Synthesis,Structure, and Spectroscopic Properties of [Feiii(tnpa)(OH)(PhCOO)]ClO4: A Model Complex for an Active Form of Soybean Lipoxygenase-1

The cis configuration between the hydroxo and the carboxylato and the three amino groups of the tetradentate, tripodal ligand tris(6-neopentylamino-2-pyridylmethyl)amine favors the formation of hydrogen bonds which stabilize the hydroxo–Feⁱⁱⁱ complex 1 . Thus, its structure closely resembles that of the active center of Feⁱⁱⁱ –soybean lipoxygenase-1, which also contains a six-coordinate Feⁱⁱⁱ atom.     

铜离子交换分子筛上NO吸附的IR光谱及TPD研究

采用原位IR光谱及TPD技术研究了NO在铜离子交换分子筛上各种表面物种的生成及脱附,并与NO在Cu-ZSM-5上的分解反应性能相关联,考察了Cu-ZSM-5反应活性高的原因及O₂的生成机理。NO的吸附状态随分子筛母体种类及铜离子交换度的不同而变化,交换度较高的ZSM-5催化剂上容易形成NO-3物种,该物种对NO分解及O₂的生成具有重要作用。     

Assignment of Nonclassical [Cu(CO)(n)](+) (n = 1, 2) Complex Ions in Zeolite Cages

A time-resolved FT-IR technique combined with an isotopic tracer method has been applied to study CO adsorbates on Cu(+) ions in copper ion-exchanged zeolites. Three kinds of monocarbonyl species were found to adsorb strongly on Cu-zeolite samples after admission and subsequent evacuation of gas phase CO at room temperature. Their absorption bands were observed at 2146-2160, 2128-2150, and 2097-2129 cm(-1), respectively, dependent on the zeolite structures. In the presence of gaseous CO, the monocarbonyl species at 2146-2160 cm(-1) (so called nonclassical [Cu(CO)](+) complexes) could react with a CO molecule to form a dicarbonyl species [Cu(CO)(2)](+) with nu(sym) bands at 2169-2180 cm(-1). The reactivity of the nonclassical [Cu(CO)](+) complexes was dependent on the zeolite structures, ferrierite > mordenite > ZSM-5 > X-type left harpoon ovet right harpoon offretite/erionite left harpoon ovet right harpoon Y-type > L-type. The remaining two types of monocarbonyl species have little been affected by gas phase CO.     

Phase transition of alkylsilane monolayers studied by temperature-dependent grazing incidence X-ray diffraction

The phase transition of organosilane monolayers on Si-wafer substrate surfaces prepared from octadecyltrichlorosilane (OTS) or docosyltrichlorosilane (DOTS) was investigated on the basis of grazing incidence X-ray diffraction (GIXD) at various temperatures. The OTS monolayer was prepared by a chemisorption method. The DOTS monolayer was prepared by a water-cast method (DOTS). The GIXD measurement clarified that the OTS monolayer also changed from hexagonal phase to amorphous state above a melting point of otadecyl groups. The GIXD measurements also clarified that the molecular aggregation state of the DOTS monolayer changes from an anisotropic phase to an isotropic phase with an increase in temperature. An estimated linear thermal expansion coefficient of the lattice lengths of a and b of the DOTS monolayer in the rectangular crystalline state assigned a similar value to those of bulk polyethylene with an orthorhombic crystalline lattice. The setting angle of the ab plane of the rectangular DOTS monolayer also showed similar behavior to that of the ab plane of bulk polyethylene.     

Controlling 3(10)-helix and alpha-helix of short peptides in the solid state

L-Leu hexapeptide containing alpha-aminoisobutyric acid (Aib) forms a right-handed (P) 3(10)-helix, whereas that containing cyclic alpha,alpha-disubstituted amino acid Ac(5)c(dOM) assumes a right-handed (P) alpha-helix in the solid state.     

Degradation of Lignin Model Compounds in Organic Solvents. Part 1. Preliminary Studies

Preliminary studies were conducted on the degradation of guaiacylglycerol-β-aryl ether (β-O-4′), phenylcoumaran (β-5′) and biphenyl (5–5′) type lignin model compounds in the organic solvent systems such as ethanol-water (1:1, v/v) and 2-butanone-water (1:1, v/v), in the presence of a di- or trivalent inorganic salt to act as a Lewis acid in the temperature range 140–170°C and with a reaction time up to 60 minutes. The inorganic salts investigated include aluminum chloride, aluminum sulfate, ferric chloride, ferric sulfate, and stannic chloride. The results indicate that lignin model compounds of both phenolic and non-phenolicβ-O-4′ types are susceptible to degradation in organic solvent systems in the presence of one of these salts. Stannic chloride was found to be the most suitable catalyst for the degradation of β-O-4′ type lignin model compounds in the organic solvent systems. In contrast, lignin model compounds of β-5′ and 5–5′ types did not undergo degradation under the same reaction conditions. A possible reaction mechanism for the degradation of β-O-4′ type lignin model compounds in organic solvent system in the presence of stannic chloride is discussed.     

Asymmetric 1,4-Addition Reactions Catalyzed by N-Terminal Thiourea-Modified Helical l-Leu Peptide with Cyclic Amino Acids

N-terminal thiourea-modified l -Leu-based peptide {(3,5-diCF₃Ph)NHC(=S)-(l -Leu-l -Leu-Ac₅c)₂-OMe} with five-membered ring α,α-disubstituted α-amino acids (Ac₅c) catalyzed a highly enantioselective 1,4-addition reaction between β-nitrostyrene and dimethyl malonate. The enantioselective reaction required only 0.5 mol % chiral peptide-catalyst in the presence of ⁱPr₂EtN (2.5 equiv.), and gave a 1,4-adduct with 93 % ee of an 85 % yield. As Michael acceptors, various β-nitrostyrene derivatives such as methyl, p-fluoro, p-bromo, and p-methoxy substituents on the phenyl group, 2-furyl, 2-thiophenyl, and naphthyl β-nitroethylenes could be applied. Furthermore, various alkyl malonates and cyclic β-keto-esters could be used as Michael donors. It became clear that the length of the peptide chain, a right-handed helical structure, amide N−Hs, and the N-terminal thiourea moiety play crucial roles in asymmetric induction.     

Molecular crystalline capsules that release their contents by light

Here, we present single crystalline capsules of a photoresponsive molecule produced by simple recrystallization from organic solutions without direct human processing. During the crystal growth process, a movie was taken of the capsule taking in the organic solution. The capsules responded rapidly (<1 s) to the UV light stimuli and released the captured solution or solute. In principle, they can take in any substance dissolved in organic solvents, and their size can be controlled. Moreover, the capsule can be broken by multi-photon excitation using a near-infrared laser within the biological window. Furthermore, because the molecular packing in the crystal is unidirectional, the response can be controlled by the polarization of the light. This study shows the new potential of photoresponsive molecules.

A novel diarylethene formed “crystalline capsules” containing liquid inclusions, and chemicals trapped in the capsules were released by photoinduced breaking. Operations by multiphoton and linear polarized light were demonstrated.     

The facile synthesis of graphitic carbon nitride from amino acid and urea for photocatalytic H<Subscript>2</Subscript> production

We report on the facile synthesis of g-C₃N₄ based polymers by co-condensing urea with glycine for photocatalytic hydrogen evolution. The as-prepared photocatalysts were then characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence emission spectrometry, electron paramagnetic resonance spectrometry and transmission electron microscopy. Compared with pristine g-C₃N₄, obtained from direct pyrolysis of urea, the CNU-G₅ photocatalyst showed largely enhanced photocatalytic H₂ activities about 75 μmol h^?1, which is 5 times higher than of the pristine CNU. The enhanced activities are ascribed to the larger specific area surface, strengthened optical absorption and improved electron transport ability. Our work opens up a new pathway for the synthesis graphitic carbon nitride photocatalysts with glycine modification to enhance photocatalytic activities.