Doppler-free two-photon excitation spectroscopy and the Zeeman effects of the S1 1B1u(v21=1) <-- S0 1Ag(v=0) band of naphthalene-d8

Doppler-free two-photon excitation spectrum and the Zeeman effect of the S1 1B1u(v21=1) <-- S0 1Ag(v=0) transition of naphthalene-d8 have been measured. 908 lines of Q(Ka)Q(J)KaKc transition of J=0-41, Ka=0-20 were assigned, and the molecular constants of the S1 1B1u(v21=1) state were determined. Perturbations were observed, and those were identified as originating from Coriolis interaction. No perturbation originating from an interaction with triplet state was observed. The Zeeman splittings from lines of a given J were observed to increase with Kc, and those of the Kc=J levels increased linearly with J. The Zeeman effects are shown to be originating from the magnetic moment of the S1 1B1u state, which is along the c axis and is induced by mixing of the S2 1B3u state to the S1 1B1u state by J-L coupling. Rotationally resolved levels were found not to be mixed with a triplet state from the Zeeman spectra. Accordingly, it is concluded that nonradiative decay of an isolated naphthalene excited to low rovibronic levels in the S1 1B1u state does not occur through the intersystem mixing. This is at variance with generally accepted understanding of the pathways of the nonradiative decay.     

A layered tungstic acid H2W2O7 x nH2O with a double-octahedral sheet structure: conversion process from an aurivillius phase Bi2W2O9 and structural characterization

The conversion process of an Aurivillius phase, Bi(2)W(2)O(9), into a layered tungstic acid by hydrochloric acid treatment has been investigated, and resultant H(2)W(2)O(7) x nH(2)O has been fully characterized. The c parameter of Bi(2)W(2)O(9) [2.37063(5) nm] decreases to 2.21(1) nm in an acid-treated product dried at ambient temperature. The a and b parameters of Bi(2)W(2)O(9) [a = 0.54377(1) nm and b = 0.54166(1) nm] also decrease slightly to a = 0.524(1) nm and b = 0.513(1) nm in the acid-treated product dried at ambient temperature, indicating structural changes in the ReO(3)-like slabs in Bi(2)W(2)O(9) upon acid treatment. Drying at 120 degrees C leads to a further decrease in the c parameter [1.86(1) nm] with no notable change in the a and b parameters [a = 0.5249(2) nm and b = 0.513(2) nm]. The formation of an expandable layered structure is demonstrated by the successful intercalation of n-octylamine [interlayer distance 2.597(9) nm] and n-dodecylamine [interlayer distance 3.56(2) nm]. The compositions of the acid-treated products are determined to be H(2)W(2)O(7) x nH(2)O typically with n = 0.58 for the air-dried product and n = 0 for the product dried at 120 degrees C. As a consequence, the composition of the layer is H(2)W(2)O(7), and the decrease in the c parameter upon drying is ascribable to the loss of interlayer water. Scanning electron microscopy reveals no morphological change during acid treatment, which strongly suggests a selective leaching of the bismuth oxide sheets as a reaction mechanism. High-resolution transmission electron microscopy (HREM) observation of the acid-treated product shows consistency with a structural model for H(2)W(2)O(7), derived from Bi(2)W(2)O(9) through removal of the bismuth oxide sheets and contraction along the c axis. HREM observation also reveals that the WO(6) octahedra arrangement changes slightly with acid treatment. A one-dimensional electron density map projected on the c axis for the product dried at 120 degrees C, H(2)W(2)O(7), shows good consistency with that calculated for the structural model.     

Time-domain theoretical analysis of the noncoincidence effect, diagonal frequency shift, and the extent of delocalization of the C=O stretching mode of acetone/dimethyl sulfoxide binary liquid mixtures

A time-domain method for simulating vibrational band profiles that simultaneously takes into account both the diagonal and off-diagonal effects is developed and applied to the C=O stretching bands of neat liquid acetone and the acetone/dimethyl sulfoxide (DMSO) binary liquid mixtures. By using this method, it is possible to examine the influence of liquid dynamics on the noncoincidence effect (NCE), which arises from the off-diagonal vibrational interactions, as well as the frequency shifts and band broadening, which are related to both the diagonal and off-diagonal effects. It is shown that the simulations for the C=O stretching bands of acetone in acetone/DMSO binary liquid mixtures on the basis of this method can reproduce the experimentally observed concave curvature of the concentration dependence of the NCE and the unusually large frequency shift of the anisotropic Raman band. The widths of the infrared, isotropic Raman, and anisotropic Raman bands calculated for neat liquid acetone are also in good agreement with those observed. Based on these calculations, the extent of delocalization of the C=O stretching vibrational motions is examined by referring to two quantitative measures of this property, one calculated in the frequency domain and the other in the time domain. It is shown that the extent of delocalization gets larger as the mole fraction of acetone increases, the C=O stretching vibrations being delocalized over a few tens of molecules in neat liquid acetone. It is also shown that the extent of delocalization is related to the quantity called NCE detectability, which is the ratio between the magnitude of NCE and the bandwidth. It is therefore suggested that the extent of delocalization of vibrational motions may be estimated from observable features of Raman band profiles.     

Identification of novel substituted fused aromatic compounds, meshimakobnol A and B, from natural Phellinus linteus fruit body

Novel 1H,6H-pyranyl[4,3-c][2]benzopyrane-1,6-diones, meshimakobnol A and B, were isolated from natural Phellinus linteus fruit body. The structure elucidation of these fused aromatic compounds was achieved by a spectroscopic method including the measurement of FG-HMBC with various delay times.     

Aerobic catechol oxidation catalyzed by a bis(mu-oxo)dimanganese(III,III) complex via a manganese(II)-semiquinonate complex

A 3,5-di-tert-butyl-1,2-semiquinonato (DTBSQ) adduct of Mn(II) was prepared by a reaction between Mn(II)(TPA)Cl(2) (TPA = tris(pyridin-2-ylmethyl)amine) and DTBSQ anion and was isolated as a tetraphenylborate salt. The X-ray crystal structure revealed that the complex is formulated as a manganese(II)-semiquinonate complex [Mn(II)(TPA)(DTBSQ)](+) (1). The electronic spectra in solution also indicated the semiquinonate coordination to Mn. The exposure of 1 in acetonitrile to dioxygen afforded 3,5-di-tert-butyl-1,2-benzoquione and a bis(mu-oxo)dimanganese(III,III) complex [Mn(III)(2)(mu-oxo)(2)(TPA)(2)](2+) (2). The reaction of 2 with 3,5-di-tert-butylcatechol (DTBCH(2)) quantitatively afforded two equivalents of 1 under anaerobic conditions. The highly efficient catalytic oxidation of DTBCH(2) with dioxygen was achieved by combining the above two reactions, that is, by constructing a catalytic cycle involving both manganese complexes 1 and 2. It was revealed that dioxygen is reduced to water but not to hydrogen peroxide in the catalytic cycle.     

Data processing method for the determination of accurate molecular weight distribution of polymers by SEC/MALDI-MS.

A novel data processing method for a hyphenated technique, size exclusion chromatography/matrix-assisted laser desorption/ionization-mass spectrometry (SEC/MALDI-MS), has been proposed to determine accurate molecular weight distributions on the basis of the individual oligomer species of a polymer. This method is based on the concept that the individual peak intensities of MALDI mass spectrum observed for every SEC fraction with narrow molecular weight distribution could be adjusted to the quantified values to reveal the accurate molecular weight distribution using the signal intensity of the corresponding fraction on the SEC chromatogram observed with a refractive index detector. At first, the theory of the proposed date processing is described in detail. Then, experimental verification of the method is described. This was performed through the characterization of mixtures of three kinds of monodispersed polystyrene reference materials (weight average molecular weight = ca. 6000, 10000, and 18000) as model samples. An accurate trimodal molecular weight distribution for the individual oligomer species of the sample was obtained without any influence of the chromatographic band broadening observed in the original SEC chromatogram. Moreover, the method for depicting the elution profiles of individual oligomer species during SEC separation was also obtained as a "mass chromatogram" using the data processing procedure.     

Reactivity of 2-Methylene-1,3-dicarbonyl Compounds. Stereoselective and Asymmetric Diels-Alder Reactions

The Diels-Alder reaction of 1,1-dicarbonylethenes 1 with dienes was investigated. The adduct of the reaction of 1, whose two carbonyl groups were different, with cyclopentadiene showed moderate stereoselectivity and this was explained by FMO theory. However, in the Lewis acid-catalyzed addition, the reaction proceeded with high stereoselectivity to give the exo adduct 3x. This might be due to steric hindrance because the benzene ring cannot orient in the plane of the conjugated system in the metal-chelated enedione 6. Applying this principle to (1'R,2'S,5'R)-5-methyl-2-(1-methyl-1-phenylethyl)cyclohexyl 2-benzoylacrylate (1d), we achieved a diastereomeric Diels-Alder reaction to afford 3x-R, whose structure was confirmed by the X-ray crystal analysis.     

New Combinatorial Bounds for Authentication Codes and Key Predistribution Schemes

This paper provides new combinatorial bounds and characterizations of authentication codes (A-codes) and key predistribution schemes (KPS). We first prove a new lower bound on the number of keys in an A-code without secrecy, which can be thought of as a generalization of the classical Rao bound for orthogonal arrays. We also prove a new lower bound on the number of keys in a general A-code, which is based on the Petrenjuk, Ray-Chaudhuri and Wilson bound for t-designs. We also present new lower bounds on the size of keys and the amount of users' secret information in KPS, the latter of which is accomplished by showing that a certain A-code is hiding inside any KPS.     

Strong continuity implies uniform sequential continuity

Uniform sequential continuity, a property classically equivalent to sequential continuity on compact sets, is shown, constructively, to be a consequence of strong continuity on a metric space. It is then shown that in the case of a separable metric space, uniform sequential continuity implies strong continuity if and only if one adopts a certain boundedness principle that, although valid in the classical, recursive and intuitionistic setting, is independent of Heyting arithmetic.