Terpyridyl Substituent Effects on Ruthenium CO2 Reduction Catalysts (2024)

Undergraduate: Benjamin Butler

Faculty Advisor: Alex Miller
Department: Chemistry

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The Center for Hybrid Approaches in Solar Energy (CHASE) seeks to develop methods of producing liquid fuels by harnessing solar energy to electrocatalytically reduce CO2 with water. Within the cascades thrust of CHASE, one method of reducing CO2 to methanol is by first reducing it to CO. This can be done via [Ru(tpy)(Me-bimpy)MeCN]2+ catalysts, where tpy represents 2,2′:6′,2″-terpyridine and Me-bimpy represents 1-methylbenzimidazol-2-ylidene-3-(2′-pyridine). Although it has been shown that having the carbene electron donor in the Me-bimpy ligand trans (C-trans) to the ligand binding site of CO2 yields much higher activity than the N-trans variant, more information is to be found on the impact of chemical structure in the catalyst’s capability and efficiency of reducing CO2. Research is currently being conducted on alterations of the bidentate Me-bimpy ligand, so this project seeks to quantify effects of alterations to the tridentate terpyridyl ligand. The 4’-H on the tpy ligand can be substituted by varying electron-donating groups (EDG) and electron-withdrawing groups (EWG) with different Hammett substituent constants to quantify catalyst activation/deactivation via their redox potentials and peak currents which are measured with cyclic voltammetry.