Preparation and characterization of ruthenium(II), rhodium(III) and iridium(III) complexes of isocyanide bearing the azo group

Reactions of [(η⁶-arene)RuCl₂]₂ (1) (η⁶-arene=p-cymene (1a), 1,3,5-Me₃C₆H₃ (1b), 1,2,3-Me₃C₆H₃ (1c) 1,2,3,4-Me₄C₆H₂(1d), 1,2,3,5-Me₄C₆H₂ (1e) and C₆Me₆ (1f)) or [Cp*MCl₂]₂ (M=Rh (2), Ir (3); Cp*=C₅Me₅) with 4-isocyanoazobenzene (RNC) and 4,4′-diisocyanoazobenzene (CN–R–NC) gave mononuclear and dinuclear complexes, [(η⁶-arene)Ru(CNC₆H₄N=NC₆H₅)Cl₂] (4a–f), [Cp*M(CNC₆H₄N=NC₆H₅)Cl₂] (5: M=Rh; 6: M=Ir)_, [{(η⁶-arene)RuCl₂}₂{μ-CNC₆H₄N=NC₆H₄NC}] (8a–f) and [(Cp*MCl₂)₂(μ-CNC₆H₄N=NC₆H₄NC)}] (9: M=Rh; 10: M=Ir)_, respectively. It was confirmed by X-ray analyses of 4a and 5 that these complexes have trans-forms for the ---N=N--- moieties. Reaction of [Cp*Rh(dppf)(MeCN)](PF₆)₂ (dppf=1,1′-bis (diphenylphosphino)ferrocene) with 4-isocyanoazobenzene gave [Cp*Rh(dppf)(CNC₆H₄N=NC₆H₅)](PF₆)₂ (7), confirmed by X-ray analysis. Complex 8b reacted with Ag(CF₃SO₃), giving a rectangular tetranuclear complex 11b, [{(η⁶-1,3,5-Me₃C₆H₃)Ru(μ-Cl}₄(μ-CNC₆H₄N=NC₆H₄NC)₂](CF₃SO₃)₄ bridged by four Cl atoms and two μ-diisocyanoazobenzene ligands. Photochemical reactions of the ruthenium complexes (4 and 8) led to the decomposition of the complexes, whereas those of 5, 7, 9 and 10 underwent a trans-to-cis isomerization. In the electrochemical reactions the reductive waves about −1.50 V for 4 and −1.44 V for 8 are due to the reduction of azo group, [---N=N---]→[---N=N---]²⁻. The irreversible oxidative waves at ca. 0.87 V for the 4 and at ca. 0.85 V for 8 came from the oxidation of Ru(II)→Ru(III).     

Search of Optimum Conditions for Sublimation Growth of Thiophene/Phenylene Co-Oligomer Crystals

Optimum crystal growth conditions of thiophene/phenylene co-oligomers (TPCOs) have been studied by means of sublimation recrystallization method with changing both gas flow rate and gas pressure. The largest flaky crystal, more than 10 mm², was produced at the gas flow rate ∼50 ml/min and reduced pressure ∼0.05 Mpa, while no crystals were obtained at pressure less than 0.01 MPa. Excess supply of N₂ gas or reduced pressure for accelerating sublimation might obstruct the crystal growth of TPCOs.     

Removal of residual images in parallel phase-shifting digital holography

Parallel phase-shifting digital holography (PPSDH) is a technique of single-shot phase-shifting digital holography. We found that there are two problems with this technique. (1) Some extraneous noises caused by the intensity unevenness of the reference wave become slightly superimposed on the object image. (2) The conjugate image cannot be completely removed. This is because the object wave causes the phase-shift error by illuminating an image sensor with a large incident angle. To solve these problems, we propose an algorithm for removing residual 0th-order diffraction and conjugate images in PPSDH. In the proposed algorithm, we modified phase-shifting interferometry in order to work through the unevenness of the intensity distribution and applied the Fourier transform technique to PPSDH to remove the residual conjugate image. The effectiveness of the proposed algorithm was experimentally verified.     

Single-Crystal-to-Single-Crystal Installation of Ln4(OH)4 Cubanes in an Anionic Metallosupramolecular Framework

Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single-crystal-to-single-crystal (SCSC) transformation is presented. Soaking single crystals of K₆[Rh₄Zn₄O(l -cys)₁₂] (K₆[ 1 ]; l -H₂cys=l -cysteine) in a water/ethanol solution containing Ln(OAc)₃ (Ln³⁺=lanthanide ion) results in the exchange of K⁺ by Ln³⁺ with retention of the single crystallinity, producing Ln₂[ 1 ] ( 2_Ln ) and Ln_0.33[Ln₄(OH)₄(OAc)₃(H₂O)₇][ 1 ] ( 3_Ln ) for early and late lanthanides, respectively. While the Ln³⁺ ions in 2_Ln exist as disordered aqua species, those in 3_Ln form ordered hydroxide-bridged cubane clusters that connect [ 1 ]⁶⁻ anions in a 3D metal-organic framework through coordination bonds with carboxylate groups. This study shows the utility of an anionic metallosupramolecular framework with carboxylate groups for the creation of a series of metal cubanes that have great potential for various applications, such as magnetic materials and heterogeneous catalysts.     

Improvement in carrier mobility of poly(3,4‐ethylenedioxythiophene) nanowires synthesized in porous alumina templates

Polymeric nanowires of poly(3,4‐ethylenedioxythiophene) (PEDOT) are electrochemically synthesized using porous anodic alumina oxide (AAO) membranes as templates. Four‐point resistivity measurements on more than 100 PEDOT nanowires with different diameters (50–250 nm) reveal a statistically significant size‐dependent phenomenon in which the nanowires with a smaller diameter exhibit higher conductivity. Structural characterization with Raman spectroscopy and doping level estimation with energy‐dispersive X‐ray spectrometry and X‐ray photoelectron spectroscopy indicate that the observed conductivity enhancement can be attributed to improved carrier mobility in PEDOT nanowires having an elongated conjugation structure because of the effect of the AAO template. From the estimated doping levels (～5%) and conductivity data (～100 S/cm), it is found that the carrier mobility reach 2.0 cm²/V s for the nanowire with the smallest diameter, as compared with 4.0 × 10^?4 cm²/V s for a bulk PEDOT film. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Improvement in interactive remote in situ visualization using SIMD-aware function parser and asynchronous data I/O

Journal of Visualization - An in situ visualization system based on the particle-based volume rendering offers a highly scalable and flexible visual analytics environment based on multivariate...     

Effect of internal stress disturbance on the stress-induced transformation toughening of an alumina/zirconia dual-phase composite

The toughening and strengthening of a dual-phase composite, consisting of alpha-alumina (α-Al₂O₃) and tetragonal-zirconia (t-ZrO₂), were investigated. The toughness of the composite was evaluated through the precise measurement of work-of-fracture (WOF), which is a measure of total fracture resistance involving the rising R-curve effect. It was found that both the WOF and flexural strength of the composite were maximized at a t-ZrO₂ volume fraction f _Z of about 0.7. The thermal degradation of the mechanical properties was also observed. The effect of the internal stresses arising from the thermoelastic mismatch between α-Al₂O₃ and t-ZrO₂ on the critical stresses of the reversible phase transformation of t-ZrO₂ was numerically examined to describe the f _Z?- and temperature-dependencies of WOF quantitatively.     

A preparation of 3,3-difluoropyruvate from trifluoroacetic anhydride

Difluoropyruvate was prepared from trifluoroacetic anhydride via 3 steps (Friedel-Crafts type addition, reductive defluorination, and ozonolysis) in 30% yield.     

Dry Reforming of Dimethyl Ether with Carbon Dioxide over a Cu-Containing Hybrid Catalyst

Reforming of dimethyl ether with carbon dioxide into synthesis gas has been carried out over a mixed catalyst containing Cu-based methanol decomposition catalyst and alumina. The catalyst is found to show a high activity and selectivity. Catalyst stability and deactivation mechanism was also examined.