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Synthesis, π‐Face‐Selective Aggregation, and π‐Face Chiral Recognition of Configurationally Stable C 3 ‐Symmetric Propeller‐Chiral Molecules with a π‐Core
Author(s) -
Saito Nozomi,
Terakawa Ryo,
Yamaguchi Masahiko
Publication year - 2014
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.201400094
Subject(s) - molecule , vapor pressure osmometry , chemistry , stereochemistry , chirality (physics) , crystallography , racemic mixture , nuclear magnetic resonance spectroscopy , spectroscopy , enantiomer , chiral symmetry , physics , organic chemistry , vapor pressure , quantum mechanics , nambu–jona lasinio model , quark
Abstract The C 3 ‐symmetric propeller‐chiral compounds ( P , P , P )‐ 1 and ( M , M , M )‐ 1 with planar π‐cores perpendicular to the C 3 ‐axis were synthesized in optically pure states. ( P , P , P )‐ 1 possesses two distinguishable propeller‐chiral π‐faces with rims of different heights named the ( P / L )‐face and ( P / H )‐face. Each face is configurationally stable because of the rigid structure of the helicenes contained in the π‐core. ( P , P , P )‐ 1 formed dimeric aggregates in organic solutions as indicated by the results of 1 H NMR, CD, and UV/Vis spectroscopy and vapor pressure osmometry analyses. The ( P / L )/( P / L ) interactions were observed in the solid state by single‐crystal X‐ray analysis, and they were also predominant over the ( P / H )/( P / H ) and ( P / L )/( P / H ) interactions in solution, as indicated by the results of 1 H and 2D NMR spectroscopy analyses. The dimerization constant was obtained for a racemic mixture, which showed that the heterochiral ( P , P , P )‐ 1 /( M , M , M )‐ 1 interactions were much weaker than the homochiral ( P , P , P )‐ 1 /( P , P , P )‐ 1 interactions. The results indicated that the propeller‐chiral ( P / L )‐face interacts with the ( P / L )‐face more strongly than with the ( P / H )‐face, ( M / L )‐face, and ( M / H )‐face. The study showed the π‐face‐selective aggregation and π‐face chiral recognition of the configurationally stable propeller‐chiral molecules.