The effect of bath pH on electrodeposition and corrosion properties of ternary Fe-W-Zn alloy platings

Journal of Solid State Electrochemistry - As a new trial to improve the corrosion resistance of the Fe-W alloy platings, Fe-W alloys incorporating a small amount of Zn, namely novel ternary Fe-W-Zn...     

Synthesis and properties of novel fluorinated subnaphthalocyanines for organic photovoltaic cells

Novel fluorinated subnaphthalocyanine derivatives were newly designed and synthesized as donor materials for low molecular organic photovoltaic cells using fullerene as an acceptor. They were designed to have the low-lying HOMO energy levels for improvement of open circuit voltage without any expense of short-circuit current density. The HOMO/LUMO energy levels of hexafluoro-, heptafluoro-, dodecafluoro-, tridecafluoro- and the parent subnaphthalocyanine estimated based on the photoelectron spectroscopy were −5.69/−3.93, −5.67/−3.90, −5.96/−4.19, −5.92/−4.11 and −5.30/−3.58 eV, respectively, showing that frontier orbital energy levels can be effectively tuned by fluorination.     

Coexistence of wave propagation and oscillation in the photosensitive Belousov-Zhabotinsky reaction on a circular route

The photosensitive Belousov-Zhabotinsky (BZ) reaction was investigated on a circular ring, which was drawn using computer software and then projected on a film soaked with BZ solution using a liquid-crystal projector. Under the initial conditions, a chemical wave propagated with a constant velocity on the black ring under a bright background. When the background was rapidly changed to dark, coexistence of the oscillation on part of the ring and propagation of the chemical wave on the other part was observed. These experimental results are discussed in relation to the nature of the photosensitive BZ reaction and theoretically reproduced based on a reaction-diffusion system using the modified Oregonator model.     

Nonadiabatic effects in the photoelectron spectrum of the pyrazolide-d3 anion: three-state interactions in the pyrazolyl-d3 radical

The 351.1 nm photoelectron spectrum of the 1-pyrazolide-d(3) anion has been measured. The photoelectron angular distributions indicate the presence of nearly degenerate electronic states of the 1-pyrazolyl-d(3) radical. Equation-of-motion ionization potential coupled-cluster singles and doubles (EOMIP-CCSD) calculations have been performed to study the low-lying electronic states. The calculations strongly suggest that three electronic states, energetically close to each other, are accessed in the photodetachment process. Strong interactions of the pseudo-Jahn-Teller type in each pair of the three states are evident in the calculations for the radical at the anion geometry. Model diabatic potentials of the three states have been constructed around the anion geometry in terms of the anion reduced normal coordinates up to the second order. An analytic method to parametrize the quadratic vibronic coupling (QVC) model potentials has been introduced. Parameters of the QVC model potentials have been determined from the EOMIP-CCSD and CCSD(T) calculations. Simulations of the 1-pyrazolide-d(3) spectrum have been performed with the model Hamiltonian, treating all vibronic interactions amongst the three states simultaneously. The simulation reproduces the fine structure of the observed spectrum very well, revealing complicated nonadiabatic effects in the low-lying states of the radical. The ground state of the 1-pyrazolyl-d(3) radical is (2)A(2) and the electron affinity is 2.935+/-0.006 eV. The first excited state is (2)B(1) with a term energy of 32+/-1 meV. While the high-symmetry (C(2v)) stationary points of the X (2)A(2) and A (2)B(1) states are minima, that of the state is a saddle point as a result of the pseudo-Jahn-Teller interactions with the other two states. The topology of the adiabatic potential energy surfaces is discussed.     

Pd(OAc)2-catalyzed carbonylation of amines

A phosphine-free catalytic system [Pd(OAc)2-Cu(OAc)2-air] induced a substrate-specific carbonylation of amines in boiling toluene under CO gas (1 atm). Symmetrical N,N'-dialkylureas were obtained by the carbonylation of primary amines. N,N,N'-Trialkylureas were selectively formed by addition of a secondary amine to the above reaction vessel. Secondary amines did not give tetraalkylureas. However, dialkylamines with a phenyl group on their alkyl chains, such as N-monoalkylated benzylic amine or phenethylamine derivatives, underwent a direct aromatic carbonylation to afford five- or six-membered benzolactams. In the carbonylation, the chelation effect or steric repulsion between Pd(II) and the meta-substituent in the ortho-palladation and the ring sizes of cyclopalladation products that were formed prior to carbonylation were found to generate good site selectivity and increase the reaction rate. In contrast, carbonylation of omega-arylalkylamines with a hydroxyl group gave neither ureas nor benzolactams but instead produced 1,3-oxazolidinones smoothly. Hydrochlorides of amines also underwent carbonylation to afford the corresponding amides under the conditions used. This procedure made it possible to prepare ureas of amino acid esters and N-alkylcarbamates in practical yields.     

Global calculations of ground-state axial shape asymmetry of nuclei

Important insight into the symmetry properties of the nuclear ground-state (gs) shape is obtained from the characteristics of low-lying collective energy-level spectra. In the 1950s, experimental and theoretical studies showed that in the gs many nuclei are spheroidal in shape rather than spherical. Later, a hexadecapole component of the gs shape was identified. In the 1970-1995 time frame, a consensus that reflection symmetry of the gs shape was broken for some nuclei emerged. Here we present the first calculation across the nuclear chart of axial symmetry breaking in the nuclear gs. We show that we fulfill a necessary condition: Where we calculate axial symmetry breaking, characteristic gamma bands are observed experimentally. Moreover, we find that, for those nuclei where axial asymmetry is found, a systematic deviation between calculated and measured masses is removed.     

Circular dichroism of copoly(γ-stearyl-L-glutamate–γ-methyl-L-glutamate)

Copoly(γ-stearly-L -glutamate-γ-methyl-L -glutamate)s with various compositions were synthesized by the ester exchange reaction of poly(γ-methyl-L -glutamate). Circular dichroism studies were carried out for solution and solid film as a function of the degree of stearylation and temperature. The slight and gradual temperature dependence of molecular ellipticity was observed for solution of all the copolyglutamates studied here and for the solid film of the copolyglutamate with the degree of stearylation of 16%, indicative of no reversal in the helix sense. However the remarkable change in negative molecular ellipticity with temperature was detected for the solid film of the copolyglutamate with a low degree of stearylation, e.g., 52%, whereas the drastic change in molecular ellipticity from a negative to positive value appeared for that with a higher degree of stearylation. This is discussed in terms of the reversal in the helix sense from a right- to left-handed α helix with the increase of temperature occurring at the melting temperature of the ordered side chain region.     

Synchrotron radiation for structure analysis—EXAFS and XANES

In this paper, a newly developed technique for the structure analysis of materials by the use of the X-rays emitted from storage ring of synchrotron is introduced. Principle, applications and limitations of the extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) are discussed.