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21.
Burkhard Schmidt Ingo Franke Franz-Josef Witteler Michael Binder 《Helvetica chimica acta》1983,66(8):2564-2571
The novel cannabinoids (6aR, 10aR)-N-ethyl-Δ8-tetrahydrocannabinol-18-amide (15) and (6aR, 10aR, 17 RS)-N-ethyl-17-methyl-Δ8- tetrahydrocannabinol-18-amide (16) , designed as cannabinoid affinity ligands, were synthesized from the corresponding acids 11 and 12 via the N-hydroxysuccinimide esters. Amide 16 was tested in the rat and was generalized to Δ9-tetrahydrocannabinol, being 5 times less potent than the training drug. An improved synthesis of (6aR, 10aR)-17,18-didehydro-Δ8-tetrahydrocannabinol (23) is reported. As model reaction for the preparation of a tritiated Δ8-tetrahydrocannabinol, compound 23 was selectively deuterated at C(17) and C(18) in benzene/Et3N using [(C6H5)3P]3RuCl2 as catalyst. 相似文献
22.
Liliana Cseh Carol Csunderlik Ingo Pantenburg Gerd Meyer Otilia Costisor 《无机化学与普通化学杂志》2003,629(6):985-988
The complex Co(C14H13NO)2Cl2 with the protonated N‐salicylidene‐p‐toluidine ligand was synthesized from an ethanolic solution of CoCl2·6H2O and N‐salicylidene‐p‐toluidine. The crystal structure was determined from X‐ray single crystal data (monoclinic, space group Cc, a = 1496.2(3) pm, b = 1257.4(4) pm, c = 1544.6(3) pm, β = 115.01(1)°, Z = 4). Co2+ adopts a distorted tetrahedral geometry. The UV‐Vis and IR spectra of the complex are discussed. 相似文献
23.
In solid-state NMR, deuteron (2H) spectroscopy can be performed in full analogy to1H spectroscopy, including2H chemical-shift resolution and2H-X dipolar correlation schemes, when the NMR experiments are conducted in a “rotor-synchronized” fashion under fast magic-angle
spinning. Here, 2H-X NMR experiments of this type, including2H-15N and2H-1H chemical-shift correlations and distance measurements, are introduced and demonstrated on cytosine monohydrate, whose acidic
protons can readily be replaced by deuterons by recrystallization from D2O. In this way,2H NMR spectroscopy provides information complementary to1H NMR data, which is particularly useful for studying hydrogen bonds in supra- or biomolecular systems.
Electronic supplementary material Supplementary material is available in the online versionof this article atand is accessible for authorized users. 相似文献
24.
Roland Wilberger Holger Piotrowski Marcus Warchhold Ingo‐Peter Lorenz 《无机化学与普通化学杂志》2003,629(14):2485-2492
Novel Neutral and Cationic Mono‐Aziridine Complexes of the Type [CpMn(CO)2Az], [CpCr(NO)2Az]+, and [(Ph3P)(CO)4ReAz]+ via CO‐, Hydride‐, and Chloride‐Elimination Reactions The monoaziridine complexes 1 — 5 are obtained by three differently induced substitution reactions. The photolytically induced CO substitution reaction of [CpMn(CO)3] with 2, 2‐dimethylaziridine leads to the neutral N‐coordinate aziridine complex [Cp(CO)2Mn{$\overline{N(H)CMe2C}$ H2}] ( 1 ). The protonation of [(Ph3P)(CO)4ReH] with CF3SO3H and consecutive treatment with 2, 2‐dimethylaziridine or 2‐ethylaziridine gives the salt‐like aziridine complexes [(Ph3P)(CO)4Re{$\overline{N(H)CMe2C}$ H2}](CF3SO3) ( 2 ) or [(Ph3P)(CO)4Re{ H2}](CF3SO3) ( 3 ) by hydride elimination reactions. The like‐wise salt‐like complexes [Cp(NO)2Cr{$\overline{N(H)CMe2C}$ H2}](BF4) ( 4 ) and [Cp(NO)2Cr{ H2}](CF3SO3) ( 5 ) are synthesized from [CpCr(NO)2Cl] by chloride elimination with AgX (X = BF4, CF3SO3) in the presence of 2, 2‐dimethylaziridine or 2‐ethylaziridine, respectively. As a result of X‐ray structure analyses, the metal atoms are trigonal pyramidally ( 1, 4, 5 ) or octahedrally ( 2, 3 , cis‐position) configurated; the intact three‐membered rings coordinate through the distorted tetrahedrally configurated N atoms. All compounds 1‐5 are stable with respect to the directed thermal alkene elimination to give the corresponding nitrene complexes; the IR, 1H‐ and 13C{1H}‐NMR, and MS spectra are reported and discussed. 相似文献
25.
Ingo Althöfer Gautam Das David Dobkin Deborah Joseph José Soares 《Discrete and Computational Geometry》1993,9(1):81-100
Given a graphG, a subgraphG' is at-spanner ofG if, for everyu,v V, the distance fromu tov inG' is at mostt times longer than the distance inG. In this paper we give a simple algorithm for constructing sparse spanners for arbitrary weighted graphs. We then apply this algorithm to obtain specific results for planar graphs and Euclidean graphs. We discuss the optimality of our results and present several nearly matching lower bounds.The work of G. Das and D. Joseph was supported by NSF PYI Grant DCR-8402375. The work of D. Dobkin was supported by NSF Grant CCR-8700917. The work of J. Soares was supported by CNPq proc 203039/87.4 (Brazil) and NSF Grant CCR-9014562. This research was accomplished while G. Das was a student at the University of Wisconsin-Madison. A preliminary version was presented at the Second Scandinavian Workshop on Algorithm Theory, Bergen, Norway, 1990, under the title Generating Sparse Spanners for Weighted Graphs, and proceedings appear in the series Lecture Notes in Computer Science, Springer-Verlag. The preliminary version also appears as Princeton University Technical Report CS-TR-261-90, and as University of Wisconsin-Madison Computer Sciences Technical Report 882. 相似文献
26.
Apostolidis A Lehmann H Schwotzer G Willsch R Prior A Wolfgang J Klimant I Wolfbeis OS 《Journal of chromatography. A》2002,955(2):183-189
On-line coupling continuous-flow liquid membrane extraction (CFLME) with HPLC, a novel automatic system was developed for the determination of sulfonylurea herbicides in water. After an automatic trace-enrichment process by CFLME, which is the combination of continuous flow liquid-liquid extraction and support liquid membrane (SLM) extraction, the target analytes were concentrated in 50 microl of 0.2 M Na2CO3-NaHCO3 (pH 10.0) buffer. The concentrated sample solutions were injected directly onto a C18 analytical column with a valve, and detected at 240 nm with a diode array detector. Metsulfuron methyl (MSM), and DPX-A 7881 were baseline separated with a mobile phase consisting of methanol and 67 mM KH2PO4-Na2HPO4 (pH 5.91) buffer (45+55, v+v) at a flow-rate of 1.0 ml min(-1). With an enrichment time of 10 min and enrichment sample volume of 20 ml, the enrichment factors and detection limits are 100 and 0.05 microg l(-1) for MSM, and 96 and 0.1 microg l(-1) for DPX-A 7881, respectively. The linear range and precision (RSD) are 0.1-50 microg l(-1) and 7.0% for MSM, and 0.2-50 microg l(-1) and 9.2% for DPX-A 7881, respectively. This proposed method was applied to determine MSM and DPX-A 7881 in seawater, tap water, and bottled mineral water with spiked recoveries in the range of 83-95% for MSM and 88-100% for DPX-A 7881, respectively. 相似文献
27.
Colourless single crystals of [Hg(OH)](NO3)(H2O) were obtained by slow evaporation of an aqueous solution of Hg(NO3)2 and Bi(NO3)3. The crystal structure (orthorhombic, Pbca, Z = 8, a = 943.2(2), b = 697.6(1), c = 1349.0(2) pm, R1(all) = 0.0780) contains [Hg(OH)] = …OH–Hg–OH–Hg… zig zag chains (O–Hg–O angle: 168°, Hg–O–Hg angle: 112°, Hg–OH distance: 212 pm) to which one water molecule is attached loosely. The [Hg(OH)](H2O) chains are connected via bis‐monodentate‐bridging nitrate ions to corrugated layers that are stacked in the [001] direction. Hg2+ has an effective 2+2+2(+1) coordination. 相似文献
28.
I. Calliari M. Dabalŕ G. Brunoro G. M. Ingo 《Journal of Radioanalytical and Nuclear Chemistry》2001,247(3):601-608
Patinae on Cu-base alloys have been characterized by means of GDOS, SEM, XRD and AFM. The effect of a protective coating was tested in aggressive artificial solutions. Patinae and the bulk of several metal Punic objects were also examined. The GDOS results combined with SEM capabilities allow exhaustive investigation of composition, element distribution and microstructure of modified surface in modern bronzes exposed to accelerated ageing tests as well as in ancient bronzes. The SEM data of the patina thickness agree with the GDOS data. The XRD and SEM investigations allow an exhaustive characterization of corrosion products. Corrosion growth in its early stages determines the effectiveness of the patina's protective role and the AFM is a promising technique for investigating this. 相似文献
29.
Marx T Mosel B Pantenburg I Hagen S Schulze H Wesemann L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(18):4472-4478
The tetrasubstituted polyanions of platinum, palladium, and gold [M(SnB(11)H(11))(4)](x-) (x=6, M=Pd, Pt; x=5, M=Au) have been prepared and characterized by single-crystal X-ray diffraction, elemental analysis, IR, Raman, (11)B, and (119)Sn heteronuclear NMR spectroscopy. In the case of the platinum derivative [Bu(3)MeN](6)[Pt(SnB(11)H(11))(4)] (2) (119)Sn M?ssbauer spectroscopy has been carried out. The isolated salts are stable towards moisture and air and the complexes 2 and 3 were treated with 1,3-bis(diphenylphosphino)propane (dppp) to give the respective substitution products [Bu(3)MeN](2)[(dppp)M(SnB(11)H(11))(2)] (M=Pd, Pt). 相似文献
30.
Iris Reimann Steffen Mergemeier Ingo Ebner Fritz Scholz 《Fresenius' Journal of Analytical Chemistry》1995,353(2):206-210
A determination of ethanol is described, which is based on a purging system in conjunction with a photoionization detector. With that system a fast and reliable determination of ethanol in aqueous solutions is possible. The system has been used for the analysis of wine. The 3-detection limit has been 0.005% ethanol, the relative standard deviation 4.8 to 6.0% and the time constant of the entire analytical system 20 s. The photoionization detector has been also applied to the analysis of artificial and genuine human breath. A comparison with gas-chromatography and non-dispersive IR-detection has been proven the reliability of results. 相似文献