title: Detailed NMR investigation of cyclodextrin-perfluorinated surfactant interactions in aqueous media.
abstract: Perfluorochemicals (PFCs) are contaminants of serious concern because of their toxicological properties, widespread presence in drinking water sources, and incredible stability in the environment. To assess the potential application of α-, β-, and γ-cyclodextrins for PFC remediation, we investigated their complexation with linear fluorinated carboxylic acids, sulfonates, and a sulfonamide with carbon backbones ranging from C4-C9.19F Nuclear Magnetic Resonance (NMR) spectroscopy studies demonstrated β-CD formed the strongest complexes with these PFCs. The polar head group had a modest influence, but for PFCs with backbones longer than six carbons, strong association constants are observed for 1:1 (K1:1∼105M-1) and 2:1 (K2:1∼103M-1) β-CD:PFC complexes. Excess β-CD can be used to complex 99.5% of the longer chain PFCs. Competition studies with adamantane-carboxylic acid and phenol confirmed the nature and persistence of the β-CD:PFC complex. Detailed analyses of the individual NMR chemical shifts and Job plots indicate the favored positions of the β-CD along the PFC chain. Solution pH, ionic strength, and the presence of humic acid have modest influence on the β-CD:PFC complexes. The strong encapsulation of PFCs by β-CD under a variety of water quality conditions demonstrates the tremendous potential of CD-based materials for the environmental remediation of PFCs.
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, 11200 SW Eighth Street, Miami, FL 33199, United States.
authors.forename: Mary Jo
authors.initials: MJ
authors.lastname: Weiss-Errico
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, 11200 SW Eighth Street, Miami, FL 33199, United States. Electronic address: osheak@fiu.edu.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Shea
keywords: Cyclodextrin; NMR spectroscopy; Perfluorochemical; Perfluorooctanoic acid; Remediation