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Tomoji Ozeki

Publications and source records attributed to Tomoji Ozeki.

18 recordsLinked to original sources
PubMed2006

Fluorous nanodroplets structurally confined in an organopalladium sphere.

The distinct properties of fluorous phases are practically useful for separation, purification, and reaction control in organic synthesis. Here, we report the formation of a liquid-like fluorous droplet, composed of 24 perfluoroalkyl chains confined in the interior of a 5-nanometer-sized, roughly spherical shell that spontaneously assembled in solution from 12 palladium ions and 24 bridging ligands. Crystallographic analysis confirmed the rigid shell framework and amorphous interior. Perfluoroalkanes can dissolve in this well-defined fluorous phase, whereas they can hardly dissolve in a surrounding polar organic solution, and their solubility (up to approximately eight perfluoroalkane molecules per spherical complex) can be finely controlled by tuning the length of perfluoroalkyl chains tethered to the shell.

Journal Article↗
PubMed2006

Direct crystallographic observation of a coordinatively unsaturated transition-metal complex in situ generated within a self-assembled cage.

In situ crystallographic observation of an extremely labile coordinatively unsaturated transition-metal complex, Cp'Mn(CO)2 (Cp' = methylcyclopentadienyl), was achieved by generating and trapping it within the confined cavity of a self-assembled cage in the crystalline state at a low temperature. The labile target Cp'Mn(CO)2 was formed by the photodissociation of the CO ligand from stable Cp'Mn(CO)3, which was accommodated within the cavity of the coordination cage. Being trapped in the cage at a low temperature, Cp'Mn(CO)2 showed sufficient stability to be analyzed by X-ray crystallography. The diffraction study revealed that the 16-electron unsaturated Mn complex adopted a pyramidal geometry rather than a planar geometry.

Journal Article↗
PubMed2005

Methoxide of an Anderson-type polyoxometalate and its conversion to a new type of species, [IMo9O32(OH)(OH2)3]4-.

A totally new type of polyoxometalate, [IMo(9)O(32)(OH)(OH(2))(3)](4)(-), has been synthesized by reacting [IMo(6)O(22)(OMe)(2)](3)(-) with water. The [IMo(9)O(32)(OH)(OH(2))(3)](4)(-) anion further transforms into [(IMo(7)O(26))(2)](6)(-), a molecular oxide that has a rutile core, in dry acetonitrile, while it stays intact for several hours in wet acetonitrile.

Journal Article↗
PubMed2005

Cation-controlled assembly of Na+-linked lacunary alpha-Keggin tungstosilicates.

Two novel salts of lacunary tungstosilicates with guanidinium and alkali metal cations, (CH6N3)7Na[SiW11O39].(CH3)2CO.8H2O (1) and (CH6N3)K6Na[SiW11O39].11.5H2O (2), have been synthesized and their crystal structures have been determined by synchrotron X-ray diffraction. In both crystals, the Na+ cations link the lacunary Keggin-type tungstosilicate anions into linear structures. The neighboring [SiW11O39]8- anions are related by two-fold screw and translational operations in compounds 1 and 2, respectively. Second harmonic generation was observed for compound 1.

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PubMed2005

A new 19-metal-atom cluster [(Me2PhP)10Au12Ag7(NO3)9] with a nearly staggered-staggered M5 ring configuration.

New mixed metal clusters with M19 metal frameworks have been synthesized by NaBH4 reduction of Au(NO3)(PMe2Ph) together with AgNO3 in ethanol. Single crystal X-ray diffraction has revealed Au12Ag7 and Au17Ag2 metal skeletons for these clusters, which are best described in terms of bicapped pentagonal antiprismatic cages with a staggered-staggered M(5) ring configuration. These clusters connect the missing link between M13 icosahedral and M25 biicosahedral clusters providing a view of the cluster growth process. A TEM image of this cluster has been observed, which has clearly demonstrated single-sized nano-particles of less than 1.0 nm.

Crystallography, X-Ray↗
PubMed2005

Sequence-selective recognition of peptides within the single binding pocket of a self-assembled coordination cage.

The single binding pocket of a self-assembled Pd6L4 coordination cage recognizes oligopeptides in a highly sequence-selective fashion. In particular, the Trp-Trp-Ala sequence is strongly bound by the cavity (Ka >/=106 M-1). Tripeptides possessing the same residues but in different sequences (i.e., Trp-Ala-Trp and Ala-Trp-Trp) show much poorer affinity. Even singly mutated tripeptides with aromatic-aromatic-aliphatic sequences of the residues (e.g., Trp-Trp-Gly and Trp-Tyr-Ala) are not recognized efficiently. X-ray analysis and NMR reveal that all residues of the Trp-Trp-Ala sequence cooperatively interact with the cage via CH-pi and pi-pi interactions.

Alanine↗
PubMed2005

Reversible photoelectronic signal conversion based on photoisomerization-controlled coordination change of azobenzene-bipyridine ligands to copper.

A new "molecular photoelectronic transducer", working in a cyclic manner totally powered with light irradiation, has been constructed. The UV/blue-controlled repetitive motion of azobenzene moieties in 6,6'-bis(4' '-tolylazo)-4,4'-bis(4-tertbutylphenyl)-2,2'-bipyridine causes reciprocal CuI translocation between two coordination environments, resulting in pumping of the redox potential of CuI. Therefore, UV/blue light information can be successfully transformed into an electrode potential change and positive/negative current response, which is closely related to natural visual transduction both functionally and mechanically. This result demonstrates a new strategy for artificial molecular machine assembly, i.e. forming a path with multistep chemical reactions between input/output couples at choice.

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PubMed2004

[(IMo(7)O(26))(2)](6)(-): A missing link between molecular and solid oxides.

A new molecular oxide, [(IMo(7)O(26))(2)](6)(-), that has a self-contained structure has been synthesized. Its structural relevance both to the rutile structure and several molecular oxides that had been classified as "strange ones with odd structures" has given some insights as to why those species assume such structures. The novel yet self-contained nature of the structure suggests the existence of a new class of molecular oxides of related structures.

Journal Article↗
PubMed2004

A 3.5-nm coordination nanotube.

A 3.5-nm coordination nanotube was self-assembled from 12 Pd(II) ions and four tape-shaped ligands with the aid of a 3.0-nm template. This tubular structure was unambiguously determined by the single-crystal X-ray analysis. Being cooperatively sustained by 24 Pd(II)-pyridine interactions, the framework was kinetically stable even when the template was removed. The empty tube was, of course, capable of binding other molecules in the cavity.

Crystallography, X-Ray↗
PubMed2004

Mg(2)Na(2)V(10)O(28).20H(2)O and Mg(3)V(10)O(28).28H(2)O.

The crystal structures of dimagnesium disodium decavanadate icosahydrate, Mg(2)Na(2)V(10)O(28).20H(2)O, (I), and trimagnesium decavanadate octacosahydrate, Mg(3)V(10)O(28).28H(2)O, (II), have been determined by single-crystal X-ray diffraction. They crystallize with monoclinic (C2/c) and triclinic (P-1) symmetry, respectively. All the Mg(2+) cations in (I) and (II) are octahedrally coordinated by six water molecules. The Na(+) cations in (I) are coordinated by three water molecules and three O atoms of the decavanadate anions, and link the latter into a three-dimensional network. The decavanadate anions in (II) are not linked to one another.

Journal Article↗
PubMed2003

Cu3V10O28.24H2O and CuNa4V10O28.23H2O.

The crystal structures of tricopper decavanadate tetracosahydrate, (I), and copper tetrasodium decavanadate tricosahydrate, (II), have been determined by single-crystal X-ray diffraction. Both compounds exhibit a catenary structure consisting of [V10O28](6-) anions linked by Cu2+ cations in (I) or by Na+ cations in (II). Compound (II) also contains a polymeric linear array of edge-sharing [Na(OH2)6](+) and [Cu(OH2)6](2+) octahedra. In both compounds, the [V10O28](6-) ions lie about inversion centres and the Cu2+ ions in (I) also lie about inversion centers.

Journal Article↗
PubMed2003

Synchrotron structure determination of an alpha-Keggin doubly PtIV-substituted silicotungstate, (CH6N3)8[alpha-SiPt2W10O40].6H2O.

The crystal structure of octaguanidinium alpha-silicodiplatinodecatungstate hexahydrate, (CH(6)N(3))(8)[alpha-SiPt(2)W(10)O(40)].6H(2)O, has been analyzed via a high-energy X-ray diffraction experiment at the SPring-8 BL04B2 beamline. The title compound contains a novel alpha-Keggin heteropolyanion in which two of the addenda atoms are replaced by Pt atoms. W and Pt atoms occupy the same coordinates; the occupancy fractions are 5/6 (W) and 1/6 (Pt), and the alpha-Keggin anion has -4 symmetry. The two types of W(Pt)-W(Pt) distance are in the ranges 3.3565 (4)-3.3704 (4) and 3.7033 (4)-3.7100 (4) A, the four types of W(Pt)-O bond length are in the ranges 1.721 (5)-1.725 (5), 1.910 (5)-1.932 (5), 1.934 (5)-1.956 (5) and 2.339 (4)-2.348 (4) A, and the Si-O bond length is 1.646 (4) A.

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PubMed2002

Self-assembly of a lacunary alpha-Keggin undecatungstophosphate into a three-dimensional network linked by s-block cations.

The crystal structure of [(CH3)4N]4Na2H[alpha-PW11O39].8H2O has been determined by using the Weissenberg camera at the BL04B2 beamline of SPring-8, revealing that it contains a disorder-free lacunary [alpha-PW11O39]7- anion with one sodium cation embedded into its lacuna that links the oxometalate building blocks into a one-dimensional chain, which is then woven into a three dimensional latticework by another Na+.

Journal Article↗
PubMed2002

(Et4N)4[V4O12].2H2O.

The title compound, tetrakis(tetraethylammonium) cyclo-tetra-micro-oxo-tetrakis[dioxovanadium(V)] dihydrate, (C(8)H(20)N)(4)[V(4)O(12)].2H(2)O, was obtained by reacting V(2)O(5) with (C(2)H(5))(4)NOH. It consists of a discrete centrosymmetric molecular anion, [V(4)O(12)](4-), where four tetrahedral VO(4) units share two vertices with each other to form a ring. A water molecule is attached on each side of the ring through hydrogen bonds.

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