Takeru Ito

Dual-emissive photoluminescent Langmuir-Blodgett films of decatungstoeuropate and an amphiphilic iridium complex.

Langmuir monolayers and Langmuir-Blodgett (LB) films of the decatungstoeuropate [Eu(W(5)O(18))(2)](9-) (EuW(10)) and the amphiphilic Ir complex 1 have been successfully fabricated by using the adsorption properties of the EuW(10) polyanion dissolved in the aqueous subphase onto a positively charged 1 monolayer at the air-water interface. The compression isotherms and Brewster angle microscopy (BAM) of monolayers of 1 on pure water (1 monolayer) and on a subphase containing 10(-6) M EuW(10) and 10(-3) M NaCl (1/EuW(10) monolayer) have been studied. Infrared and UV-vis spectroscopy of the transferred LB films indicate that EuW(10) and 1 molecules are incorporated within these LB films. X-ray reflectivity (SXR) and atomic force microscopy (AFM) experiments indicate that LB films of 1 present a heterogeneous morphology while 1/EuW(10) films show a flatter and more homogeneous surface as well as a layered structure with a periodicity of 4.1 nm. Mixed monolayers of 1 and DODA (dimethyldioctadecylammonium bromide) have been prepared with EuW(10) polyanions in the subphase to control the concentration of 1 and EuW(10) polyanions within the LB films. AFM and SXR experiments with the transferred LB films show that the dilution of 1 with DODA improves the layered structure. The luminescence of 1 is partially quenched by EuW(10) in the 1/EuW(10) LB films, while emission from EuW(10) is not detected. On the other hand, emission from both entities is preserved in the LB films prepared from mixed DODA/1 monolayers, in which the red and yellow emissions arise independently from EuW(10) and 1, respectively. The different DODA:1 ratios lead to changes in the emission color. Therefore, they constitute a promising color-tunable luminescent material.

Controllable Layered Structures in Polyoxomolybdate-Surfactant Hybrid Crystals

Inorganic-organic hybrid crystals containing α-octamolybdate (Mo8) or hexamolybdate (Mo6) were isolated by using hexadecyltrimethylammonium (C16) surfactant. The packing mode of the inorganic layers depended on a difference in the polyoxomolybdate molecular structure. The structure for both crystals consisted of alternate stacking of C16 organic bilayers and polyoxomolybdate inorganic layers with a periodicity of 24.4–24.6 Å. However, the C16-Mo8 crystals contained Mo8 monolayers, while the C16-Mo6 crystals contained Mo6 bilayers. These lattice structures for the polyoxometalate/organic hybrid will be designed by the molecular structures of polyoxometalate.

Polymerizable Ionic Liquid Crystals Comprising Polyoxometalate Clusters toward Inorganic-Organic Hybrid Solid Electrolytes

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.

Compositional introduction of lithium ions into conductive polyoxovanadate–surfactant hybrid crystals

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.

Hybrid inorganic–organic layered crystals constructed by oxide clusters and surfactant

Veblenite: a new ti-silicate related to hoh structures Fernando Cámara,a,b Elena Sokolova,c Frank C. Hawthorne,c Ralph Rowe,d Joel Grice,d and Kim Tait,e aDipartimento di Scienze Mineralogiche e Petrologiche, Università di Torino, (Italy). bCNR Istituto di Geoscienze e Georisorse, Pavia, (Italy). cDepartment of Geological Sciences, University of Manitoba (Canada). dResearch Division, Canadian Museum of Nature, Ottawa, (Canada). eDepartment of Natural History, Royal Ontario Museum, Toronto, (Canada). E-mail: fernando.camaraartigas@unito.it