Metastable Chiral Azobenzenes Stabilized in a Double Racemate. Issue 8 (7th January 2020)

• Record Type: Journal Article
• Authors: Mohan, Amalu; Sasikumar, Devika; Bhat, Vinayak; Hariharan, Mahesh
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 8(2020)
• Page Start: 3201
• Page End: 3208
• Publication Date: 2020-01-07
• Subjects: axial chirality -- cocrystals -- donor–acceptor stacks -- host–guest chemistry -- symmetry-adapted perturbation theory; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201910687
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The self‐assembly of chiral organic chromophores is gaining huge significance due to the abundance of supramolecular chirality found in natural systems. We report an interdigitated molecular assembly involving axially chiral octabrominated perylenediimide (OBPDI) which transfers chiral information to achiral aromatic moieties. The crystalline two‐component assemblies of OBPDI and electron‐rich aromatic units were facilitated through π‐hole⋅⋅⋅π donor–acceptor interactions, and the charge‐transfer characteristics in the ground and excited states of the OBPDI cocrystals were established through spectroscopic and theoretical techniques. The OBPDI cocrystals entail a remarkable homochiral segregation of P and M enantiomers of both molecular entities in the same crystal system, leading to twisted double‐racemic arrangements. Synergistically engendered cavities with the stored chiral information of the twisted OBPDI stabilize higher‐energy P/M enantiomers of trans ‐azobenzene through non‐covalent interactions. Abstract : Put a twist on it : Double‐racemic cocrystals of axially chiral octabrominated perylenediimide (OBPDI) and several achiral aromatic molecules are analyzed. It is shown that chiral information is transferred from the OBPDI host to the achiral guests through noncovalent π‐hole⋅⋅⋅π donor–acceptor interactions.