Revealing the non-covalent interactions existing between CO2 and succinimide-based ionic liquid: A DFT exploration

Abstract

CO2 being the major contributor to the greenhouse gas (GHG) accumulation, it needs to be mitigated immediately. The CO2 capture and storage (CCS) technology is recognized as a promising strategy. Among the various absorbents such as zeolites and metal organic frameworks that are known to capture CO2, ionic liquids (ILs) have emerged as better absorbents due to its unique characteristics. In this context, Wang et al. have proposed [P4442][Suc] as a potential candidate for low concentration CO2 absorption exploiting preorganization and cooperation strategy. The present work deals with studying the geometry, structural parameters of interaction of CO2 with the chosen ionic liquids using state-of-the-art quantum chemical tools. A maximum of up to 8 CO2 molecules were computationally found to be possible to interact with the chosen ionic liquid. MESP analysis revealed that the nucleophilicity of [Suc] part is decreased upon increase in nCO2 molecules while the electrophilicity of [P4442][Suc] was computed to be increased with increase in nCO2 absorption. The experimentally obtained FT-IR spectrum was verified with DFT computed results. In addition, the nature of non-covalent interactions existing between the CO2 molecules and [P4442][Suc] anion has also been investigated using NCI and QTAIM analysis. Thus, the results and findings of this work will lead to significant advancement in the field of CO2 capture and storage using ionic liquids.