Masato Sone

Origin of Helix in Achiral Banana-Shaped Molecular Systems.

Helical structures were confirmed for both the SmAb and SmBlue phases of banana-shaped molecular systems from observations of the microscopic fringe pattern and the selective reflection of blue color, respectively. X-ray and optical microscopy indicate that the helical axes in the SmAb and SmBlue phases are normal and parallel to the smectic layer, respectively. In these two helical phases, 13C NMR spectra show two C=O peaks, suggesting two different configurations of ester group, whereas only one C=O peak appears in the isotropic and crystal phases. This indicates that the two C=O groups in the mesogenic core are not in the same plane but are twisted. The addition of chiral dopant makes the dichroic ratio of the right- and left-circularly polarized scattered light positive or negative in the SmBlue phase, although the wavelength (?430 nm) of the scattering peak does not change significantly. The origin of the helix will be discussed in view of the twisted molecular conformation (conformational chirality) and the escape from macroscopic polarization.

Application of emulsion of dense carbon dioxide in electroplating solution with nonionic surfactants for nickel electroplating

Abstract An electroplating reaction using nickel was carried out in an emulsion of dense carbon dioxide (CO2) and an electroplating solution with nonionic surfactants. The current efficiency and electrical resistance values were measured as a function of CO2 volume fraction in the emulsion with three kinds of surfactants. These results show that dense CO2 beyond the critical point of CO2 is effective to form an emulsion for the electroplating reaction. The nonionic surfactant octa(ethylene oxide) dodecyl ether, two kinds of poly (ethylene oxide)-b-poly (propylene oxide) with molecular weights of 745 and 950, respectively, were employed for emulsification. Moreover, a hydrophilic CO2-philic balance of the surfactants strongly influences on the stability of the emulsion. On the basis of the electrical conductivity measurements, the emulsion was classified into a CO2 in water (C/W) type with the CO2 volume fraction ranging from 0 to 80%. Compared to electroplating from the only solution, higher quality nickel films have been prepared by this method. The nickel films that were produced have a higher uniformity, a smaller grain size (sub-100 nm), and a significantly higher Vickers hardness.

Nematic Liquid Crystals with Polar Ordering Formed from Simple Aromatic Polyester

In this study, we describe a distinct nematic liquid crystal with polar ordering which is formed from the polar rod-like aromatic copolyester comprising 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. The polarity in the nematic phase appears along the nematic director as determined by second-harmonic generation (SHG). It was found that SHG activity appears in compounds with a high degree of polymerization. This suggests that the strong dipole-dipole interaction between polar rod-like molecules is the origin of the polar structure.

Study on liquid crystallinity in 2,9‐dialkylpentacenes

A series of semiconducting and symmetrical 2,9‐dialkylpentacenes was successfully synthesized via a five‐step process and their structures confirmed by 1H NMR, IR and elemental analyses. Their liquid crystallinity was investigated by differential scanning calorimetry and polarizing optical microscopy. The introduction of alkyl chains also improved their solubility. For alkyl chains longer than butyl, focal conic or baton texture was observed, indicating the existence of an ordered smectic phase. Thermal analyses revealed that the both melting and smectic–isotropic transition temperatures show an odd–even effect when the alkyl chain is larger than heptyl or octyl. The synthesized compounds are promising candidates for semiconductors in organic field‐effect transistors because their liquid crystallinity allows easy molecular alignment in the device fabrication process.

Influence of sensitizer on organic electroluminescence

We synthesized a polymer, poly(N,N′-diphenyl-N,N′-bis(4-methylphenyl)-1,4-phenylenediamine1,3-diisopropenylbenzene) (PDAIPB), of which the energy of the highest occupied molecular orbital was measured to be 5.6 eV below vacuum level. In this article, PDAIPB was used as a hole transporter in a light emitting diode, with tri(8-hydroxyquinoline)-aluminum (Alq3) as an electron transporter and emitting layer to ameliorate the stability of the device, and fullerene doped in the hole transporting layer as a sensitizer to study the influence of sensitizer on organic electroluminescence (EL). Internal EL quantum efficiency as high as 7.8% was obtained under an applied electric field of 1.2×106 V/cm and doping fullerene concentration of 0.9 wt %. A function for EL quantum efficiency in terms of the dopant concentration is derived. The theoretical analysis is consistent with the experimental results.

Uniform Ni – P Film Using an Electroless Plating Method with an Emulsion of Supercritical Carbon Dioxide

This paper proposes a method for electroless plating by combining supercritical fluid technology and electroless plating in a hybrid technique. The electroless plating reactions are carried out in an emulsion of supercritical carbon dioxide and an electroless plating solution with surfactant. The Ni-P film obtained by this proposed technique was a uniform and conformal film without the pinholes that form from the hydrogen bubbles produced by the electrolysis of water, and without the nodules that form from the nuclear growth on the electroless plating reaction. The dissolution of the hydrogen bubbles in the dense CO 2 particles of the emulsion prevented the pinholes from forming. The formation of nodules might have been prevented by the transport properties of the emulsion with the diffusive dense CO 2 and the suppression of the dissolved oxygen concentration when the oxygen dissolved in the dense CO 2 particles of the emulsion. The Ni-P film fabricated by our technique was smoother and more uniform than the substrate. The roughness of the plated film was constant during film growth, whereas the surface of the film fabricated by conventional electroless plating tended to roughen as the reaction time increased.

Rigid-Rod Polyesters with Flexible Side Chains Based on 1,4-Dialkyl Esters of Pyromellitic Acid and 4,4‘-Biphenol. 7. Fluorescence Studies on Crystalline and Liquid Crystalline Layered Phases over a Wide Range of Temperatures

Rigid-rod polyesters with flexible side chains denoted as B-Cn form two types of layered crystals and two types of layered mesophases. These layered phases are characterized by a layered structure, in which the aromatic main chains are paced into a layer with the side chains occupying the space between the layers. The detailed aggregated structures for these two crystalline phases were studied by fluorescence spectroscopy, from which it was found that the ground-state charge-transfer complexes are formed between the biphenyl and pyromellitic moieties in the adjacent main chains and that these two moieties have an alternating lateral alignment inside a layer. Two layered crystals, K1 and K2, show charge-transfer fluorescence (475 and 505 nm) and its excitation spectra (400 and 425 nm) in different wavelengths, respectively. This difference in wavelengths is related to the difference in lateral packing distances (4.6 A for K1 and 3.45 A for K2 crystals) and suggested to be due to the distance between the electron-donating and -accepting units in the adjacent chains. In the isotropic phase, the charge-transfer bands were also observed. This result means that the isotropic state in this polymeric system can be defined by the state that a layered segregation is maintained, but the molecular ordering and the interlayer correlation are lost. It is well-known that the driving force of the adoption for layered structures is a segregation of aliphatic and aromatic domains. We have demonstrated here, moreover, that a charge-transfer interaction between the electron-donating and -accepting units in the neighboring main chains contributes to the organization of phase structures and spatial arrangements.

Large increase in fracture resistance of stishovite with crack extension less than one micrometer

The development of strong, tough, and damage-tolerant ceramics requires nano/microstructure design to utilize toughening mechanisms operating at different length scales. The toughening mechanisms so far known are effective in micro-scale, then, they require the crack extension of more than a few micrometers to increase the fracture resistance. Here, we developed a micro-mechanical test method using micro-cantilever beam specimens to determine the very early part of resistance-curve of nanocrystalline SiO2 stishovite, which exhibited fracture-induced amorphization. We revealed that this novel toughening mechanism was effective even at length scale of nanometer due to narrow transformation zone width of a few tens of nanometers and large dilatational strain (from 60 to 95%) associated with the transition of crystal to amorphous state. This testing method will be a powerful tool to search for toughening mechanisms that may operate at nanoscale for attaining both reliability and strength of structural materials.

Side-chain conformation of poly(l-proline) form II in the crystalline state as studied by high-resolution solid-state 13C NMR spectroscopy

Abstract High-resolution 13 C NMR spectra of poly( l -proline) from II in the solid state were measured using the CP/MAS and PST/MAS techniques over a wide range of temperatures. From these results, it was found that the pyrrolidine ring in the form II takes two types of conformations, and the mobilities of the pyrrolidine rings in the two types of conformations are different from each other. The behaviour of the main-chain and side-chain conformations of poly( l -proline) was elucidated through the observed 13 C NMR chemical shifts and the calculations of the 13 C NMR shielding constant and total energy of these polypeptides within the tight-binding INDO/S sum-over-states framework.

Light-induced formation of curved needle texture by circularly polarized light irradiation on a discotic liquid crystal containing a racemic chromium complex

We have found that the discotic nematic liquid crystal, hexakis(4‐nonylphenylethynyl)benzene (HNEB), doped with the racemic chromium complex Cr(Ocacac)3, shows a novel straight‐needle texture with hexagonal columnar alignments, changing to a curved‐needle texture under irradiation of circularly polarized light (CPL). This novel phenomenon is specific to the mixture of HNEB and Cr(Ocacac)3. The formation of curved needles means that chiroselective photoinversion of racemic Cr(Ocacac)3 by CPL irradiation induces a needle direction change in a discotic liquid crystal. The change in chirality of Cr(Ocacac)3 in HNEB induced by CPL irradiation, and the resulting nano‐segregation of its enantiomers during cooling from the isotropic to mesophase of HNEB, are considered to influence changes in the alignment of columns and/or small domains of column aggregates in the discotic liquid crystal.