G. Eric Oosterom

Bio: G. Eric Oosterom is an academic researcher from University of Amsterdam. The author has contributed to research in topics: Dendrimer & Catalysis. The author has an hindex of 6, co-authored 8 publications receiving 749 citations.

Transition Metal Catalysis Using Functionalized Dendrimers.

Abstract: Dendrimers are well-defined hyperbranched macromolecules with characteristic globular structures for the larger systems These novel polymers have inspired many chemists to develop new materials and several applications have been explored, catalysis being one of them The recent impressive strides in synthetic procedures increased the accessibility of functionalized dendrimers, resulting in a rapid development of dendrimer chemistry The position of the catalytic site(s) as well as the spatial separation of the catalysts appears to be of crucial importance Dendrimers that are functionalized with transition metals in the core potentially can mimic the properties of enzymes, their efficient natural counterparts, whereas the surface-functionalized systems have been proposed to fill the gap between homogeneous and heterogeneous catalysis This might yield superior catalysts with novel properties, that is, special reactivity or stability Both the core and periphery strategies lead to catalysts that are sufficiently larger than most substrates and products, thus separation by modern membrane separation techniques can be applied These novel homogeneous catalysts can be used in continuous membrane reactors, which will have major advantages particularly for reactions that benefit from low substrate concentrations or suffer from side reactions of the product Here we review the recent progress and breakthroughs made with these promising novel transition metal functionalized dendrimers that are used as catalysts, and we will discuss the architectural concepts that have been applied

Übergangsmetallkatalyse mit funktionalisierten Dendrimeren

Abstract: Dendrimere sind wohldefinierte hochverzweigte Makromolekule, die bei hinreichender Grose charakteristische globulare Strukturen aufweisen. Sie haben viele Chemiker zur Entwicklung von neuen Materialien angeregt, und eine Reihe von Anwendungen, auch in der Katalyse, wurde bereits untersucht. Die jungsten Fortschritte bei den Syntheseverfahren haben den Zugang zu funktionalisierten Dendrimeren sehr vereinfacht, was zu einer raschen Entwicklung der Dendrimerchemie gefuhrt hat. Sowohl die Lage der katalytischen Zentren als auch die raumliche Trennung der Katalysatoren scheinen hier wesentlich zu sein. Dendrimere, die im Kern mit Ubergangsmetallen funktionalisiert sind, sind potentielle Enzymmimetika; die an der Oberflache funktionalisierten hingegen konnten die Lucke zwischen homogener und heterogener Katalyse fullen. Dies konnte vorzugliche Katalysatoren mit neuartigen Eigenschaften – besonderer Reaktivitat oder Stabilitat – liefern. Sowohl die kern- als auch die peripherieorientierte Strategie ergeben Katalysatoren, die die meisten Substrate und Produkte an Grose deutlich ubertreffen, sodass eine Abtrennung durch moderne Membrantrenntechniken moglich ist. Diese neuen homogenen Katalysatoren lassen sich in kontinuierlich betriebenen Membranreaktoren verwenden, was vor allem bei solchen Reaktionen sehr vorteilhaft ware, die von niedrigen Substratkonzentrationen profitieren oder durch Nebenreaktionen des Produkts beeintrachtigt werden. Wir geben hier einen Uberblick uber die jungsten Fortschritte auf dem Gebiet der Ubergangsmetall-funktionalisierten Dendrimere, die als Katalysatoren eingesetzt werden; auch die unterschiedlichen Konzepte fur ihre Architektur werden besprochen.

Core-functionalized dendrimeric mono- and diphosphine rhodium complexes; application in hydroformylation and hydrogenation

Abstract: Three novel series of core-functionalized dendrimeric phosphine ligands were synthesized and their rhodium complexes were studied as catalysts in both hydroformylation and hydrogenation of alkenes. Generally similar activities were obtained for the dendrimeric systems and the parent compounds except in the hydroformylation of a bulky substrate, 4,4,4-triphenylbut-1-ene, which gave a significant decrease in activity when the larger dendrimers were used. The rhodium complexes of the dppf-type dendrimeric ligands were studied in the hydrogenation of dimethyl itaconate in a continuous-flow membrane reactor showing a reasonable constant formation of the product compared to the non-dendrimeric catalyst.

Dendrimer-Encapsulated Metal Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

Abstract: This Account reports the synthesis and characterization of dendrimer-encapsulated metal nanoparticles and their applications to catalysis. These materials are prepared by sequestering metal ions within dendrimers followed by chemical reduction to yield the corresponding zerovalent metal nanoparticle. The size of such particles depends on the number of metal ions initially loaded into the dendrimer. Intradendrimer hydrogenation and carbon−carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO2 are also described.

Platinum Group Organometallics Based on “Pincer” Complexes: Sensors, Switches, and Catalysts

Abstract: Since the first reports in the late 1970s on transition metal complexes contain- ing pincer-type ligands—named after the particular coordination mode of these ligands—these systems have at- tracted increasing interest owing to the unusual properties of the metal centers imparted by the pincer ligand. Typical- ly, such a ligand comprises an anionic aryl ring which is ortho,ortho-disubsti- tuted with heteroatom substituents, for example, CH2NR2 ,C H 2PR2 or CH2SR, which generally coordinate to the met- al center, and therefore support the MC s bond. This commonly results in a terdentate and meridional coordina- tion mode consisting of two metalla- cycles which share the MC bond. Detailed studies of the formation and the properties of a large variety of pincers containing platinum group metal complexes have provided direct access to both a fundamental under- standing of a variety of reactions in organometallic chemistry and to a range of new applications of these complexes. The discovery of alkane dehydrogenation catalysts, the mecha- nistic elucidation of fundamental transformations (for example, CC bond activation), the construction of the first metallodendrimers for sustain- able homogeneous catalysis, and the engineering of crystalline switches for materials processing represent only a few of the many highlights which have emanated from these numerous inves- tigations. This review discusses the synthetic methodologies that are cur- rently available for the preparation of platinum group metal complexes con- taining pincer ligands and especially emphasizes different applications that have been realized in materials science such as the development and engineer- ing of sensors, switches, and catalysts.

Dendritic Encapsulation of Function: Applying Nature's Site Isolation Principle from Biomimetics to Materials Science.

Abstract: The convergence of our understanding of structure-property relationships for selected biological macromolecules and our increased ability to prepare large synthetic macromolecules with a structural precision that approaches that of proteins have spawned a new area of research where chemistry and materials science join with biology. While evolution has enabled nature to perfect processes involving energy transfer or catalysis by incorporating functions such as self-replication and repair, synthetic macromolecules still depend on our synthetic skills and abilities to mesh structure and function in our designs. Clearly, we can take advantage of our understanding of natural systems to mimic the structural features that lead to optimized function. For example, numerous biological systems make use of the concept of site isolation whereby an active center or catalytic site is encapsulated, frequently within a protein, to afford properties that would not be encountered in the bulk state. The ability of the dendritic shell to encapsulate functional core moieties and to create specific site-isolated nanoenvironments, and thereby affect molecular properties, has been explored. By utilizing the distinct properties of the dendrimer architecture active sites that have either photophysical, photochemical, electrochemical, or catalytic functions have been placed at the core. Applying the general concept of site isolation to problems in materials research is likely to prove extremely fruitful in the long term, with short-term applications in areas such as the construction of improved optoelectronic devices. This review focuses on the evolution of a natural design principle that contributes to bridging the gap between biology and materials science. The recent progress in the synthesis of dendrimer-encapsulated molecules and their study by a variety of techniques is discussed. These investigations have implications that range from the preliminary design of artificial enzymes, catalysts, or light-harvesting systems to the construction of insulated molecular wires, light-emitting diodes, and fiber optics.

Supramolecular catalysis. Part 2: artificial enzyme mimics

Abstract: The design of artificial catalysts able to compete with the catalytic proficiency of enzymes is an intense subject of research. Non-covalent interactions are thought to be involved in several properties of enzymatic catalysis, notably (i) the confinement of the substrates and the active site within a catalytic pocket, (ii) the creation of a hydrophobic pocket in water, (iii) self-replication properties and (iv) allosteric properties. The origins of the enhanced rates and high catalytic selectivities associated with these properties are still a matter of debate. Stabilisation of the transition state and favourable conformations of the active site and the product(s) are probably part of the answer. We present here artificial catalysts and biomacromolecule hybrid catalysts which constitute good models towards the development of truly competitive artificial enzymes.