Search results for "spectrum"

Studies in organic mass spectrometry. Part 9—mass spectra of 9,10-disubstituted 2,3,6,7-tetraalkoxy-9,10-dihydroanthracenes: A remarkable loss of rad…

1991

The electron impact-induced fragmentations of 23 9,10-disubstituted 2,3,6,7-tetraalkoxy-9,10-dihydroanthracenes, including six stereoisomeric pairs, were studied. The loss of the 9-(or 10-)substituent constitutes the main fragmentation route. The resulting ions give rise to a remarkable violation of the so-called even-electron rule as they eject the second substituent at the 10-(or 9-)position as a radical. The latter aspect was particularly investigated with the aid of low-energy (nominal value 15 eV) and mass-analysed ion kinetic energy spectra

Fast microscopic method for large scale determination of structure, morphology, and quality of thin colloidal crystals.

2006

We present a novel fast microscopic method to analyze the crystal structures of air-dried or suspended colloidal multilayer systems. Once typical lattice spacings of such films are in the range of visible light, characteristic Bragg scattering patterns are observed. If in microscopic observations these are excluded from image construction, a unique color coding for regions of different structures, morphologies, and layer numbers results. Incoherently scattering defect structures, however, may not be excluded from image construction and thus remain visible with high resolution.

Cover Picture: Photo-Chromium: Sensitizer for Visible-Light-Induced Oxidative C−H Bond Functionalization-Electron or Energy Transfer? (ChemPhotoChem …

2017

Durch elektronenübertragung initiierte diradikalische polykombination zu linearen und cyclischen polyanionen, 2. Umsetzung von bis[4-(1-phenylvinyl)p…

1975

Die Umsetzung von Bis[4-(1-phenylvinyl)phenyl]methan (1) mit Natrium in THF wird beschrieben. Die protonierten und methylierten Reaktionsprodukte werden durch GPC, NMR- und Massenspektren charakterisiert. Die Bildung von linearen Produkten und von Oligo-anion-paracycolophanen wird diskutiert. The reaction of bis[4-(1-phenylvinyl)phenyl]methane (1) with sodium in THF is described. The protonated and methylated products are characterized by GPC, NMR, and mass spectra. The formation of linear products and of oligo-anion-paracyclophanes is discussed.

Oxygen K-edge XANES investigation of NicMg1−cO solid solutions

2005

A series of Ni(c)Mg(1-c)O solid solutions are characterized by means of synchrotron radiation X-ray diffraction and X-ray absorption near-edge-structure spectroscopy at oxygen K-edge (532 eV). A dramatic drop of the pre-edge peak intensity is observed in the Ni(c)Mg(1-c)O system upon dilution. It can be attributed to a decrease of 3d(8)(Ni(2+))-2p(O(2-)) mixing upon dilution with magnesium ions due to a decrease of the number of 3d vacancies as nickel ion is replaced by magnesium ion. Similarly, the decrease of the number of 4s and 4p vacancies also leads to a decrease of 4s4p(Ni(2+))-2p(O(2-)) hybridization, and hence a drop of intensities of features B and C. The features E and F are more…

Antimykotische Wirkstoffe, 18. Mitt. Aromatisch substituierte 2-(4-Toluidino)pyrimidine

1985

Die Kondensation von 4-Tolylguanidin (1) mit den aromatische und heteroaromatische Substituenten tragenden β-Diketonen 2a–d fuhrt zu den korrespondierend substituierten 2-(4-Toluidino)pyrimidinen 3a–d. Antimycotic Agents, XVIII: Aromatically Substituted 2-(4-Toluidino)pyrimidines Condensation of 4-tolylguanidine (1) with the β-diketones 2a–d bearing aromatic or heteroaromatic substituents leads to the 2-(4-toluidino)pyrimidines 3a–d.

Antivirale Wirkstoffe, 27. Mitt. Die Aminomethinylierung von 5-Oxo-2-pyrazolin-3-carbonsäurederivaten

1986

Aus der mit s-Triazin (1) durchgefuhrten Aminomethinylierung der 5-Oxo-2-pyrazolin-3-carbonsaurederivate 2a,b gehen die 4-Aminomethylen-5-oxo-2-pyrazolin-3-carbonsaurederivat 4a,b und die C-Rubazonsauren 5a,b hervor. Bei 4a deuten die spektroskopischen Daten auf das Vorliegen der Z-Form (Abb. 1), fur 5a auf das der Z-s-cis-(OH)-Form (Abb. 2) hin. Die Strukturtypen 4 und 5 weisen Vertreter mit antiviraler, entzundungshemmender, temperatursenkender und antimykotischer Wirkung auf. Antiviral Agents, XXVII: Aminomethynylation of 5-Oxo-2-pyrazoline-3-carboxylic Acid Derivatives Aminomethynylation of the 5-oxo-2-pyrazoline-3-carboxylic acid derivatives 2a,b by means of s-triazine (1) yields the 4…

Über polygermane

1980

Abstract A complete series of 5-membered heterocycles (Ph 2 Ge) 4 X with X = O, S, Se and Te has been prepared and investigated by mass spectra, 13 C NMR spectra and vibrational spectra. The 13 C signals of the phenyl groups in the compounds (Ph 2 Ge) 4 X were compared with the related values in the homocycle (Ph 2 Ge) 5 . Frequency values for the symmetrical and asymmetrical stretching vibrations of the units GeGeGe and GeXGe are given. The crystal structure of the compound (Ph 2 Ge) 4 S has been determined and refined to a R of 0.051. The 5-membered ring Ge 4 S exhibits envelope conformation.

Synthese von oligo-l-prolinen bis zum pentadecapeptid

1970

Antibakterielle wirkstoffe. IX . Die aminomethinylierung im system des 3-methyi-1-(4-nitrophenyl)-2-pyrazolin-5-ons

1986

Die mit Hilfe von s-Triazin (1) durchgefuhrte Aminomethinylierung von 3-Methyl-1-(4-nitrophenyl)-2-pyrazolin-5-on (2) fuhrt zu dem Aminomethinylierungsprodukt 4 und dem C-Rubazonsauretypus 5. In den zur Untermauerung der erhaltenen Strukturen aufgenommenen Massenspektren treten als charakteristische Fragmente von 4 das Pyrazolo[4,3-d]isoxazolyliumion 6 (m/e 245), p-Benzochinonmonoiminylkation (m/e 106) und Mthylenaminophenylkation (m/e 104) auf. The aminomethinylation of 3-methyl-l-(4-nitrophenyl)2-pyrazolin-5-one (2) by means of s-triazine (1) leads to the aminomethinylation product 4 and the C-rubazoic acid type 5. The mass spectra supporting the structures obtained exhibit the pyrazolo[4…