Multistate Aggregation‐Induced Chiroptical Properties of Enantiopure Disulfide‐Mediated Bispyrene Macrocycles
Kefeng Zhang, Nidal Saleh, Michał Swierczewski, Arnulf Rosspeintner, Francesco Zinna, Gennaro Pescitelli, Céline Besnard, Laure Guénée, Thomas Bürgi, Jérôme Lacour
Abstract
Abstract 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 Et 3 B/O 2 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 % H 2 O : THF threshold. In luminescence, high g lum 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.