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Benzo‐Fused Double [7]Carbohelicene: Synthesis, Structures, and Physicochemical Properties
Author(s) -
Hu Yunbin,
Wang XiaoYe,
Peng PiXian,
Wang XinChang,
Cao XiaoYu,
Feng Xinliang,
Müllen Klaus,
Narita Akimitsu
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201610434
Subject(s) - enantiopure drug , helicene , chemistry , conformational isomerism , terphenyl , isomerization , crystallography , circular dichroism , density functional theory , imine , chiral column chromatography , spectroscopy , stereochemistry , enantiomer , computational chemistry , molecule , organic chemistry , enantioselective synthesis , catalysis , physics , quantum mechanics
A benzo‐fused double [7]carbohelicene (D7H) was synthesized through a regioselective cyclodehydrogenation of a tetranaphthyl‐ p ‐terphenyl‐based precursor. The twisted (D7H‐1) and anti ‐folded (D7H‐2) conformers of D7H were separated by recrystallization, and their double helicene structures with overlapping terminal benzene rings were unambiguously elucidated by X‐ray crystallography. A record‐high isomerization barrier (46.0 kcal mol −1 ) in double helicenes was estimated based on density functional theory (DFT) calculation, which resulted in the excellent conformational stability of D7H. The physicochemical properties of D7H‐1 and D7H‐2 were investigated by UV/Vis absorption spectroscopy and cyclic voltammetry, displaying the variation of electronic structure upon conformational changes. The optical resolution of the racemic D7H‐1 was carried out by chiral HPLC, offering enantiopure D7H‐1‐( P , P ) and D7H‐1‐( M , M ), which were further characterized by circular dichroism spectroscopy.