Dr Andrew C. Marr

Research

We investigate the role of molecular catalysts in the design of processes that conform to the principles of green chemistry. Homogeneous catalysis is combined with biocatalysis and / or materials in order to create unique systems.

 

Molecular Catalysts, Functional Models of Enzymes

We are exploring molecular catalysts that model the reactivity of metalloenzymes. Of particular interest is the similarity in reactivity between alcohol dehydrogenases and hydrogen transfer catalysts. We have developed new classes of hydrogen transfer catalyst by protecting active metal centres using highly chelating ligands to create reactive pockets within which we can control the electronic, steric and stereo-environment.

 

 

 

Combining Chemical and Bio-catalysis

We are studying processes that result from the combination of chemical and biological catalysts. The operation of multiple catalysts in cascade or tandem one-pot reactions removes separation steps that require additional reagents, solvents and energy. One example is the Dynamic Kinetic Resolution (DKR) of racemic alcohols into chiral esters by the combination of enzyme (lipase) and chemical racemization catalyst activity. We have recently published a protocol for DKR employing a rhodium or iridium N-heterocylic carbene complex in the absence of added base that gives high conversion, rate and enantioselectivity for dialkyl and aryl-alkyl alcohols.

 

In collaboration with researchers at the University of Nottingham and Slovak University of Technology in Bratislava we are aiming to combine the catalytic activity of chemical catalysts and anaerobic cells. It is hoped that the methods developed can be used to transform biomass-derived chemical feeds into value added chemical intermediates cleanly and efficiently in one pot.

 

 

From Biomass to Value Added Chemicals

As petroleum becomes less accessible there is a need to find alternative sources for chemicals. The importance of this has been highlighted in a white paper.

The role of transition metal catalysts in the design of new processes based on bio-renewables is being explored.

 

 

Entrapped Molecular Catalysts

In collaboration with materials scientist Dr Pat Marr we have been looking at methods of recycling homogeneous catalysts that involve entrapping the catalyst within an inorganic oxide to create a porous prison. A recent highlight was the entrapment of rhodium phosphine hydrogenation catalysts within ionic liquid / silica hybrid materials (ionogels) to create a highly active, selective and recyclable catalytic material. The nano-environment inside the material reinforces molecular reactivity and gives catalytic performance superior to the parent homogeneous catalyst.