Activating circularly polarized luminescence through environment-modulated polymorphic assembly of glycerolipid-modified carbazolyl phthalonitriles

Abstract

Lipid molecules can self-assemble to form various supramolecular structures due to lipid polymorphism. Based on this property, conjugation of functional dyes with lipids can form a wide range of nanostructures with intriguing properties that have potential applications in various disciplines. In particular, materials that exhibit circularly polarized luminescence (CPL) are of much current interest. We report herein a simple molecular design of luminophore–glycerolipid conjugates, which can be molecularly engineered to induce CPL activity through changing the self-assembled environments. It involves an amphiphilic lipid chain substituted with a tris(carbazolyl)phthalonitrile moiety at the chiral center. With only one lipid chain, one polar head, one chiral center, and one luminophore, these molecules undergo self-assembly on a polar glass surface, on a nonpolar polydimethylsiloxane surface, and in water, leading to the formation of lipid nanocones, nanohemispheres, and nanotubes, respectively. Interestingly, while the latter two were CPL silent, the lipid nanocones could emit CPL with a significant luminescence dissymmetry factor of 0.01.