Chemiluminescence of Cypridina Luciferin Analogs. Part 3. MCLA Chemiluminescence with Singlet Oxygen Generated by the Retro-Diels-Alder Reaction of a Naphthalene Endoperoxide

The chemiluminescence of the Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroirnidazo[1,2-a]pyrazin-3-one (MCLA), with O₂ (¹Δ_g) generated by the retro-Diels-Alder reaction of 3-(4′-methyI-l'-naphthyl)-propionic acid endoperoxide was studied in an aqueous solution with pH 7.12 at 37°C. The retro-Diels-Alder reaction occurs with a first-order rate constant of (4.16 ± 0.13) × 10^?4/s to quantitatively yield O₂ (¹Δ_g) and 3-(4′-methyl-l'-naphthyl (-propionic acid. MCLA consumed equimolar amounts of O₂ (¹Δ_g) with a second-order rate constant (6.96 ± 0.27) × 10⁸/M/s to emit light in an aqueous solution with pH 7.12 at 37°C. The chemiluminescence spectrum was identified as the fluorescence spectrum of 2-acetylamino-5-(p-methoxyphenyl)pyrazine (OMCLA), a major chemiluminescence reaction. Chemiluminescence spectra and product yields for MCLA reactions with O₂¹Δ_g, with O₂ (³Σ^?_g) and with superoxide anion radicals are identical, suggesting that all of these reactions occur via a common MCLA-2-hydrope-roxide intermediate formed by a combination of MCLA radicals and superoxide anion radicals. We have established practical use of NEPO as an O₂ (¹Δ_g) source and MCLA as a biological probe for detecting O₂ (¹Δ_g).     

Phase transition and conductive acceleration of phosphonium-cation-based room-temperature ionic liquid

An unusual ionic conduction phenomenon related to the phase transition of a novel phosphonium-cation-based room-temperature ionic liquid (RTIL) is reported; we found that in the phase change upon cooling, a clear increase in ionic conductivity was seen as the temperature was lowered, which differs from widely known conventional RTILs; clearly, our finding of abnormality of the correlation between temperature change and ionic conduction is the first observation in the electrolyte field.     

Potential energy landscape of bis(fluorosulfonyl)amide

The conformational landscape of the bis(fluorosulfonyl)amide, [FSI]-, anion was analyzed using data obtained from Raman spectroscopy, molecular dynamics (MD), and ab initio studies. The plotting of three-dimensional potential energy surfaces and the corresponding MD simulation conformer-population histograms show the existence of two stable isomers, C2 (trans) and C1 (cis) conformers, and confirm the nature of the anion as a flexible molecule capable of interconversion between conformers in the liquid state. In ionic liquids, the two [FSI]- conformers coexist in equilibrium, a result confirmed by the Raman data. The implications of the conformational behavior of the ion [FSI]- are discussed in terms of the solvation properties of the corresponding ionic liquids.     

Monopoles in gluodynamics and blocking from continuum to lattice

We review the method of blocking of topological defects from continuum to lattice as a nonperturbative tool to construct effective actions for these defects. The actions are formulated in the continuum limit, while the couplings of these actions can be derived from simple observables calculated numerically on lattices with a finite lattice spacing. We demonstrate the success of the method in deriving the effective actions for Abelian monopoles in the pure SU(2) gauge models in an Abelian gauge. In particular, we discuss the gluodynamics in three and four spacetime dimensions at zero and nonzero temperatures. Besides the action, the quantities of our interest are the monopole density, the magnetic Debye mass, and the monopole condensate.     

Release control of fragrances by complexation with β-cyclodextrin and its derivatives

The release control of fragrances, benzyl acetate (BA), citral (CR), linalool (LL), citronellol (CL) and linalyl acetate (LA), was conducted using β-cyclodextrin (β-CyD), 2-hydroxypropyl-β-CyD (HP-β-CyD) and 2,6-di-O-methyl β-CyD (DM-β-CyD). The release rate of the fragrances from 30% ethanol/water solution was significantly suppressed by the complexation with these CyDs, and the suppressing effect increased in the order of β-CyD?<?HP-β-CyD?<?DM-β-CyD. The concentration-dependent change of the release rate was quantitatively analyzed to obtain the stability constant (Kc) of the fragrance-CyD complexes. These Kc values were in good agreement with those determined by the solubility method. The results suggest that the release of fragrances can be prolonged by the complexation with β-CyDs and their effects can be controlled by choosing appropriate CyD derivatives with higher Kc values and by setting proper concentrations of the host molecules.     

Sulfate adsorption and surface precipitation on a volcanic ash soil (allophanic andisol)

Sulfate strongly adsorbs on metal oxides and soils with variable charges. However, its surface precipitation has not been clearly evaluated and its adsorption mechanism has been in dispute. In the present study, an allophanic andisol, a typical volcanic ash soil having both negative and positive variable charges, was used to identify the adsorption mechanism of sulfate. Sulfate adsorption isotherms were obtained by a batch method at pH values of 4, 5, 6, and 7 in a wide range of concentrations in an Na-H-SO(4)-OH system. Theoretical isotherms were applied to the measured values for the evaluation. The surface precipitation was detected by the measured adsorption isotherms, and the BET isotherm confirmed the presence of multilayer adsorption. Stronger and weaker adsorption sites were suggested by using the Langmuir isotherm for the monolayer adsorption. The adsorption energies obtained from the Langmuir equation and recent spectroscopic analysis suggested that the stronger adsorption corresponded to an inner-sphere surface complex and that the weaker adsorption corresponded to outer-sphere surface complexation. The BET and Langmuir equations showed three types of adsorption mechanisms for the sulfate adsorption on the soil.     

Synthesis, crystal structure and magnetic properties of o-carboranyl nitronyl nitroxide biradical: a prototype of a three-dimensional analogue of o-benzoquinodimethane

We have designed and synthesised a new carborane derivative containing two nitronyl nitroxides. This molecule can be considered as a prototype of a three-dimensional analogue of o-benzoquinodimethane. The magnetic susceptibility of a crystalline sample revealed that this biradical possesses a weak antiferromagnetic interaction (theta = -1.05(4) K) and an ESR study in frozen matrix in the 5.4-104 K range gave an intramolecular antiferromagnetic interaction of -27(2) K. The synthesis, physical properties and DFT calculation result are also reported.     

High-performance dispersion-compensating fibers

An optimum fiber structure for a practical dispersion-compensating fiber (DCF) has been explored theoretically and experimentally, taking dispersion, attenuation, bending loss characteristics, polarization mode dispersion, and nonlinear effects into account. A high figure of merit (FOM) of 280 ps/nm/dB has been successfully achieved with a simple matched cladding design. Furthermore, it was confirmed that the optimized structure with enhanced FOM also benefits self-phase modulation (SPM) suppression.     

Individual solvation numbers around the nickel(II) ion in an N,N-dimethylformamide and N,N-dimethylacetamide mixture determined by Raman spectrophotometry.

Individual solvation numbers around the nickel(II) ion have been determined by titration Raman spectroscopy in N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) mixtures at 298 K. The in-plane bending vibration (delta(O=C-N)) of DMF and the stretching vibration (v(N-CH3)) of DMA were used in the present analysis. These Raman bands of solvent molecules shift to higher frequencies upon coordination of the solvent molecules to the metal ion. By analyzing the band intensities of free and bound solvent molecules with increasing concentration of the metal ion, the solvation number around the metal ion can be evaluated. Because the individual solvation numbers of DMF and DMA around the nickel(II) ion in the mixture are determined independently, the total solvation number is obtained as their sum. It was found that the total solvation number remains 6 in all mixtures of the DMA mole fraction x = 0 - 1. Although DMF and DMA have practically the same electron-pair donor capacities, the nickel(II) ion prefers DMF to DMA, and an equal solvation number is attained at x = 0.75. This is ascribed to the solvation steric effect of DMA.