Novel and Versatile Cobalt Azobenzene-Based Metal-Organic Framework as Hydrogen Adsorbent

A novel URJC-3 material based on cobalt and 5,5′-(diazene-1,2-diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC-3, with polyhedral morphology, crystallizes in the tetragonal and P4₃2₁2 space group, exhibiting a three-dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77–298 K) and pressures (1–170 bar). The hydrogen storage capacity of URJC-3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single-walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials.     

Use of liquid chromatography-electrospray ionization tandem mass spectrometry to identify diarylheptanoids in turmeric (Curcuma longa L.) rhizome

LC-ESI-MS/MS coupled to DAD analysis was used as an on-line tool for identification of diarylheptanoids in fresh turmeric rhizome extracts. Based on their mass spectra, from both negative and positive mode LC-ESI-MS/MS analysis, and supported by their DAD spectra, 19 diarylheptanoids were identified. Among these 19 compounds, curcumin, demethoxycurcumin, and bisdemethoxycurcumin were identified by comparing their chromatographic and spectral data with those of authentic standard compounds. The other diarylheptanoid compounds were identified or tentatively identified based on comparison to the three curcuminoids and each other. Twelve of the identified diarylheptanoids have not been previously reported from turmeric and six of these are new compounds.     

ACTION SPECTRA FOR HYPHAL AGGREGATION,THE FIRST STAGE OF FRUITING,IN THE BASIDIOMYCETE Pleurotus ostreatus*

Abstract. Action spectra were determined for hyphal aggregation in Pleurotus ostreatus at wavelengths between 360 and 600 nm. The action spectrum for a 50% response had two maxima, one at 370 nm in the near-UV and the other a broad peak at 440–450 nm in the blue. Both were approximately of the same magnitude. A minimum was present at 400 nm and wavelengths greater than 530 nm invoked no response. Action spectra for a range of responses, 10–90%, were also determined which showed gradual changes in the peaks in the blue region. It was concluded that hyphal aggregation in P. ostreatus is under the control of a cryptochrome-like photoreceptor system.     

Zur Oxidation von 1,2-Thiazolen: Ein einfacher Zugang zu 1,2-Thiazol-3(2H)-on-1,1-dioxiden

Oxidation of 1,2-Thiazoles; A Convenient Approach to 1,2-Thiazol-3(2H)-one 1,1-Dioxides The 1,2-thiazoles obtained from 3-chloroalk-2-enals and ammonium thiocyanate ( 7 → 9 , Scheme 1) are easily transformed to 1,2-thiazol-3(2H)-one 1,1-dioxidcs 10 on treatment with H₂O₂ in AcOH at 80°. Hydrogenation of 10 in AcOH yields the corresponding saturated 1,2-thiazolidin-3-one 1,1-dioxides 16 (Scheme 3). Cycloalka[c]-1,2-thiazoles 18 are prepared from 2-[(thiocyanato)methyliden]cycloalkan-1-ones and ammonia (Scheme 4). Surprisingly, oxidation of 18a with H₂O₂ in AcOH yields the tricyclic oxaziridine 19.     

Azidokomplexe des Zirkoniums: ZrCl3N3, [ZrCl4N3]22⊝, [ZrCl4(N3)2]2⊝; die Kristallstruktur von (PPh4)2[ZrCl4N3]2

Azido Complexes of Zirconium: ZrCl₃N₃, [ZrCl₄N₃]₂^2?, [ZrCl₄(N₃)₂]^2?; Crystal Structure of (PPh₄)₂ [ZrCl₄N₃]₂ Highly explosive ZrCl₃N₃ is formed by the reaction of ZrCl₄ with iodine azide in dichloromethane suspension. According to the i.r. spectra, the compound is polymeric by azide and chlorine bridges. Zirconium tetrachloride reacts with one and two moles of tetraphenylphosphonium azide respectively, forming the thermally and mechanically stable complexes (PPh₄)₂[ZrCl₄N₃]₂ and (PPh₄)₂[ZrCl₄(N₃)₂]. The crystal structure of (PPh₄)₂[ZrCl₄N₃]₂ was determined by X-ray methods (1942 reflexions, R = 6.5%). The complex crystallizes in the monoclinic space group P2₁/n with two formula units per unit cell. The structure consists of tetraphenylphosphonium cations and dimeric anions [ZrCl₄N₃]₂^2?, in which the Zr atoms are linked by the α-N atoms of the azide groups, forming a centrosymmetric Zr₂N₂ ring with symmetry D_2h. According to the i.r. spectra, the azide groups in the complex (PPh₄)₂[ZrCl₄(N₃)₂] are covalently bonded at the Zr atom in trans positions.     

HYDROGEN PEROXIDE MEDIATES UV-INDUCED IMPAIRMENT OF ANTIGEN PRESENTATION IN A MURINE EPIDERMAL-DERIVED DENDRITIC CELL LINE

Abstract— Ultraviolet-B (290–320 nm) radiation is known to impair the antigen-presenting cell (APC) function of Langerhans cells (LC), skin-specific members of the dendritic cell (DC) family. We sought to address mechanisms of this effect, focusing on the role played by hydrogen peroxide. For this purpose, we used a newly established murine DC line, XS52, which resembles epidermal LC in several respects. The APC capacity of XS52 cells, using two different CD4* T cell clones as responders, was inhibited significantly (>50%) by exposure to UV radiation (unfiltered FS20 sunlamps) at relatively small fluences (50–100 J/m²). Ultraviolet radiation also inhibited growth factor-dependent proliferation of XS52 cells. On the other hand, cell surface phenotype was relatively well preserved after irradiation; expression levels of B7-1 and B7-2 were reduced slightly, while other molecules ( e.g. Ia, CD54, CD1 la and CD18) were not affected. With respect to the role played by hydrogen peroxide, pretreatment with purified catalase (900 U/mL) prevented UV-induced inhibition of APC function. Short-term exposure to 3 miM H₂0₂ or f-butyl H₂0₂ mimicked UV radiation by inhibiting APC function. Finally, intrinsic catalase activity was substantially lower in XS52 cells compared with Pam 212 keratinocytes. These results indicate that the generation of hydrogen peroxide alone is sufficient to produce some, but not all, of the deleterious effects of UV radiation on DC derived from the skin.