Premium
An Enantiomeric Nanoscale Architecture Obtained from a Pseudoenantiomeric Aggregate: Covalent Fixation of Helical Chirality Formed in Self‐Assembled Discotic Triazine Triamides by Chiral Amplification
Author(s) -
Ishii Tsutomu,
Kuwahara Rempei,
Takata Akihiko,
Jeong Yeonhwan,
Sakurai Kazuo,
Mataka Shuntaro
Publication year - 2006
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.200500720
Subject(s) - chirality (physics) , enantiomer , covalent bond , nanoscopic scale , triazine , self assembly , supramolecular chirality , chemistry , combinatorial chemistry , materials science , fixation (population genetics) , nanotechnology , polymer chemistry , organic chemistry , supramolecular chemistry , molecule , physics , biochemistry , chiral symmetry breaking , quantum mechanics , nambu–jona lasinio model , quark , gene
Covalent fixation of a chiral helical structure which is created in a self‐assembling system by a chiral‐amplification method based on the sergeants/soldiers principle is reported. Disk‐shaped triazine triamides self‐assembled to form columnar‐type helical aggregates through π‐stacking interactions among the central triphenyltriazine moieties, hydrogen‐bonding interactions among the amide groups, and van der Waals interactions among the alkyl groups in nonpolar solvents such as hexane, octane, toluene, and p ‐xylene. When the achiral triazine triamide soldier component is mixed with a tiny amount of the chiral triazine triamide sergeant component, control of the intrinsic supramolecular helicity of the self‐assembled soldier component by the sergeant component leads to chiral amplification and formation of a pseudoenantiomeric aggregate with only one handedness of the helix. The helicity can be preserved by ring‐closing olefin metathesis polymerization mediated by Grubbs catalyst when an achiral component with terminal olefinic groups forms the pseudoenantiomeric aggregate in the presence of a tiny amount of the chiral component without olefinic groups. After polymerization and removal of the chiral component, the polymeric architecture obtained from the achiral soldier component is optically active and thus can be regarded as an enantiomeric object in which the chiral information transferred from the chiral sergeant component is preserved. The nanoscale chiral structure is fixed perfectly, as indicated by CD spectroscopic evidence obtained in a polar THF medium at high temperature and low concentration. AFM and TEM observations show a nanoscale fibrous structure with a diameter of 2–4 nm, which corresponds to the molecular size of the triazine triamide monomer.