238. Multistate Aggregation-Induced Chiroptical Properties of Enantiopure Disulfide-Mediated BisPyrene Macrocycles
     Ke-Feng Zhang, Nidal Saleh, Michal Swierczewski, Arnulf Rosspeintner, Francesco Zinna, Gennaro Pescitelli, Céline Besnard, Laure Guénée, Thomas Bürgi, Jérôme Lacour
     Angew. Chem. Int. Ed. 2023, 62, e202304075

A chiral bispyrene macrocycle designed for exclusive intermolecular excimer fluorescence upon aggregation was synthesized by a double hydrothiolation of a bis enol ether macrocycle followed by intramolecular oxidation of free thiols. Unusually high stereoselectivity was achieved for the thiol-ene additions under templated conditions and Et₃B/O₂ radical initiation. After enantiomer separation (chiral stationary phase HPLC), aqueous conditions provoked aggregation. Detailed structural evolution was afforded by ECD/CPL monitoring. Three regimes can be observed and characterized by strong modifications in chiroptical patterns under, at, or above a 70% H₂O:THF threshold. In luminescence, high glum dissymmetry factors values were obtained, up to 0.022, as well as a double sign inversion of CPL signals during the aggregation, a behavior rationalized by time-dependent density functional theory (TDDFT) calculations. Langmuir layers of enantiopure disulfide macrocycles were formed at the air-water interface and transferred onto solid substrates to afford Langmuir-Blodgett films, which were then studied by AFM and UV/ECD/fluorescence/CPL.

DOI : 10.1002/anie.202304075 

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