A series of asymmetric dimers with an odd number of atoms in the spacer were found to form different types of twisted structures despite being achiral. The formation of a variety of helical structures is accompanied by a gradual freezing of molecular rotation. The tight pitch heliconical nematic (NTB) phase and heliconical tilted smectic C (SmCTB) phase are formed. In the lowest temperature smectic phase, HexI, the twist is expressed through the formation of hierarchical structure: nano-scale helices and mesoscopic helical filaments. The short pitch helical structure in smectic phases is confirmed by resonant x-ray measurements.
@article{arxiv.1708.08632,
title = {Heliconical smectic phases formed by achiral molecules},
author = {Jordan P. Abberley and Ross Killah and Rebecca Walker and John M. D. Storey and Corrie T. Imrie and Miroslaw Salamonczyk and Chenhui Zhu and Ewa Gorecka and Damian Pociecha},
journal= {arXiv preprint arXiv:1708.08632},
year = {2018}
}