We report on the use of a 2 nd -generation Hoveyda-Grubbs-type catalyst immobilized inside mesoporous silica for the application in selective macro(mono)cyclization (MMC) of an α,ω-diene under spatially confined and continuous-flow conditions. Reactions carried out with different flow rates allow for variations in residence time; conversion and MMC selectivity can be determined for well-defined reaction times. Analysis of the reaction mixtures obtained for different reaction times and temperatures in a single flow experiment by NMR and MALDI-TOF-MS allows to address confinement effects and to determine olefin metathesis pathways. These investigations revealed that ring-chain equilibria are quickly established but substantially affected by residence time and flow, allowing for the determination of conditions under which MMC selectivity reaches a maximum. In contrast to reactions carried out in solution, in which oligomers up to the hexamer were observed, MMC under confinement predominantly proceeds via ring-closing metathesis of the monomer and backbiting from the dimer and trimer, but not from higher oligomers as their formation is suppressed. This leads to the observed high MMC selectivity, reaching 60 % at a 25 mM substrate concentration.

Well-defined multiwalled carbon nanotube structures are generated on stainless steel AISI 304 (EN AW 1.4301) by chemical vapor deposition. Pulsed laser-induced dewetting (PLiD) of the surface, by 532 nm nanosecond laser pulses, is utilized for the preparation of metal oxide nanoparticle fields with a defined particle number per area. The reduction of the precursor particles is achieved in an Ar/H2 (10% H2) atmosphere at 750 °C, thereby generating catalytic nanoparticles (c-NPs) for carbon nanotube (CNT) growth. Ethylene is used as a precursor gas for CNT growth. CNT lengths and morphology are directly related to the c-NP aerial density, which is dependent on the number of dewetting cycles during the PLiD process. Within a narrow window of c-NP per area, vertically aligned carbon nanotubes of great lengths are obtained. For more intense laser treatments, three-dimensional dewetting occurs and results in the formation of cauliflower-like structures. The laser process enables the creation of all kinds of CNT morphologies nearby on the microscale.