectroscopy revealed that the Mo132/DODA LB film had a well-defined layered structure containing a densely packed two-dimensional array of the Mo132 nanoballs. The electrochemical characteristics of the Mo132 nanoballs were retained after the deposition onto the solid substrates, which verifies that the LB semiamphiphilic method is an effective way to fabricate thin films composed of functional nanosized clusters toward a two-dimensional molecular device.

Decatungstoeuropate/dimethyldioctadecylammonium (EuW10/DODA) Langmuir-Blodgett (LB) monolayers and multilayers (7 layers) were fabricated by using aqueous solution of EuW10 with different concentration (1.0–3.0 μmol dm−3). The results of specular X-ray reflectivity (SXR) and grazing incidence X-ray diffraction (GIXD) measurements for the EuW10/DODA LB films indicated an increase in the interlayer distance and in-plane molecular ordering for the film fabricated with the concentrated EuW10 solution, reflecting the dense packing of DODA and EuW10 molecules. Their photoluminescence property also depended on the concentration of the EuW10 solution. With an increase in the EuW10 concentration in the subphase, both the relative intensity of the 5D0→7F1 transition and the emission lifetime increased. The lifetime of emission of the EuW10 LB monolayers changed from 0.8±0.1 ms (1.0 μmol dm−3) to 1.0±0.1 ms (2.1 μmol dm−3) and 1.3±0.1 ms (3.0 μmol dm−3), which became closer to that (2.6 ms) of the solid, and EuW10/DODA LB multilayers had the same tendency. The elongation of the emission lifetime was due to a decrease in the number of aqua molecules within the Eu3+-coordination sphere, which will be caused by the dense and regular packing of EuW10 molecules.

Polyoxomolybdate inorganic–organic hybrid crystals were synthesized by using long-tailed primary amine and ionic-liquid surfactants. Dodecylamine and 1-dodecyl-3-methylimidazolium bromide were empl...

A polyoxovanadate–surfactant hybrid layered crystal was synthesized by using decyltrimethylammonium (C10) cation. The hybrid crystal with a formula of (C10)4[H2V10O28]·8H2O (C10–V10) contained dipr...

Solid electrolytes are crucial materials for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. Emergence of high conductivity in solid electrolytes requires precise control of the composition and structure. A promising strategy toward highly-conductive solid electrolytes is employing a thermally-stable inorganic component and a structurally-flexible organic moiety to construct inorganic-organic hybrid materials. Ionic liquids as the organic component will be advantageous for the emergence of high conductivity, and polyoxometalate, such as heteropolyacids, are well-known as inorganic proton conductors. Here, newly-designed ionic liquid imidazolium cations, having a polymerizable methacryl group (denoted as MAImC1), were successfully hybridized with heteropolyanions of [PW12O40]3− (PW12) to form inorganic-organic hybrid monomers of MAImC1-PW12. The synthetic procedure of MAImC1-PW12 was a simple ion-exchange reaction, being generally applicable to several polyoxometalates, in principle. MAImC1-PW12 was obtained as single crystals, and its molecular and crystal structures were clearly revealed. Additionally, the hybrid monomer of MAImC1-PW12 was polymerized by a radical polymerization using AIBN as an initiator. Some of the resulting inorganic-organic hybrid polymers exhibited conductivity of 10−4 S·cm−1 order under humidified conditions at 313 K.

An inoranic–organic hybrid crystal was synthesized by using polyoxomolybdate and hexadecylpyridinium surfactant. The unit cell was monoclinic having quite a long cell dimension (b = 75.0111(14) A)....

Microporous dodecahedral aggregates of a polyoxotungstate were synthesized by homogeneous precipitation from aqueous solution using hydrolysis of urea at 373 K (H3PW12O40 + 3/2(NH2)2CO + 3/2H2O → (NH4)3PW12O40↓ + 3/2CO2). The aggregates isolated after various reaction periods were characterized by several methods such as high-resolution scanning electron microscopy, N2 and Ar adsorption, X-ray and electron diffraction, and solid-state NMR. The formation process is also discussed. Each of these aggregates (0.3−5 μm in size) consisted of 5−10 nm nanocrystallites of (NH4)3PW12O40, which connected epitaxially (the same orientation of crystal planes), leaving pores between the nanocrystallites. With an increase in the reaction time, the initially formed spherical aggregates having micro- and mesopores gradually turned in to dodecahedral aggregates having only micropores and higher crystallinity. The dodecahedral aggregates obtained after 24 h were almost stoichiometric, (NH4)3PW12O40, according to 31P NMR, and...

Hybrid inorganic–organic crystals containing α- and β-type octamolybdates (α-Mo8 and β-Mo8) were successfully prepared by using hexadecylpyridinium (C16py). Although both hybrid crystals consisted ...

The microstructures of aggregates of heteropoly compounds Cs3PW12O40 and (NH4)3PW12O40 precipitated at various temperatures were characterized by SEM, XRD, TEM, ED, and N2 adsorption. The microstructures were remarkably different according to the precipitation temperature and the kind of cation. Cs3PW12O40 precipitated at 298 K formed dispersed or loosely aggregated fine particles of ca. 10 nm with random crystal orientation. As the temperature increased to 368 K, Cs3PW12O40 self-assembled to form microporous aggregates in which the crystal planes of microcrystallites were oriented unidirectionally, but were not much connected epitaxially with each other. (NH4),PW12O40 precipitated at 273 K formed round aggregates similar to Cs3PW12O40 precipitated at 368 K, while the NH4 salt precipitated at 368 K formed dodecahedral aggregates in which microcrystallites were epitaxially connected with each other (epitaxial self-assembly). These observations indicate that microstructure is controlled by the solubility at the precipitating conditions; with increasing precipitation temperature or decreasing ionic radii of cation, the microstructure of aggregates varies from the random aggregates to unidirectionally oriented microcrystallites and the epitaxial connection between microcrystallites develops.

A hybrid layered crystal containing polyoxomolybdate was successfully synthesized from reduced Mo-blue species as starting material. The hybrid crystal, [C5H5N(C16H33)]2[β-H2Mo8O26]·2C2H5OH (C16py-H2Mo8), was obtained as a single phase by the gradual oxidation of hexadecylpyridinium-Mo-blue (C16py-Mo-blue) hybrid. The X-ray structure analysis revealed that C16py-H2Mo8comprisedβ-type octamolybdate anion with two protons (β-H2Mo8). Theβ-H2Mo8anions and ethanol molecules of crystallization formed two-dimensional anionic layers. The pyridine rings of C16py did not attend to form the two-dimensional inorganic layers, and the interdigitated C16py bilayers were sandwiched by theβ-H2Mo8anionic layers with periodicity of 18.2 Å. These C16py-H2Mo8hybrid layered crystals possibly work as a new class of proton conductor.

A polyoxometalate layered crystal containing surfactant with π electrons was successfully prepared by using hexadecyl-pyridinium (C 16 py). X-ray single-crystal structure analysis revealed that monolayers of hexamolybdate (Mo 6 ) and bilayers of C 16 py were stacked alternately. The hexadecyl chains of the C 16 py in the bilayer interdigitated each other. The pyridine rings were inserted into the monolayers of the Mo 6 to form the inorganic layers together with the Mo 6 anions.

The single crystals of ammonium dodecatungstophosphate were successfully synthesized and the structure was analyzed. The intrinsic crystal structure (cubic, Pn3- m) had no cavity. It follows that the microporosity observed for the powdery sample originated from narrow spaces surrounded by the fine nanocrystallites.

Three different microstructures of self-assembled microcrystallites (or of aggregates) of heteropoly compounds, (NH4)3PW12O40 and Cs3PW12O40, have been found: (1) microcrystallites that self-assembled with unidirectional orientation and were epitaxially connected with each other to form dodecahedra, (2) microcrystallites that self-assembled with unidirectional orientation, but were little connected epitaxially each other to form round aggregates, and (3) dispersed fine particles. This variation of the microstructure was consistently explained by the change in the solubility of the compounds, that is, the precipitation temperature and the kind of cation.

Microcrystallites of (NH4)3PW12O40 self-assembled to form symmetric dodecahedral aggregates (ca. 0.5–6 μm in size) in which the microcrystallites joined together with the same crystal orientation, by controlled deposition of NH4 salts from a heated aqueous solution of H3PW12O40. These aggregates were highly porous, where microcrystallies were connected each other by epitaxial interfaces.

Dimethyldioctadecylammonium salts of reduced polyoxomolybdates in the organic solvent are gradually oxidized to provide bis(dimethyldioctadecylammonium) hexamolybdate, the crystal structure of which affords a molecular model for Langmuir–Blodgett films.