Novel Trifunctional Intramolecular Frustrated Lewis Pair Derived From Aminoboronic Acid for Converting CO2 Into Valuable Chemicals

Abstract

The conversion of CO₂ into valuable chemicals remains a significant challenge for achieving environmental sustainability, primarily due to the stability of the CO₂ molecule. This necessitates the development of efficient and ecofriendly catalysts. In recent years, frustrated Lewis pairs (FLPs) have shown promise for CO₂ utilization. In this study, we introduce α-aminodiboronic acid (DBA), a novel trifunctional aminoboronic acid, as an intramolecular FLP for converting CO₂ into cyclic carbonate and formic acid. Using density functional theory (DFT) calculations, we explored the reaction mechanism and investigated DBA's electronic structure through molecular electrostatic potential surface (MESP) and natural bond orbital (NBO) analyses. Our results reveal that one −B (OH)₂ group induces an unusual state of frustration in the molecule due to charge transfer from the nitrogen atom's lone pair to the π* orbitals, enhancing catalytic performance. The additional −B (OH)₂ group serves as an anchoring site for reactive species. The epoxide activation energy is reduced by approximately 27 kcal/mol compared to the uncatalyzed reaction, and the reduction of CO₂ occurs with a requirement of 26 kcal/mol. The additional −B (OH)₂ plays a crucial role in the catalytic mechanism and minimizes the energies of various structures observed in the reaction path. The reaction energetics align with structural analysis observations, marking this study as the first report on single-molecule trifunctional FLPs for transforming CO₂ into valuable chemicals.