Interactions of CO2 with various functional molecules

Abstract

The CO₂ capturing and sequestration are of importance in environmental science. Understanding of the CO₂-interactions with various functional molecules including multi-N-containing superbases and heteroaromatic ring systems is essential for designing novel materials to effectively capture the CO₂ gas. These interactions are investigated using density functional theory (DFT) with dispersion correction and high level wave function theory (resolution-of-identity (RI) spin-component-scaling (scs) Möller–Plesset second-order perturbation theory (MP2) and coupled cluster with single, double and perturbative triple excitations (CCSD(T))). We found intriguing molecular systems of melamine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 7-azaindole and guanidine, which show much stronger CO₂ interactions than the well-known functional systems such as amines. In particular, melamine could be exploited to design novel materials to capture the CO₂ gas, since one CO₂ molecule can be coordinated by four melamine molecules, which gives a binding energy (BE) of ∼85 kJ mol⁻¹, much larger than in other cases.