1D Chain and 3D framework of silver(I) organo-metallic polymers self-assembled with triptycene

For the purpose of investigating the coordination behavior of sterically congested alkenes and exploring the possibility of non-planar complexation in the polycyclic aromatic system for formation of extended polymeric networks, triptycene (tpty) has been studied with regard to its complexation with the silver(I) ion. The crystal structures of [Ag(tpty)(THF)₂](ClO₄) (1) and [Ag₆(tpty)₄(CF₃SO₃)₂(H₂O)₆](CF₃SO₃)₄ (2) have been determined by single-crystal X-ray diffraction. The polycyclic aromatic hydrocarbon triptycene is found to offer a potential site for complexation, which can be utilized to generate an interesting array of organo-metallic polymers with one-dimensional (1D) chain and three-dimensional (3D) porous frameworks.     

A characterization of a certain real hypersurface of type (A<Subscript>2</Subscript>) in a complex projective space

In the class of real hypersurfaces M ^2n?1 isometrically immersed into a nonflat complex space form \(\widetilde {{M_n}}\left( c \right)\) of constant holomorphic sectional curvature c (≠ 0) which is either a complex projective space ?P ⁿ (c) or a complex hyperbolic space ?H ⁿ (c) according as c > 0 or c < 0, there are two typical examples. One is the class of all real hypersurfaces of type (A) and the other is the class of all ruled real hypersurfaces. Note that the former example are Hopf manifolds and the latter are non-Hopf manifolds. In this paper, inspired by a simple characterization of all ruled real hypersurfaces in \(\widetilde {{M_n}}\left( c \right)\), we consider a certain real hypersurface of type (A₂) in ?P ⁿ (c) and give a geometric characterization of this Hopf manifold.     

Variations of lattice constants and thermal expansion coefficients of indium at high pressure and high temperature

ABSTRACT

The effects of pressure and temperature on the lattice constants and thermal expansion coefficients of Indium were studied up to 18.6?GPa and 506?K based on in situ X-ray diffraction method with an externally heated diamond anvil cell. The results show that the measured axial ratio (c/a) decreases with increasing temperature and its temperature dependence decreases with increasing pressure. The thermal expansion coefficient of the a-axis decreases with increasing pressure up to 7?GPa and remains almost constant above 7?GPa, whereas that of the c-axis increases monotonously with pressure and changes from negative to positive at around 7?GPa. The observed behavior suggests that temperature reduces the tetragonal distortion on the lattice, and its effect is dominant below 7?GPa; in contrast, pressure enhances lattice distortion, and tends to have a stronger effect above 7?GPa.     

Chemical oscillation with periodic adsorption and desorption of surfactant ions at a water/nitrobenzene interface.

Chemical oscillations with periodic adsorption and desorption of surfactant ions, alkyl sulfate ions, at a water/nitrobenzene interface have been investigated. The interfacial tension was measured with a quasi elastic laser scattering (QELS) method and the interfacial electrical potential was obtained. We found that this oscillation consists of a series of abrupt adsorptions of ions, followed by a gradual desorption. In addition, we observed that each abrupt adsorption was always accompanied by a small waving motion of the liquid interface. From the analysis of the video images of the liquid interface or bulk phase, we could conclude that each abrupt adsorption is caused by nonlinear amplification of mass transfer of ions from the bulk phase to the liquid interface by a Marangoni convection, which was generated due to local adsorption of the surfactant ions at the liquid interface that resulted in the heterogeneity of the interfacial tension. In the present paper, we describe the mechanism of the chemical oscillation in terms of the hydrodynamic effect on the ion adsorption processes, and we also show the interfacial chemical reaction with ion exchange during the ion desorption process.     

Catalytic decomposition of CFCs

Catalytic decomposition of CCI₂F₂ was studied over a number of single and complex metal oxides using a fixed-bed reactor. The ZrO₂–Cr₂O₂ catalyst exhibited the highest activity and CO₂ and CCIF₃ were formed at 350–450°C. Selective decomposition of CCI₂F₂ required the presence of both oxygen and water vapor over the catalyst. Catalytic activity gradually declined with time on stream because of the fluorination of ZrO₂. Treatment of the catalyst with both oxygen and water vapor promoted the removal of fluoride ions in sub-surface layers of the catalyst, which is effective for the recovery of the activity. CCI₂F₂ was decomposed at 300–450°C over AIPO₄. No fluorination of the AIPO₄ catalyst took place after the reaction for 1000 h. CH₂FCF₃, an alternative CFC, was completely decomposed over the mixed catalyst of Ce promoted AIPO₄ and Cr₂O₃ at 400–500°C. Catalytic decomposition is a rational method for destruction of used CFCs.     

Hydrodynamically induced chemical oscillation at a water/nitrobenzene interface

By measuring a time course of interfacial tension and interfacial electrical potential, we successfully observed oscillatory phenomena that were based on alternatively appearing adsorption and desorption processes of anionic surfactant molecules (sodium dodecyl sulfate (SDS)) at the water/nitrobenzene interface. These oscillation patterns were drastically modified by slightly changing the rate of SDS aqueous solution injection into the water phase. When 10 mM of SDS aqueous solution was injected at a low rate, for example, at less than 1 microl/min, abrupt adsorption was repeatedly followed by slow desorption of DS- ions; in other words, the sequence of the oscillation and relaxation processes was repeated. However, when it was injected at a higher rate, no remarkable periodic phenomenon occurred after the first oscillation. In addition, the rapid adsorption process was observed to be accompanied by a flip motion of the liquid/liquid interface and a flow along the interface. This is caused by a Marangoni convection that is brought about by the generation of heterogeneity of interfacial tension. Furthermore, by estimating the flow speed, it was determined that the faster flow tends to quench the periodic oscillation patterns.     

Poly(thiaheterohelicene): a stiff conjugated helical polymer comprised of fused benzothiophene rings

A novel helical aromatic polymer comprised of fused benzothiophene rings, poly(thiaheterohelicene), was synthesized via an intramolecular ring-closing reaction with a controlled helicity to one-sided bias. The synthetic helicity control involved the induction of the helical conformation and its fixation. The ladder polymer showed both an extended pi-conjugation and planarity and a very stiff helical structure. [structure: see text]     

Selective reduction of NOX with C3H6 over Cu incorporated into silicoalumino-phosphate (SAPO)

Cu ion-exchanged SAPO-34 which is a highly active catalyst for selective reduction of NO with C₃H₆, was synthesized and the Cu ion was characterized in the SAPO-34 by ESR, XPS, IR, and XAFS. ESR study indicated that two kinds of Cu(II) with different environments exist in SAPO-34. The Cu(II) species disappeared immediately by C₃H₆ treatment and recovered by oxygen treatment. XAFS study indicated that most of the Cu(II) was reduced to Cu(I) under the presence of C₃H₆. These studies revealed that a selective NO reduction by C₃H₆ over SAPO-34 should proceed by the redox reaction of a copper ion between Cu(I) and Cu(II).