Fusion of phosphole and 1,1'-biacenaphthene: phosphorus(V)-containing extended π-systems with high electron affinity and electron mobility

A profusion of phospholes: Diacenaphtho[1,2-b:1',2'-d]phospholes, a new class of arene-fused phosphole π-systems, were synthesized and their structural and electrochemical properties studied. The P-sulfide derivative has a high electron-transporting ability (μ(E) =2.4×10(-3) cm(2) V(-1) s(-1)) in a vacuum-deposited film.     

In situ X-ray probing reveals fingerprints of surface platinum oxide

In situ X-ray absorption spectroscopy (XAS) at the Pt L(3) edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard X-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF code and complementary extended X-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at high electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.     

Vibrational properties of CaAlH5 and α-AlH3 with different AlH6 networks studied by inelastic neutron scattering

We performed a combined study using inelastic neutron scattering (INS) and first-principles calculations of the vibrational properties of CaAlH(5) and α-AlH(3) with different AlH(6) networks, a zigzag one-dimensional AlH(6) network for CaAlH(5), and a three-dimensional AlH(6) network for α-AlH(3). Both materials showed qualitatively similar INS spectra, in which CaAlH(5)/α-AlH(3) was mainly divided into three regions: (i) the translational modes (318/316 cm(-1)), (ii) the librational modes of the octahedral AlH(6) units (external molecular motion) in the lower frequency range and H-Al-H bond-bending modes (intra molecular motion) at a higher frequency (420-1157/513-1038 cm(-1)), and (iii) the Al-H bond-stretching modes (1238-1750/1486-1942 cm(-1)). In region ii, the appearance of both librational and bond-bending modes was determined by the networked nature of the octahedral AlH(6) units. In addition, the librational modes of AlH(6) on α-AlH(3) exhibit higher frequencies than CaAlH(5) due to the tighter bonding between the octahedral AlH(6) units. With regard to average frequencies for the Al-H, ω(S), bond-stretching modes, and average Al-H bond distances on the aluminum-based hydrides including CaAlH(5) and α-AlH(3), ω(S) showed lower frequencies that correlate with lengthening of the Al-H bond distances.     

Formation of dimer, trimer, and tetramer of C60 and C70 by γ-ray, charged-particle irradiation, and their HPLC separation

C₆₀ and C₇₀ fullerenes were irradiated by high-energy γ-rays and charged particles. Coalesced products of C₆₀ and C₇₀ have been isolated and detected in the liquid phase by a radiochromatographic technique. It was found that not only ¹¹C radioactive fullerene dimer, trimer, and possibly tetramer were produced by a recoil implantation process following nuclear reaction, but also such non-radioactive coalesced products were produced by the recombination process after ionization by γ-rays or charged particles.     

Examination of Dislocation Mechanism on Grain Boundary Sliding in High Angle Grain Boundaries by Stress Change Test

In order to understand the factors dominating grain boundary sliding, stress change tests and stress reversal tests were conducted on aluminum bicrystal specimens with high angle grain boundaries. It is found that small change in stress results in the remarkable change in the rate of grain boundary sliding. Stress reversal tests showed that grain boundary slide hardening does not work for the sliding to the direction opposite to that before the stress reversal. Mean internal stresses for the dislocations contributing to grain boundary sliding are experimentally measured by a method consisting of stress change and annealing. It is found that the velocity of dislocations in the grain boundary is in proportion to the mean effective stress.     

Dispersive Coherence Spectrotomography with White-Light Continuum

We propose dispersive coherence spectrotomography with white-light continuum to extract both range and spectral properties inside a medium. The main feature is that the dispersive coherence spectrotomography has a high dynamic range in depth and high signal-to-noise ratio making the most of the extreme brightness of the white-light continuum.     

Synthesis,structure, and oxidation of 3,4-dihydro-1,2,5-benzotrithiepins

Stable benzene-fused polysulfide compounds, 3,4-dihydro-1,2,5-benzotrithiepins ( 1a-c ), have been prepared, and the structure of 1a has been determined by X-ray crystallographic analysis. While the electrophilic oxidation of compounds 1 with m-chloroperbenzoic acid gave the corresponding 3,4-dihydro-1,2,5-benzotrithiepin 5-oxides ( 2 ) in moderate yields, the oxidation of 1 with N-bromosuccinimide afforded a mixture of 5-oxides 2 , unexpected, inseparable 3,4-dihydro-1,2,5-benzotrithiepin 2,2-dioxides ( 3 ), and 3,4-dihydro-1,2,5-benzotrithiepin 1,1-dioxides ( 4 ). Semiempirical PM3 calculations were carried out, and the computed HOMO of 1a suggested a significant favoring of electrophilic reactions at the sulfur atom at the 5-position. The treatment of 5-oxides 2 with acetyl bromide or oxalyl dibromide as halogenating reagents gave 2,2-dioxides 3 and 1,1-dioxides 4 , suggesting that an intramolecular halogen transfer from the 5-position (sulfide moiety) to the 1- and 2-positions (disulfide moiety) took place in the reactions.