No abstract

No abstract

Functional polyolefins (i.e., polyethene or polypropene bearing functional groups) are highly desired materials, due to their beneficial surface properties. Many different pathways exist for the synthesis of these materials, each with its own advantages and drawbacks. This review focuses on those synthetic pathways that build up a polymer chain from ethene/propene and functionalised polar vinyl monomers. Despite many recent advances in the various fields of olefin polymerisation, it still remains a challenge to synthesise high molecular-weight copolymers with tuneable amounts of functional groups, preferably with consecutive insertions of polar monomers occurring in a stereoselective way. To overcome some of these challenges, polymerisation of alternative functionalised monomers is explored as well.

The reactivity of organotransition metal complexes is dependent on the ligand environment of the metal. This Account describes the development and application of new diphosphine ligands, designed to induce large P-M-P angles in transition metal complexes. Aided by computational chemistry, a homologous range of diphosphines based on rigid heterocyclic aromatic backbones of the xanthene-type with natural bite angles of approximately 100-134 degrees have been developed. The special structure of the ligands has an enormous impact on stability and reactivity of various transition metal complexes. Highly active and selective catalysts have been obtained by influencing this reactivity.

Confined nanospaces in which reactions can take place, have been created by various approaches such as molecular capsules, zeolites and micelles. In this tutorial review we focus on the application of self-assembled nanocapsules with well-defined cavities as nanoreactors for organic and metal catalysed transformations. The self-assembly of nanocapsules based on noncovalent bonds such as hydrogen bonds and metal-ligand interactions is discussed to introduce the properties of the building blocks and capsules thereof. We will elaborate on the encapsulation effects that can be expected when reactions are carried out in a capsule-protected environment. Subsequently, literature examples will be described in which self-assembled nanocapsules are applied as nanoreactors, for various types of organic and metal catalysed reactions.

Supramolecular catalysis - the assembly of catalyst species by harnessing multiple weak intramolecular interactions - has, until recently, been dominated by enzyme-inspired approaches. Such approaches often attempt to create an enzyme-like 'active site' and have concentrated on reactions similar to those catalysed by enzymes themselves. Here, we discuss the application of supramolecular assembly to the more traditional transition metal catalysis and to small-molecule organocatalysis. The modularity of self-assembled multicomponent catalysts means that a relatively small pool of catalyst components can provide rapid access to a large number of catalysts that can be evaluated for industrially relevant reactions. In addition, we discuss how catalyst-substrate interactions can be tailored to direct substrates along particular reaction paths and selectivities.

Transition metal catalysis plays an important role in both industry and in academia where selectivity, activity and stability are crucial parameters to control. Next to changing the structure of the ligand, introducing a confined space as a second coordination sphere around a metal catalyst has recently been shown to be a viable method to induce new selectivity and activity in transition metal catalysis. In this review we focus on supramolecular strategies to encapsulate transition metal complexes with the aim of controlling the selectivity via the second coordination sphere. As we will discuss, catalyst confinement can result in selective processes that are impossible or difficult to achieve by traditional methods. We will describe the template-ligand approach as well as the host-guest approach to arrive at such supramolecular systems and discuss how the performance of the catalyst is enhanced by confining it in a molecular container.

Co@NH2-MIL-125(Ti): Cobaloxime-derived Metal-Organic Framework-based Composite for Light-driven H2 Production Nasalevich, M.A.; Becker, R.; Ramos-Fernandez, E.V.; Castellanos, S.; Veber, S.L.; Fedin, M.V.; Kapteijn, F.; Reek, J.N.H.; van der Vlugt, J.I.; Gascon, J. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We present a synthetic strategy for the efficient encapsulation of a derivative of a well-defined cobaloxime proton reduction catalyst within a photoresponsive metal-organic framework (NH 2 -MIL-125(Ti)). The resulting hybrid system Co@MOF is demonstrated to be a robust heterogeneous composite material. Furthermore, Co@MOF is an efficient and fully recyclable noble metal-free catalyst system for lightdriven hydrogen evolution from water under visible light illumination. Broader contextThe development of new strategies for the efficient valorization of solar light is one the most important challenges we face nowadays. Among the different possibilities, dihidrogen molecule is considered as one of the possible future energy carriers allowing for CO 2 -free energy cycle. Although the photocatalytic water splitting was the rst photocatalytic reaction to be discovered, no photocatalytic systems for this reaction have been industrially applied. This is both due to the fact that most discovered catalysts rely on the use of noble metals and to the low activities achieved so far by alternative catalysts. The application in this eld of materials such as metal-organic frameworks (MOFs) can be a game changer in this research eld. MOFs have been proven to be photoactive and their optical properties can be easily tuned towards visible light operation. The current challenge lies in the development of more appropriate active sites for the desired photocatalytic cycle. In this manuscript, we report a new strategy to achieve this goal. By introducing a derivative of the well-known molecular Co-based electrocatalyst Co-dioxime-diimine into the pores of a photo-active NH 2 -MIL-125(Ti) following a 'Ship-in-a-bottle' strategy, we were able to synthesize a highly active photocatalyst composite free of noble metals, and fully recyclable. Because of the novelty and the implications of this work, we feel that it might appeal to the interdisciplinary readership of energy and environmental science. The journal has previously been an important forum for the research topics touched upon in this paper (new earth abundant materials and their application in (photo) catalysis and hydrogen evolution from water under visible light illumination). We would be glad t...