Carbon Dioxide Encapsulations and Anomalous Behaviors of Assemblies With Water

Self-assemblies of water and carbon dioxide are of relevance in the greenhouse effect and also in energy management. A systematic study of different structures from optimized geometries of assemblies of water in different proportions with carbon dioxide nH₂O·mCO₂ (n = 1-8, m = 1, 2) has revealed anomalous changes in interaction energies. The study has disclosed the propensity to form pentameric and heptameric hydrogen-bonded cyclic assemblies of water that encapsulate a carbon dioxide molecule. The heptameric assembly of water molecules with included carbon dioxide provided extra stability to the water-carbon dioxide assembly. The structural effect of different schemes of weak interactions contributed to thermodynamic properties and caused deviations from a linear trend in interaction energies and associated thermodynamic parameters among the homologous series of assemblies, showing anomalous behavior.