Synthesis and properties of an Au(III) complex with N-nitrosated ethylenediamine AuEn(ONNC2H4,NH2) (ClO4)2

Conclusions The feasibility of the isolation of an N-nitrosoamidated ethylenediamine product in an Au(III) complex has been demonstrated for the first time; this has previously been observed only in the case of Pt(IV) complexes. The compound was characterized by elemental analysis and by spectroscopic studies.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2654–2659, December, 1987.     

Production of metal atoms,clusters and complexes in pulsed discharge-excited jets : Studies via mass-resolved laser multiphoton ionization

A pulsed, high-voltage, discharge-excited nozzle source has been developed and exploited to study the possibility of sputtering and entraining various metal atoms into the gas expansion from the discharge electrodes. By appropriate choice of electrode materials, atomic beams of copper, silver, tin and lead have been generated and spectroscopically characterized by 2 + 1 laser multiphoton ionization with mass analysis. Sufficiently high atomic densities are achieved with this nozzle system that metal clustering also takes place, producing dimers such as Ag₂, species of mixed composition such as AgSn and trimers, Ag₃. In addition, chemical reactions have been observed which can be initiated in the discharge and which lead to the formation of metal–ligand complexes when suitable molecules are seeded into the carrier gas. Mass spectral evidence for two such silver complexes is presented.     

Platinum-based catalysts for the hydroamination of olefins with sulfonamides and weakly basic anilines

Electrophilic Pt(II) complexes catalyze efficient hydroaminations of olefins by sulfonamides and weakly basic anilines. Catalysts include the structurally characterized complex (COD)Pt(OTf)2 (1) and the known dimer [PtCl2(C2H4)]2, activated by AgBF4. Experiments with substituted anilines establish an empirical pKa cutoff (conjugate acid pKa < 1) for the participation of nitrogen-containing substrates in this catalysis. Arylsulfonamides (conjugate acid pKa approximately -6) with various para substituents hydroaminate olefins such as cyclohexene in yields greater than 95% at 90 degrees C. Hydroamination of propylene by p-toluenesulfonamide proceeds with Markovnikov selectivity, suggesting a mechanism that involves olefin activation at Pt. With norbornene and p-toluenesulfonamide as the substrates and 1 as the catalyst, intermediate [(COD)Pt(norbornene)2][OTf]2 (3) was identified and characterized by 19F and 195Pt NMR spectroscopies and mass spectrometry. Kinetic studies provide the empirical rate law, rate = k(obs)[Pt][sulfonamide], and are consistent with a mechanism in which attack of a sulfonamide on the Pt-coordinated olefin is the rate-determining step.     

Rapid, accurate and precise quantitative drug analysis: comparing liquid chromatography tandem mass spectrometry and chip-based nanoelectrospray ionisation mass spectrometry

We have developed a liquid chromatography tandem mass spectrometry (LC-MS/MS) system capable of achieving better than 2% accuracy, routinely over a wide concentration range of 1800 ng mL-1. We demonstrate that the necessary high precision, high accuracy and rapid analysis can be achieved using LC-MS/MS technology. Automated nanoelectrospray ionisation tandem mass spectrometry (nanoESI-MS/MS) technology can be employed to eliminate the chromatographic step completely. In this paper, nanoESI-MS/MS is evaluated and compared directly with LC-MS/MS for the quantitative analysis of two-test analytes, amitriptyline (ATT) and 5-methoxytryptamine (5-MTT), in aqueous/organic mixture. Calibration curves were found to be linear over a wide concentration range of 1800 ng mL-1 for both analytes using LC-MS/MS. Using nanoESI-MS/MS ATT gave a linear response while 5-MTT gave a non-linear response using nanoESI-MS/MS over the same concentration range as in LC-MS/MS. Accuracy and precision values of quality control samples (QCs) at four concentration levels were analysed in replicates of six at each level using 5-MTT and ATT as test analytes for both techniques. The LC-MS/MS system was capable of achieving accuracy levels of 99.50101.96% for ATT and 100.17100.40% for 5-MTT. Accuracy levels using nanoESI-MS/MS were not comparable to LC-MS/MS, they ranged from 90.09100.18% for ATT and 95.95113.55% for 5-MTT. The precision values obtained for nanoESI-MS/MS were in good agreement with those obtained by LC-MS/MS.     

Nitrogen photochemistry. Cocaine and its model compounds

The ultraviolet irradiation of the π → π* transition of cocaine, p-anisoyl-l-ecognine methyl ester, p-toluoyl-l-ecognine methyl ester benzoyl tropine and benzoylpseudotropine in methanol using a Corex filter produces the corresponding N-demethylated products. Formaldehyde is quantitatively produced. 1-Methyl-3-piperidyl benzoate and 1-methyl-4-piperidyl benzoate yield benzoic acid under the same conditions but no demethylated products. Phenylacetyl-l-ecognine methyl ester gives no demethylation during irradiaiton. The phosphorescence bands of cocaine and its model compound, methyl benzoate, have been shown to be strongly dependent upon solvent polarity suggesting charge transfer in the triplet state.     

Principles of mucin architecture: structural studies on synthetic glycopeptides bearing clustered mono-, di-, tri-, and hexasaccharide glycodomains

The structural characteristics of a mucin glycopeptide motif derived from the N-terminal fragment STTAV of the cell surface glycoprotein CD43 have been investigated by NMR. In this study, a series of molecules prepared by total synthesis were examined, consisting of the peptide itself, three glycopeptides having clustered sites of alpha-O-glycosylation on the serine and threonine side chains with the Tn, TF, and STF carbohydrate antigens, respectively, and one with the beta-O-linked TF antigen. Additionally, a glycopeptide having the sequence SSSAVAV, triglycosylated with the Le(y) epitope, was investigated. NMR data for the tri-STF-STTAV glycopeptide were used to solve the structure of this construct through restrained molecular dynamics calculations. The calculations revealed a defined conformation for the glycopeptide core rooted in the interaction of the peptide and the first N-acetylgalactosamine residue. The similarity of the NMR data for each of the alpha-O-linked glycopeptides demonstrates that this structure persists for each construct and that the mode of attachment of the first sugar and the peptide is paramount in establishing the organization of the core. The core provides a common framework on which a variety of glycans may be displayed. Remarkably, while there is a profound organizational effect on the peptide backbone with the alpha-linked glycans, attachment via a beta-linkage has little apparent consequence.     

Immunologic relatedness of extracellular ligninases from the actinomycetesstreptomyces viridosporus t7a andstreptomyces badius 252

Four isoforms of the extracellular lignin peroxidase of the ligninolytic actinomyceteStreptomyces viridosporus T7A (ALip-P1, P2, P3, and P4) were individually purified by ultrafiltration and ammonium sulfate precipitation, followed by electro-elution using polyacrylamide gel electrophoresis. Three of the purified peroxidases were compared for their immunologic relatedness by Western blot analysis using a polyclonal antibody preparation produced in rabbits against pure isoform P3. The anti-P3 antibody was also tested for its reactivity towards a lignin peroxidase from the white-rot fungusPhanerochaete chrysosporium and another ligninolytic actinomyceteStreptomyces badius 252. Results showed that peroxidases ALip-P1 through ALip-P3 are immunologically related to one another. The peroxidases ofS. badius, but not the peroxidase ofP. chrysosporium, also reacted with the antibody, thus indicating that the lignin peroxidases ofS. viridosporus andS. badius are immunologically related. Based upon its specific affinity, lignin peroxidase isoform ALip-P3 ofS. viridosporus was readily purified using an anti-P3 antibody affinity column.     

Spaces betweenX and its Freudenthal compactification

Let X indicate the Freudenthal compactification of a rimcompact, completely regular Hausdorff spaceX. In this paper the spacesY which satisfyXYX are characterized. From this a characterization of whenX lies between its locally compact partL(X) and (L(X)) follows. Such spaces necessarily possess a compactification X for whichCl _X (X–X) is 0-dimensional. Conditions, including those internal toX, are provided which are necessary and sufficient for this property to hold.This research was partially supported by a grant from Moorhead State University.     

Comparison of four scattering mechanisms in cyclotron resonance in InSb

Summary  Four scattering mechanisms are compared in the quantum limit cyclotron resonance inn-InSb on the basis of a many body theory introduced recently. In the quite low temperature region (T<70 K ) for the wavelength of the electromagnetic wave of 84 μ m, the electrons are scattered mostly by the ionized impurities, although the deformation potential phonon and the piezoelectric scattering are non-negligible. In the high temperature region (T>70 K ) the polar optical phonon scattering is found to be most dominant. It is also shown that the impurities give place to the phonons for the scattering mechanism above 70 K. On the other hand, at 20 K the ionized impurity scattering is dominant in the magnetic field region 0.2 T<B<2 T. This work has been supported by the Basis Science Research Institute Program, Korea Ministry of Education (Project No. BSRI-96-2405).