Quantification of ultrasonic intensity based on the decomposition reaction of porphyrin

A simple method is proposed for quantification of the effective ultrasonic intensity in the reaction vessel based on the decomposition reaction of 5,10,15,20-tetrakis(4-sulfotophenyl) porphyrin (H₂TPPS⁴⁻). The change of concentration of porphyrin in solution irradiated by the ultrasound wave depends on the irradiation time and the output power of ultrasound generator. The decomposition ratio of porphyrin is defined as the ratio of the concentration of porphyrin after ultrasonic irradiation to that before ultrasonic irradiation. A linear relationship between the decomposition ratio of porphyrin and the concentration Fe³⁺ in the Fricke solution under sonication was obtained. The decomposition ratio was related to the absorption dose in radiation chemistry.     

Proton nuclear magnetic resonance spectra of brain tumors

Proton nuclear magnetic resonance (NMR) spectra were successfully measured in human brain tumor tissues and experimental rat brain tumors. The investigation was performed on clinical materials which consisted of tissue from one normal brain and 36 brain tumors. Normal rat brain tissue and rat glioma implanted in the brain were also analysed. NMR measurements were carried out at the resonance frequency of 99.54 MHz. The proton NMR spectrum of the normal brain consisted of one broad component and eight superimposed sharp peaks. The sharp peaks obtained from the brain tumors varied from those of the normal brain. A decrease in the signal intensity from N-acetyl aspartate was the most common finding in all tumors. Spectral patterns were similar within the same histological types, but varied among the different types. Therefore, ¹H-NMR spectra might indicate the metabolism characteristic of each tumor type which would be invaluable for clinical differential dagnosis of brain tumors.     

Configurational stabilization of mixed-valence states in the star-burst tetranuclear ruthenium complex bridged with acetylene links

A new tetranuclear ruthenium complex in which a metal was bridged radially to three identical metals with acetylene links showed a mixed-valence state in cyclic voltammograms. The peak potential difference for the mixed-valence state was twice the potential difference for a mixed-valence state of the corresponding binuclear complex. This fact suggests stabilization of the mixed-valence state twice by configurational modification of redox centers. However, this is inconsistent with the prediction from the additive pair model of the redox interaction. A quantum chemical model of the redox interaction was presented, in which the potential difference was expressed by the overlap integral S and the nearest neighbor interaction energy between the reduced center and the oxidized one. Application of the theory gave a negative value of S, which demonstrated reasonably the stabilization of the mixed-valence state from a quantum chemical viewpoint.     

Small-angle X-ray scattering from a dual-component organogel to exhibit a charge transfer interaction

The structure of a dual-component organogel consisting of methyl 4,6-O-(p-aminobenzylidene)-alpha-D-glucopyranoside and methyl 4,6-O-(p-nitrobenzylidene)-alpha-D-glucopyranoside in diphenyl ether was investigated with small-angle X-ray scattering (SAXS). The individual components gelatinized the solvent to yield a colorless gel and the gel fiber consisted of the crystal, providing the crystalline peaks at the same diffraction angles as those of the solid samples. When the components were mixed in equimolar ratio and dissolved in diphenyl ether, a yellow gel was formed and the crystalline peaks disappeared. For all compositions, the SAXS profiles were well fitted by a cylinder model. The cross-sectional radius of gyration, r(c), was determined from the cross-sectional Guinier plot (qI vs q(2), where I and q are the scattering intensity and the magnitude of the scattering vector). The value of r(c) reached a minimum of 3.0 nm at the equimolar composition. By correcting the data for the thermal scattering background, we obtained the entire SAXS profile for the equimolar dual-component gel. From this profile, the radial electron density distribution was determined and the radius of the cylinder was estimated to be 2.6 nm. The electron density distribution thus obtained revealed that four gelator molecules are packed in the sectional direction. This model was consistent with the size of the gelator molecules.     

Stoichiometry and conformation of the azacrown moiety in sodium complexes of azacrown ethers. A Raman/IR spectroscopic study. Part I: Complexes of 4,13-Diaza-18-crown-6

Three sodium complexes (bromide, iodide and thiocyanate) of 4,13-diaza-18-crown-6 were studied using Raman and IR spectroscopy and normal coordinate calculations to probe the stoichiometry of the complexes and the variation in the conformation of azacrown moiety on complex formation. complex formation is accompanied by characteristic shifts of the bands, especially of those in the 800–900 cm^–1 region. Complexes of both 11 and 21 stoichiometry were observed. Normal coordinate calculations showed the reduction of symmetry of azacrown moiety toC _i , in contrast to theC _2h symmetry known for the parent azacrown and potassium thiocyanate complex.     

Efficient photocleavage of DNA utilising water-soluble lipid membrane-incorporated [60]fullerenes prepared using a [60]fullerene exchange method

Various types of lipid membrane-incorporated C60 with high C60 concentrations can be prepared easily in several hours using the C60 exchange method and the photocleaving activity of cationic lipid membrane-incorporated C60 was appreciably higher than that of the C60.gamma-CDx complex.     

Photodissociation spectrum of cyanobenzene dimer cation. Absence of intermolecular resonance interaction

Electronic spectra of a homo-molecular dimer cation, (C₆H₅CN)₂ ⁺, are measured by photodissociation spectroscopy in the gas phase. Broad features appeared in the 450–650 nm region are characteristic of π₃ → π_CN transitions of the C₆H₅CN⁺ chromophore. No intense band is observed in the 650–1300 nm region, where other aromatic dimer cations usually show charge resonance bands. Two component molecules of (C₆H₅CN)₂ ⁺ cannot take a parallel sandwich configuration suitable for the resonance interaction, because of geometrical constraints due to other stronger interactions.     

Dissolved states of ionene polymers in water-acetone and their relation to the ionic partial molar adiabatic compressibility and volume

Solution properties of water-soluble synthetic polymer, 3,3-ionene and 6,6-ionene chloride and bromide disolved in water-acetone mixtures up to acetone content 50 wt% were investigated. Their partial molar volumes V ₂ ^o and partial molar adiabatic compressibilities K _s ^o were determined. Ionic additivity of V ₂ ^o with respect to the cation of backbone polymer chain and the counter-anion was confirmed quantitatively. The ionic additivity of V ₂ ^o is discussed along with the K _s ^o in their relation to the counterion binding of ionene polymers. Effects of ionic sites on the ionene are strong but they don't break the solvation layer.