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Title: Heliconical smectic phases formed by achiral molecules

Chiral symmetry breaking in soft matter is a hot topic of current research. Recently, such a phenomenon was found in a fluidic phase showing orientational order of molecules - the nematic phase; although built of achiral molecules, the phase can exhibit structural chirality - average molecular direction follows a short-pitch helix. Here in this paper, we report a series of achiral asymmetric dimers with an odd number of atoms in the spacer, which form twisted structures in nematic as well as in lamellar phases. The tight pitch heliconical nematic (N TB) phase and heliconical tilted smectic C (SmC TB) phase are formed. The formation of a variety of helical structures is accompanied by a gradual freezing of molecular rotation. In the lowest temperature smectic phase, HexI, the twist is expressed through the formation of hierarchical structure: nanoscale helices and mesoscopic helical filaments. The short-pitch helical structure in the smectic phases is confirmed by resonant X-ray measurements.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [4]
  1. Univ. of Aberdeen, King's College, Aberdeen, Scotland (United Kingdom)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Kent State Univ., Kent, OH (United States). Dept. of Physics and Liquid Crystal Inst.
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  4. Univ. of Warsaw (Poland). Faculty of Chemistry
Publication Date:
Grant/Contract Number:
AC02-05CH11231; 2016/22/A/ST5/00319; DMR-1411344; DMR-1307674
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1433133