Non‐Covalent PL, CD, and CPL Activation of Linear Aromatic Oligomers within Axially Chiral Aromatic Capsules

Abstract

ABSTRACT Covalent functionalization is requisite to enhancing/inducing the luminescent and chiroptical properties of oligo‐aromatic compounds, owing to their rigid framework and strong aggregation characters. Here we report that linear aromatic oligomers display intense PL, CD, and CPL properties upon encapsulation by axially‐chiral aromatic capsules under ambient aqueous conditions. The treatment of para ‐phenylene oligomers with chiral BINOL‐based amphiphiles generates host‐guest composites in water, exhibiting oligomer‐based PL, CD, and CPL bands with strong intensities (up to Φ F = 36%, | g abs | = 6 × 10 −3 , and | g lum | = 3 × 10 −3 ). This method is applicable to other aromatic oligomers, comprising fluorene, carbazole, and thiophene rings, and further PL and CPL enhancement (up to Φ F = 87% and | g lum | = 4 × 10 −3 ) is demonstrated with the resultant composites. The observed chiroptical features stem from tight host‐guest CH‐π interactions in the adaptable aromatic cavity. Besides the oligomers, polymer‐based chiroptical activities are found from the corresponding polymers upon encapsulation. In the solid state, the host‐guest composites display further prominent CD and CPL bands, using fluorene trimers (| g abs | = | g lum | = ∼3 × 10 −2 ). This study is the first example of the PL, CD, and CPL activation of simple aromatic oligomers to a large extent, via non‐covalent encapsulation. The present strategy will facilitate the supramolecular fusion between aromatic oligo/polymers and chiral functions.