Problems of Quantitative Spectroscopic Measurements in Heterogeneous Catalysis: Molar Absorption Coefficients of Vibrations in Adsorbed Substances

Published data on the molar absorption coefficients and integral intensities A ₀ of vibrations in physically and chemically adsorbed molecules are reviewed. Analysis of published data shows that bonds characterized by high values of the dipole momentum derivative with respect to the normal coordinate change during adsorption toward decreasing this derivative, whereas bonds characterized by a low value of the derivative change toward increasing the derivative. Thus, adsorption results in a decrease in the difference in values of the dipole momentum derivative with respect to the normal coordinate of different bonds compared with the same bonds in the individual molecules. In addition, the interval of changing the molar absorption coefficients for the surface complexes are at least two orders of magnitude lower than that for the same bonds in the molecules in the gas phase. A series for the degree of easiness in detecting complexes on the catalyst surface (the series of decreasing the molar absorption coefficient) is proposed.     

Synthesis and transformations of metallacycles. 23. Cp2TiCl2-Catalyzed cyclometallation of fullerene C60 with EtAlCl2

1-Ethyl-2,3-fullerenoaluminacyclopropanes (EtAl)_n(²-C₆₀) were synthesized by the reaction of fullerene C₆₀ with an excess of EtAlCl₂ in the presence of Mg and using Cp₂TiCl₂ as the catalyst in a THF--toluene solution at 20 °C. Deuterolysis of fullerenoaluminacyclopropanes afforded a mixture of deuteriofullerenes C₆₀D_m, where m = 6--12.     

Coulometric determination of NAD+ and NADH in normal and cancer cells using LDH, RVC and a polymer mediator

An electrochemical method for the measurement of NAD(+) and NADH in normal and cancer tissues using flow injection analysis (FIA) is reported. Reticulated vitreous carbon (RVC) electrodes with entrapped l-lactate dehydrogenase (LDH) and a new redox polymer containing covalently bound toluidine blue O (TBO) were employed for this purpose. Both NAD(+) and NADH were estimated coulometrically based on their reaction with LDH. The latter was immobilized on controlled pore glass (CPG) by cross-linking with glutaraldehyde and packed within the RVC. The concentrations of NAD(+) and NADH in the tissues, estimated using different electron mediators such as ferricyanide (FCN), meldola blue (MB) and TBO have also been compared. The effects of flow rate, pH, applied potential (versus Ag/AgCl reference) and adsorption of the mediators have also been investigated. Based on the measurements of NAD(+) and NADH in normal and cancer tissues it has been concluded that the NADH concentration is lower, while the NAD(+) concentration is higher in cancer tissues. Amongst the electron mediators TBO was found to be a more stable mediator for such measurements.     

Synthesen in der Naphthalinreihe: Methoxylierte Tetralone und Naphthole

Ohne ZusammenfassungHerrn Prof. Dr.A. Franke in aufrichtiger Verehrung zum 80. Geburtstag gewidmet.     

Thermal transformations of oligoarylenes

Journal of Thermal Analysis and Calorimetry - Thermal transformations of oligoarylenes, relating to polymers with conjugate systems, have been investigated in air and in vacuo, depending on the...     

Zu den Spektren aromatischer Azine. I Berechnung der Energieterme des Benzalazins mit Hilfe der LCAO-MO-Methode

Zusammenfassung Mit Hilfe der einfachen LCAO-MO-Methode werden die Energieterme der -Elektronen des Benzalazins, seiner Ammoniumionen und die von 12 weiteren Strukturen, die durch Verdrehung bestimmter Teile des Moleküls als isolierte Systeme auftreten können, berechnet. Die Diskussion der Lage der Energieterme im Termschema des Benzalazins und seiner Ionen an Hand der Säkulardeterminanten und der aus ihnen abgeleiteten Größen führt zu einer Eingrenzung der einzelnen Energieterme und der Anregungsenergien.Mit 4 AbbildungenMeinem verehrten Lehrer, Herrn, Prof. Dr.F. Wessely, zum 60. Geburtstag in Dankbarkeit gewidmet.     

Bifunctional monodisperse microspheres of copolymers of methyl methacrylate and N-vinylformamide

Emulsion copolymerization of methyl methacrylate and N-vinylformamide in the presence of azo initiators and dextran as a polymeric stabilizer was analyzed with the aim to prepare monodisperse polymer microspheres with a polyfunctional surface. Hydrolysis of comonomer units and cationic groups of the initiator residues in the surface layer of the particles to give amphoteric surfaces containing carboxy and amino groups was studied. The optimal conditions of formation of monodisperse microspheres with diameter varied in the 340–660 nm range and the conditions of their hydrolysis, which allow direct control of the amount and nature of functional groups on their surface, were found.