Takashi Nogami

Possibilities of organic ferromagnets and ferrimagnets by the use of charge-transfer (CT) complexes with radical substituents. Ab initio MO studies

Abstract Approximately projected unrestricted Hartree-Fock (APUHF) STO-3G and 4-31G calculations have been carried out for charge-transfer (CT) complexes with radical substituents. The computations reveal that the signs of intermolecular effective exchange integrals are variable with stacking modes of donor-acceptor pairs. Organic ferromagnets and/or ferrimagnets are conceivable for appropriately stacked CT complexes with radical groups. The calculated results are also discussed in relation to possibilities of conversions of CT complexes into organic magnetic conductors such as ferromagnetic metal.

Phase transition of quaternary alkyl halide salts of diazabicyclo [2.2.2] octane

Abstract A series of quaternary alkyl halide salts of diazabicyclo [2.2.2] octane were found to exhibit first-order phase transitions at 64–103°C. Drastic changes of halide anion conductivities by three to four orders of magnitude were found to occur at the transition temperatures. X-ray diffractions of powdered sample revealed that the transition was induced by a structural change of the crystal. Differential scanning calorimetries were also measured.

Synthesis of bis(vinylenedithio)tetrathiafulvalene and its methyl derivatives

Abstract BVDT-TTF † , BMVDT-TTF † , and BDMVDT-TTF † were synthesized as attractive donor molecules for highly conductive organic salts. The ethylene units of BEDT-TTF are replaced by carbon-carbon double bonds in these donor molecules. They have analogous structures to BEDT-TTF † with possibly more planar structures. Another synthetic method of BEDT-TTF and BVDT-TTF was investigated starting from the reduction of 1,3,4,6-tetrathiapentalene-2,5-dione with Aliquat 336/Na 2 CO 3 . A new and general synthetic method of aryl-substituted BEDT-TTF is also described.

Electrochemically doped poly(N-Vinylcarbazole) as an electrode material for rechargeable batteries

Abstract Secondary lithium batteries using electrochemically-doped poly(N-vinyl-carbazole) (PVCz) deposited on a Pt plate or gauze, and doped PVCz-graphite as cathodes exhibit flat discharge voltages and good cyclability with high coulombic efficiencies.

Optical second-harmonic generation from a series of [cyano(alkyloxycarbonyl)methylene]-2-ylidene-1,3-dithioles and their methyl and dimethyl derivatives

Abstract Second-order nonlinear optical properties of a series of [cyano(alkyloxycarbonyl)methylene]-2-ylidene- 1,3-dithioles and their methyl and dimethyl derivatives were investigated by the powder technique. An Nd:YAG laser was used for the fundamental. [cyano(ethoxycarbonyl)methylene]-2-ylidene-4,5-dimethyl-1,3-dithiole recrystallized from methyl alcohol gave large optical second-harmonic (SH) intensity (24 times that of urea), while that recrystallized from acetone gave no SHG. [cyano(ethoxycarbonyl)methylene]-2-ylidene-4-methyl-1,3-dithiole also gave large SH intensity (10 times that of urea). These materials are almost colorless. They are attractive materials for frequency doubling of infrared semiconductor lasers in the blue wavelength region.

Bromide anion conductivities of quaternary phosphonium bromides possessing long alkyl chains

Abstract Halide anion conductivities of several quaternary alkylphosphonium bromides and tetrabutylphosphonium chloride were measured by a complex impedance method. Tetrahexylphosphonium bromide (C6PBr) showed the highest bromide anion conductivity. The bromide anion conductivities decreased as the alkyl lengths of quaternary phosphonium bromides become both longer and shorter than C6PBr. Bromide anion conductivities of quaternary alkylphosphonium bromides were higher than those of quaternary alkylammonium bromides reported. The mixture of tetrabutylphosphonium bromide, tetrahexylphosphonium bromide, and tetraoctylphosphonium bromide was found to be a new kind of a room temperature molten salt.

Bromide ion conductivities of eutectic mixtures of quaternary ammonium bromides possessing long alkyl chains

Abstract Several quaternary ammonium bromides possessing long alkyl chains and their mixtures were found to be bromide ion conductors. The ionic conductivities of quaternary ammonium bromides themselves were lower than 10 −9 S cm −1 at a room temperature. On the other hand, the eutectic mixtures of the quaternary ammonium bromides showed large increase of ionic conductivity. The best bromide ion conductors were found for the eutectic of Q 5 , Q 7 , Q 8 , and Q 12 : 4×10 −8 S cm −1 at 30°C, and 6.3×10 −6 S cm −1 at 50°C. Addition of asymmetric quarternary ammonium bromides had a negative effect on the ionic conductivity. These results were explained by a space filling factor in the solid.

Halide-ion conductivities of the complexes of cryptand[2.2.2] with alkali-metal halides and alkaline earth metal halides

Abstract Halide ion conductivities of the complexes of cryptand[2.2.2] with alkali-metal halides or alkaline-earth metal halides were measured at 20–160°C. The halide ion conductivities of the complexes were found to be much higher than those of the crown ether complexes with alkali-metal halides or alkaline-earth metal halides. This is caused by the much weaker Coulomb attraction between metal-cation and halide ion in cryptand complexes than in crown ether complexes.

Lithium ion conductors of polyion complexes dispersed with LiClO4 and their application to solid-state batteries

Abstract Polyion complexes between poly(sodium acrylate) 2 and polybrene 3 , or poly(2-acrylamino-2-methylpropane sulfonate) 2 and 2 were synthesized. After removing sodium bromide, these polymers were dispersed with LiClO 4 , and their Li + conductivities were measured at 80 ∼ 200°C. Their ionic conductivities changed from 10 -3 to 10 -8 S cm -1 at 100 ∼ 200°C. These polymers and poly(ethylene oxide) dispersed with LiBF 4 were used as solid electrolytes of Li-activated carbon fiber (ACF) batteries and ACF-ACF capacitor.

1,4,9,10-Tetrathiaanthracene, a promising donor molecule for highly conductive organic complexes

Abstract 1,4,9,10-Tetrathiaanthracene (TTA) was prepared, and the complex, TTA·I 1.2′ showed the conductivity of 4.2 (Ω cm) −1 .