Long-lived states involving a manifold of fluorine-19 spins in fluorinated aliphatic chains.

Long-lived states (LLSs) have lifetimes T LLS that exceed longitudinal spin-lattice relaxation times T 1 . In this study, lifetimes T LLS (19F) have been measured in three different achiral per- and polyfluoroalkyl substances (PFAS) containing two or three consecutive CF2 groups. In a static magnetic field B 0 = 11.7 T, the lifetimes T LLS (19F) exceed the longitudinal relaxation times T 1 ( 19 F) by about a factor of 2. The lifetimes T LLS (19F) can be strongly affected by binding to macromolecules, a feature that can be exploited for the screening of fluorinated drugs. Both T LLS (19F) and T 1 (19F) should be longer at lower fields where relaxation due to the chemical shift anisotropy (CSA) of 19F is less effective, which is demonstrated here by running experiments at two fields of 11.7 and 7 T.