Synthesis and properties of poly(phenylacetylenes) having two polar groups or one cyclic polar group on the phenyl ring

Phenylacetylene (PA) derivatives having two polar groups (ester, 2a – d ; amide, 4) or one cyclic polar group (imide, 5a – c ) were polymerized using (nbd)Rh⁺[(η⁶‐C₆H₅)B^?(C₆H₅)₃] catalyst to afford high molecular weight polymers (～1 × 10⁶ – 4 × 10⁶). The hydrolysis of ester‐containing poly(PA), poly( 2a) , provided poly(3,4‐dicarboxyPA) [poly ( 3 )], which could not be obtained directly by the polymerization of the corresponding monomer. The solubility properties of the present polymers were different from those of poly(PA) having no polar group; that is, poly( 2a )–poly( 2d ) dissolved in ethyl acetate and poly( 4 ) dissolved in N,N‐dimethylformamide, while poly(PA) was insoluble in such solvents. Ester‐group‐containing polymers [poly( 2a )–poly( 2d )] afforded free‐standing membranes by casting from THF solutions. The membrane of poly( 2a ) showed high carbon dioxide permselectivity against nitrogen (PCO₂/PN₂ = 62). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5943–5953, 2006     

Apparent molal volumes of phosphonium halides at 15, 25 and 35°C

The densities of aqueous solutions of the phosphonium halides, Bu _4-n Ph _n PX(n=0–4), some of which were synthesized from the phosphines, were measured at 15, 25 and 35°C. Partial molal volumes at infinite dilution, , and B _v coefficients for the apparent molal volumes were determined at each temperature. For the first four cations varies little with n. For all salts B _v are negative but become less negative with increasing n. The temperature dependence of B _v is positive for butyl-rich salts (n<2) but negative for phenyl-rich salts (n>1). Also it appears that is relatively large for phenyl-rich cations in comparison with that for butyl-rich cations.     

Selective formation of AAB- and ABC-type heterotrimeric alpha-helical coiled coils

The alpha-helical coiled coils have a representative amino acid sequence of (abcdefg)(n) heptad repeats. We previously reported that two peptides named IZ-2A and IZ-2W formed an (IZ-2A)(2)/IZ-2W heterotrimer with an Ala-Ala-Trp interaction in the hydrophobic core. In this paper, we describe the selective formation of AAB- and ABC-type heterotrimers. To increase the selectivity of the AAB-type heterotrimeric formation, Lys residues at the f position were mutated to either an Ala or a Gln residue to form IZ-2A(fA) or IZ-2W(fQ). Separately, both IZ-2A(fA) and IZ-2W(fQ) have a random structure at pH 7 and 20 degrees C. However, together IZ-2A(fA) and IZ-2W(fQ) form a 2:1 complex with a thermal transition midpoint (Tm) of 48 degrees C. This procedure was applied to prepare the ABC-type heterotrimer, in which two sets of Ala-Ala-Trp interactions were designed in the hydrophobic core. Interhelical interaction between the e and g positions and the alpha-helical propensity of the amino acid at the f position were also considered in the design. The resultant three peptides selectively formed the ABC-type heterotrimer with a Tm of 51 degrees C. Other peptide combinations had random coil properties.     

Infrared spectroscopic study on the reaction mechanism of CO hydrogenation over Pd/CeO2

In situ infrared spectroscopy was applied to elucidate the reaction mechanism of CO hydrogenation over Pd/CeO₂. Instead of direct dissociation of CO, a new reaction pathway is proposed for methane formation, involving geminal dicarbonyl intermediates and (HCO)₂(a) intermediates, which may be located on the surface of Pd covered with thin layers of reduced ceria (SMSI effect). Transformation of methane formation sites into methanol formation ones by the oxidation with water vapor formed during the CO?H₂ reaction is proposed, which may be located on the Pd (111) planes adjacent to ceria support.     

A distance-controlled oligopeptide linker as a novel photo-induced energy transfer switch by secondary structural transition

By using an oligopeptide chain as a functional linker and introducing coumarin 2 and coumarin 343 at the chain ends, an effective photo-induced energy transfer system was constructed and energy transfer from coumarin 2 to coumarin 343 was switched on and off by a solvent-induced helix-coil secondary transition of the oligopeptide chain.     

Structures of a CO adlayer on a Pt(100) electrode in HClO4 solution studied by in situ STM

We have obtained the first in situ STM atomic images of a CO adlayer on a Pt(100)-(1 x 1) electrode in 0.1 M HClO(4) solution, exhibiting a phase transition from c(6 x 2)-10CO to c(4 x 2)-6CO at E > 0.3 V vs. RHE.     

Y-931, a novel atypical antipsychotic drug,is less sensitive to oxidative phenomena

The oxidation behavior of Y-931, a potent atypical antipsychotic drug, was compared with that of clozapine and olanzapine. In two enzymatic systems (horseradish peroxidase (HRP)/glutathione (GSH) and HRP/H(2)O(2)/GSH) which generate thiyl radicals, clozapine markedly strengthened the electron paramagnetic resonance (EPR) signal for the radical. Olanzapine, Y-931 and the major metabolites (compounds 1-3) had no or minimal effect on the intensity of this signal. In addition, the redox potential values for the three derivatives were in accord with the EPR spin trapping results. In toxicological experiments in human leukocytes, a concentration-dependent toxicity was observed when neutrophils were incubated with clozapine (1-10 micromol/l) and H(2)O(2) (1 mmol/l). However, Y-931 and olanzapine did not show remarkable toxicity under the conditions.     

Synthesis of Substituted Phenyl Esters of Amino Acids and Polycondensation in Langmuirblodgett Films

Long-alkyl-chain phenyl esters of β-alanine, glycine, and L-valine were prepared, and their monolayer properties were correlated with their molecular structures. These compounds formed stable monolayers on acidic subphases. In particular, the p-hexadecylphenyl esters of β-alanine and glycine were remarkably stable, and their monolayers could be deposited on calcium fluoride plates as Y-type film by Blodgett's technique. The polycondensation of multilayers under an atmosphere saturated with triethylamine was investigated by changes in the IR spectra. It was determined that the polycondensation proceeded by a first-order reaction mechanism in the initial stage and that the rate in multilayers was faster than that in the bulk crystalline powder. These results suggest that the polycondensation is accelerated by a regular arrangement of the monomer in the multilayers, where the active sites are concentrated and located better for the polycondensation. In the case of the polycondensation in multilayers of the glycine ester, two kinds of condensation proceeded to afford poly(glycine) and 2,5-piperazinedione.     

Synthesis of 1,6-dihydropyrimidines via copper-catalyzed multistep cascade reactions between O-propargylic aldoximes and isocyanates

Multi-step cascade reactions of O-propargylic oximes with isocyanates were carried out in the presence of copper catalysts to afford the corresponding 1,6-dihydropyrimidines in good yields. The multi-step reactions consisted of a 2,3-rearrangement, a [3+2] cycloaddition, decarboxylative ring opening involving a 1,4-hydrogen shift, and a 6π-electrocyclization.     

Phase-locked laser system for a metastable states qubit in 40 Ca+

We describe the development of a phase-locked laser system tailored to an ion-trap-based quantum information processor with (40)Ca(+). Laser outputs from an extended cavity diode laser and a Ti:sapphire laser with output laser wavelengths of approximately 850 and 854 nm, respectively, were phase locked and used to excite a Raman transition between the D(3/2) and D(5/2) metastable states qubit. Development and the performance of the laser system are described. We also compare the characteristics and the benefits of the developed qubit coupling with those in the conventional approaches.