Pascal Steffanut

Photocatalytically Active Polyelectrolyte/Nanoparticle Films for the Elimination of a Model Odorous Gas

Virtually transparent films of Aeroxide TiO(2) P25 were fabricated via layer-by-layer assembly with sodium poly(styrene sulfonate). Nanoscale films are formed on model surfaces for characterization or inside of cylindrical reactors for investigating the catalytic properties. Films are fairly homogeneous and smooth over large areas and show different optical interference colors depending on film thickness. The application-relevant photocatalytic performance of such films toward on-flow degradation of hydrogen sulfide under UV-A irradiation was investigated. Scanning electron microscopy reveals a nanoporous structure allowing for the permeation of gas. Consequently, the catalytic efficiency of the films increases with increasing film thickness retaining a considerable activity of the corresponding nanoparticle powder. Scheme 1 depicts in a general way the functionalized reactor and the principle of the measurement.

Combining NHC bis-phenolate ligands with oxophilic metal centers: a powerful approach for the development of robust and highly effective organometallic catalysts.

The present paper describes an overview of a novel family of tridentate NHC pincer ligand in which two phenoxide moieties are directly connected to the nitrogen atoms of a central N-heterocyclic carbene. It was envisioned that such a structure might be suitable for coordination to a variety of metal centers across the periodic table, including oxophilic metals. Various metal complexes bearing such ligand are indeed readily accessible in high yields via straightforward routes. Interestingly, a robust zirconium-NHC complex was found to polymerize rac-lactide in a highly controlled, living and stereoselective manner to afford heterotactic PLA.