Crystallinity of bulk polyacetylene

The fine structure of bulk trans-polyacetylene (PA) was investigated by x-ray diffraction. The degree of crystallinity 0.81, determined by Ruland's method, was significantly higher than the value for linear polyethylene. The disorder parameter k was 5, which is much larger than the value for polyethylene. These results led us to propose that PA crystals are more disordered than PE crystals owing to the higher rigidity of PA chains. Small-angle x-ray diffraction indicated that the crystal morphology is of the extended-chain type rather than lamellar. All results obtained in this work showed that the fine structure of PA bulk is such as to facilitate electrical conduction of bulk PA.     

The electronic structures of cis-polyacetylene

The electronic structures of two possible forms of the so-called $\text{cis}$-skeletal polyacetylene ($\text{cis}$-polyacetylene) are investigated on the basis of the tight-binding LCAO-SCF-MO method under the CNDO/2 version. The analyses of the total energies per unit cell, the π bond orders and the interatomic interaction energies as to the both forms predict the $\text{cis}$-transoid backbone for the $\text{cis}$-polyacetylene. The examination of the patterns of particular molecular orbitals of the hypothetical $\text{cis}$-polymer with equal C-C bond lengths also supports the $\text{cis}$-transoid form.     

Palladium-catalyzed silylation of alcohols with hexamethyldisilane

The combination of hexamethyldisilane and a catalytic amount of [PdCl(eta3-C3H5)]2-PPh3 was found to be effective for the trimethylsilylation of alcohols, where both of the two trimethylsilyl groups of hexamethyldisilane were transferred to alcohols without coproduction of any stoichiometric amount of byproduct but H2.     

Modified Black Hole Thermodynamics with Generalized Uncertainty Principle

In this paper we propose a way of determining the subleading corrections to the Bekenstein-Hawking black hole entropy by considering a modified generalized uncertainty principle with two parameters. In the context of modified generalized uncertainty principle, coefficients of the correction terms of black hole entropy are written in terms of combination of the parameters. We also obtained the corrections to the Stefan-Boltzman law and the black hole evaporation in terms of the parameters. By estimating those parameters, say by experiment, one can test results from other context of quantum gravity theories such as black hole entropy.     

Carboxylic acid catalyzed three-component aza-Friedel-Crafts reactions in water for the synthesis of 3-substituted indoles

[reaction: see text] The carboxylic acid catalyzed three-component aza-Friedel-Crafts reactions of aldehydes, primary amines, and indoles in water have been developed. The aza-Friedel-Crafts products could be easily transformed to various 3-substituted indoles including biologically active compounds. This system offers a novel efficient method for the synthesis of 3-substituted indoles.     

Pd/C-catalyzed chemoselective hydrogenation in the presence of diphenylsulfide

[Structure: see text] A Pd/C-catalyzed chemoselective hydrogenation using diphenylsulfide as a catalyst poison has been developed. This methodology selectively hydrogenates olefin and acetylene functionalities without hydrogenolysis of aromatic carbonyls and halogens, benzyl esters, and N-Cbz protective groups.     

Charge Transfer Transitions from Cyclohexadienyl-Type Radicals to Host Molecules in Anthracene Single Crystals

The optical absorption spectra of 1-, 2- and 9-dibenzo-cyclohexadienyl radical in anthracene crystals have been obtained and analyzed. It is shown that the absorption lines consist of vibrational progression and charge-transfer lines for 2- and 9-DBCR. Each line belonging to the former has the same polarization as the most intense 0–0 vibrational line and the latter show polarization character depending on the direction of charge transfer and the transition energy was found to have a coulombic dependence on the distance of charge transfer. It is pointed out that only charge transfer lines were observed for 1-DBCR. The splitting of lines were observed and ascribed either to the resonance transfer interaction between two neighboring molecules situated at an equal distance from the radical or to the site symmetry. It is suggested that the intensity of the charge-transfer lines are borrowed from the intra-radical transition. The result that the charge transfer lines are more intense than the intra-radical lines for 1-DBCR was discussed.     

Diode-pumped 65 fs Kerr-lens mode-locked Yb(3+):Lu(2)O(3) and nondoped Y(2)O(3) combined ceramic laser

Diode-pumped Kerr-lens mode-locked laser operation of Yb(3+):Lu(2)O(3) and nondoped Y(2)O(3) combined ceramics has been achieved; 65 fs pulses with an average power of 320 mW under 5 W of pump power were obtained at the center wavelength of 1032 nm. The spectral bandwidth and the time bandwidth product were 18.9 and 0.345 nm, respectively. To our knowledge, this is the first demonstration of a Kerr-lens mode-locked laser operation based on Yb(3+):Lu(2)O(3) ceramic.     

Synthesis,Structure, Optical,and Electrochemical Properties of Triple‐ and Quadruple‐Decker Co‐facial Tetrathiafulvalene Arrays

Understanding the details of the electronic structure in face‐to‐face arranged tetrathiafulvalenes (TTFs) is very important for the design of supramolecular functional materials and superior conductive organic materials. This article is a comprehensive study of the interactions among columnar stacked TTFs using trimeric (trimer) and tetrameric (tetramer) TTFs linked by alkylenedithio groups (‐S(CH₂)_nS‐, n=1–4) as models of triple‐ and quadruple‐decker TTF arrays. Single‐crystal X‐ray analyses of neutral trimeric TTFs revealed that the three TTF moieties are oriented in a zigzag arrangement. Cyclic voltammetry measurements (CV) reveal that the trimer and tetramer exhibited diverse reversible redox processes with multi‐electron transfers, depending on the length of the ‐S(CH₂)_nS‐ units and substituents. The electronic spectra of the radical cations, prepared by electrochemical oxidation, showed charge resonance (CR) bands in the NIR/IR region (1630–1850 nm), attributed to a mixed valence (MV) state of the triple‐ and quadruple‐decker TTF arrays. In the trimeric systems, the dicationic state (+2; 0.66 cation per TTF unit) was found to be a stable state, whereas the monocationic state (+1) was not observed in the electronic spectra. In the tetrameric system, substituent‐dependent redox processes were observed. Moreover, π‐trimers and π‐tetramers, which show a significant Davydov blueshift in the spectra, are formed in the tricationic (trimer) and tetracationic (tetramer) state. In addition, these attractive interactions are strongly dependent on the length of the linkage unit.