Reactivity of metal-organic coordination networks for CO2 activation

D. HURTADO SALINAS; G RUANO; K KERN; M. LINGENFELDER

Honolulu - Hawaii

Congreso; PACIFCHEM 2015; 2015

American Chemical Society

Photosynthesis, the model system for energy conversion, uses CO2 as its starting reactant to convert solar energy into chemical energy, i.e. organic molecules or biomass. The first and rate-determining step of this process is the immobilization and activation of CO2, a carboxylation reaction catalyzed by the enzyme RuBisCO. The active center of the RuBisCO is Mg2+ ion surrounded by amino acid residues that anchor the ribulose and provide the CO2 as a cofactor bonded to a lysil residue in the surroundings of Mg2+. In this way, inorganic carbon is transformed into organic carbon-based molecules.Metal-organic structures observed in nature, can be replicated in the laboratory by self-assembly. Scanning Tunneling Microscopy (STM) is a powerful tool that offers a dynamical structural insight to study the self-assembly of nanostructures at conductive surfaces. Our group has developed a large expertise in tailoring and characterizing 2D hybrid networks consisting of metal nodes bonded to organic bridging ligands. These structures hold a great potential to mimick active centers of enzymes due to their tunability of metal centers, organic linker, pore size and physical/chemical properties.Inspired by the active site of RuBisCO, we designed the first network using an alkaline earth metal (Group 2): magnesium (Mg). Here we present a method for producing stable networks of Mg and organic molecules by direct deposition onto a clean metal substrate. We track their reactivity and dynamic response to CO2, O2 and H2 by STM and X-Ray Photoelectron Spectroscopy (XPS). Specific phase transformations are identified upon gas exposure at room temperature.