Multivariate analysis of NMR spectra

In this paper, we report multivariate analyses, such as principal component analysis (PCA) and partial least-squares (PLS) regression, of NMR spectra of poly(N-isopropylacrylamide)s [poly(NIPAAm)s]. PCA successfully interpreted the assignments of NMR spectra of poly(NIPAAm)s in terms of stereostructures for the methine carbons at triad levels and for the methylene protons at tetrad levels. Furthermore, triad tacticity was successfully predicted by PLS regression of 1H NMR spectra of the methine and methylene groups, although the low resolution of the signals of the methine protons confines determination of tacticities by conventional methods to the diad levels. Consequently, it is assumed that chemometric approaches are useful for assigning NMR spectra in terms of stereostructures and for predicting tacticity distributions

Thermodynamic formulation on Ostwald’s law of dilution and the acid dissociation constant Ka

The thermodynamic background of Ostwald’s law of dilution, which gives the acid dissociation constant (Ka), is revealed. The feature of Ka as a constant is understandable in the same context as the equilibrium shift of the gas reaction by pressure. The Ka quantity becomes constant under dilution as far as the solution is an ideal mixture. Because the character depends only on the number of solute particles present, the constant Ka is one of the colligative properties of a dilute solution

Phase coexistence observed in phosphonium-based and imidazolium-based ionic liquids : Influence of thermal history and water content

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Effects of dipole interaction and solvation on the C=O stretching band of N,N-dimethylacetamide in nonpolar solutions: Infrared, isotropic and anisotropic Raman measurements

The concentration dependence of the C=O stretching (nu(C=O)) band of N,N-dimethylacetamide (NdMA) in cyclohexane, n-hexane, and CCl4 has been investigated by infrared (IR) and polarized Raman spectroscopy. For the neat liquid of NdMA, the noncoincidence of the aniso- and isotropic Raman wavenumbers is evident. In the 0.47 M cyclohexane solution of NdMA, the noncoincidence effect almost disappears and the nu(C=O) envelopes in both the Raman and IR spectra are asymmetric to the low-wavenumber side. When the concentration of NdMA decreases from 0.33 to 0.023 M. the peak of these bands slightly shifts to a higher wavenumber and the band shape becomes symmetric. The shape of the nu(C=O) envelope does not show any significant change below 0.023 M. These results Suggest that the asymmetric shape of the nu(C=O) band observed for the 0.33 M cyclohexane solution is associated with the intermolecular interaction among NdMA molecules, which vanishes at around 0.02 M. Spectral changes for the CCl4 solution of NdMA show a similar tendency. However, the shape and peak wavenumber of the nu(C=O) band observed in a highly diluted CCl4 solution (<= 0.023 M) indicate that the solvation effect of CCl4 is more complicated than those of cyclohexane and n-hexane. The analyses of the nu(C=O) band, which is sensitive to the intermolecular interaction between Solutes and between Solute and solvent for NdMA dissolved in nonpolar solvents. Would serve to clarify the electronic property of the molecule in a solution

Matrix-isolation infrared spectra of 2-, 3- and 4-pyridinecarboxaldehyde before and after UV irradiation

Three structural isomers of pyridinecarboxaldehydes (2-, 3- and 4-pyridinecarboxaldehyde) have been investigated in detail with matrix-isolation infrared spectroscopy in the 3000.600 cm.1 region, combined with the UV photoexcitation and the density-functional theory (DFT) calculations. Two rotamers (anti and syn) were identified for 2- and 3-pyridinecarboxaldehyde (2- and 3-PCA, respectively) upon the photoexcitation and most of the observed bands of each rotamer have been assigned. Both of the infrared data and the results of the DFT calculations strongly support that the syn rotamer exists as a less stable isomer for 2- and 3-PCA. It is shown that the formation of the intramolecular C.H...N hydrogen bond for the anti rotamer of 2-PCA results in the shortening of the aldehyde C.H bond length, while for the syn rotamer the C=O bond length is shortened due to the repulsion between the N and aldehyde O atoms. With 2-PCA, the photoinduced rotational isomerism and photolysis were observed simultaneously upon the UV irradiation. Keywords: 2-, 3- and 4-Pyridinecarboxaldehyde, Rotamer, Matrix-isolation infrared spectroscopy, UV photoexcitation, Energetics, Density-functional theory calculatio

環境刺激(放射線や活性酸素)による直接および間接的DNA損傷生成のメカニズム

研究期間:平成16-18年度 ; 研究種目:基盤研究A ; 課題番号:16205003原著には既発表論文の別刷を含む

Controlling the kinetics of interaction between microtubules and kinesins over a wide temperature range using the deep-sea osmolyte trimethylamine N-oxide

Trimethylamine N-oxide is found to be effective in regulating the interaction between microtubules and kinesins over a wide temperature range. The lifetime of the motility of microtubules on kinesins at high temperatures is prolonged using trimethylamine N-oxide. The activation energy of microtubule motility is increased by trimethylamine N-oxide. Prolonged operation at high temperatures decreased the activation energy of MT motility despite the increase in concentration of trimethylamine N-oxide