Carl Vercaemst

Ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores

E-configured ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores and unprecedented pore volumes have been developed for the first time.

Isomeric periodic mesoporous organosilicas with controllable properties

The synthesis procedure for isomeric periodic mesoporous organosilicas with E-configured ethenylene bridges was investigated using the homemade pure E-isomer of 1,2-bis(triethoxysilyl)ethene. The pH, aging temperature and the presence of cosolvents played a key role in obtaining well-ordered mesoporous materials with controllable properties and morphologies. By fine-tuning the reaction mixture acidity, PMOs with high surface areas and pore volumes could be attained. By selecting various alcohols as cosolvents and optimizing the alcohol concentration, PMOs with crystal-like disc shaped, fibrous and spherical particle morphologies were obtained. The synthesis temperature of these ethenylene-bridged PMOs influences the pore size, structure, connectivity and volume.

A new sulphonic acid functionalized periodic mesoporous organosilica as a suitable catalyst

Abstract A new solid acid catalyst is developed by the direct sulphonation of the ethene bond of a pure trans ethene bridged Periodic Mesoporous Organosilica. The catalytic activity of this mesoporous material is evaluated in an esterification reaction and compared with p-toluenesulphonic acid. The sulphonated ethene PMO can compete with a homogeneous catalyst and maintains its porosity.

Active Ru catalysts in carbene chemistry: A kinetic study of carbene formation and an evaluation of selective cyclopropanation

p-Cymene–Ru catalysts containing bidentate N,O-Schiff base ligands, known as active catalysts in various reactions, are studied in relation to the cyclopropanation of olefins with ethyl diazoacetate. The study is divided into two parts. (1) The decomposition of ethyl diazoacetate is followed by FT-IR and elementary kinetic parameters calculated. (2) The selectivity and diastereoselectivity of cyclopropanation is then determined by GC analysis. The catalysts and ligands are fully characterized by FT-Raman and NMR spectroscopy. Furthermore, catalyst stabilities are checked by means of TGA measurements. It is found especially that the electronic properties of the ligands determine catalyst performance.