Final Report Summary - NANOSONWINGS (A new vision on nanocatalysts)
A range of ligands has been investigated for RuNPs and RuPtNPs and indeed the catalytic activity for hydrogenation varied enormously with the nature of the ligand, the substrate and the solvent. New phosphine ligands were designed and synthesized carrying wings that were thought to protect the nanoparticles. Several known carbene ligands carrying wings were applied on NMPs for the first time. As the ligands change during the preparation process it was important to establish their nature on the actual nanoparticle catalyst, also after the catalysis. A variety of state-of-the-art spectroscopic techniques were used to ascertain the bonding mode to the metal and the nature of the ligands, and also the dynamics of the species at the surface.
It was found that for arene hydrogenation the strongest donor ligands gave the fastest catalysts, but unfortunately they are also the least stable. However, the second best systems still are the fastest catalysts known today per gram of metal used. An immobilized version gave unusually high rates and for this one we applied for a patent.
During the hydrogenation studies of organic substrates by ruthenium nanoparticles we found a new reaction to forma pyrazines from diketones, which was found to be a reaction that only took place when nanoparticles were used and not for any other catalyst, be they homogeneous or heterogeneous. The products are useful in medicinal chemistry.
Selective hydrogenations of substrates containing more unsaturated groups were studied and interesting selectivities were found. Amongst these substrates also bio-feedstocks were hydrogenated and remarkable selectivities were observed in some cases. A new gold catalyst was developed using ligands not earlier used in metal nanoparticle research that selectively only catalyses the hydrogenation of aldehydes. However, when electron rich ligands were used, gold returned to its common activity for nitro reduction and the selectivity of the catalyst was lost for substrates that contain both functional groups.
We found an easy and reproducible low temperature process for the tunable synthesis of monodisperse, high quality iron carbide and iron/iron carbides nanocrystals, air-stable after some initial losses and displaying excellent magnetic properties with tunable magnetic anisotropy. These particles have no precedent. Like for the other nanoparticles the synthesis is based on an organometallic approach, unprecedented in this instance. Several new spectroscopic techniques were explored and one of them was entirely new which gave our results an extra push forward.
In summary with new nanoparticles in hand, new synthetic routes developed, state-of-the-art spectroscopy applied, we have made major progress in the field.