Single-crystal structures of polyphenylene dendrimers

A series of first-generation polyphenylene dendrimers based on three different cores were prepared by Diels-Alder cycloaddition and their single-crystal structures were determined. Consisting exclusively of interlocked, twisted phenyl rings, these polyphenylene nanostructures have exciting structural and dynamic properties. Single crystals of dendrimers, suitable for X-ray structure analysis, were grown from different solvent mixtures by slow evaporation at room temperature. It should be pointed out that one of the described polyphenylene dendrimers represents up to now the biggest oligophenylene nanostructure from which crystallographic data is available.     

Quantitative depth profiling in glow discharge spectroscopies – A new deconvolution technique to separate effects of an uneven erosion crater shape

An algorithm is presented as a concept for the quantification in direct current and radiofrequency glow discharge (GD) modes for GD optical emission spectroscopy. The algorithm is divided into excitation and sputtering part and thus it is possible to distinguish between the different excitation processes and to consider equivalent sputtering crater formations in both modes. Intensity-time profiles are affected corresponding to the method by several effects. One important effect is that sputtering occurs at a single time in different depths because of curved crater bottoms, this is usually called crater effect. The main purpose is to introduce an iterative deconvolution technique which for the quantification numerically takes into account the curved sputtering crater bottom. Input data for the deconvolution technique are the calibrated mass-time profile, the partial densities of the sample constituents and the measured final shape of the sputtering crater. Using a relatively simple model for ion sputtering the deconvolution technique improves iteratively the calculated layer structure by means of information on crater formation. The mathematical handling is illustrated for the quantification of a depth profile of a multilayer sample of ten 100 nm layers. The resulting concentration-depth profile reflects excellently the real elemental distribution of the multilayer system.     

carbon-carbon bond formation between 1,3-dienes and electron deficient alkenes

1,3-Dienes and electron deficient alkenes are coupled in a one pot carbon-carbon bond formation reaction under mild conditions.     

Gold

Ohne Zusammenfassung     

Vibronic spectral behavior of molecules: XVIII. Theoretical contribution to the S1→S0 fluorescence of the isomeric phenyl naphthalenes within the Herzberg-Teller approach

Theoretical vibronic S₁S₀ line spectra of the isomeric phenyl naphthalenes calculated within the Condon as well as the Herzberg-Teller approaches on the basis of completely optimizedS ₀ andS ₁ molecular geometries, are presented and are contrasted with the experimental fluorescence spectra. The theory-experiment comparison is successful only within the Herzberg-Teller approximation by explicitly including the Dushinsky transformation. An analysis of the significant vibrational modes is given.