Showing papers by "Hiroshi Nishihara published in 1996"

Synthesis, electrochemistry and photoconductivity of oligo- and poly-(1,1′-dihexylferrocenylenes)

Abstract: Oligo- and poly-(1,1′-dihexylferrocenylenes), more soluble than unsubstituted oligo- and poly-(1,1′-ferrocenylenes), were synthesized by reaction of dihexylfulvalene dianion with [FeCl2(thf)2](thf = tetrahydrofuran). Electrochemical properties of pentamers and a hexamer were revealed and compared with theory for a system with a linear combination of redox centres. Charge-transfer complexes of poly(dihexylferrocenylene)(M= 5000, M/Mn= 1.2) with tetracyanoethylene and 7,7,8,8-tetracyanoquino-dimethane exhibit photoconductivity.

Inhibition Effects of Amines and Thiols on Iron Corrosion in Anhydrous Methanol Solution Containing FeCl3

Abstract: Polarization and impedance measurements were carried out on an iron electrode in an anhydrous methanol solution of 0.1 M LiClO{sub 4} and 0.01 M FeCl{sub 3} containing organic corrosion inhibitors. They were alkylamines, N,N-dimethylalkylamines, and alkanethiols with various carbon numbers. These inhibitors suppressed both cathodic and anodic processes of iron corrosion in the methanol solution by their chemisorption on the surface via sharing electrons between nitrogen or sulfur and iron atoms. X-ray photoelectron and Fourier transfer infrared reflection spectra of the iron surface treated with the methanol solution containing the inhibitors revealed their adsorption on the surface. The double-layer capacitances obtained from impedance data for the electrode inhibited with N,N-dimethylalkylamines and alkanethiols were lower at various potentials near the corrosion potential than the values for the uninhibited electrode, whereas the capacitance values for the electrode inhibited with alkylamines were higher than those for the uninhibited one. It was proposed that the alkylamine molecule is adsorbed on the surface jointly with adsorbed Cl{sup {minus}} by the formation of a hydrogen bond between Cl{sup {minus}} and a H-N group of alkylamine.

Synthesis of poly(arylene cobaltacyclopentadienylene)s, a new class of organometallic π-conjugated polymers, by metallacycling polymerization and their physical properties

Abstract: Reaction of Cp‘Co(PPh3)2, where Cp‘ = η5-cyclopentadienyl (Cp) or η5-n-hexylcyclopentadienyl (hexCp), with conjugated diacetylenes, RC⋮CAC⋮CR, where A = p-phenylene, p-fluorophenylene, p-2,5-difluorophenylene, or 4,4‘-biphenylene and R = H or Me affords new organometallic polymers, [−C4R2{CoCp‘(PPh3)}−A−]n (1−6) involving linearly π-conjugated chains. The polymers are insoluble when Cp‘ = Cp but soluble in common organic solvents when Cp‘ = hexCp. It is suggested by the results of reactions of (hexCp)Co(PPh3)2 with PhC⋮CH and PhC⋮CMe that stereoregularity favorable to π-conjugation, i.e., connection of cobaltacyclopentadienylene moieties at 2,5 position is higher when R = Me compared to when R = H. The cobaltacyclopentadiene polymers undergo quasi-reversible oxidation and irreversible reduction at low temperatures. The oxidation potential is not significantly changed, but the reduction potential shifts considerably in the positive direction for the polymers compared to monomeric cobaltacyclopentadienes. T...

Monolithic Integration of Waveguide Gratings and Quantum-Well Distributed-Feedback Laser for Implementation of Subminiature Optical-Disc Pickup Head

Abstract: We propose a subminiature optical-disc pickup head implementation by monolithic integration of wave- guide grating components, a graded-index separate-confinement heterostructure single-quantum-well distributed-feedback laser and photodiodes. Fabrication of a prototype device and the results of a preliminary experiment are presented.

Synthesis of poly (arylene cobaltacyclopenta-dienylene)S and their oxidative doping behaviors

Abstract: Two poly(arylene cobaltacyclopentadienylene)s, 3b and 3c were synthesized and their electrochemical properties investigated. The polymer with methyl groups at 3,4-positions of cobaltacyclopentadiene ring, 3b undergoes reversible oxidation at room temperature and shows 10−4 Scm−1 of electrical conductivity when chemically doped with I2.

Electrolyte effects on mixed valence state stability of an electropolymerized bis(fulvalene)diiron film

Abstract: Cyclic voltammetry and spectroelectrochemistry of an electropolymerized film of [Fe2(C10H8)(C10H7CClCHCHO)] (1) were carried out in acetonitrile with Bu4NPF6, Bu4NBF4, Bu4NClO4 or Bu4NHSO4 to determine how the two parameters concerning the stability of the mixed valence state, comproportionation constant, Kc, and mixing coefficient, α, depend on the type of counterions. The difference in electrolyte anions causes slight changes in α exhibiting the magnitude of delocalization of charge between two metal centers. However, significant changes in Kc, suggest that the ion-pairing and electrostatic repulsion are main factors that alter the electrochemical stability of the mixed valence state.

The Synergistic Inhibition Effect of Octylmercaptopropionate and 8- Quinolinol on the Corrosion of Iron in an Aerated 0.5 M Na2SO4 Solution.

Abstract: The synergistic inhibition effect of sodium octylmercaptopropionate, C 8 H 17 S(CH 2 ) 2 COONa (SOMP), and 8-quinolinol, C 9 H 6 NOH (Ql), on the corrosion of iron in an aerated 0.5M Na 2 SO 4 solution was investigated by polarization measurement, X-ray photo-electron and FTIR spectroscopies and electron-probe micro-analysis. A high inhibition efficiency, 98.2%, was obtained by a mixture of 3 × 10 −4 M SOMP and 5 × 10 −4 M Ql. It was concluded that the high synergism of the mixture is mostly attributed to coverage of the iron surface with a precipitate layer composed of iron oxide and a chelate of Ql with Fe 3+ and with a layer of Fe 3+ -SOMP complex precipitated at defects preferentially.

Atomic design of π-conjugated metal complex oligomers and polymers

Abstract: As a model to understand electronic communication between transition metal centres in π-conjugated metal complex polymers, redox properties of soluble oligo(1,1’-ferrocenylene)s were investigated. The dependence of redox potentials on the number of redox nuclei can be explained using not only the neighboring site interaction energies,U OR,U OO andU RR, but also the second neighbouring site interaction energy,U OXR. IR-spectroelectrochemistry of the (cyclopentadiene) Fe(CO)3-attached ferrocene, biferrocene and terferrocene has proved the theoretical prediction on the thermodynamically favorable forms of electronic isomers in the mixed valence states based on the neighboring site interaction energy.

The Inhibition Effect of Bismuth(III) Compounds on the Corrosion of Iron in 1 N HCl at Elevated Temperatures.

Abstract: The inhibition effects on iron corrosion of inorganic bismuth(III) compounds, which seem to be promising for industrial uses, were investigated in 1 N HCl at elevated temperatures. BiCl3 was fairly effective in the temperature region between 30 and 65 °C but ineffective at temperatures higher than 80 °C. BiI3 was a good inhibitor for iron corrosion at 1 × 10−8 M in 1 N HCl at 80 °C. A protective film formed on the iron surface was analyzed by X-ray photo-electron spectroscopy and electron-probe micro-analysis.