Synthesen,chemische und elektrische Eigenschaften von Tetrathiafulvalen mit 1,6-Methano[10]annulen-Partialstruktur und von Chalcogendiimid-derivaten

Syntheses, Chemical and Electrical Properties of Tetrathiafulvalene with a 1,6-Methano[10]annulene Moiety and of Chalcogendiimide-Derivatives The synthesis of the tetrathiafulvalene 6 has been described: the reaction of 1 with the benzenedithoil 2 yielded the bis-dithioacetal 3 of 1,6-methano[10]annulene-dicarbaldehyde 1 . The oxidation of 3 in the presence of HBF₄ in Et₂O yielded the salt 4 , elimination of a hydride anion with triphenylmethylium tetrafluoroborate the salt 5 , and elimination of a proton in 5 with Et₃N the tetrathiafulvalene 6 with a 1,6-methano[10]annulene moiety. The spectroscopic and electrochemical properties of 6 are described, and also the syntheses and properties of charge-trasnfer complexes 7 and 8 , including the properties of electric conductivity of 7 and 8 . the syntheses of 9-13 are reported and also their spectroscopic properties.     

Chloroalkylsulfonate ionic liquids by ring opening of sultones with organic chloride salts

An efficient route to prepare ionic liquids with chloroalkylsulfonate anions is presented; the synthesis proceeds in a one-step ring-opening reaction of sultones with an organic chloride salt and provides a very attractive access to new anion functionalised ionic liquids.     

Understanding the contrast mechanism in scanning tunneling microscopy (STM) images of an intermixed tetraphenylporphyrin layer on Ag(111)

The appearance of tetraphenylporphyrins in scanning tunneling micrographs depends strongly on the applied bias voltage. Here, we report the observation and identification of certain features in scanning tunneling microscopy (STM) images of intermixed layers of tetraphenylporphyrin (2HTPP) and cobalt-tetraphenylporphyrin (CoTPP) on Ag(111). A significant fraction of an ordered monolayer of commercially available CoTPP appears as "pits" at negative bias voltages around -1 V. The obvious possibility that these pits are missing molecules within the ordered layer could be ruled out by imaging the molecules at reduced bias voltages, at which the contrast of the pits fades, and at positive bias voltages around +1 V, at which the image contrast is inverted. With the investigation of the electronic structure, in particular the density of states (DOS) close to the Fermi level, of CoTPP and 2HTPP layers by means of ultraviolet photoelectron spectroscopy (UPS) and scanning tunneling spectroscopy (STS), the contrast mechanism was clarified. The correlation of the bias dependent contrast with the UPS data enabled us to interpret the "pits" as individual 2HTPP molecules. Additional evidence could be provided by imaging layers of different mixtures of 2HTPP and CoTPP and by high-resolution STM imaging of the features in CoTPP.     

Chemical sensor based on a long-period fibre grating modified by a functionalized polydimethylsiloxane coating

A chemical sensor based on a coated long-period grating has been prepared and characterized. Designer coatings based on polydimethylsiloxane were prepared by the incorporation of diphenylsiloxane and titanium cross-linker in order to provide enhanced sensitivity for a variety of key environmental pollutants and optimal refractive index of the coating. Upon microextraction of the analyte into the polymer matrix, an increase in the refractive index of the coating resulted in a change in the attenuation spectrum of the long-period grating. The grating was interrogated using ring-down detection as a means to amplify the optical loss and to gain stability against misalignment and power fluctuations. Chemical differentiation of cyclohexane and xylene was achieved and a detection limit of 300 ppm of xylene vapour was realized.     

Interfacial Reactions of Tetraphenylporphyrin with Cobalt-Oxide Thin Films

We have studied the adsorption and interfacial reactions of 2H-tetraphenylporphyrin (2HTPP) with cobalt-terminated Co₃O₄(111) and oxygen-terminated CoO(111) thin films using synchrotron-radiation X-ray photoelectron spectroscopy. Already at 275 K, we find evidence for the formation of a metalated species, most likely CoTPP, on both surfaces. The degree of self-metalation increases with temperature on both surfaces until 475 K, where the metalation is almost complete. At 575 K the porphyrin coverage decreases drastically on the reducible cobalt-terminated Co₃O₄(111) surface, while higher temperatures are needed on the non-reducible oxygen-terminated CoO(111). The low temperature self-metalation is similar to that observed on MgO(100) surfaces, but drastically different from that observed on TiO₂(110), where no self-metalation is observed at room temperature.     

Zur Stetigkeit rationaler T-Approximationen über unbeschränkten Intervallen

Summary In this paper, we study the continuity of the dependence of best rational. approximations to functions real-valued and continuous on unbounded intervals. We give sufficient conditions for continuity which seem to be also necessary.