A new method was presented to estimate the strength distribution of hydrogen bonds in coal. The hydrogen bonds include the coal intramolecule hydrogen bonds and coal-water hydrogen bonds formed by hydroxyls in coal. The method analyzes the FTIR spectrum ranging from 2400 to 3700 cm -1 obtained using the in-situ diffuse reflectance IR Fourier transform (DRIFT) technique with neat, undiluted, coal samples. The FTIR spectra during the heat-up of eight coals (seven Argonne premium coals and an Australian brown coal), an ion-exchange resin, and a lignin were measured every 20 °C from room temperature to 300 °C. Each spectrum was divided into six hydrogen-bonded absorption bands by a curve-resolving method, then the amount of hydroxyls contributing to each hydrogen bond was estimated by Beer's law by using different absorptivity for each band. The strength of each hydrogen bond was estimated using a relation presented by Drago et al. that is known as one of the "linear enthalpy-spectroscopic shift relations". Using this analysis method, changes in hydrogen bond distributions (HBD) with increasing temperature were successfully estimated for all the samples examined. By utilizing the HBD the changes in enthalpies associated with the desorption of adsorbed water, the glass transition, and the decomposition of COOH groups were well estimated. Only FTIR spectra measurements were found to be enough to obtain such enthalpies. This greatly simplified the calculation procedure and increased the accuracy of the enthalpies. The validity of the proposed in situ FTIR measurement method and the analysis method for obtaining HBD was well clarified.
Perfluorophenyl-substituted compounds, 3-hydroxy-1,3-bis(pentafluorophenyl)-2- propen-1-one (H1) and 1,5-dihydroxy-1,5-bis(pentafluorophenyl)-1,4-pentadien-3-one (H22), were prepared in 56 and 30% yields, respectively, and only the enol forms were preferentially obtained among the keto-enol tautomerism. Molecular conformations and tautomerism of the fluorine-substituted compounds were certified based on X-ray crystallographic studies and density functional calculations. The solvent dependency of the absorption spectra was only observed for the fluorinated compounds. The compounds H1 and H22 quantitatively formed co-crystals with the corresponding non-perfluorinated compounds, dibenzoylmethane (H3) and 1,5-dihydroxy-1,5-diphenyl-1,4-pentadien-3-one (H24), respectively, through the arene–perfluoroarene interaction to give the 1:1 co-crystals H1•H3 and H22•H24, which were characterized by X-ray crystallographic and elemental analysis studies.
Expanded π-conjugated coordination complexes, [M(L2)2] (M = Cu2+, Pd2+, Pt2+; L2 = dinaphthoylmethanido−), were prepared and their unique electron contributions and electrophile/nucleophile characteristics were found due to the supramolecular associations.
The lower critical field of type-II organic layered superconductor l-(BETS)2GaCl4 has been estimated by magnetic measurements. The demagnetization factor of a needle-like sample shape has been taken into account for the measurements by applying the external field, parallel and perpendicular to the conducting plane. The lower critical field for the field parallel to the conducting plane is 5.5(2) G, in contrast with the previous studies. This allows us to discuss the anisotropy of lower critical field Hc1 in a quasi-two-dimensional organic layered superconductor l-(BETS)2GaCl4.
The lower critical field of type-II organic layered superconductor λ-(BETS)2GaCl4 has been estimated by magnetic measurement. In this study, the demagnetization factor of a needle-like sample shape has been taken into account for the measurements by applying external field, parallel and perpendicular to the conducting plane. The lower critical field for the field perpendicular to the conducting plane is 8(1) G, convincing the previous study. This estimation allows us to predict the ideal external field that should be applied for London penetration depth measurement by using muon-spin rotation (SR) spectroscopy.
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