Takahiro Nakae

Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen or hydrogen peroxide and sodium cyanide: sp3 C-H bond activation and carbon-carbon bond formation.

Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen in the presence of sodium cyanide and acetic acid gives the corresponding alpha-aminonitriles, which are highly useful intermediates for organic synthesis. The reaction is the first demonstration of direct sp(3) C-H bond activation alpha to nitrogen followed by carbon-carbon bond formation under aerobic oxidation conditions. The catalytic oxidation seems to proceed by (i) alpha-C-H activation of tertiary amines by the ruthenium catalyst to give an iminium ion/ruthenium hydride intermediate, (ii) reaction with molecular oxygen to give an iminium ion/ruthenium hydroperoxide, (iii) reaction with HCN to give the alpha-aminonitrile product, H2O2, and Ru species, (iv) generation of oxoruthenium species from the reaction of Ru species with H2O2, and (v) reaction of oxoruthenium species with tertiary amines to give alpha-aminonitriles. On the basis of the last two pathways, a new type of ruthenium-catalyzed oxidative cyanation of tertiary amines with H2O2 to give alpha-aminonitriles was established. The alpha-aminonitriles thus obtained can be readily converted to alpha-amino acids, diamines, and various nitrogen-containing heterocyclic compounds.

Photocurrent-Generating Properties of Organometallic Fullerene Molecules on an Electrode

Compact, rigid, five-legged fullerene derivatives C60R5Me and M(C60R5)Cp (M = Fe and Ru; R = C6H4COOH, C6H4C6H4COOH, and CH2COOH) were synthesized and arrayed on an indium-tin oxide (ITO) surface. These devices exhibit a respectable quantum yield with photocurrent generation up to 18%, and, more importantly, the direction of the photocurrent can be changed not only by the molecular structure itself but also by changing the geometric configuration of the photoactive acceptor (fullerene) and donor (metal atom) on the ITO surface.

Width‐Controlled Sub‐Nanometer Graphene Nanoribbon Films Synthesized by Radical‐Polymerized Chemical Vapor Deposition

Radical-polymerized chemical vapor deposition, a new bottom-up method, was developed to produce graphene nanoribbons (GNRs) efficiently, despite the use of extremely low vacuum. Using this technique, a systematic synthesis of a multilayered high-density array of width-controlled sub-1 nm GNRs on a metal surface, with width-dependent band gap, is made possible. GNR films transferred onto insulating substrates behave as an excellent photoconductor.

Water-soluble diruthenium complexes bearing acetate and carbonate bridges: highly efficient catalysts for aerobic oxidation of alcohols in water

The aerobic oxidation of alcohols in water can be performed efficiently in the presence of a catalytic amount of the water-soluble diruthenium complex Ru2(micro-OAc)3(micro-CO3) under an atmospheric pressure (1 atm) of O2.

Dual emitting Langmuir–Blodgett films of cationic iridium complexes and montmorillonite clay for oxygen sensing

Langmuir–Blodgett (LB) films were prepared by hybridizing a floating monolayer of an amphiphilic cationic iridium(III) complex with clay particles in a subphase. Two kinds of iridium(III) complexes were used: [Ir(dfppy)2(dc9bpy)]+ (denoted by DFPPY: dfppyH = 2-(4′,6′-difluoro-phenyl)pyridine; dc9bpy = 4,4′-dinonyl-2,2′-bipyridine) with the maximum emission wavelength (λmax) at 500 nm and [Ir(ppy)2(dc9bpy)]+ (denoted by PPY: ppyH = 2-phenylpyridine) with λmax at 550 nm. Stationary emission spectra were recorded on the following films under vacuum: {DFPPY or PPY/clay}n (n = 1–3), {DFPPY/clay/PPY/clay} and {PPY/clay/DFPPY/clay}. The intensity of emission from {PPY/clay}n or {DFPPY/clay}n increased nearly in proportion to the layer number (n). Both DFPPY and PPY emitted simultaneously from {DFPPY/clay/PPY/clay}, indicating the low contribution of energy transfer. Contrarily PPY emitted exclusively from {PPY/clay/DFPPY/clay} as a result of the efficient quenching of excited DFPPY in the lower layer by PPY in the upper layer. The introduction of oxygen gas resulted in the decrease of emission for all films. Notably {DFPPY/clay/PPY/clay} exhibited a dual emitting character under an oxygen atmosphere, that is, the broad emission maximum was observed around 530 nm at lower oxygen pressure (0 4 kPa).

Iron and Ruthenium Nanoparticles in Carbon Prepared by Thermolysis of Buckymetallocenes

Thermolysis of fullerene iron and ruthenium complexes (buckymetallocene M(C(60)R(5))Cp (M = Fe; R = Ph (1) and Me (2), M = Ru; R = Ph (3), Me (4)) under a nitrogen atmosphere produced metal nanoparticles dispersed in carbon materials. The thermal degradation processes of the buckymetallocenes were studied by TG-DTA, TEM with a heating sample stage, and VT-XRD. Variation of the thermolysis temperature led to a change in the size of the nanoparticles and the morphology of the carbon materials. Thermolysis of buckyferrocene at 700 degrees C gave highly dispersed iron nanoparticles (average diameter of 7.4 nm). After thermal treatment at 900 degrees C, graphite structures such as carbon nanocapsules and carbon nanotubes formed because of the catalytic activity of the iron nanoparticles. Ruthenium nanoparticles prepared from buckyruthenocene were much smaller than the iron counterparts, and did not catalyze the formation of graphite structures. When buckyruthenocene absorbed on silica gel was heated at 500 degrees C under a hydrogen atmosphere, the resulting ruthenium nanoparticles showed high activity in catalytic hydrogenation.

Strain-induced skeletal rearrangement of a polycyclic aromatic hydrocarbon on a copper surface

Controlling the structural deformation of organic molecules can drive unique reactions that cannot be induced only by thermal, optical or electrochemical procedures. However, in conventional organic synthesis, including mechanochemical procedures, it is difficult to control skeletal rearrangement in polycyclic aromatic hydrocarbons (PAHs). Here, we demonstrate a reaction scheme for the skeletal rearrangement of PAHs on a metal surface using high-resolution noncontact atomic force microscopy. By a combination of organic synthesis and on-surface cyclodehydrogenation, we produce a well-designed PAH—diazuleno[1,2,3-cd:1′,2′,3′-fg]pyrene—adsorbed flatly onto Cu(001), in which two azuleno moieties are highly strained by their mutual proximity. This local strain drives the rearrangement of one of the azuleno moieties into a fulvaleno moiety, which has never been reported so far. Our proposed thermally driven, strain-induced synthesis on surfaces will pave the way for the production of a new class of nanocarbon materials that conventional synthetic techniques cannot attain.

Synthesis, structure and properties of ethyl naphth[2,3-f]isoindole-1-carboxylate

Ethyl 12-oxo-4,11-dihydro-4,11-ethanonaphth[2,3-f]isoindole-1-carboxylate (2) was prepared from 7-tert-butoxynorbornadiene and quantitatively converted to ethyl naphth[2,3-f]isoindole-1-carboxylate (3) by the thermal or photochemical cheletropic reaction. Ethyl naphth[2,3-f]isoindole-1-carboxylate (3) existed in a 2H-form both in solution and as a solid, and gradually dimerized to give a dianthradiazafulvalene derivative under aerobic conditions.

Orientation and Electronic Structures of Multilayered Graphene Nanoribbons Produced by Two-Zone Chemical Vapor Deposition

The orientation and electronic structure of multilayered graphene nanoribbons with an armchair-edge (AGNRs) were determined by low-temperature scanning tunneling microscopy in this study. The orientation of AGNRs was found to be an edge-on structure when positioned as a top layer, while previous reports showed a face-on structure for monolayered AGNRs on Au(111). According to density functional theory calculations, AGNRs in a top layer preferentially form as edge-on structures rather than face-on structures due to the balance of CH-π and π-π interactions between AGNRs. Scanning tunneling spectroscopy and density functional theory calculations revealed that the electronic structures of multilayered AGNRs are similar to those in a gas-phase due to the lack of interaction between AGNRs and the Au(111) substrate. The observation of AGNRs in mutilayers might suggest the conformation-assisted mechanism of dehydrogenation when there is no contact with the Au(111) substrate.

Synthesis of NIR-emitting O-chelated BODIPYs fused with benzene and acenaphthylene

A series of O-chelated BODIPYs fused with aromatic rings such as benzene and acenaphthylene at β,β-positions was synthesized as a near-infrared dye. The photophysical properties were examined by UV-vis-NIR absorption and fluorescence measurement. Acenaphthylene-fused O-BODIPYs showed a intense absorption at 750–840 nm with the e of 105 M-1.cm-1. and a fluorescence emission at 770–850 nm with the high Φ value of 0.06–0.43.