Dynamic Mirror‐Symmetry Breaking in Bicontinuous Cubic Phases |
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Authors: | Christian Dressel Prof?Dr Feng Liu Dr Marko Prehm Dr Xiangbing Zeng Prof?Dr Goran Ungar Prof?Dr Carsten Tschierske |
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Institution: | 1. Institute of Chemistry, Organic Chemistry, Martin‐Luther‐University Halle‐Wittenberg, Kurt‐Mothes‐Str. 2, 06120 Halle (Germany);2. State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049 (P.R. China);3. Department of Engineering Materials, University of Sheffield, Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (UK);4. Department of Physics, Zhejiang Sci‐Tech University, Xiasha College Park, Hangzhou 310018 (China) |
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Abstract: | Chiral segregation of enantiomers or chiral conformers of achiral molecules during self‐assembly in well‐ordered crystalline superstructures has fascinated chemists since Pasteur. Here we report spontaneous mirror‐symmetry breaking in cubic phases formed by achiral multichain‐terminated diphenyl‐2,2′‐bithiophenes. It was found that stochastic symmetry breaking is a general phenomenon observed in bicontinuous cubic liquid crystal phases of achiral rod‐like compounds. In all compounds studied the ${{\it Im}\bar 3m}$ cubic phase is always chiral, while the ${Ia\bar 3d}$ phase is achiral. These intriguing observations are explained by propagation of homochiral helical twist across the entire networks through helix matching at network junctions. In the ${Ia\bar 3d}$ phase the opposing chiralities of the two networks cancel, but not so in the three‐networks ${{\it Im}\bar 3m}$ phase. The high twist in the ${{\it Im}\bar 3m}$ phase explains its previously unrecognized chirality, as well as the origin of this complex structure and the transitions between the different cubic phases. |
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Keywords: | chiral isotropic liquid conglomerate deracemization polycatenar liquid crystal spontaneous chiral induction |
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