High-performance carbon dioxide capture and storage by multi-functional sphingosine kinase inhibitors through a CO2-philic membrane

Abstract

The “all in one” environmentally friendly sphingosine kinase inhibitor (SphKI) molecule could combine the advantages of various organic functional groups, and ambiphilic and amphipathic nature together for effective carbon dioxide (CO₂) capture. The CO₂ molecule interacts with various functional molecules including aromatic and multi-heteroatom (such as nitrogen and oxygen) systems through both physical and chemical absorption. In this study, the ability of SphKI with multiple reaction centers to bind CO₂ is investigated using symmetry-adapted perturbation theory and a non-covalent interaction approach. The combination of these two analyses allowed us to explore the nature and strength of the SphKI⋯CO₂ interactions. We found that the variety of functional groups in SphKI including guanidine, oxadiazole, phenyl, and alkyl groups allowed it to act as both an electrophile and a nucleophile (ambiphilic nature) for the CO₂ physisorption. But on the other hand, the chemisorption of CO₂ by SphKI only proceeded through the guanidine group in the polar head (hydrophilic) region. These results revealed that the interaction energy values are divided into physical interactions with a binding energy in the range of ∼2–32 kJ mol⁻¹, which are mainly dominated by both electrostatic and dispersion contributions, and chemical interactions (∼16–45 kJ mol⁻¹). Also, according to the amphipathic nature of SphKIs, a simple sphingosine-based membrane is proposed and shown to be stable by molecular dynamics simulation under aqueous conditions. By considering the chemical equilibrium between CO₂ and water (H₂CO₃ (aq)), we used the proposed membrane to evaluate the large scale CO₂-capturing efficacy of SphKIs. The simulation results showed that the CO₂ molecules can diffuse into the hydrophobic phase of the SphKI membrane, while the H₂CO₃ molecules remain in the aqueous phase.