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Deterministic and Stochastic Chiral Symmetry Breaking Exhibited by Racemic Aminomethylenehelicene Oligomers
Author(s) -
Kushida Yo,
Sawato Tsukasa,
Shigeno Masanori,
Saito Nozomi,
Yamaguchi Masahiko
Publication year - 2017
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.201601792
Subject(s) - pentamer , chirality (physics) , random coil , helix (gastropod) , symmetry breaking , crystallography , chiral symmetry breaking , self assembly , racemic mixture , stereochemistry , chemistry , enantiomer , materials science , physics , circular dichroism , organic chemistry , nambu–jona lasinio model , quantum mechanics , ecology , snail , biology , biochemistry
Racemic mixtures of aminomethylenehelicene ( P )‐ and ( M )‐pentamers exhibited deterministic and stochastic chiral symmetry breaking during hetero‐double‐helix formation and self‐assembly in solution. Heating a 50:50 mixture of ( P )‐ and ( M )‐pentamers at 90 °C, and then cooling the mixture to 70 °C resulted in hetero‐double‐helix formation; a Cotton effect with negative Δ ε at λ =315 nm appeared. Chiral self‐assembly occurred when the mixture was cooled to 25 °C. A strong tendency of deterministic chiral symmetry breaking appeared at the molecular and self‐assembled levels, which was indicated by the negative Δ ε at λ =315 nm that appeared in most cases in repeated experiments. Mixtures containing 60:40 and 40:60 ( P )‐/( M )‐pentamers also self‐assembled with the same chirality. When a homo‐double‐helix ( P )‐/( M )‐pentamer and a random coil ( M )‐/( P )‐pentamer were mixed, the chiral self‐assembly formed stochastically, and heating and cooling resulted in deterministic chiral symmetry breaking.