Rectangular-shaped expanded phthalocyanines with two central metal atoms

Expanded phthalocyanine (Pc) congeners with two Mo or W central metal ions and four isoindole ring moieties have been synthesized using normal Pc formation conditions in the presence of urea. The products have been characterized by electrochemistry; mass spectrometry (MS); IR, electron paramagnetic resonance (EPR), NMR, electronic absorption, and magnetic circular dichroism (MCD) spectroscopies; and X-ray analysis. The X-ray structures have rectangular C(2v) symmetry and provide evidence that the central Mo atoms are linked by a single bond and coordinated by two isoindole nitrogen atoms and two nitrogen atoms from the amine moieties. The electronic absorption bands extend into the 1200-1500 nm region. This can be explained using Gouterman's four-orbital theory. The experimental NMR data and theoretical calculations provide evidence for a heteroaromatic 22-π-electron conjugation system for the ring-expanded Pc system, which satisfies Hückel's (4n + 2)π aromaticity.     

An Experimental Study of the Modulation of the Bubble Motion by Gas–Liquid-Phase Interaction in Oscillating-Grid Decaying Turbulence

The purpose of the present research is to understand dynamic bubble–liquid interaction in a bubbly flow based on the experimental results of the modulation of the bubble motion in oscillating-grid decaying turbulence. By comparing the experimental results obtained from stagnant water and those from oscillating-grid decaying turbulence, we discussed and described detailed process of the modulation of the bubble motion in a water vessel. We discussed the enhancement of the transition of the bubble motion from 2D to 3D by combining the liquid-phase motion obtained through particle imaging velocimetry/laser-induced fluorescence (PIV/LIF) measurement and the bubble wake motion captured through the LIF/HPTS (8-hydroxypyrene-1, 3, 6-trisulfonic acid) method, under both conditions (in the stagnant water and in the oscillating-grid decaying turbulence) in which the initial bubble formation and the bubble motion (gravity-center motion and surface oscillation) were considered to be the same. In addition, by using PIV/LIF measurement along with an infrared shadow technique, we simultaneously obtained the bubble motion (2D zigzagging motion in stagnant water, and 3D motion in the decaying turbulence) and the standard deviation of the liquid-phase motion (the bubble Reynolds number: 775; the turbulent Reynolds number: 62.2). Taking all of the results together, the modulation of the bubble motion in the decaying turbulence, and the dynamic interaction between the bubble and the liquid-phase motion were experimentally and carefully investigated. Consequently, the enhancement and the modulation of the bubble wake motion were considered to be triggered by the collapse of the symmetric property of the bubble–liquid (i.e. ambient liquid-phase turbulence) interaction.     

Speckle control using high-frequency signal superposition to semiconductor laser

Speckle contrast of images generated by a red semiconductor laser was measured precisely utilizing a state-of-the-art speckle measurement system with a cooled CCD camera with auto-light-power-level adjustments. By using high-frequency signal (～500 MHz) superposition to the single-mode semiconductor laser, the 3 dB spectrum of the laser beam was broadened from 0.1 to 2.3 nm. As a result, the speckle contrast value was drastically reduced from 0.9 to 0.2.     

RF spectral modulation caused by delayed interference and photodetection of optical noise

We demonstrate that an RF spectral fringe appears when a nonpolarized optical noise and its delayed replica are combined and photo-detected without any polarization control. A theoretical analysis explains the visibility of the fringe and its insensitivity to polarization.     

Polymorphism of Compound Existing as Both Racemic Compound Crystals and Mixed Crystals of Enantiomers

Abstract

By recrystallization of certain racemic compound (ST), racemic compound crystals, mixed crystals of two enantiomers, or a mixture of these two types of crystals were obtained, depending on the recrystallization conditions employed. Their crystal forms were determined by X-ray diffraction of the single crystals and powdered materials. The space group and lattice parameters of the mixed crystals were identical with those of the enantiomeric crystals. This polymorphism of ST crystals would be ascribed to the small difference in the thermodynamic stability between the enantiomeric and racemic crystals. The physicochemical properties of ST are described, too.     

Decay Pion Spectroscopy of Electro-Produced Hypernuclei

The investigation of light hypernuclei is quite important for understanding the basic YN interaction and the mechanism of hypernuclear structure. We started the commissioning of the decay pion spectroscopy of light hypernuclei at MAMI-C in 2011. In order to realize the K⁺ tagging efficiently, some detectors on KAOS spectrometer were upgraded or newly installed. The existing and well-studied spectrometers, SpekA, SpekC were used as pion spectrometers. The analysis is ongoing to estimate the detectors performance and develop the spectrometers for future experiments with higher beam intensity. The preliminary results of the particle identification are presented in this article.     

Metal (Co,Fe) tribenzotetraazachlorin–fullerene conjugates: Impact of direct π-bonding on the redox behaviour and oxygen reduction reaction

Novel hexabutylsulphonyltribenzotetraazachlorin–fullerene (C₆₀) complexes of iron (FeHBSTBTAC–C₆₀) and cobalt (CoHBSTBTAC–C₆₀) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoOBSPc). It is proved that electron-withdrawing substituents (–SO₂Bu and C₆₀) on phthalocyanine macrocycle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C₆₀ substituent suppressed ORR compared to the –SO₂Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of ～1 × 10⁸ cm³ mol^?1 s^?1 and a Tafel slope of ?171 mV dec^?1.     

Phthalocyanine–C60 Fused Conjugates Exhibiting Molecular Orbital Interactions Depending on the Solvent Polarity

New covalently C₆₀‐connected zinc phthalocyanine (ZnPc) derivatives have been synthesized by utilizing successive cycloaddition reactions of C₆₀ with a ZnPc derivative containing a pyridazine moiety employing Komatsu’s method in reaction of C₆₀ with phthalazine. The UV/Vis absorption spectrum of the fused conjugate ( 5 ) shows red shifts from the corresponding absorption of ZnPc derivative ( 8 ), indicating interactions between the ZnPc and C₆₀ moieties. The DFT calculations under non‐polar medium predict that the HOMO and LUMO of 5 localize on the ZnPc moiety, whereas LUMO+1 localizes on the C₆₀ moiety, which reasonably explain the magnetic circular dichroism (MCD) and absorption spectra in toluene. Electrochemical redox potentials of 5 in polar solvents indicate the first‐oxidation potential arises from the ZnPc moiety, whereas the first reduction potential is associated with the C₆₀ moiety, suggesting the LUMO localizes on the C₆₀ moiety in polar solvent. This reversal of the LUMO is supported by the ZnPc‐fluorescence quenching with a nearby C₆₀ moiety in benzonitrile, which leads to the charge‐separation via the excited singlet state of the ZnPc moiety. In toluene on the other hand, such a ZnPc‐fluorescence quenching owing to the photoinduced charge separation is not observed as predicted by the DFT‐calculated LUMO on the ZnPc moiety.     

The Calculated Ionization Potential and Electron Affinity of Cationic Cyanine Dyes

The ionization potential (IP) and electron affinity (EA) of the isolated single dye molecule and a hypothetical isolated J-aggregated dimer are calculated as an energy difference between separately minimized ground and ionized states. Three quantum methods are employed: density functional theory (DFT) Gaussian03 B3LYP/6-311G** (++G**); DFT using Dmol³; and a modification of CNDO/S, called CNDO/S-Δζ, which is developed for rapid calculation of the IP and EA. Results indicate that for the monomer, 1,1'-dimethyl-2,2'carbocyanine chloride, the vertical IP and EA are 6.2 ± 0.1 and 1.90 ± 0.05 eV, respectively. This is consistent with the threshold IP and EA predicted by the Yianoulis and Nelson "Statistical Model" of spectral sensitization. For the isolated J-aggregated dimer, whose configuration is consistent with being adsorbed on a dielectric substrate, the calculations predict a value of 5.2 ± 0.2 and 2.35 ± 0.05 eV for the IP and EA, respectively. Significant charge density is removed from the halide anion in the ionization process. The HOMO of the dye molecule is an MO associated with the halide anion. Calculation of the isolated entities is a necessary preliminary step in the study of the IP and EA of the adsorbed dye monomer and aggregate.