Capture of CO₂ by Melamine Derivatives: A DFT Study Combining the Relative Energy Gradient Method with an Interaction Energy Partitioning Scheme

A theoretical study of the interaction between melamine and CO₂ was carried out using density functional theory (DFT) with the B3LYP-D3­(BJ)/aug-cc-pVTZ level of theory. The presence of anions interacting with melamine transforms the weakly bonded tetrel complexes into adducts. Thus, melamine acts as an FLP (frustrated Lewis pair) with acid groups (NHs as hydrogen bond donors) and a base group (N of the triazine ring). The application of the relative energy gradient formalism (REG) along the reaction coordinate has demonstrated that the ability of the melamine-anion systems to capture CO₂ is linked to its capacity to polarize the CO₂ molecule. These results have been confirmed by placing the melamine:CO₂ complex in a uniform electric field with different strengths.