Investigating the interaction of sunset yellow aggregates and 6-fluoro-2- naphthoic acid: increasing probe molecule complexity

The interaction of small molecules with non-covalent assemblies is of wide interest. The use of a magnetically-active reporter nucleus allows information to be obtained in the presence of spectral overlap or in cases of high dynamic range. In this paper we explore the interaction of a larger probe molecule, 6-fluoro-2-naphthoic acid with assemblies of sunset yellow using 19F chemical shifts and diffusion NMR methods. Comparing the observations with previous studies using fluorophenols, 6-fluoro-2- naphthoic acid prefers to associate as clusters at the ends of the sunset yellow stacks.