Title
Internal‐Edge‐Substituted Coumarin‐Fused [6]Helicenes: Asymmetric Synthesis, Structural Features, and Control of Self‐Assembly
Author
Kazuteru Usui, Kosuke Yamamoto, Yuhei Ueno, Kazunobu Igawa, Ryusuke Hagihara, Toshinobu Masuda, Akio Ojida, Satoru Karasawa, Katsuhiko Tomooka, Go Hirai, Hiroshi Suemune
Year
2018
Journal
Chemistry A European Journal
Abstract
π‐Conjugated helicenes containing heteroatoms have attracted significant attention due to their diverse chemical and electronic structures, as well as tunable physical properties. We rationally anticipated that the self‐assembly of coumarin‐fused helicenes would be controlled by the effects of a substituent on the internal edge of the helix. Here, we report the efficient syntheses of coumarin‐fused helicenes 1a,b (R = Ph, Me), and the enantioselective synthesis of 1a (R = Ph) by chiral Au(I)‐catalyzed hydroarylation. The helical structure of 1 was unambiguously determined by X‐ray crystallography. Of particular note, the enantiomerically pure crystal of 1a adopted a one‐dimensional columnar structure based on π‐π stacking interactions, as expected. Furthermore, a significant difference between the fluorescence quantum yields of the enantiomerically pure form and racemate of 1a was observed.
Instrument
FP-8500
Keywords
Fluorescence, Quantum yield, Solid state, Chemical stability, Pharmaceutical