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Herein a highly active non-precious transition metal catalyst for the homogeneous hydrogenation of carbon dioxide to formate is presented. Detailed ligand optimisation enabled the development of a nickel-based catalytic system with exceptional productivity., Herein a highly active non-precious transition metal catalyst system for homogeneous hydrogenation of carbon dioxide to formate is presented. The application of selected nickel(ii) salts in combination with tailored multidentate ligands enabled the effective transformation of carbon dioxide with an exceptional TON of up to 4.65 × 106. This unprecedented productivity based on the novel nickel catalyst not only outmatches that of existing systems containing first row transition metals, but also established catalysts based on precious transition metals.

This article introduces the EU Horizon 2020 research project MIX-UP, "Mixed plastics biodegradation and upcycling using microbial communities". The project focuses on changing the traditional linear value chain of plastics to a sustainable, biodegradable based one. Plastic mixtures contain five of the top six fossil-based recalcitrant plastics [polyethylene (PE), polyurethane (PUR), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS)], along with upcoming bioplastics polyhydroxyalkanoate (PHA) and polylactate (PLA) will be used as feedstock for microbial transformations. Consecutive controlled enzymatic and microbial degradation of mechanically pre-treated plastics wastes combined with subsequent microbial conversion to polymers and value-added chemicals by mixed cultures. Known plastic-degrading enzymes will be optimised by integrated protein engineering to achieve high specific binding capacities, stability, and catalytic efficacy towards a broad spectrum of plastic polymers under high salt and temperature conditions. Another focus lies in the search and isolation of novel enzymes active on recalcitrant polymers. MIX-UP will formulate enzyme cocktails tailored to specific waste streams and strives to enhance enzyme production significantly. In vivo and in vitro application of these cocktails enable stable, self-sustaining microbiomes to convert the released plastic monomers selectively into value-added products, key building blocks, and biomass. Any remaining material recalcitrant to the enzymatic activities will be recirculated into the process by physicochemical treatment. The Chinese-European MIX-UP consortium is multidisciplinary and industry-participating to address the market need for novel sustainable routes to valorise plastic waste streams. The project's new workflow realises a circular (bio)plastic economy and adds value to present poorly recycled plastic wastes where mechanical and chemical plastic recycling show limits.

Dissertation, RWTH Aachen University, 2017; Aachen, 1 Online-Ressource (XI, 104 Seiten) : Illustrationen, Diagramme (2017). = Dissertation, RWTH Aachen University, 2017, The combination of hyperpolarization methods and imaging enables the detection of heteronuclei and opens up innovative fields of application in medical diagnostics. The fascinating properties, such as almost background-free signaling and large chemical shifting differences, which allow the tracking of chemical changes of low-concentrated biomarkers, can provide detailed insight into biochemical processes at the molecular level. The hyperpolarization methods based on parahydrogen (p-H2) have the potential for a wide application as they are simple, cost-effective and fast. However, the biocompatibility in combination with high polarization efficiency is a major challenge. The aim of the work was to optimize the PHIP methods with regard to these points.In the first part, a basis for a proper characterization of PHIP systems was established. A method based on kinetic studies has been developed that allows the determination of the polarization transfer efficiency (PTE) in PHIP experiments. This method was then applied to study homogeneous catalysts to investigate the influence of the chemical system. It was found that the T1 time as well as the lifetime and the concentration of the intermediates decisively influence the PTE. The PTE is a precise parameter which properly characterizes the chemical PHIP system, thus enabling comparison and optimization of known systems as well as the development of new systems. Furthermore, for the first time, PHIP was demonstrated with the help of a novel, artificial metalloenzyme consisting of a Rhodium triphos catalyst covalently bound to a biomolecular framework. The polarization efficiency is exceptionally high compared to other systems. The metalloenzyme is an innovative immobilization method for PHIP catalysts and is ideally suited for biomedical applications due to the activity in water, the easy separability and the high polarization efficiency.In the next chapter, the water-soluble catalyst precursor [Ir(IDEG)(COD)Cl] was used to demonstrate SABRE in a pure water system for the first time. Here, the polarization could be transferred to both protons and 15N nuclei of biomarker molecules, such as diazirine and nicotinamide. The hyperpolarization in pure water without the use of toxic solvents opens the door to the biomedical application of SABRE.The last chapter deals with the polarization of solvents. For the first time, water could be hyperpolarized by means of p-H2 in the presence of [Ir(IDEG)(COD)Cl] and histidine. The polarization of solvent protons can be transferred to heteronuclei of biomedical relevant molecules that are not polarizable by the typical SABRE mechanism.In summary, the hyperpolarization methods based on p-H2 could be significantly optimized with regard to their biocompatibility and thus great steps towards biomedical application could be achieved., Published by Aachen