Enabling Racemization of Axially Chiral Subphthalocyanine‐Tetracyanobutadiene‐Aniline Enantiomers by Triplet State Photogeneration

Abstract

In recent years, several tetracyanobuta‐1,3‐diene (TCBD) conjugates have been prepared by linking the tetracyano unit to various electroactive moieties. These push–pull conjugates, besides showing interesting physicochemical properties, are axially chiral, a feature arising from the restricted rotation around the central bond of the butadiene. Yet, only in a few cases, separation and isolation of the enantiomers have been successfully achieved, owing to the configurational lability of the corresponding enantiopure species. Herein, we report the first example of photo‐ and electroactive TCBD‐based derivatives showing unprecedented configurational stability and a peculiar light‐triggered enantiomer conversion mechanism enabled by triple‐state photogeneration. These systems represent a nice addition to the fast‐increasing arsenal of artificial, light‐controllable molecular switches.