Halogen bond-modulated solid-state reordering and symmetry breaking of azahelicenes

Abstract Spontaneous symmetry breaking predominately occurs during the aggregation of discrete molecules in solution. Herein, we report a unique solid-state symmetry breaking process of dynamically chiral aza[4]helicenes that emerged in vacuum-driven transformation of halogen bond-woven crystals. Du...

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Bibliographic Details
Main Authors: Juncong Liang, Fuwei Gan, Guoli Zhang, Chengshuo Shen, Huibin Qiu
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-59222-2
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Summary:Abstract Spontaneous symmetry breaking predominately occurs during the aggregation of discrete molecules in solution. Herein, we report a unique solid-state symmetry breaking process of dynamically chiral aza[4]helicenes that emerged in vacuum-driven transformation of halogen bond-woven crystals. Due to the weak feature of the halogen bonding, the halides in the cocrystals can be completely removed under vacuum at an elevated temperature. Interestingly, the aza[4]helicene molecules released from the halogen bond network solely adopt one chiral conformation upon reordering and symmetry breaking instantly occurs in a solid state. The Cotton effects gradually increase with the extension of vacuum–heating treatment, indicating a unidirectional transformation of the chiral conformations and an amplification of symmetry breaking during the solid-state reorganization. Moreover, the use of aza[6]helicene as a chiral inducer further enables a precise manipulation for the absolute configuration of the solid-state symmetry breaking, paving a distinctive route to chiral organic materials from achiral/racemic precursors.
ISSN:2041-1723