Double resonance NMR/ON of185IrNi and188IrFe

In order to establish small quadrupole splittings the double resonance NMR/ON method was applied to¹⁸⁵IrNi and¹⁸⁸IrFe at 7 and 8.6 mK, respectively. With r.f. power applied at the strongest resonance frequency, a second frequency was used to simultaneously investigate the second resonance component, where the splitting is caused by an electric quadrupole interaction. Enhanced quadrupole subresonances were observed. In these experiments we have demonstrated the powerful capability of the double resonance NMR/ON method to observe a small quadrupole interaction when the resulting subresonances are well resolved.     

The half-life of 207Bi and decays of 211At and 211Po

The half-life of ²⁰⁷Bi was obtained from the genetic relation between ²⁰⁷Po and ²⁰⁷Bi, and between ²¹¹At and ²⁰⁷Bi. The half-life was found to be 33.4 ± 0.8 y. The half-life of ²⁰⁷Po was determined to be 5.81 ± 0.04 h by following the decay of the characteristic γ-rays from ²⁰⁷Po. The half-life of ²¹¹ At was determined tobe 7.23 ± 0.02 h by following the decay of γ-rays and α-particles from ²¹¹At and ²¹¹Po. The half-lives determined in the present work for ²⁰⁷Po and ²¹¹At agree with the literature although the half-life of ²⁰⁷Bi differs considerably from the currently accepted value of 38 y. The branching ratio of ²¹¹ At decaying through EC and α-decay modes was determined together with the branching ratios of the three α-particles emitted from ²¹¹Po.     

Preparation of a Completely Oriented Molecular Sieve Membrane

Growth of oriented seed crystals on a substrate led to a completely oriented and continuous membrane of LTA-type zeolite. The seed crystals of cubic morphology were dip-coated onto a tilted substrate (see schematic diagram) with the zeolite channels normal to the surface. The substrate was hydrothermally treated in a reaction mixture containing the organic ligand 2,2-bis(hydroxymethyl)-2,2',2"-nitrilotriethanol, which lowers the degree of supersaturation of [Al(OH)(4)](-) ions and preferentially facilitates the intergrowth of the seed crystals.     

Fabrication of vertically aligned liquid crystal cell without using a conventional alignment layer

We propose a novel method to fabricate a vertical alignment (VA) of liquid crystal (LC) molecules without using a conventional alignment layer such as polyimide film. The method produces the vertical alignment polymer layer (VAPL) by polymerisation of a monomer or mixed monomers including in the LC layer above T_NI of the LC material. The VA mode LC cell with the VAPL (VAPL-LC cell) produced from the mixed monomers of acrylic acid 4-(4?-octyloxy-biphenyl-4-yloxy)-butyl ester and 1,2-bis-(4-methacryloxy-phenyl)-2,2-dimethoxy-ethane-1-one exhibited enough level of alignment state and electro-optical property with high voltage holding ratio. We can expect that the VAPL-LC cell is useful for next-generation displays such as flexible liquid crystal displays because the method does not need the process including high temperature over 200°C.     

Cobalt‐Catalyzed E‐Selective Cross‐Dimerization of Terminal Alkynes: A Mechanism Involving Cobalt(0/II) Redox Cycles

A highly E‐selective cross‐dimerization of terminal alkynes with either terminal silylacetylenes, tert‐butylacetylene, or 1‐trimethylsilyloxy‐1,1‐diphenyl‐2‐propyne in the presence of a dichlorocobalt(II) complex bearing a sterically demanding 2,9‐bis(2,4,6‐triisopropylphenyl)‐1,10‐phenanthroline, activated with two equivalents of EtMgBr, gives a variety of (E)‐1,3‐enynes. A well‐characterized diolefin/cobalt(0) complex, with divinyltetramethyldisiloxane, acted as a catalytically active species without any activation, clearly indicating that a cobalt(0) species is involved in the catalytic cycle.     

Single‐Crystalline Optical Microcavities from Luminescent Dendrimers

Microcrystallites are promising minute mirrorless laser sources. A variety of luminescent organic compounds have been exploited along this line, but dendrimers have been inapplicable owing to their fragility and extremely poor crystallinity. Now, a dendrimer family that overcomes these difficulties is presented. First‐, second‐, and third‐generation carbazole (Cz) dendrimers with a carbon‐bridged oligo(phenylenevinylene) (COPV2) core (GnCOPV2, n=1–3) assemble to form microcrystals. The COPV2 cores align uni/bidirectionally in the crystals while the Cz units in G2‐ and G3COPV2 align omnidirectionally. The dendrons work as light‐harvesting antennas that absorb non‐polarized light and transfer it to the COPV2 core, from which a polarized luminescence radiates. Furthermore, these crystals act as laser resonators, where the lasing thresholds are strongly coupled with the crystal morphology and the orientation of COPV2, which is in contrast with the conventional amorphous dendrimers.     

Ion‐Pairing Assemblies of Porphyrin–AuIII Complexes in Combination with π‐Electronic Receptor–Anion Complexes

Anion complexes of anion‐responsive π‐electronic molecules can behave as pseudo π‐electronic anions providing various ion pairs in combination with countercations. In this study, single crystals of ion‐pairing assemblies comprising porphyrin–Au^III complexes and Cl^? complexes of dipyrrolyldiketone BF₂ complexes were prepared from 1:1 mixtures of anion receptors and the Cl^? salts of cationic porphyrins in solution. In the solid state, the ion pairs formed characteristic assemblies, depending on the substituents of the anion receptors and porphyrin–Au^III complexes. Theoretical calculations on the ion pairs revealed that the stacking structures are stabilized by compensating positive and negative charges as well as π–π interactions.     

Tuned polymer electrolyte membranes based on aromatic polyethers for fuel cell applications

Poly(arylene ether sulfone)-based ionomers containing sulfofluorenyl groups have been synthesized for applications to polymer electrolyte membrane fuel cells (PEMFCs). In order to achieve high proton conductivity and chemical, mechanical, and dimensional stability, the molecular structure of the ionomers has been optimized. Tough, flexible, and transparent membranes were obtained from a series of modified ionomers containing methyl groups with the ion-exchange capacity (IEC) ranging from 1.32 to 3.26 meq/g. Isopropylidene tetramethylbiphenylene moieties were more effective than the methyl-substituted fluorenyl groups in giving a high-IEC ionomer membrane with substantial stability to hydrolysis and oxidation. Dimensional stability was significantly improved for the methyl-substituted ionomer membranes compared to that of the non-methylated ones. This new ionomer membrane showed comparable proton conductivity to that of the perfluorinated ionomer membrane (Nafion 112) under a wide range of conditions (80-120 degrees C and 20-93% relative humidity (RH)). The highest proton conductivity of 0.3 S/cm was obtained at 80 degrees C and 93% RH. Although there is a decline of proton conductivity with time, after 10 000 h the proton conductivities were still at acceptable levels for fuel cell operation. The membranes retained their strength, flexibility, and high molecular weight after 10 000 h. Microscopic analyses revealed well-connected ionic clusters for the high-IEC membrane. A fuel cell operated using the polyether ionomer membrane showed better performance than that of Nafion at a low humidity of 20% RH and high temperature of 90 degrees C. Unlike the other hydrocarbon ionomers, the present membrane showed a lower resistance than expected from its conductivity, indicating superior water-holding capability at high temperature and low humidity.