Recognition of Perfluoroalkyl Substances via Synthetic Porphyrin Compounds

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Date of Award

9-1-2026

Abstract

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants of growing global concern due to their chemical stability, bioaccumulation, and adverse health impacts (Fenton et al, 2021). Developing molecular receptors capable of selectively recognizing and capturing PFAS is, therefore, a critical step toward improved sensing and remediation strategies (Zhang et al, 2024). In this work, we report supramolecular investigation of a library of functionalized porphyrin-based receptors for the selective binding of perfluorooctanoic acid (PFOA) and octanoic acid (OA) guests using UV-visible spectroscopic titrations. Host-guest interactions were evaluated for four synthetic free-base and Zinc-metalated porphyrin hybrid hosts (SD032, SPB007, and chiral derivatives R-SD034 and S-SD034) against guests PFOA, PFOA salt, OA, and OA salt. Complex formation was consistently evidenced by pronounced bathochromic shift of porphyrin Soret band (417-427 nm to 431–438 nm). Quantitative analysis using the Benesi-Hildebrand and binding isotherm models revealed structure-property relationships governing PFAS recognition. Among the hosts, non-fluorinated host SD032 displays excellent affinity for non-fluorinated hydrocarbon carboxylates (OA: K = 3.7 × 10⁷; OA salt: K = 9.0 × 10⁶) and moderate binding for PFOA (K = 2.4 × 10⁵). The chiral host SD034, which has a fluorinated binding pocket, exhibited an exceptional association constant of K =1.1 × 10⁸ and near ideal model fit (R2 =0.997). The strong and selective binding exhibited by R-SD034 establishes porphyrin-based supramolecular platforms as promising molecular scaffolds for PFAS sensing and capture remediation technologies.

Advisor

Stephen Starnes

Subject Categories

Chemistry | Physical Sciences and Mathematics

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