Hisashi Fujihara

Synthesis of small palladium nanoparticles stabilized by bisphosphine BINAP bearing an alkyl chain and their palladium nanoparticle-catalyzed carbon–carbon coupling reactions under room-temperature

A new bisphosphine ligand, C8-BINAP, and C8-BINAP-stabilized palladium nanoparticles have been prepared; C8-BINAP was found to be an effective protecting ligand for preparing and stabilizing palladium nanoparticles with very small core size and narrow size distribution and the C8-BINAP-Pd nanoparticles behave as an efficient catalyst for carbon-carbon coupling reactions at room temperature.

Remarkably stable gold nanoparticles functionalized with a zwitterionic liquid based on imidazolium sulfonate in a high concentration of aqueous electrolyte and ionic liquid

A new type of gold nanoparticle with a zwitterionic liquid function (zwitter-Au) has been prepared using an imidazolium sulfonate-terminated thiol as a capping agent. Zwitter-Au was found to be remarkably stable in high concentrations of aqueous electrolytes, ionic liquids, and protein.

Nanotube composites consisting of metal nanoparticles and polythiophene from electropolymerization of terthiophene-functionalized metal (Au, Pd) nanoparticles.

We have developed a new method for the fabrication of metal nanoparticle/polythiophene nanotube composites, i.e., the template-based electrochemical polymerization of terthiophene-linked oligoethyleneoxy-thiol (1) and -phosphine (2)-stabilized gold and palladium nanoparticles (1-Au, 1-Pd, and 2-Pd) in a nanoporous alumina membrane as a template gave the nanotube composites (1-Au-PT-NTs, 1-Pd-PT-NTs, and 2-Pd-PT-NTs) of polythiophene and the metal nanoparticles without aggregation of the metal nanoparticles. The nanotube composites were characterized by scanning electron microscopy and transmission electron microscopy. The Pd/polythiophene nanotube composites (2-Pd-PT-NTs) are recyclable highly effective catalysts for carbon−carbon coupling reactions. This new method is currently being extended to other metal and metal oxide nanoparticles/polythiophene nanotube composites to realize a wide range of hybrid nanomaterials with controllable surface chemistry.

[2+1] Cycloaddition of Nitrene onto C60 Revisited: Interconversion between an Aziridinofullerene and an Azafulleroid†

It is known that organic azides react with a [6,6] bond of C60 through a 1,3-dipolar [3+2] cycloaddition to afford triazolines. Thermolysis of a triazoline, followed by concomitant loss of nitrogen, gives rise to a [1,6]azafulleroid 1 and a [1,2]aziridinofullerene 2 (Scheme 1). Both 1 and 2 can also be obtained directly from the reaction of C60 and azides at higher temperatures, but the ratio of 1:2 depends on the nature of the substituent. Furthermore, azides have major associated problems in regards to toxicity and explosibility. Thus, new useful methods for the preparation of azafulleroids and aziridinofullerenes are expected. Sulfilimines are known to generate an N-substituted nitrene in thermal and photochemical reactions. Recently, it has been reported that N-sulfenylsulfilimine generates a sulfenylnitrene under mild conditions. Nitrenes readily react with alkenes to afford the corresponding three-membered aziridines. In this context, a nitrene is expected to be a key intermediate, instead of an azide, in the aziridination of fullerene. In the course of our study on the development of synthetic methodology for the preparation of [1,2]aziridinofullerene, we carried out the photoreaction of C60 with an N-p-toluenesulfonylsulfilimine having a dibenzothiophene structure (3 ; Scheme 2) to accomplish the regioselective

Preparation and characterization of gold nanoparticles with a ruthenium-terpyridyl complex, and electropolymerization of their pyrrole-modified metal nanocomposites

The reduction of tetrachloroaurate with sodium borohydride in the presence of 2,2′:6′,2″-terpyridyloctanethiol gave terpyridine-functionalized gold nanoparticles (Tpy–Au, core size 2.0 nm). Metal complexation of Tpy–Au with ruthenium-terpyridyl trichloride, Ru(tpy)Cl3, led to new gold nanoparticles bearing the ruthenium-terpyridine complex (Ru–Tpy–Au, core size 5.5 nm) which showed a characteristic MLCT (metal-to-ligand charge transfer) band in the visible region at 483 nm due to the terpyridine-ruthenium complex and a plasmon resonance at ∼510 nm in the UV-vis spectrum. The redox behavior of Ru–Tpy–Au was studied by cyclic voltammetry. Surface modification of metal electrodes was performed by the electropolymerization of pyrrole-functionalized Ru–Tpy–Au nanoparticles (Pyr–Ru–Tpy–Au) which were obtained from the ligand-exchange reaction of Ru–Tpy–Au with ω-(N-pyrrolyl)decanethiol.

Radical Copolymerization of Methyl Methacrylate with Styrene in Several Solvents

Abstract Radical copolymerization of styrene (M1) with methyl methacrylate has been carried out in several solvents. The monomer reactivity ratio (r) was affected by the solvent. The values of log 1/r, Q2, and e2 were found to increase with the decreases of the V C[dbnd]O and v n[dbnd]c stretcning frequencies determined in the corresponding solvents.

Synthesis of 5H,7H-dibenzo[b,g][1,5]selenoxocine from a selenonium salt of 5H,7H-dibenzo[b,g][1,5]diselenocine and first X-ray evidence for the transannular oxygen-selenium interaction

Abstract A new heterocyclic compound, 5 H ,7 H -dibenzo[ b , g ][1,5]selenoxocine ( 1 ), has been prepared from the benzylic selenonium salt of 5 H ,7 H -dibenzo[ b , g ][1,5]diselenocine. Treatment of the selenoxide of 1 with acetylenedicarboxylate gave the stable selenonium ylide ( 4 ); the X-ray structure of 4 shows the strong transannular contact between oxygen and selenium atoms.

Redox-active π-conjugated polymer nanotubes with viologen for encapsulation and release of fluorescent dye in the nanospace.

We report the encapsulation of negatively charged Au nanoparticles and anionic fluorescent (FL) dye in the inner cavity of redox-active cationic polymer nanotubes with viologen via electrostatic interaction and the release of the FL dye from the FL dye confined in the cavity of the polymer nanotubes by electrochemical and chemical reduction.

Water-soluble palladium and gold nanoparticles functionalized by a new phosphine with zwitterionic liquid based on imidazolium sulfonate linked ethylene glycol moiety

A new phosphine with zwitterionic liquid based on imidazolium sulfonate linked ethylene glycol moiety (1) as a protective ligand for metal nanoparticles has been prepared. Its phosphine 1-stabilized palladium and gold nanoparticles (1-Pd and 1-Au) were found to be soluble in water, and remarkably stable in high concentration of aqueous electrolyte and ionic liquid. 1-Pd nanoparticles behave as an efficient catalyst for the Suzuki cross-coupling reaction in an aqueous medium.

Dendritic effects on the ordered assembly and the interfacial one-electron oxidation of redox-active dendron-functionalized gold nanoparticles

A higher generation dendron with a long-alkyl chain thiol (DA2-SH) induced the formation of nanoparticles with a small core with quite a narrow size distribution (1.5 +/- 0.1 nm), the self-assembly of one-dimensional arrays of these gold nanoparticles (DA2-Au), and the stabilization for the formation of the radical cation of the phenothiazine of DA2-Au nanoparticles from the interfacial one-electron oxidation of the nanoparticles with NOBF4.