A molecule may have different conformational isomers with distinct Gibbs free energies due to the hydrogen-bonding effect, conjugation effect, and so on. Since a large number of N-H and O-H bonds in amine-solvent-CO2 systems will form intermolecular hydrogen bonds and affect the reaction energy barriers , it is necessary to consider the influences of conformational effects of reactants and transition states on 𝐺 a θ,L .