Method to determine quadruple points of a two-component system containing a simple hydrate phase and behavior of the system near these points

A method for determining quadruple points of a two-component system containing a simple hydrate phase is proposed. This method utilizes the quasi-static change of the system along three-phase equilibrium lines and was proved to be able to determine the quadruple points as accurately as the conventional method. By using this method, even though some preparation is necessary, a quadruple point can be determined in just a single experimental run. The behavior of the system near the quadruple points was also examined experimentally, for both the quasi-static and the irreversible change cases. At the quadruple points, the temperature and pressure of the system were kept constant for a while, as at the triple point of water. In both cases, the representative point of the state of the system passed through the quadruple point on a p–T diagram.     

Cyclic esters of aliphatic diacids with pyrocatechol and hydroquinone

Cyclic esters of adipic acid, suberic acid and sebacic acid were prepared by reaction of the acid dichlorides and pyrocatechol or hydroquinone in benzene under high dilution conditions. While only the cyclic dimers could be obtained from hydroquinone, pyrocatechol formed cyclic monomers as well as cyclic dimers (and also a cyclic dimer with succinic acid). The structure of all compounds was confirmed by¹H-NMR- and mass spectra. The crystal structures of the pyrocatechol esters were determined by single crystal X-ray analysis.

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Cyclische Ester aliphatischer Dicarbonsäuren mit Brenzcatechin und Hydrochinon

Zusammenfassung Es wurden cyclische Ester von Adipinsäure, Korksäure und Sebacinsäure durch Reaktion der entsprechenden Säure-Dichloride mit Brenzcatechin oder Hydrochinon bei hoher Verdünnung hergestellt. Während mit Hydrochinon lediglich die cyclischen Dimeren erhalten werden konnten, wurden mit Brenzcatechin sowohl cyclische Monomere als auch cyclische Dimere erhalten (ebenfalls das cyclische Dimer mit Bernsteinsäure). Die Strukturen wurden mittels¹H-NMR und Massenspektren gesichert. Die Kristallstrukturen der Brenzcatechin-Ester wurden mittels Röntgenstrukturanalyse bestimmt.

     

Efficient photochemical oxetane formation from 1-methyl-2,4,5-triphenylimidazole and benzophenones

In contrast to simple imidazoles, 1-methy1–2,4,5-triphenylimidazole ($\text{1}$) produced stable oxetane photoadducts $\text{3b}$ - $\text{e}$ with good efficiency upon irradiation in the presence of benzophenone derivatives $\text{2b}$ - $\text{e}$ in acetonitrile solution. Irradiation in the solid-phase was also studied. The oxetanes $\text{3b}$ - $\text{e}$ readily underwent cycloreversion by acid catalysis or by heating.     

Transformation of Thia[7]helicene to Aza[7]helicenes and [7]Helicene-like Compounds via Aromatic Metamorphosis

[n]Helicenes with helically twisted structures have attracted increasing interest owing to their unique properties. Therefore, it has been an important issue to develop facile synthetic methodologies which allow access to a variety of [n]helicenes. Here we report the synthesis of [7]helicenes and [7]helicene-like compounds from the thia[7]helicene as a common starting material. Desulfurative dilithiation of the thia[7]helicene and the subsequent reaction with silicon and phosphorus electrophiles afforded the silole- and phosphole-fused [7]helicene-like compounds, respectively. The cyclopentadiene-fused [7]helicene-like compound and the pyrrole-fused aza[7]helicenes were also successfully synthesized via twofold S_NAr reactions of the thia[7]helicene S,S-dioxide with the carbon and nitrogen nucleophiles, respectively. The thia[7]helicene S,S-dioxide showed a slightly red-shifted absorption spectrum than the parent thia[7]helicene, which was well demonstrated by the theoretical calculations. The substituents on the silicon atom of silole-fused [7]helicene-like compounds have little impact on the longest absorption maximum. Such little effect of the substituents on absorption properties was also observed for cyclopentadiene-fused [7]helicene-like compounds and aza[7]helicenes and was well demonstrated by the theoretical calculations. The thia[7]helicene S,S-dioxide and the silole-fused [7]helicene-like compound exhibited bright blue emission, and the cyclopentadiene-fused [7]helicene-like compound and the aza[7]helicenes showed strong violet emission. Each single enantiomer of the aza[7]helicenes showed circularly-polarized luminescence with the dissymmetry factors of 4.2~4.4 × 10⁻³.     

Highly sensitive tITP‐CZE determination of l‐histidine and creatinine in human blood plasma using field‐amplified sample injection with mobility‐boost effect

2D computer simulation revealed that amino acids and weak electrolytes were cationized because of the migration of counter‐ion from a BGE zone to a sample zone, which encouraged electrokinetic injection (EKI) of these analytes (by the mobility‐boost (MB) effect). To investigate the effects of kinds and concentrations of counter‐ions on the MB effect and the analyte amount injected into the capillary, experiments, and 1D computer simulations were performed. When acetate was used as the counter‐ion, the LODs (S/N = 3) of l ‐histidine and creatinine, respectively, reached 0.10 and 0.25 nM because of the concentration effect by transient ITP (tITP). The concentrations of l ‐histidine and creatinine in human blood plasma obtained using the proposed method were agreed with those obtained using the conventional methods. The proposed method can be applied to the analysis of amino acids and weak bases that have similar pI and pK_a to l ‐histidine and creatinine.     

The Effects of Ultraviolet Eye Irradiation on Dextran Sodium Sulfate‐Induced Ulcerative Colitis in Mice

Ultraviolet (UV) eye irradiation denatures the cells of the intestine. This study examined the action of UVA and UVB on dextran sodium sulfate (DSS)‐induced ulcerative colitis. We produced a mouse model of ulcerative colitis by administering DSS for 5 days and irradiated the eye with UVB or UVA for each day of the DSS treatment period. DSS‐induced ulcerative colitis was deteriorated by the UVB eye irradiation. Conversely, the symptoms improved with UVA eye irradiation. The levels of adrenocorticotropic hormone (ACTH), corticotropin‐releasing hormone (CRH), urocortin 2, interleukin (IL)‐18, IL‐6 and histamine in the blood increased after the UVB eye irradiation of DSS‐treated mice (UVB/DSS‐treated mice). In contrast, the β‐endorphin level in the blood of the UVA/DSS‐treated mice increased and the levels of urocortin 2, tumor necrosis factor (TNF)‐α and histamine decreased. Furthermore, in the colon, the expression of melanocortin‐2 receptors (MC2R) increased in the UVB/DSS‐treated mice, while the expression of μ‐opioid receptors increased in the UVA/DSS‐treated mice. When an ACTH inhibitor was administered, UVB eye irradiation caused the deterioration of DSS‐treated ulcerative colitis, while the effect of UV eye irradiation disappeared with a μ‐opioid receptor antagonist. These results suggested that UV eye irradiation plays an important role in DSS‐induced ulcerative colitis.     

Absolute configuration and conformation analysis of 1-phenylethanol by matrix-isolation infrared and vibrational circular dichroism spectroscopy combined with density functional theory calculation

The absolute configuration and conformation of 1-phenylethanol (1-PhEtOH) have been determined by matrix-isolation infrared (IR) and vibrational circular dichroism (VCD) spectroscopy combined with quantum chemical calculations. Quantum chemical calculations have identified that there are three conformers, namely, I, II, and III, in which characteristic intramolecular interactions are found. The IR spectrum-conformation correlation for 1-PhEtOH has been developed by the Ar matrix-isolation IR measurement and used for the assignments of the observed IR bands. In a dilute CCl(4) solution, 1-PhEtOH exists predominantly as conformer I along with a trace amount of conformer II. By considering conformations and intermolecular hydrogen-bonding in the spectral simulation for (S)-1-PhEtOH, we have successfully reproduced the VCD spectrum of (-)-1-PhEtOH observed in a dilute CS(2) solution. Thus, (-)-1-PhEtOH is of S-configuration and conformer I in the dilute solution. The same method has been applied to analyze the VCD spectra measured in the liquid state of (-)-1-PhEtOH. The absolute configuration of 1-PhEtOH in the condensed phase is enabled by identifying VCD bands that are insensitive to conformational changes and intermolecular interactions. The present work provides a combinatorial procedure for determination of both the absolute configuration and the conformation of chiral molecules in a dilute solution and condensed phase.     

Tensyuic acids, new antibiotics produced by Aspergillus niger FKI-2342

Six new alkylitaconic acids, designated tensyuic acids A to F, were isolated from the culture broth of Aspergillus niger FKI-2342 by solvent extraction, silica gel column chromatography and HPLC. Their structures were elucidated by spectroscopic analysis including UV, NMR, and MS. They are all alkylitaconic acid derivatives. Only tesyuic acid C showed moderate antimicrobial activity against Bacillus subtilis.     

Matrix-isolation infrared spectroscopy of the rotational isomers of 1,2-, 1,3-, and 1,4-benzenedicarboxaldehyde

Rotational isomers (rotamers) of the three structural isomers of benzenedicarboxaldehydes (1,2-, 1,3-, and 1,4-derivatives) have been investigated in detail using matrix-isolation infrared spectroscopy in the 600-4000 cm-1 region, combined with UV photoexcitation and density-functional theory (DFT) calculations. Two rotamers were identified for 1,2- and 1,4-benzenedicarboxaldehyde (1,2- and 1,4-BDA, respectively), while three rotamers were identified for 1,3-benzenedicarboxaldehyde (1,3-BDA) in infrared spectra upon UV-irradiation. Most of the observed infrared bands of each rotamer have been assigned. The energetic relationships among the rotamers were revealed based on the infrared data and the DFT calculations. It is shown that the intramolecular C-H...H-C interaction in the H-syn rotamer or the C-H...O=C hydrogen bonding in the anti rotamer of 1,2-BDA results in the blue-shift of the aldehyde C-H stretching band and the shortening of the aldehyde C-H bond length. Both photoinduced rotational isomerization and rearrangement were observed upon UV irradiation for 1,2-BDA. The structure of the major enol isomer formed as the result of the photochemical rearrangement of 1,2-BDA is determined.