A Molecular Dynamics Study of the Solvation Properties of Sugars in Supercritical Carbon Dioxide
2025
Alexandrine Lambert | Francesca Ingrosso
Among the various strategies used to enhance the solvation power of supercritical carbon dioxide (scCO2), the use of CO2-philic compounds has been extensively studied over the recent two decades. Given the biocompatibility of this medium, extraction technologies based on scCO2 are particularly attractive, and a molecular-level understanding of intermolecular interactions is crucial for optimizing processing conditions. Functionalized sugars and cyclic oligosaccharides, such as cyclodextrins, can be rendered soluble in scCO2, opening new avenues for vectorization strategies and supramolecular chemistry in this medium. To support the exploration of CO2-philic compounds relevant to these research goals, we conducted a molecular dynamics investigation into the solvation properties of cyclodextrins functionalized with CO2-philic groups. We thoroughly analyzed the key solute&ndash:solvent interactions and their influence on the cavity shape. Additionally, we provided insights into the solvation behavior of peracetylated &alpha: and &beta:-glucose across different regions of the carbon dioxide phase diagram. We were able to confirm the importance of the well-known (acetyl)C&ndash:O⋯:C(CO2) interaction, as the most important signature of CO2-philicity of carbonyl compounds. Depending on the substituent, this interaction can be assisted by a cooperative (methyl)2HCH⋯:O(CO2) intermolecular bond. In cyclodextrins, conformational flexibility, with a possible change in the conformation of some pyranose units, was observed in the macromolecular structure. On the other hand, these structural modifications were not present for &alpha:- and &beta:-glucose.
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