Since their synthesis and commercialization over seven decades ago, per- and polyfluoroalkyl substances (PFAS) have notoriously become known as worldwide environmental contaminants due to their toxicity to biota, bioaccumulation in the environment, and inability to degrade using high energy decomposition techniques. This is due to their robust properties, which make them chemically and thermally inert, oleophobic, hydrophobic, and resistant to reduction and oxidation. Their properties are largely attributed to a high C–F bond strength (~120 kcal mol<sup>-1</sup>) since fluorine is the most electronegative element. Yet another unique characteristic of PFAS is their ability to adopt helical conformations, which is defined by the twisting of their C-C-C-C and F-C-C-F dihedral angles by about 16° and not observed in the corresponding hydrocarbon analogues. The impact of the helical structure on the properties of PFAS is not well understood and previous research correlating helicity to properties has been misguided. The work presented herein focuses on the relationship between the helicity and fundamental properties of short- and long-chain PFAS as well as a class of four-carbon long polyfluoroalkanes as a representative. These properties, including electronegativity, chemical potential, nucleophilicity, electrophilicity, and global hardness and softness, are computed using Density Functional Theory. Since properties impact environmental fate and transport, it is important to understand how helicity, a structural trait of PFAS, may govern environmentally relevant properties. By understanding the influence of structure, this work has implications in designing safer, robust PFAS alternatives which are easier to degrade.

Impact of structure on the properties of per- and polyfluoroalkyl substances

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.