Sustainable chemical transformations of renewables for fine chemical synthesis require tremendous activity and high selectivity. Homogeneous/bio-catalysts in aqueous media often suffer from poor substrate solubility, difficult catalyst/product separation and subsequent poor catalyst recycle. This may be overcome by protecting the active site in a chemical ‘raincoat’. This raincoat must be designed to keep water out, but let substrates and products pass through. We are investigating the protection of metal catalysts in ionic liquid gels and proteins.
Ionic liquids possess a number of tunable properties favorable for supporting homogeneous/bio-catalyst integrity. Hydrophobicity, hydrophilicity, acid-base properties and intermolecular interactions can be altered, hence ionic liquids are emerging as a reaction medium for both homogeneous and bio-catalytic reactions.1,2,3,4 Catalyst immobilization is an expanding research area, which can in principle efficiently overcome the many challenges in catalytic processes. There are many immobilization methods available such as cross linking, adsorption, covalent modification and entrapment, however, the provision of a fast and low-cost method is still a real challenge.5
We are developing strategies to immobilize homogeneous and bio-catalysts in ionic liquid gels and incorporate homogeneous catalysts into a protein scaffold to make an artificial metalloenzyme that can perform homogeneous/bio-catalysis in aqueous and/or aqueous biphasic media. Two representative examples will be presented. An Fe containing homogeneous catalyst immobilized in an ionic liquid gel exhibited excellent aqueous dye oxidation.6 Rhodium (Rh) containing artificial metalloenzymes with engineered protein scaffolds enhanced the hydroformylation activity and selectivity of 1-octene.7
Hasan T. Imam (QUB)
Hasan T. Imama, Peter McNeicea, Andrew Reida, Patricia C. Marr*a and Andrew C. Marr*a
aSchool of Chemistry and Chemical Engineering, Queen’s University Belfast, Belfast, UK
Acknowledgement: Thanks to our collaborators Terrence J. Collins (Carnegie Mellon University, USA), Dr Amanda Jarvis (Edinburgh University, UK) and Dr Veronica Celorrio (Diamond light source, UK). EPSRC and UK catalysis Hub for funding.
Funding: This work is supported by Engineering and Physical Sciences Research Council (UK) grants EP/ R026645/1, The UK Catalysis Hub‘Science’: 2 Catalysis at the Water-Energy Nexus, and EP/M013219/1, Biocatalysis & Biotransformation: A 5th Theme for the National Catalysis Hub.
Dedication: This poster is dedicated in loving memory of Professor Paul C. J. Kamer, a truly inspirational collaborator and mentor.
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6 P. Mcneice, A. Reid, H. T. Imam, C. Mcdonagh, J. D. Walby, T. J. Collins, A. C. Marr and P. C. Marr, Environ. Sci. Technol., 2020, 54, 14026−14035.