Predictive energetic tuning of C-Nucleophiles for the electrochemical capture of carbon dioxide

• Published in: iScience 2022-04, Vol.25 (4), p.103997-103997, Article 103997
• Main Authors: Petersen, Haley A., Alherz, Abdulaziz W., Stinson, Taylor A., Huntzinger, Chloe G., Musgrave, Charles B., Luca, Oana R.
• Format: Article
• Language: English
• Subjects: Applied chemistry; Chemistry; Computational chemistry; Electrochemistry; Theoretical chemistry
• ISSN: 2589-0042; 2589-0042
• DOI: 10.1016/j.isci.2022.103997

This work maps the thermodynamics of electrochemically generated C-nucleophiles for reactive capture of CO2. We identify a linear relationship between the pKa, the reduction potential of a protonated nucleophile (Ered), and the nucleophile’s free energy of CO2 binding (ΔGbind). Through synergistic experiments and computations, this study establishes a three-parameter correlation described by the equation ΔGbind=−0.78pKa+4.28Ered+20.95 for a series of twelve imidazol(in)ium/N-heterocyclic carbene pairs with an R2 of 0.92. The correlation allows us to predict the ΔGbind of C-nucleophiles to CO2 using reduction potentials or pKas of imidazol(in)ium cations. The carbenes in this study were found to exhibit a wide range CO2 binding strengths, from strongly CO2 binding to nonspontaneous. This observation suggests that the ΔGbind of imidazol(in)ium-based carbenes is tunable to a desired strength by appropriate structural changes. This work sets the stage for systematic energetic tuning of electrochemically enabled reactive separations. [Display omitted] •CO2 binding energy was calculated for a set of N-heterocyclic carbenes (NHCs)•CO2 binding energy of NHCs is widely synthetically tunable•pKa, reduction potential, and CO2 binding energy correlate linearly for NHCs•3D correlation enables easy prediction of CO2 binding strength for novel NHCs Chemistry; Theoretical chemistry; Electrochemistry; Computational chemistry; Applied chemistry