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991.
A method has been developed for preconcentrating the volatile sulfur compounds from gaseous samples using a trap filled with a sorption material, polydimethylsiloxane(PDMS), without the need for extensive cryotrapping with liquid cryogens. The system is based on enrichment of the solutes on a packed bed of 50% (w/w) PDMS on solid support without cryotrapping and is then analysed by using thermal desorption followed by capillary column (GS‐GASPRO) gas chromatography with simultaneous sulfur‐selective detection. The practicality of the system was demonstrated by the analysis of natural gas. Using the system described here, the sulfur gaseous compounds known to cause nuisance odors in the natural gas could be quantitatively trapped. The application of 50% PDMS on silcoport? for the analysis of sulfur compounds from gaseous samples has been proved to be useful. 相似文献
992.
Abe K Abt I Ash WW Aston D Bacchetta N Baird KG Baltay C Band HR Barakat MB Baranko G Bardon O Barklow T Bazarko AO Ben-David R Benvenuti AC Bienz T Bilei GM Bisello D Blaylock G Bogart JR Bolton T Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Busza W Calcaterra A Caldwell DO Calloway D Camanzi B Carpinelli M Cassell R Castaldi R Castro A Cavalli-Sforza M Church E Cohn HO Coller JA Cook V Cotton R Cowan RF Coyne DG D'Oliveira A Damerell CJ Dasu S Decker FJ De Sangro R 《Physical review letters》1994,73(1):25-29
993.
Koleva BB Kolev T Seidel RW Mayer-Figge H Spiteller M Sheldrick WS 《The journal of physical chemistry. A》2008,112(13):2899-2905
The novel hydrogensquarate salt of 4-cyanopyridine was synthesized, and its structure and properties were elucidated in detail spectroscopically, thermally, and structurally, using single-crystal X-ray diffraction, linear-polarized solid-state IR spectroscopy, UV spectroscopy, TGA, DSC, DTA, and positive and negative ESI MS as well as 1H and 13C NMR methods. Quantum chemical methods were used to calculate the electronic structure, vibrational data, and electronic spectra. 4-Cyanopyridinium hydrogensquarate monohydrate crystallizes in the space group P and exhibits a layered structure with molecules linked by intermolecular NH...O(HSq-) (2.651 A) and HOH...O(HSq-) (2.792 and 2.563 A) hydrogen bonds with participation of cations, anions, and the solvent molecule. The formation of stable layers of the type (2HSq-.2H2O)n and the observation of a red color in the solid state is discussed. The optical and magnetic properties were elucidated in comparison to the data for neutral 4-cyanopyridine as well as its four known salts. 相似文献
994.
995.
996.
The synthesis of some 1-oxygenated derivatives of murrayafoline A (1) and their antifungal properties is reported. Three derivatives, 1-hydroxy-3-methyl-9H-carbazole (2), 1-(3-methylbut-2-enyloxy)-3-methyl-9H-carbazole (3) and 1-(2,3,4,6,-tetra-O-acetyl-alpha-D-O-glucopyranosyl)-3-methyl-9H-carbazole (4), of murrayafoline A were synthesized. Compounds 1 and 2 exhibit strong fungicidal activity against Cladosporium cucumerinum at the dose of 12.5 microg. 相似文献
997.
Jishnunil Chakraborty Partha Roy Heike Mayer-Figge William S. Sheldrick Pradyot Banerjee 《Polyhedron》2007
This work describes the synthesis and X-ray crystallographic characterization of three nickel(II) complexes [Ni(3,2,3-tet){Ag(CN)2}2] (1), [Ni(3,2,3-tet)(μ-tp)]n · 1.5nH2O (2) and {[Ni(3,2,3-tet)(μ1,5-dca)](ClO4)}n (3) where 3,2,3-tet = N,N′-bis(3-aminopropyl)-1,2-ethylenediamine, tp = terephthalate and dca = dicyanamide. Compound 1 is a heterotrinuclear discrete distorted octahedral molecule whereas compound 2 forms a 1D polymeric network and an extended 2D network is formed by intermolecular hydrogen bonding. Interestingly, two adjacent 1D chains execute a novel double-helical network constructed by Ni(II) and the bridging dca ligand in compound 3. The variable temperature magnetic susceptibility measurements for compounds 2 and 3 were also carried out. 相似文献
998.
Ring-closing metathesis (RCM) was employed to join carboxy-terminal alkenyl glycine side chains together with vinyl- and allyl-functionality appended to the beta-methylene of amino-terminal phosphotyrosyl (pTyr) mimetics. This required the synthesis of a variety of new pTyr mimetics, including a novel aza-containing analogue. Many of the resulting 15-member macrocyclic tetrapeptide mimetics exhibited low nanomolar Grb2 SH2 domain-binding affinities in spite of the fact that differing ring junction stereochemistries and geometries of the RCM-derived double bond were employed. The finding that significant latitude exists in the structural requirements for ring closure may facilitate the development of therapeutically relevant macrocyle-based Grb2 SH2 domain-binding antagonists. The synthetic approaches used in this study may also find application to peptide mimetics directed at other biological targets. 相似文献
999.
We present a set of experiments that provide a complete mapping of coherent and incoherent vibrational relaxation times for a molecule on a metal surface, CO/Ir{111}. Included is the first detection of a midinfrared photon echo from a metallic surface, some 15 years after the analogous measurement on a semiconductor surface, which sets a precedent for the ability to manipulate and rephase polarization on a subpicosecond time scale on surfaces. For the C-O stretch in a strongly dipole-coupled CO layer we obtain a total linewidth of 5.6 cm-1, composed of a homogeneous width of 2.7 cm-1 and an inhomogeneous contribution of 3.0 cm-1. Pure dephasing is negligible at liquid nitrogen temperatures, making CO/Ir{111} an attractive model system for quantum computing. 相似文献
1000.
Bishomoallylic secondary amines embodying the 2-allyl-N-benzylcyclohexylamine unit react with NIS to undergo cyclization through 6-endo processes in either the cis or trans series. Nevertheless, when the resulting cis-3-iododecahydroquinolines are treated with Al2O3, the exo derivatives evolve into octahydroindoles and the endo derivatives keep the same backbone, the configuration being retained in the generated alcohols. 相似文献