The synthesis of a series of new donor molecules, 1,6-dioxa-pyrenes, is reported. Also reported is a series of dimeric TTF systems. For the dimeric TTF structures the implications for the Fermi surface in 1:1 donor-acceptor salts are discussed. Preliminary results for a few new conducting salts derived from the dimeric TTFs are given.
A theoretical calculation method of nonlinear optical susceptibilities of organic materials is reported. The method consists of semi-empirical (CNDO/S3-CI) and ab initio molecular orbital calculations to evaluate molecular hyperpolarizabilities and a crystal energy calculation to evaluate the crystallization property. In the hyperpolarizabilities calculation, the semi-empirical molecular orbital (MO) calculation is applied to the study of second harmonic generation (SHG) materials, and a suitable chemical structure is described. The ab initio MO calculation for hyperpolarizabilities is performed and basis set dependence of the hyperpolarizability values calculated by a time independent perturbation method and a coupled-perturbed Hartree-Fock method is investigated. A space group limiting calculation for crystal energy of second order nonlinear materials by the accelerating convergence method is described. The calculated structures agree well with the experimental data.
Volatilities of precursors for CVD of superconducting oxide materials have been investigated. The precursors studied were Cu, Y, Ba, Sr, Ca and Bi ß-diketonates and triphenyl Bi. Thermal stabilities for each precursors were measured by a thermal analysis. Bi(DPM)3 was transformed into a Bi2O3 by a thermal decomposition and did not volatilize, while in the case of Sr(DPM)2 and Ba(DPM)2, evaporation and thermal decomposition occurred simultaneously. For Cu(DPM)2, Y(DPM)3, Ca(DPM)2 and Bi(ph)3, vapor pressures were estimated using a transpiration method. The temperature dependence of equilibrium vapor pressure has been measured. The latent heats of sublimation for Cu(DPM)2 and Y(DPM)3 were evaluated as 25.3 and 32.5 kcal/mol, respectively. The latent heats of evaporation for Y(DPM)3 and Bi(ph)3 were evaluated as 15.9 and 22.3 kcal/mol, respectively. In the case of Ca(DPM)2, the latent heats of sublimation and evaporation were almost the same each other and its value was 17.2 kcal/mol.
(μ-Oxo)bis[octakis(alkoxy)phthalocyaninatoiron (III)] 6a-c are obtained by treatment of the cyclotetramerisation product of 4,5-bis(alkoxy)-phthalonitriles in lithium pentanolate with iron(II) acetate. Compounds 6a-c are reduced to bisaxially coordinated octaalkoxyphthalocyaninatoiron(II) in the presence of ligands such as pyridine and t-butylisocyanide. Reaction of 6a with bidentate bridging ligands (e.g. pyrazine, 1,4-diisocyanobenzene) yields the bridged complexes 8a and 9a. The Mößbauer spectroscopic data are described and compared with the analogous unsubstituted phthalocyaninatoiron derivatives.
Textures of methyl cellulose/dichloroacetic acid mesomorphic solution were studied by polarizing microscope and small angle light scattering. It was found that the mesomorphic solution showed the characteristics of cholesteric liquid crystals and the mesophase texture was closely related with the concentration. The mesomorphic solution showed the disk-like texture when mesophase appeared at first. After the mesophase became a continuous phase, however, there were observed the band-like texture and the pseudoisotropic texture in the solution. With the further increasing of concentration, the band-like texture was gradually destroyed and the pseudoisotropic texture changed to focal-conic structure. In the disk-like texture and the band-like texture, the axes of helicoids in cholesteric phase were parallel to the solution plane. In the pseudoisotropic texture they were perpendicular to it. The pitch of cholesteric mesophase decreased with changing from the disk-like texture to the band-like texture.
Phase diagrams of the Nd2O3-CuO and (Nd. Ce)2O3-CuO systems were investigated by differential thermal analysis. It was found that Nd2CuO4 and Nd2-xCexCuO4 melt incongruently at 1270±5 °C and 1315±5 °C respectively, and the solids of Nd2CuO4 and Nd2-xCexCuO4 exist in equilibrium with the liquid of 79–91 mol% CuO, respectively. On the base of these results, Nd1.86Ce0.14CuO4 single crystals were grown by the traveling solvent, floating zone (TSFZ) method. The as-grown crystals were 5 mm in diameter and 50 mm in length with a lusterless black, and had a few subgrains. The Meissner signal was not observed from the as-grown crystals, but it was observed below 19 K from the crystals annealed in N2 at 900 °C for 70 hours.
This contribution deals with theoretical investigations of the electronic and optical properties of all-trans linear polyenes. The focus is on the geometry relaxation processes occurring in the first singlet, one-photon optically allowed excited state. Calculations are performed at various levels of sophistication, from a simple Su-Schrieffer-Heeger (Hückel-like) Hamiltonian up to Pariser-Parr-Pople single CI and Restricted Hartree-Fock ab initio Hamiltonians. It is found that explicit consideration of the electron-lattice coupling is essential in order to obtain a coherent evolution of the 1Bu state geometry relaxation, in going from short polyenes to long polyenes and polyacetylene. The relevance of our results in terms of the nonlinear optical properties of these compounds is pointed out.
A novel process using polyaniline for plating through hole technology has been developed. Polyaniline was dip-coated onto printed circuit boards and in turn acted as a thin conducting electrode for the electrolytic metallization of Cu on the through holes. This eliminates the necessity for expensive precious metal seeds and toxic electroless copper baths. This process offers simplification, cost reduction, and performance enhancement over current methods used in the industry. Spontaneous deposition of noble metals, e.g. Pd, Ag, occurred on polyaniline coated epoxy substrate by simply immersing the substrate in an aqueous solution containing the corresponding metal salt, e.g., CH3-C6H4-SO3Ag, PdCl2. The thin metallic layer so plated was then used as an electrode for subsequent electroplating of Cu.
Effects of various substituents including chromophores on the second harmonic generation (SHG) of Cyanovinylheteroaromatics were examined. The molecular polarizability was calculated by the PPP MO method to correlate SHG responsiveness with chemical structures. 3-[(2-cyano-2-ethoxycarbonyl)ethenyl]indole 8b exhibited good SHG efficiency (PE = 25 U). The X-ray analysis of 8b showed that the crystals belong to novel and the most favorable P1 space group.
We present the results of recent theoretical and experimental studies of optical wave mixings and switchings based on the optical nonlinearities of nematic liquid crystals. These studies have demonstrated several new fundamental understandings of stationary and transient optical wave mixing and switching processes.
X-ray diffraction, ESR, and Raman scattering measurements were performed on Bi(Pb)-Sr-Ca-Cu-O superconductors. Variations in the oxygen content and the number of CuO2 planes in the unit are responsible for a change in the phonon mode for oxygen in BiO layers. In contrast with the result of the band calculation for the low-Tc phase, our result suggests that the transition temperature is not affected by the BiO configuration.
The polar and bipolar uniaxial molecular rotational biasing effect as described by the model of the on an circular arc confined simple rotational diffusion, have been investigated on the Sm E phase neutron incoherent elastic structure factor, as well as on the asymmetry parameter of the electric field gradient tensor.
The optical corrections for the polarized fluorescence intensities of the dyes oriented homogeneously by the nematic liquid crystals in “sandwich” cells are theoretically calculated. The improvements are found to be of a great importance for accurate measurements of the fluorescence intensities and may be useful in the liquid crystal display technology.
The dielectric relaxation of a model solution of polydisperse rods is studied numerically, using a modified Doi-Edwards model. A new model of the dielectric relaxation in the biphasic range of concentration is proposed.
Effects of the central polymethylene group (CH2)n on the liquid crystalline properties displayed by cyanobiphenyl esters of ω-phenyl and cyclohexylalkanic acids were studied.
The soluble block copolymers of acetylene and isoprene produced by Aldissi1 using anionic polymerisation and Zeigler-Natta coupling catalysts show a strong dependence of electrical conductivity (after doping) on the volume fraction of polyacetylene.2 The threshold for this conductivity occurs at about 16% (v/v) and rises very steeply at higher concentrations. Preparations up to c 25% are soluble in toluene or hexane and have the property of retaining residual solvent when pumped to 10−3 τ at 300 K in a gel state. At 30% polyacetylene, the material is a hard solid which can be slightly swollen by solvent above room temperature and which is susceptible to iodine doping from the vapour.2
A sharp maximum of the soft mode strength has been observed at the chiral smectic C* - smectic A phase transition using on optical detection method. The soft mode peak has been used as an indicator of the phase trantision in the absence of external electric field. Electric field broadens the maximum and shifts it towards higher temperatures. Analysis of the soft mode critical behaviour shows that the dc field does not affect the phase transition temperature.
