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91.
Matthias Freytag Frank T. Edelmann Ludger Ernst Peter G. Jones Reinhard Schmutzler 《无机化学与普通化学杂志》2004,630(3):377-383
The reaction of the symmetric diphosphene 2, 4, 6‐(CF3)3‐C6H2‐P=P‐C6H2‐2, 4, 6‐(CF3)3 4 with Ru3(CO)12 led to the 50‐electron Ru3P2 nido‐cluster Ru3(CO)9[μ‐P‐C6H2‐2, 4, 6‐(CF3)3]2 5 , which in solution at room temperature displays hindered rotation of the aromatic rings about the C(aryl)—P bonds. The structure of 5 was determined by X‐ray crystal structure analysis; its Ru3P2 centre forms a distorted square pyramid with one ruthenium atom at the apex. One of the two C6H2(CF3)3 groups is also appreciably distorted. Temperature‐dependent 19F NMR studies of the [A3M3X]2 spin system (A = M = CF3, X = 31P) of 5 indicated a rotational barrier ΔG≠ of 82.3 kJ mol‐1 at 141 °C. The same Ru3P2 core was obtained by the reaction of the unsymmetric diphosphene Mes*‐P=P‐Mes 11 with Ru3(CO)12; hindered rotation about the C(aryl)—P bonds was also observed, in this case. 相似文献
92.
Reinhard Haase Dorit S. Meinhold Berthold Thomas Edwin Weber Gerd Rheinwald 《Structural chemistry》2002,13(5-6):471-477
The crystal structures of inclusion compounds of 3,3-bis(9-hydroxy-9-fluorenyl)-2,2-binaphthyl host (1) and its chloro (2) or bromo (3) derivatives substituted in 2,7-positions of the fluorene units with acetone guests (1A–3A) were determined by X-ray studies as well as by 1H-CRAMPS solid-state NMR. Using this NMR technique allows identification of differently bound guest molecules due to their different chemical shifts caused by the influence of the ring current effects of the host aryl units. 相似文献
93.
Th. Weber E. Riedle H. J. Neusser 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,20(1):43-46
Sub-Doppler electronic spectra with hundreds of resolved rotational lines are now available for benzene-Ar dimers and trimers. From their analysis the structure of these clusters is precisely determined. The analysis of two bands, 6 0 1 and 16 0 2 , of C6H6 · Ar is presented in detail. It leads to accurate values of the van der Waals bond length in the electronic ground and excited state. The change in frequency upon clustering is found to be a factor of 17 larger for the overtone of the out-of-plane modev 16 than for the in-plane vibrationv 1. This can be tentatively explained by an interaction of the low frequency out-of-plane motion of the ring with the van-der-Waals motion of the Ar atom. 相似文献
94.
Galina Strand Reinhard Renneberg Frieder Scheller 《Journal of Electroanalytical Chemistry》1985,194(1):123-130
The enzyme α-amylase splits blue starch in fragments bearing electroactive groups which exhibit two waves in the pulse polarograms. This behaviour is the basis of the polagraphic determination of bacterial and human serum α-amylase activity. The differential pulse mode is more sensitive by a factor of 25 as compared with normal pulse polarography. With serum α-amylase, protein adsorption disturbs the determination of low activities. 相似文献
95.
Kratzsch C Peters FT Kraemer T Weber AA Maurer HH 《Journal of mass spectrometry : JMS》2003,38(3):283-295
A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (APCI-LC/MS) is presented for the fast and reliable screening and identification and for the precise and sensitive quantification of 15 neuroleptic (antipsychotic) drugs and three of their relevant metabolites in plasma. It allows confirmation of the diagnosis of a neuroleptic overdose and monitoring of psychiatric patients' compliance. The neuroleptics amisulpride, bromperidol, clozapine, droperidol, flupenthixol, fluphenazine, haloperidol, melperone, olanzapine, perazine, pimozide, risperidone, sulpiride, zotepine and zuclopenthixol and the pharmacologically active metabolites norclozapine, clozapine N-oxide and 9-hydroxyrisperidone were extracted from plasma using solid-phase extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. After screening and identification in the scan mode using the authors' new LC/MS library, the neuroleptics were quantified in the selected-ion mode. The quantification assay was fully validated. It was found to be selective and proved to be linear from sub-therapeutic to over therapeutic concentrations for all analytes. The corresponding reference levels are listed. The accuracy and precision data were within the required limits. The analytes were stable in frozen plasma for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with various neuroleptics. The validated LC/MS assay has proved to be appropriate for the isolation, separation, screening, identification and quantification of various neuroleptics in plasma for clinical toxicology and therapeutic drug monitoring purposes. 相似文献
96.
N. Thornton Lipscomb Edwin C. Weber 《Journal of polymer science. Part A, Polymer chemistry》1967,5(4):779-784
Studies have been made of the γ-radiation-induced polymerization of methyl methacrylate in bulk, in the solid state at a temperature of ?65°C. and a radiation intensity of 346,000 rad/hr. The reaction was found to have an extremely long induction period (~50 hr.) when pure monomer was used, and to be first-order with respect to polymer concentration. This first-order dependency was confirmed by a series of irradiations in which 0.6% poly(methyl methacrylate) was dissolved in the monomer before irradiation. These irradiations showed no induction period. Nuclear magnetic resonance spectroscopy indicated a much more heterotactic polymer than that obtained in the liquid state at ?49°C. 相似文献
97.
E. Anklam Maria Rosa Bassani Thomas Eiberger Stefan Kriebel Markus Lipp Reinhard Matissek 《Analytical and bioanalytical chemistry》1997,357(7):981-984
Pyrolysis Mass Spectrometry (Py-MS) was used for the discrimination of cocoa butters from other vegetable fats. Mass spectra
ranging from 50 amu to 250 amu were analyzed by principal component analysis (PCA) and with neural nets. The application of
neural nets leads to a good discrimination between the two classes. Detailed analysis of the nets revealed that only the first
60 masses were used within the net. The use of PCA requires a careful selection of the number of masses included in the calculation.
Canonical variance analysis was applied to determine the significant masses. Optimal performance of PCA was observed only
using the first 22 significant masses. Most of these masses were different from the ones used by the neural net. It seems
that the mass spectra obtained by Py-MS contain sufficient information for the discrimination of pure cocoa butter from other
vegetable fats, but none of the methods seems to be able to extract all information available. Neural net provides a very
robust method for this task and no prior data selection was necessary.
Received: 13 May 1996 / Revised: 7 August 1996 / Accepted: 7 August 1996 相似文献
98.
1,3-Oxazolidin-4-ones and 1,3-oxazin-4-ones were synthesized by formal cyclocondensation of imines with α- or β-hydroxy acids. 相似文献
99.
The micellar extraction and enrichment of napropamide and thiabendazole using Genapol X 80 is described. Combined with their quantification by fluorescence, detection limits below 0.2 g/l with recovery rates of up to 95% were achieved. The recovery could be improved by lowering the extraction temperature and purificaton of the surfactants. This extraction method has been applied to the isolation and preconcentration of napropamide from standard soils. Experimental parameters affecting the recovery rates were examined. 相似文献
100.
The 13C spectra of 5,6,9,10-tetradehydrocyclodeca[1,2,3,4-def]-benzo [7,8]biphenylene, 1, and 5,6,9,10-tetradehydrocyclodeca [1,2,3,4-def]-naphtho [2,3-7,8]biphenylene, 2, are reported as are those of a number of simpler acetylenic hydrocarbons used as spectral references. Most of the shifts can be assigned unambiguously. The acetylenic shift assignments were verified by ortho-proton, sp-carbon (1H(1)-13Csp(3)) decoupling experiments. A simple additive shift correlation is found for the hydrocarbons containing unstrained acetylenic groups. However, significant discrepencies are found for the 13C shifts for the strained hydrocarbons 1, 2, 1,2-bis(phenylethynyl)-benzene, 12, and 2,3-bis(phenylethynyl)-naphthalene, 13. The discrepencies are particularily large for carbons near the triple bonds and are attributed to a combination of strain, rehybridization, and other proximity effects related to the interaction between the ortho-substituted acetylenic carbons. 相似文献