Artificial photosynthetic systems are inspired by nature and attempt to mimic metalloenzymes such as carbon monoxide dehydrogenase to capture and convert CO₂. However, these systems so far lack a key feature: the secondary coordination sphere needed to stabilize the transition metal active site and its direct coordinating ligands.

To create this environment, Alfredo M. Angeles-Boza, Jie He, University of Connecticut, Storrs, USA, and colleagues have functionalized a linear copolymer (poly[methylmethacrylate-co-hydroxyethyl methacrylate]) with thiols using an esterification reaction of hydroxyethyl methacrylate and 3-mercapto-propionic acid. Upon addition of nickel chloride, an intramolecular coordination occurs, which is triggered by metal-thiolate bond formation. This drives the individual polymer chains to fold and produce a “metallofoldamer” (pictured).

The Ni-metallofoldamers have shown promising activity and selectivity for CO₂ photoreduction. According to the researchers, the approach could provide useful guidelines in the investigation of artificial enzymes and further the understanding of proteins in photosynthesis.

• “Enzymatic” Photoreduction of Carbon Dioxide using Polymeric Metallofoldamers Containing Nickel-Thiolate Cofactors,
  Srinivas Thanneeru, John K. Nganga, Alireza Shirazi Amin, Ben Liu, Lei Jin, Alfredo M. Angeles-Boza, Jie He,
  ChemCatChem 2017.
  DOI: 10.1002/cctc.201601661