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Université de Fribourg

Theoretical study of the stacking behavior of selected polycondensed aromatic hydrocarbons with various symmetries

Antony, Jens ; Alameddine, Bassam ; Jenny, Titus A. ; Grimme, Stefan

In: The Journal of Physical Chemistry A, 2012, vol. 117, no. 3, p. 616–625

Stacked dimers of four polycondensed aromatic hydrocarbons, with structures varying from high to reduced symmetries, have been calculated with dispersion-corrected density functional theory. The configurations of the stacked dimers are readily classified by two in-plane displacements and a relative rotation. The potential energy surface in these three coordinates was calculated with rigid...

Université de Fribourg

Synthesis of alkyl-Substituted tribenzopentaphenes as versatile polycondensed aromatic hydrocarbon π-π stacking building blocks

Alameddine, Bassam ; Caba, Sofia Martin ; Schindler, Mauro ; Jenny, Titus A.

In: Synthesis, 2012, vol. 44, p. 1928-1934

We show the versatile synthesis of four tribenzopentaphene derivatives bearing alkyl side chains at three different positions. Substitutions on two of these positions led to subtle intensity changes at the lines of the blue emission, whereas alkylation in the bay region led to dimerization of the pentaphene derivative, resulting in a distortion of the chromophore geometry and an emission shift to...

Université de Fribourg

Synthesis of Hexa-peri-hexobenzocoronenes Carrying Linear or Branched Perfluoroalkylated Side Chains

Aebischer, Olivier F. ; Muñoz, David T. ; Tondo, Patrick ; Débieux, Jean-Luc ; Jenny, Titus A.

In: Synthesis, 2010, vol. 7, p. 1123-1140

Substituted disc-shaped perfluoroalkylated hexa-peri-hexabenzocoronenes (HBC), known to self-assemble into conducting ordered architectures, were synthesized and characterized. A systematic variation of the linear or branched perfluoroalkylated side chains was performed in order to screen the influence of the lateral chain on their one-dimensional self-aggregation.

Université de Fribourg

Thermal runaway of dried sewage sludge granules in storage tanks

Poffet, Martine S. ; Käser, Kurt ; Jenny, Titus A.

In: Chimia, 2008, vol. 62, no. 1-2, p. 29-34

Elimination of the sewage sludge from urban wastewater occurs exclusively by incineration in Switzerland, because recycling as fertilizer in agriculture has been banned since October 2006. Two options exist for elimination, either thermal elimination of a thickened sludge in a household waste incineration plant, or drying of the thickened sludge to yield a granular material fit for storage and...

Université de Fribourg

Controlling the lateral aggregation of perfluoroalkylated hexa-peri-hexabenzocoronenes

Aebischer, Olivier F. ; Aebischer, Annina ; Donnio, Bertrand ; Alameddine, Bassam ; Dadras, Massoud ; Güdel, Hans-Ulrich ; Guillon, Daniel ; Jenny, Titus A.

In: Journal of Materials Chemistry, 2007, vol. 17, no. 13, p. 1262-1267

The investigation of two hexa-peri-hexabenzocoronene (HBC) derivatives carrying linear or branched perfluoroalkylated side chains is reported. Polycondensed aromatic hydrocarbons (PAH) such as HBC derivatives are well known to self-organize to form highly ordered monomolecular stacks, which in turn show a concentration- and solvent-dependent lateral aggregation. However, possible...

Université de Fribourg

Synthesis of perfluoroalkylated bulky triarylamines

Alameddine, Bassam ; Savary, Corinne ; Aebischer, Olivier ; Jenny, Titus A.

In: Synthesis, 2007, p. 271-276

The synthesis of two new triarylamine compounds bearing perfluoroalkylated side chains is described. Good thermal stabilities combined with a blue emission make these compounds promising candidates for materials applications.

Université de Fribourg

Self-aggregated perfluoroalkylated hexa-peri-hexabenzocoronene fibers observed by cryo-SEM and fluorescence spectroscopy

Aebischer, Olivier F. ; Aebischer, Annina ; Tondo, Patrick ; Alameddine, Bassam ; Dadras, Massoud ; Güdel, Hans-Ulrich ; Jenny, Titus A.

In: Chemical Communications, 2006, p. 4221 - 4223

The self-assembled architectures in solution of a new HBC derivative bearing perfluoroalkylated side chains were investigated by optical excitation and emission spectroscopy and correlated to cryo-SEM, a new technique in organic chemistry.

Université de Fribourg

Possible ring structures of armchair single-walled carbon nanotubes

Tamilmani, Venkatachalam ; Daul, Claude A. ; Jenny, Titus A.

In: Chimia, 2006, vol. 60, no. 4, p. 228-230

Energetics and the electronic structure of various types of single-walled carbon nanotubes have been investigated by using Density Functional Theory. Armchair [n,n], zigzag [n,0] and chiral [n,m] C₄₀H₂₀ nanotubes have been considered. Calculations show that the armchair isomer is the most stable among the three types and they further reveal the factors that stabilize this isomer....

Université de Fribourg

Synthesis of Novel Fluorinated Hexa-peri-hexabenzocoronenes

Aebischer, Olivier F. ; Tondo, Patrick ; Alameddine, Bassam ; Jenny, Titus A.

In: Synthesis, 2006, vol. 17, p. 2891–2896

The synthesis of several perfluoroalkylated hexabenzocoronene derivatives is described. The substituents range from linear semiperfluoroalkylated chains to branched perfluoroalkylated chains. Novel strategies were applied to overcome the low solubility and the low reactivity of such chains.

Université de Fribourg

Geometry determination of tetrasubstituted stilbenes by proton NMR spectroscopy

Fluxá, Viviana S. ; Jenny, Titus A. ; Bochet, Christian G.

In: Tetrahedron Letters, 2005, vol. 46(2), p. 3793-3795

A simple spectroscopic method was applied to determine the geometry of tetrasubstituted alkenes. The observation of the ⁵J-coupling constants in proton NMR spectra on the ¹³C satellite signals could confirm the previous misassignment of 2,3-diphenylbutene. Hence, the (E)-isomer showed a 1.5 Hz coupling constant, whereas the (Z)-isomer showed a 1.1 Hz coupling constant. Based on this new...