Inclusion Complexation of Native and Functionalized α-, β-, and γ-Cyclodextrins with PFAS: An Experimental and...

Area of Science:

• Environmental Chemistry
• Supramolecular Chemistry
• Computational Chemistry

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants.
• Beta-cyclodextrin (β-CD)-based polymers show promise for PFAS removal from drinking water.
• Understanding host-guest binding is key to optimizing PFAS adsorption.

Purpose of the Study:

• To quantify binding affinities between native and modified cyclodextrins (CDs) and various PFAS.
• To elucidate the molecular mechanisms governing CD-PFAS complexation.
• To evaluate the impact of solvent, ions, and linker modifications on binding.

Main Methods:

• Isothermal titration calorimetry (ITC) for experimental binding measurements.
• Molecular dynamics (MD) simulations with the attach-pull-release (APR) method.
• Implicit and explicit solvent models, interaction-energy decomposition, and solvent-accessible surface area analysis.

Main Results:

• Beta-cyclodextrin (β-CD) exhibited the strongest binding affinities for PFAS among α-, β-, and γ-CDs.
• Hydrophobic dehydration was identified as the dominant factor in host-guest binding, not hydrogen bonding.
• Explicit solvent simulations accurately captured salt dependence and linker effects on binding.
• Linker groups in modified β-CDs enhance PFAS binding through hydrophobic confinement and specific interactions.

Conclusions:

• Molecular-level insights into CD-PFAS interactions were gained.
• Explicit solvent models are crucial for accurate simulation of binding in complex aqueous environments.
• This study provides a foundation for designing advanced CD-based polymers for efficient PFAS remediation.