Elektrochemische und spektroskopische Untersuchung dünner Edelmetallfilme auf einer Ruthenium(0001)-Oberfläche

Die Münzmetalle Kupfer, Silber und Gold wurden sowohl elektrochemisch auf einer Ruthenium(0001)-Oberfläche abgeschieden, als auch im Ultrahochvakuum aufgedampft. Anschließend wurde das Desorptionsverhalten der Metallfilme in der Elektrochemie und im Vakuum untersucht und dadurch ein direkter Vergleich zwischen elektrochemischen und UHV- Messungen hergestellt. Durch den Einsatz einer Transferapparatur waren diese Experimente möglich, ohne den Rutheniumeinkristall, der sehr empfindlich gegen Sauerstoffkontaminationen ist, durch einen Transport zwischen verschiedenen Apparaturen zu verunreinigen. Zur Untersuchung im Ultrahochvakuum standen die Röntgen-Photoelektronenspektroskopie (XPS), die Ionenstreuspektroskopie (ISS), die Beugung niederenergetischer Elektronen (LEED) und die Thermische-Desorptionsspektroskopie (TDS) zur Verfügung. In der elektrochemischen Zelle wurden die Edelmetallfilme mittels zyklischer Voltammetrie (CV) untersucht. Ziel der Arbeit war es elektrochemisch abgeschiedene und im Ultrahochvakuum aufgedampfte Kupfer-, Silber- und Goldfilme auf Ruthenium(0001) vergleichend auf ihr elektrochemisches bzw. thermisches Desorptionsverhalten hin zu untersuchen. Auf diese Weise konnten Hinweise auf die Wechselwirkung dieser drei Metalle mit Ruthenium sowohl in elektrolytischer Lösung als auch im UHV erhalten werden. Auftretende Unterschiede zwischen den drei Metallen wurden zudem u.a. im Lichte von Literaturdaten diskutiert

4-tert-Butyl-2-[2-(1,3,3-trimethyl­indolin-2-yl­idene)ethyl­idene]cyclo­hexa­none

The title mol­ecule, C23H31NO, has two alternative cyclo­hexa­none configurations at the 4-position in a ratio of 0.663 (3):0.337 (3). The plane of the five-membered planar ring in the indolin-2-yl­idene subtends an angle of 2.19 (7)° with its fused aromatic ring, an angle of 16.24 (8)° with the plane of the major cyclo­hexa­none configuration and an angle of 8.54 (15)° with the bridging planar ethyl­idene C atoms. These last atoms subtend an angle of 8.37 (16)° with the mean plane through the major cyclo­hexa­none configuration. The mol­ecules pack approximately parallel to the (01) plane via C—H⋯π and C—H⋯O inter­actions

Mechanistic insights into the Nb2O5 and niobium phosphate catalyzed in situ condensation of a fluorescent halochromic assembly

[EN] Solid niobium oxides (Nb2O5 center dot nH(2)O) and niobium phosphate were used as heterogeneous acid catalysts to promote the condensation between a switchable oxazine and a fluorescent coumarin in an aprotic solvent. The catalysts were found to promote the generation of an active methylene from the enamine-based portion of the oxazine, which was followed by a nucleophilic attack on the aldehyde functionality of the coumarin reagent. In the resulting system, the emission of the conjugated fluorophore can be observed at 670 nm and, thus, the processes occurring at the catalyst surface can be monitored in real time by total internal reflection fluorescence microscopy (TIRFM).The authors wish to thank the Natural Sciences and Engineering Research Council (NSERC) and the Canada Research Chairs program. The University of Ottawa International Office provided grants to study niobium. Thanks are due to the Government of Canada and NSERC for a Banting Postdoctoral Fellowship to S. Impellizzeri and a Vanier Scholarship to C. Fasciani. S. Simoncelli acknowledges a DFAIT fellowship from ELAP (Emerging Leaders in the Americas Program) to support her visit to Canada. M. L. Marin thanks the financial support of the Generalitat Valenciana (BEST/2012/233) and the Distinguished Visiting Professor program of the University of Ottawa. We thank Dr. Jose-Carlos Netto-Ferreira of INMETRO (Rio de Janeiro, Brazil) for providing chemicals from CBMM.Impellizzeri, S.; Simoncelli, S.; Fasciani, C.; Marín García, ML.; Hallett-Tapley, GL.; Hodgson, GK.; Scaiano, JC. (2015). Mechanistic insights into the Nb2O5 and niobium phosphate catalyzed in situ condensation of a fluorescent halochromic assembly. Catalysis Science and Technology. 5(1):169-175. https://doi.org/10.1039/C4CY00703DS1691755

Thermal reversion of spirooxazine in ionic liquids containing the [NTf2]- anion

We have compared the rate of thermal reversion of Spirooxazine (SO) from its merocyanine (MC) form within ionic liquids and molecular solvents. Et(30) and Kamlet-Taft parameter studies indicate ILs are comparable to polar protic and aprotic solvents. The observed reversion kinetics within the ionic liquids were slower than that of molecular solvents with similar polarity, indicating a greater degree of interactions between the ionic liquid ions and the zwitterionic MC isomer, which led to increased lifetimes for the MC-ion complexes. Pre-metathesis cleaning of precursor salts was found to be necessary in order to obtain spectroscopic grade ILs for physiochemical analysis using solvatochromic probe dyes

Multi-branched benzylidene ketone based photoinitiators for multiphoton fabrication

In this article, we report the synthesis of a series of multi-branched benzylidene (BI) ketone-based photo-initiators for two-photon polymerisation based 3D printing/additive manufacturing. Resins prepared by the addition of 1 wt.% of these initiators were processed in a commercial 2 photon polymerisation system to fabricate 3D woodpile structures, the qualities of which were examined to determine the efficiencies of the initiators. The results showed that compared to commercial initiator Irgacure 369, the four-branched initiator 4-BI exhibited excellent performance with higher writing speeds and broader ideal processing windows. The successful fabrication of complex 3D structures at high writing speeds (up to 100 mm/s) indicated that the four-branched initiator 4-BI could potentially increase the fabrication efficiency and hence become a promising initiator for two-photon polymerisation