Observation of an optical vortex beam from a helical undulator in the XUV region

The observation of an optical vortex beam at 60 nm wavelength, produced as the second‐harmonic radiation from a helical undulator, is reported. The helical wavefront of the optical vortex beam was verified by measuring the interference pattern between the vortex beam from a helical undulator and a normal beam from another undulator. Although the interference patterns were slightly blurred owing to the relatively large electron beam emittance, it was possible to observe the interference features thanks to the helical wavefront of the vortex beam. The experimental results were well reproduced by simulation.     

SPring‐8 BL36XU: Synchrotron Radiation X‐Ray‐Based Multi‐Analytical Beamline for Polymer Electrolyte Fuel Cells under Operating Conditions

We designed and constructed a beamline BL36XU at the 8 GeV synchrotron radiation facility SPring‐8 to provide information required for the development of next‐generation polymer electrolyte fuel cells (PEFCs) by clarifying the dynamic aspects of structures and electronic states of cathode catalysts under PEFC operating conditions and in the deterioration processes by accelerated durability test protcols. To investigate the mechanism and degradation process for the cathode electrocatalysis in practical PEFCs, we developed advanced time‐ and spatially‐resolved in‐situ/operando X‐ray absorption fine structure measurement systems and complementary analytical systems (X‐ray emission spectroscopy (XES), X‐ray diffraction (XRD), X‐ray computer tomography (CT) and hard X‐ray photoelectron spectroscopy (HAXPES)) and combined them to develop multi‐analytical systems at BL36XU. Multi‐analytical systems are very powerful for observing spatial‐temporal features of the transient processes occurring in complex systems such as PEFCs. This account describes the design, performance, and research results of the BL36XU and multi‐analytical in‐situ/operando systems.     

Enantio and diastereoselective total synthesis of all four stereoisomers of germicidin N

Abstract

Germicidin N (3-ethyl-4-hydroxy-6-[(1S, 2?R)?2-hydroxy-1-methylpropyl]-2H-pyran-2-one, 1), a new α-pyrone from the extracts of a Streptomyces sp. derived from marine algae, has been synthesized for the first time as four possible diastereomers from chiral β-hydroxyester ((S)?6 and (R)?9) through the stereoselective alkylation, Claisen condensation followed by cyclization in a straightforward manner.     

Anthracene‐sensitized polymerization of vinyl ethers by onium tetrakis(pentafluorophenyl)borate initiators

Cationic photopolymerization of vinyl ethers by the sensitized photolysis of onium tetrakis(pentafluorophenyl)borate initiators has been investigated in this study. The onium borates were sensitized by anthracene and initiated the photopolymerization of the vinyl ethers. The rate of polymerization increased with the decrease in the free‐energy change from the excited singlet state of anthracene to the onium cation of the onium borates. The acid generated by the decomposition of the onium borates formed nonacidic products by heating. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 982–987, 2000     

Synthesis of linear and branched polyketones from the Rh complex catalyzed living alternating copolymerization of (4‐alkylphenyl)allene with CO

Copolymerization of (4‐hexylphenyl)allene and of (4‐dodecylphenyl)allene with carbon monoxide (1 atm) catalyzed by Rh[η³‐CH(Ar′)C{C(CHAr′)CH₂C (CHAr′)CH₂CH₂CHCHAr′}CH₂](PPh₃)₂ (A; Ar′ = C₆H₄OMe‐p) gives the corresponding polyketones: I‐[—CO—C(CHAr)—CH₂—]_n [1: Ar = C₆H₄C₆H₁₃‐p, 2 : Ar = C₆H₄C₁₂H₂₅‐p; I = CH₂C(CHAr′)C(CHAr′)CH₂C(CHAr′)CH₂CH₂CHCHAr′]. Molecular weights of the polyketone prepared from (4‐hexylphenyl)allene and CO are similar to the calculated from the monomer to initiator ratios until the molecular weight reaches to 45,000, indicating the living polymerization. Melting points of the polyketones I‐[—CO—C(CHC₆H₄R‐p)—CH₂—]_n (n = ca. 100) increase in the order R = C₁₂H₂₅ < C₆H₁₃ < C₄H₉ < CH₃ < H. Block and random copolymerization of phenylallene and (4‐alkylphenyl)allene with carbon monoxide gives the new copoly‐ ketones. The polymerization of a mixture of (4‐methylphenyl)allene and smaller amounts of bis(allenyl)benzene under CO afforded the polyketone with a crosslinked structure. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1505–1511, 2000     

Enantioselective construction of all-carbon quaternary spirocenters through a Pd-catalyzed asymmetric intramolecular ipso-Friedel–Crafts allylic alkylation of phenols

A novel catalytic asymmetric synthetic method for making spirocyclohexadienones with an all-carbon quaternary spirocenter was developed based on the Pd-catalyzed intramolecular ipso-Friedel–Crafts allylic alkylation of phenols. When 5 mol % of the Pd catalyst and 12 mol % of (?)-9-NapBN (?)-3e were used, the spirocyclic adduct was obtained with up to 93% ee, albeit with low chemical yield. On the other hand, when using 6 mol% of the Trost ligand (R,R)-3k, the spirocyclic adducts were obtained in good yields with up to 89% ee (diastereoselectivity = 9.2:1).     

High‐resolution MALDI‐TOF MS study on analysis of low‐molecular‐weight products from photo‐oxidation of poly(3‐hexylthiophene)

High‐resolution matrix‐assisted laser desorption/ionization (MALDI) time‐of‐flight mass spectrometry (TOF MS) was used for the analysis of the low‐molecular‐weight products from the photo‐oxidation of poly(3‐hexylthiophene) (P3HT) in solution and thin film. Eight new peak series were observed in the low‐mass range of the mass spectra of the products degraded in solution, and the formulas of the eight components were determined from the accurate mass. From SEC/MALDI‐TOF MS, two components were identified as the degraded products, and the other six components were derived from the fragmentation of the degraded products during the MALDI process. A mechanism for the formation of these components was proposed on the basis of the results of MALDI‐TOF MS. For the thin film degradation, a part of products in the solution degradation were observed, which supports that the oxidation of P3HT in solution and thin film proceeded in the same mechanism. This study shows that high‐resolution MALDI‐TOF MS is effective for the analysis of the low‐molecular‐weight products from P3HT photo‐oxidation and expected to be feasible for the degradation analyses of other polymers. Copyright © 2015 John Wiley & Sons, Ltd.     

C2 Symmetric chiral N-heterocyclic carbene catalyst for asymmetric intramolecular Stetter reaction

The asymmetric intramolecular Stetter reaction of ω-formyl α,β-unsaturated carbonyl compounds was catalyzed by a C2 symmetric chiral carbene, generated from (4S,5S)-diphenyl-1,3-bis(mesitylmethyl)-4,5-dihydro-1H-imidazolium tetrafluoroborate, to afford 2-substituted cyclopentanones in good enantioselectivity of up to 80%.