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Control of Axial Chirality by Planar Chirality Based on Optically Active [2.2]Paracyclophane
Author(s) -
Namba Genki,
Mimura Yuki,
Imai Yoshitane,
Inoue Ryo,
Morisaki Yasuhiro
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003188
Subject(s) - chirality (physics) , planar chirality , axial chirality , intramolecular force , moiety , molecule , planar , crystallography , stereochemistry , materials science , chemistry , enantioselective synthesis , physics , chiral symmetry , organic chemistry , computer graphics (images) , quantum mechanics , computer science , nambu–jona lasinio model , catalysis , quark
Optically active X‐shaped molecules based on the planar chiral [2.2]paracyclophane building block were prepared, in which di(methoxy)terphenyl units were stacked on the central benzene rings. At 25 °C, anisolyl rings freely rotate in solution, while in the crystal form, they are fixed by intramolecular CH–π interactions, thereby leading to the expression of the axial chirality, i.e., propeller chirality was exhibited by the planar chiral [2.2]paracyclophane moiety. The X‐shaped molecule exhibited good circularly polarized luminescence (CPL) profiles with moderate Φ PL and a large g lum value in the order of 10 −3 at 25 °C, in solution. In contrast, at −120 °C, dual CPL emission with opposite signs was observed. According to the theoretical studies, the rotary motion of the anisolyl units is suppressed in the excited states, and so emission from two isomers could be observed. These results demonstrate that the axial chirality was controlled by the planar chirality, leading ultimately to propeller chirality.