Optical Axial Chirality Enhancement and Transfer within Aromatic Micelles upon (Co-)encapsulation

Abstract

Axial chirality is the key physiochemical element, yet its chiroptical utilities have been largely limited to covalent synthesis and infinitely assembled systems so far. Here we report a new application of axially chiral binaphthyls for efficient, optical chirality enhancement and transfer upon noncovalent encapsulation by achiral aromatic micelles in water. The CD activities of dialkoxy binaphthyls are significantly enhanced (up to 7-fold) upon encapsulation by an anthracene-based aromatic micelle. Large emission enhancement (∼4-fold) and efficient guest-to-guest, optical chirality transfer are achieved through coencapsulation of the binaphthyls with achiral cycloparaphenylenes, in a guest-within-guest fashion, by the micelle. The observed unusual properties are derived from the tight inclusion of the chiral guests into the macrocyclic guests, efficiently generated only in the aromatic cavity. Moderate CPL can be observed from the coencapsulated macrocycles within the ternary composites. Furthermore, more than ∼4-fold enhanced guest-to-guest chiroptical transfer is demonstrated with a functionalized cycloparaphenylene through the present coencapsulation strategy.