Fluorescence Mapping of Atropisomer Populations enabled by Through-Space Conjugation

Multi-axis atropisomers are ubiquitous in nature, and their intricate stereoconformations not only deepen stereochemical understanding but also elucidate fundamental principles of molecular atropisomeric dynamics. Nevertheless, insights into multi-axis atropisomerism remain limited. This work presents a systematic investigation of three classes of LaPlente-type biaxial atropisomers based on naphthalene rotors and phenyl linkers. Thermodynamically and kinetically controlled interconversion of molecular conformations is achieved in 22-NB, 11-NB, and 11-NB-8DMe. Concurrently, a direct correlation between molecular dynamics and electronic through-space conjugation (TSC) is elucidated. Furthermore, absolute separation of syn and anti conformers is accomplished in 11-NB-2DMe, whose distinct TSC-induced fluorescence enables direct visualization of dynamic conformer populations and kinetics during temporally sequential crystallization. This work provides fundamental mechanistic insights into multi-axis atropisomer stereochemistry and establishes a fluorescence-based approach as an in-situ platform for real-time analysis of molecular dynamics across life and materials sciences.