What are the major factors governing the formation of inclusion complexes between β-cyclodextrin (β-CD) and gaseous substances?

The formation of inclusion complexes between β-CD and gaseous substances is influenced by various factors, including the polarity and size of the guest molecules, the presence of water molecules in the β-CD cavity, and the nature of non-covalent interactions.

From: "Inclusion Complexes between β-Cyclodextrin and Gaseous Substances—N2O, CO2, HCN, NO2, SO2, CH4 and CH3CH2CH3: Role of the Host’s Cavity Hydration", Inorganics 2024, 12(4), 110

The major factors governing the formation of inclusion complexes between β-CD and gaseous substances are:
Polarity of the guest molecule: Polar gases with higher dipole moments form more stable complexes due to stronger dipole-dipole interactions with the β-CD cavity.
Size of the guest molecule: Smaller guest molecules can fit better into the β-CD cavity, leading to more favorable complexation. Larger molecules may not fit well, resulting in less stable complexes.
Hydration state of the β-CD cavity: The presence of water molecules in the β-CD cavity plays a crucial role. Displacing a few water molecules to accommodate the guest is favorable, while displacing too many water molecules reduces the stability of the complex.
Hydrogen bonding: The hydrogen bond network formed between the guest molecule, β-CD, and water molecules in the cavity contributes to the stability of the complex. A richer water cloud around the guest enhances the hydrogen bond network and stabilizes the complex.