Mamoru Mizutani

Porous ceramics prepared by mimicking silicified wood

Abstract Porous titania, alumina and zirconia ceramic woods with wood-like microstructures, analogous to that of silicified wood, were prepared from natural woods as templates. The production of these ceramic woods was performed by the following process: (1) infiltration of metal alkoxide into wood specimens, (2) hydrolysis of the alkoxide in the cell structure to form titania, alumina or zirconia gels, (3) firing in air to form titania, alumina or zirconia ceramic woods. The resulting titania, alumina and zirconia ceramic woods were studied by means of an X-ray diffractometer, a mercury porosimeter and a scanning electron microscope. The microstructure of these ceramic woods retained the same structure as that of the raw wood: with the pore sizes corresponding to those of the original wood, and the major pores being unidirectionally connected.

An infinite chiral single-helical structure formed in Cu(II)-l-/d-glutamic acid system

Abstract Reaction of Cu(ClO4)2·6H2O with l -glutamic acid ( l -glu) in 1:1 or 1:2 molar ratio at pH 5 gave only the complex [Cu( l -glu)-(H2O)]·H2O, whose crystal structure revealed that the copper atom was coordinated in square-planar geometry, with the amino nitrogen and the carboxylate oxygen of l -glu, the side-chain carboxylate oxygen of a neighboring l -glu, and the oxygen of a water molecule in the equatorial positions. Weak coordination of two additional glutamate oxygens to both axial positions complete a distorted octahedron. The [Cu( l -glu)(H2O)] units linked by coordination of the side-chain carboxylate group form an infinite left-handed single helix; the use of d -glu in place of l -glu gives a right-handed helix, indicating that the glu enantiomerism determines the helicity. Thermogravimetric and differential thermal analyses of the complex showed reversible desorption of just two water molecules at 95–130°C, whose behavior was examined by ESR and circular dichroism spectral and powder X-ray diffraction methods in solid state. The crystals obtained from the reaction of Cu(II) ion with dl -glu showed spontaneous resolution.

Pore-expansion of monodisperse mesoporous silica spheres by a novel surfactant exchange method

By adapting a novel surfactant exchange method, in which surfactants inside mesopores are completely exchanged by surfactants with longer alkyl chain lengths, pore-expansion of monodisperse mesoporous silica spheres (MMSS) with radially ordered hexagonal regularity was attained while retaining spherical morphology and high monodispersity.

Syntheses and structures of tetrakis(1-methyluracilato)palladium complexes capturing alkali metal ions. A new type of metallo-podand

Four tetrakis(1-methyluracilato)palladium complexes containing alkali metal ions, [Li 2 Pd(1-MeU − ) 4 ] ( 1 ), [Na 2 Pd(1-MeU − ) 4 ] ( 2 ), [K 2 Pd(1-MeU − ) 4 ] ( 3 ), and [Cs 2 Pd(1-MeU − ) 4 ] ( 4 ), have been prepared from M 2 PdCl 4 (M=Li + , Na + , K + , and Cs + ) and 4 equiv. of 1-methyluracil (1-MeUH). The X-ray crystal structure analyses of complexes 2 , 3 and 4 have revealed that each palladium atom is coordinated in a square-planar geometry with four 1-MeUH-derived N3-deprotonated imidato groups, upright-oriented with angles of 60–70° from the basal coordination plane. Interestingly, the carbonyl groups of the four imidato rings form two cavities above and below the Pd(II) atom, and two alkali metal ions are incorporated with PdM distances of 3.007(4) and 3.137(3) A for 2 , 3.432(3) and 3.594(3) A for 3 , and 3.746(1) and 3.999(1) A for 4 , respectively. The cavity sizes of the three complexes are tunable according to the ionic radii of the alkali metal ions. 1 H NMR spectra of complexes 1 – 4 indicate that all proton signals of the 1-MeU − moiety are shifted up-field relative to those of free 1-MeU − . The magnitude of the up-field shifts, 1 2 3 4 , corresponds well to the order of the ionic potentials of alkali metal ions. These up-field shifts are reduced by coordination of 5-fluoro-1-methyluracil in place of 1-MeUH, indicating that the electron-donating character of 1-MeU − to Pd(II) is decreased by substitution with an electron-withdrawing fluoro group. These observations suggest that the up-field shifts may be rationalized in terms of π-back donation from Pd(II) dπ-orbital to imidato π*-orbital and the ionic potentials of alkali metals, which have also been investigated on the basis of the DFT calculation. On the basis of these characteristic features, the [M 2 Pd(1-MeU) 4 ] complexes may be classified as a new type of metallo-podand that captures alkali metal ions.

Synthesis and X-ray structure of a unique multinuclear complex constructed by a nucleobase-amino acid DL-willardiine

The X-ray crystal structure of a unique multinuclear complex, [Na2Cu2Pd(wil)4(H2O)4], prepared from Na2PdCl4, Cu(ClO4)2·6H2O and DL-willardiine (wil) is determined, which reveals that the palladium atom is coordinated by the imide nitrogens of four wil ligands; two sodium ions are retained in the cavities fromed by the coordinated wil molecules.

Growth and Characterization of Functionally Graded Tryglycine Sulphate–Phosphoric Acid Substituted Tryglycine Sulphate Crystals Produced by Solution-Dropping Method

Tryglycine sulphate (TGS) and (phosphoric acid)-substituted tryglycine sulphate (TGSP) crystals were fabricated on a TGS seed crystal by dropping TGS or TGSP solution. The Curie temperatures of the resultant TGS and TGS0.5P0.5 crystals were 46 and 55 °C, respectively. A compositionally graded TGSP crystal was also fabricated by dropping the concentration-controlled TGS–TGSP solution, and the composition of the functionally graded material (FGM)–TGSP crystal was changed continuously from TGS to TGS0.5P0.5 with a composition ratio step of 0.05. The FGM–TGSP specimen showed a flat dielectric curve with a dielectric constant of 2450±7% in the range from 46 to 54 °C.

Micro-Columnar Crystals with (-O=V-Pd-)n Infinite Chain Structures Assembled by Hetero-Dinuclear Metal Complexes

The inorganic and organic hybrid compound, [O=VPd(2-Pyd-)4]n (2-Pyd- = 2-pyridonate) (1), was synthesized by assembling its monomer units in the organic solution. X-ray absorption spectroscopic (XAFS) studies indicated that oxidation states of the vanadium and palladium ions in 1 were +IV and +II, and the distance between them was estimated to be 2.698-2.700 Å. Scanning electron microscope (SEM) observation revealed that the compound 1 shapes in long columnar crystals with micrometer-sized cross section. EXAFS and IR studies suggested that the O=V oxygen atom interacted to the central palladium ion in the neighboring monomer unit, forming the inorganic infinite chain structure, -(O=V-Pd)n-, in the columnar crystals of 1.