Article,
Enantioselective Recognition of Helicenes by a Tailored Chiral Benzoghiperylene Trisimide pi-Scaffold
Angew. Chem. Int. Ed., (February 2022)
DOI: 10.1002/anie.202117625
Abstract
Enantioselective molecular recognition of chiral molecules that lack specific interaction sites for hydrogen bonding or Lewis acid–base interactions remains challenging. Here we introduce the concept of tailored chiral π-surfaces toward the maximization of shape complementarity. As we demonstrate for helicenes it is indeed possible by pure van-der-Waals interactions (π–π interactions and CH–π interactions) to accomplish enantioselective binding. This is shown for a novel benzoghiperylene trisimide (BPTI) receptor whose π-scaffold is contorted into a chiral plane by functionalization with 1,1′-bi-2-naphthol (BINOL). Complexation experiments of enantiopure (P)-BPTI with (P)- and (M)-6helicene afforded binding constants of 10 700 M−1 and 550 M−1, respectively, thereby demonstrating the pronounced enantiodifferentiation by the homochiral π-scaffold of the BPTI host. The enantioselective recognition is even observable by the naked eye due to a specific exciplex-type emission originating from the interacting homochiral π-scaffolds of electron-rich 6helicene and electron-poor BPTI.
