Supramolecular Aggregates of Amino Acid-Functionalized 1,8-Naphthalimides for Chiral Recognition

Abstract

Methods for fast enantioselective recognition hold relevance in several fields of chemical research. In this context, we studied the chiral recognition ability of fluorescent supramolecular aggregates formed in solution by chiral, amino acid-functionalized 1,8-naphthalimide derivatives, namely L-Phe-NI, L-Ala-NI, and D-Ala-NI. First, we studied the photophysical properties of the fluorophores and their self-assembly process, by concentration- and temperature-dependent UV–vis and fluorescence spectroscopy, finding that aggregation follows different pathways, isodesmic or cooperative, depending on the functionalization of the imide position. Subsequently, we investigated the chiral recognition ability of the aggregates formed in acetonitrile solutions, toward enantiomeric pairs of aromatic alcohols and amines, such as 1-phenylethanol, 1-phenetylethylamine, 1-(2-naphthyl)-ethanol, and 1-(2-naphthyl)-ethylamine by fluorescence and resonance light scattering measurements. We found that aggregates of L-Ala-NI exhibited the highest chiral discrimination. Notably, we demonstrated that these aggregates can be embedded onto solid supports like filter paper strips or polymer films, maintaining their chiral recognition ability.