Atsutaka Kunai

A conducting polymer derived from para-aminodiphenylamine

Abstract Electrochemical preparation of poly- p -aminodiphenylamine (poly-ADPA) and its properties have been studied in aqueous acid solutions. Electrochemical characteristics of poly-ADPA deposited on a Pt electrode are markedly different from those of ordinary polyaniline. The doping current is proportional to the square root of sweep rate, not to the sweep rate itself. The CV pattern with poly-ADPA is much more sensitive to the solution pH, anion concentration and nature of anions than is ordinary polyaniline. Poly-ADPA is soluble in several polar organic solvents and has a molar mass of 2800 g as determined by GPC. The reason why poly-ADPA is an oligomer is discussed on the basis of the reaction mechanism during polymer growth.

Base-free oxidative homocoupling of arylboronic esters

Abstract Base-free oxidative homocoupling reaction of arylboronic esters has been found to proceed using a catalytic amount of a palladium–1,3-bis(diphenylphosphino)propane (DPPP) complex under an oxygen atmosphere, affording a variety of biaryls in modest to excellent yields. Even arylboronic esters bearing a base-sensitive functional group are applicable to the reaction.

Synthesis and properties of dithienosiloles

Abstract A series of dithienosilole derivatives were synthesized and some of their properties were investigated. UV spectra of dithienosiloles show absorption bands around 350 nm and their cyclic voltammograms display oxidation peaks at about 1.2 V vs. SCE. Nickel-catalyzed coupling of 2,6-dibromodithienosilole with the diGrignard reagent prepared from bis(5-bromothienyl)tetraethyldisilane afforded an alternating polymer composed of a 2,6-dithienyldithienosilole system and tetraethyldisilanylene unit. When the polymer film was doped with FeCl3 vapor, the film became conducting with the maximum conductivity of 7.0×10−3 S/cm.

Doping-induced change of carrier mobilities in poly(3-hexylthiophene) films with different stacking structures

Abstract Mobilities of positive charge carriers in poly(3-hexylthiophene) (PHT) films of 54%, 70%, 81%, and 97% in regioregularity were electrochemically measured over a range of doping levels. The results show that better ordered stacking structures enhance mobilities, but affect little features of the mobility change by doping. The common doping level of ca. 1% for the onset of the drastic mobility increase implies that the π–π stacking structures facilitating a charge transport in neutral or lightly doped PHT films are not responsible for the evolution of metallic conduction in PHT films.

Straightforward construction of diarylmethane skeletons via aryne insertion into carbon–carbon σ-bonds

Two molar amounts of arynes were found to couple with nitriles via carbon-carbon sigma-bond cleavage, assembling diverse diarylmethane skeletons in a straightforward manner.

SYNTHESIS AND PROPERTIES OF ORGANOSILICON POLYMERS CONTAINING 9,10-DIETHYNYLANTHRACENE UNITS WITH HIGHLY HOLE-TRANSPORTING PROPERTIES

Coupling reactions of 9,10-di(lithioethynyl)anthracene with dichloromono-, di-, and trisilanes, Cl(SiR 2 ) m Cl ( m =1–3) gave polymers composed of alternating 9,10-diethynylanthracene and organosilicon units. With dichlorotetraorganodisilanes, the corresponding dianthracenophanes composed of two 9,10-diethynylanthracene units linked by tetraorganodisilanylene bridges were also obtained, together with the polymers. The emission spectra of the polymers with di- and trisilanylene units suggest that intrachain aggregation takes place in solution, although it is not obvious for the silanylene polymer. Cyclic voltammetric (CV) analysis of the polymers shows the evident dependence of the CV profiles on the lengths of the silicon chain between the diethynylanthracene units. When the polymer films were treated with FeCl 3 vapor, the films became conducting with the maximum conductivities in the order of 10 −5 S cm −1 . The double-layer-type electroluminescent (EL) devices were fabricated using these polymers as a hole-transporting layer and tris(8-quinolinolato)aluminum (III) complex (Alq) as an electron-transporting-emitter layer. The turn-on voltage of the devices became higher and the maximum current density smaller, as increasing the number of silicon atoms in a polymer unit from m =1 to 3. The highest luminance of 1300 cd m −2 was obtained from the device based on the silanylene-diethynylanthracene polymer.

Multilayer electroluminescent device using organosilicon polymer as hole transport layer

Abstract Double-layer-type organic electroluminescent devices using organosilicon polymers, such as poly [4,4′-(1,2-dimethyl-1, 2-diphenyldisilan-ylene)-phenylylene], poly [4,4′-(1,2-dimethyl-1,2-diphenyldisilanylene) -biphenylylene], poly[(1,2-dimethyl-1,2-diphenyl-1, 2-disilany-lene)-1,5-naphthylene] and poly [(1,2-tetraethyldisilanylene)-9,10-anthracene] (PDEDS-AN), as hole transport layers were fabricated. In these devices, tris(8-quinolinolato) aluminum(III) complex (Alq) was used as an electron-transporting emitter layer and the effect of the π-electron system of the polymers on device performance was investigated. Among the devices, the PDEDS-AN-based device exhibited the highest external quantum efficiency (QE) of about 0.2%. The low QE values of the organosilicon-based devices compared with that (0.8%) of the double-layer-type device having poly( N -vinylcarbazole) as a typical hole transport layer may be attributed to the poor electron-blocking properties of the organosilicon polymers.

Pd/SiO2 catalyst for oxidation of benzene to phenol

Usefulness of silica supported palladium catalysts applied for the hydroxylation reaction of benzene under ambient conditions has been demonstrated. Two types of catalyst, Pd alone and CuPd composite catalysts both being supported on silica, were found to behave in remarkably different ways which are dependent also on the mode of reactant gas feeding. The Pd single component catalyst is powerful when hydrogen and oxygen are simultaneously present in the reacting system and produces phenol almost exclusively. On the other hand, the composite catalyst can be used irrespective of the mode of gas feeding. If quinones are desired, the use of the composite catalyst is recommended but if phenol is desired the Pd single component catalyst seems to be advantageous.

Thiostannylation of arynes with stannyl sulfides: synthesis and reaction of 2-(arylthio)arylstannanesElectronic supplementary information (ESI) available: experimental section. See http://www.rsc.org/suppdata/cc/b4/b405883f/

Arynes were found to insert into a sulfur-tin sigma-bond of stannyl sulfides to give a variety of 2-(arylthio)arylstannanes, whose carbon-tin bonds were applicable to further transformations.

Three-Component Coupling Using Arynes and Aminosilanes for ortho-Selective Double Functionalization of Aromatic Skeletons

Arynes were found to couple with aminosilanes and carbonyl compounds in the presence of benzoic acid to provide 2-aminobenzhydrols. Sulfonylimines could also be applied to the reaction, enabling amino and aminomethyl moieties to be incorporated into contiguous positions of aromatic skeletons. Only a small amount of the three-component coupling product was obtained in the absence of benzoic acid, which confirms its vital role in the present reaction.