Metastable Chiral Azobenzenes Stabilized in a Double Racemate

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.

Atom-Efficient Halogen–Halogen Interactions Assist One-, Two-, and Three-Dimensional Molecular Zippers

“…Overlap between the electrophilic and nucleophilic regions of interacting halogen atoms plays a pivotal role in assembling T2 in a self-complementary manner which results in unbounded 2D zipper assembly. SAPT(0) analysis was employed to explore the stability of the intermolecular interactions 53 modeling molecular zippers of NTB 2 . SAPT(0) provided a quantitative picture of the interactions by decomposing the total interaction energy into physically meaningful components (electrostatic, exchange, induction, and dispersion) (Table 1).…”

Retaining Hückel Aromaticity in the Triplet Excited State of Azobenzene

“…Aromaticity changes along the T 1 potential energy surface of stilbene have been reported with an aromatic relaxed T 1 state exhibiting a twisted geometry [21] . Recently our group could capture a similar twisted geometry of azobenzene in the crystalline state for the first time wherein the twist was induced by the host [22] …”

“…[21] azobenzene in the crystalline state for the first time wherein the twist was induced by the host. [22] Along with our previous work of antiaromaticity relief in triplet excimer of linear acenes appealing to the potential application in supramolecular architectures, [23] we were also eager to perceive monomeric excited-state processes in terms of aromaticity. Our persistent efforts aided in elucidating the Z/ E thermal isomerization of one of the most widely used molecular switches, azobenzene (Ab) through the lens of aromaticity.…”

Advances in Application of Azobenzene as a Trigger in Biomedicine: Molecular Design and Spontaneous Assembly

“…In the field of biomedicine, this mainly involves the regulation of mechanical and optical properties, and the self‐assembly process of supramolecular systems. [ 271 ] The photoisomerization of azobenzene also provides an effective way to convert light energy into mechanical driving force from a nano to a macro level, and provides insight for manufacturing optical driving biomaterials. [ 272 ]…”