Skip to main content

Catalytic Foldamers: Engineering a Second Coordination
Sphere Around a Hydrogenase Mimic

Article Category

Article available in the folowing languages:

Positive host–guest enzyme relationships

Scientists developed novel supramolecular hosts for small molecular guests that mimic industrially relevant enzymes. The host structure appears to alter the properties of the guest in a tuneable way, promising exciting control over catalytic activity.

Industrial Technologies

Catalysis, the process by which the rate and thus yield over time of a reaction is increased by chemical matchmakers (catalysts), is highly important for industry. Enzymes are nature's catalysts and hydrogenases are an important class of these compounds. Hydrogenases are metalloenzymes, enzymatic proteins with tightly bound metal ions essential to their functions. The protein surrounding the metal (active) site can affect catalytic function in direct and indirect ways. Direct effects are due to covalent binding to the metal itself, forming the first coordination sphere. Indirect effects are due to non-covalent (e.g. hydrogen) bonding to the molecules (ligands) around the metal forming the second coordination sphere. Supramolecular supports may reproduce a number of second coordination sphere effects. Scientists developed supramolecular supports for molecular models of [FeFe]-hydrogenase with EU funding of the project 'Catalytic foldamers: Engineering a second coordination sphere around a hydrogenase mimic' (CATAMERS). Foldamers, molecular chains or oligomers with highly stable and predictable structures, were used as hosts for [FeFe]-hydrogenase mimics containing a diiron complex to achieve a well defined and tuneable second coordination sphere. Extensive development was required to synthesise the two new monomer units from which the foldamers were produced, one to attach the diiron complex and one to house the catalyst. This work not only led to realisation of the oligomers but also enabled the introduction of a wide variety of functional groups, paving the way for greater diversification of foldamers in the future. Interestingly, there was no evidence of hydrogen bonding between the diiron complex and the foldamers scaffold. The complex was free to turn, rotating fast enough to equilibrate each iron site with no significant distortions in the symmetry of the complex. Despite what appears to be minimal control of the foldamer scaffold, the design affects the electrochemical properties of the diiron complex as the second coordination sphere is built around it. Such activity promises great potential for fine-tuning of the reactivity of metal complexes. Dehydrogenases are used in important industrial reactions related to energy applications such as hydrogen production and methane oxidation, and CATAMERS has opened the door to development of synthetic mimics with greater efficacy at lower cost.

Discover other articles in the same domain of application

New products and technologies
Industrial Technologies

2 February 2021

New products and technologies
Industrial Technologies

18 June 2020