Enantioselective Recognition of Helicenes by a Tailored Chiral Benzo[ghi]perylene Trisimide π‐Scaffold
Ben Teichmann, Ana‐Maria Krause, Mei‐Jin Lin, Frank Würthner
Abstract
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 benzo[ghi]perylene 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 )‐[6]helicene 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 [6]helicene and electron‐poor BPTI.