Red-Shifted Circularly Polarized Luminescence in Chiral Planar Benzothiadiazole Carbon Nanohoop

We present synthesis and investigation of two chiral macrocycles that integrate in their structure a pseudo-meta [2.2]paracyclophane with planar chirality and a highly fluorescent benzothiadiazole. Both compounds display remarkably red-shifted fluorescence with high quantum yields and large Stokes shifts. The two compounds differ in the extent of π-electron conjugation that allowed, for the first time, to systematically examine the role of exciton delocalization in the transmission of chiral information from the chiral [2.2]paracyclophane inducing circularly polarized luminescence. By a combination of steady-state spectroscopy and quantum chemical calculations, we constructed a unique structure–property relationship offering critical insights that will aid and abet the development of robust design guidelines for materials with circularly polarized luminescence of exceptional brightness.