Ruthenium-vinylhelicenes: remote metal-based enhancement and redox switching of the chiroptical properties of a helicene core

Introducing metal-vinyl ruthenium moieties onto [6]helicene results in a significant enhancement of the chiroptical properties due to strong metal-ligand electronic interactions. The electro-active Ru centers allow the achievement of the first purely helicene-based redox-triggered chiroptical switches. A combination of electrochemical, spectroscopic, and theoretical techniques reveals that the helicene moiety is a noninnocent ligand bearing a significant spin density.     

Photoluminescence spectroscopy of pure pentacene, perfluoropentacene, and mixed thin films

We report detailed temperature dependent photoluminescence (PL) spectra of pentacene (PEN), perfluoropentacene (PFP), and PEN:PFP mixed thin films grown on SiO(2). PEN and PFP are particularly suitable for this study, since they are structurally compatible for good intermixing and form a model donor/acceptor system. The PL spectra of PEN are discussed in the context of existing literature and compared to the new findings for PFP. We analyze the optical transitions observed in the spectra of PEN and PFP using time-dependent density functional theory calculations. Importantly, for the mixed PEN:PFP film we observe an optical transition in PL at 1.4 eV providing evidence for coupling effects in the blend. We discuss a possible charge-transfer (CT) and provide a tentative scheme of the optical transitions in the blended films.     

Ein Polymethinfarbstoff als spezifisches Magnesiumreagens in der Tüpfelanalyse

Zusammenfassung Der durch Kondensation von Glutaconaldehyd mit Barbitursäure entstehende Polymethinfarbstoff ist ein Mikroreagens auf Magnesium von besonderer Spezifität und Empfindlichkeit. An dem durch Magnesiumionen in alkalischer Lösung bewirkten Farbumschlag von rot auf blau läßt sich 0,1 g Magnesium erkennen.

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Summary The polymethine dyestuff produced from glutaoonic aldehyde and barbituric acid is a micro reagent for magnesium. It has outstanding specificity and sensitivity. The color change produced by magnesium ion in alkaline solution is from red to blue. It will respond to 0.1g magnesium.

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Résumé Le colorant polyméthiné obtenu par condensation de l'aldéhyde glutaconique avec l'acide barbiturique est un réactif du magnésium à l'échelle micro, de spécificité et de sensibilité particulières. On peut déceler 0, 1g de magnésium d'après le changement de couleur du rouge au bleu produit par les ions magnésium en solution alcaline.

     

Glutaconaldehyd als Tüpfelreagens. III

Zusammenfassung Farbreaktionen von m-Dihydroxyarylverbindungen und gewissen Verbindungen mit aktiver Methylengruppe mit Glutaconaldehyd werden beschrieben. Durch Tüpfeln können Mikrogrammengen der betreffenden Stoffe damit nachgewiesen werden.

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Summary Color reactions ofm-dihydroxyaryl compounds and of certain compounds containing active methylene groups with glutaconic aldehyde are described. Microgram amounts of such materials can be detected in this way.

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Résumé On décrit les réactions colorées de composésm-dihydroxyarylés et de certains produits contenant des groupes méthylènes actifs, avec l'aldéhyde glutaconique. On peut rechercher ainsi par analyse à la touche des quantités de l'ordre du microgramme des substances considérées.

     

Neue Tüpfelreaktionen auf Nitrosophenole und Nitrosonaphthole

Zusammenfassung Zwei selektive Tüpfelreaktionen auf p-Hydroxynitrosoarylverbindungen mit Thymol-Schwefelsäure und Benzalphenylhydrazon-Schwefelsäure werden beschrieben. Als selektives Reagens für o-Nitrosonaphtholderivate wird-Naphthol empfohlen. Als spezifische Reagenzien auf p-Nitrosophenol werden Benzalphenylhydrazon-Salzsäure und Diphenylbenzidin bzw. Diphenylamin-Salzsäure empfohlen. Ein spezifischer Test auf 1-Nitroso-2-naphthol mit p-Kresol wird beschrieben. Die Nachweise werden in der Arbeitsweise der Tüpfelreaktionen ausgeführt, wobei sich die Erfassungsgrenzen zwischen 0,05 und 1g bewegen.

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Summary Two selective spot reactions forp-hydroxynitrosoaryl compounds with thymol sulfuric acid and benzalphenylhydrazone sulfuric acid are described.-Naphthol is recommended as selective reagent foro-nitrosonaphthol derivatives. Benzalphenylhydrazone-hydrochloric acid and diphenylbenzidine or diphenylamine-hydrochloric acid are recommended as specific reagents forp-nitrosophenol. A specific test for 1-nitroso-2-naphthol withp-cresol is described. The tests are conducted within the methodology of spot testing, and the identification limits range between 0.05 and1 g.

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Résumé On décrit deux réactions à la touche sélectives pour les composésp-hydroxynitrosoarylés, utilisant thymol-acide sulfurique et benzylidènephénylhydrazone-acide sulfurique. On recommande le-naphtol comme réactif sélectif des dérivés de l'o-nitrosonaphtol et les systèmes benzylidènephénylhydrazone-acide chlorhydrique et diphenylbenzidine ou chlorhydrate de diphénylamine comme réactifs spécifiques dup-nitrosophénol. On décrit une recherche spécifique de l'-nitroso-naphtol par lep-crésol. On effectue les essais suivant le mode opératoire des réactions à la touche, de sorte que les limites de dilution se trouvent comprises entre 0,05 et 1g.

     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.     

Lipoide

Ohne Zusammenfassung