Tuesday, November 2, 2021 featured:
Professor Smaranda C. Marinescu from the University of Southern California (USC)
"Bioinspired Coordination Complexes and Polymers for Energy Applications"
Abstract:
Research in the Marinescu group focuses on the development of novel catalytic systems for efficient solar-to-fuel technologies. Inspired by biological systems, we design molecular catalysts that involve hydrogen bonding networks capable of small molecule activation through multiple proton and electron transfers. We have shown that cobalt complexes with pendant secondary amine (NH) moieties act as highly efficient electrocatalysts for the reduction of CO2 to CO, in comparison to the alkylated versions. Through synthetic and electrochemical studies of a series of aminopyridine complexes with zero to four pendant secondary amines, we have demonstrated that the rate of catalysis is proportional with the number of pendant NH moieties. Experiment and theory suggest that the pendant NH groups do not directly transfer protons to CO2, but instead bind acid molecules from solution, leading to the formation of a hydrogen-bonding network intermediate that enables direct proton transfer from acid to the activated CO2 substrate.
We also explore the immobilization of metal complexes via metal-organic frameworks (MOFs). We have demonstrated the successful integration of metal dithiolene units into one and two-dimensional frameworks by using dinucleating and trinucleating thiolate-based ligand scaffolds. The developed metal dithiolene frameworks display high activity for the electrocatalytic HER in acidic aqueous media. The HER performance of the MOF-based electrocatalysts was investigated, to understand the charge transfer properties of the constructed MOF/electrode architecture. Density functional theory calculations were applied to understand the structure of the MOF and its mechanistic pathways for the HER. We expect the design principles discovered in these studies to have a profound impact towards the development of advanced materials and sustainable technologies.
Bio:
Smaranda Marinescu performed her undergraduate studies at Caltech, where she did undergraduate research with Prof. John E. Bercaw working on the synthesis and reactivity of group 3 dialkyl complexes supported by tetradentate, monoanionic ligands. After graduation, Smaranda stayed one more year at Caltech, doing research in the group of Prof. Brian M. Stoltz, where she developed a homogeneous Pd-catalyzed enantioselective decarboxylative protonation. In 2007, she started her Ph.D. at MIT under the tutelage of Prof. Richard R. Schrock, exploring Mo and W alkylidene species for enatio-, Z-, and E-selective olefins metathesis reactions. After graduation in 2011, she undertook a postdoctoral position in the laboratories of Prof. Harry B. Gray at Caltech, as an NSF CCI postdoctoral fellow, working on mechanistic studies of the cobalt catalyzed hydrogen evolution reaction. In August 2013 she started her independent career as an Assistant professor of Chemistry at University of Southern California, and was promoted to Associate Professor in 2020. Marinescu has been recognized with several awards and fellowships, such as the NSF CAREER (2016), the Alfred P. Sloan Research Fellowship (2019), and the American Chemical Society Harry Gray Award for Creative Work in Inorganic Chemistry by a Young Investigator (2021). Marinescu’s research focuses on designing, synthesizing, and understanding novel catalytic systems essential to the development of efficient solar-to-fuel technologies.
Host: Prof. T. Brent Gunnoe, University of Virginia