Missing Link between Helical Nano‐ and Microfilaments in B4 Phase Bent‐Core Liquid Crystals, and Deciphering which Chiral Center Controls the Filament Handedness

Journal Article · 28 December 2019 · Small

DOI: https://doi.org/10.1002/smll.201905591 · OSTI ID:1580625

Shadpour, Sasan ^[1]; Nemati, Ahlam  ^[1]; Salamończyk, Mirosław  ^[2]; Prévôt, Marianne E.  ^[1]; Liu, Jiao ^[1]; Boyd, Nicola J. ^[3]; Wilson, Mark R.  ^[3]; Zhu, Chenhui  ^[4]; Hegmann, Elda  ^[5]; Jákli, Antal I.  ^[6]; Hegmann, Torsten  ^[7]

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1. Chemical Physics Interdisciplinary Program Advanced Materials and Liquid Crystal Institute Kent State University Kent OH 44242‐0001 USA
2. Faculty of Chemistry University of Warsaw 02‐089 Warszawa Poland
3. Department of Chemistry Durham University Durham DH1 3LE UK
4. Advanced Light Source Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
5. Chemical Physics Interdisciplinary Program Advanced Materials and Liquid Crystal Institute Kent State University Kent OH 44242‐0001 USA, Department of Biological Sciences Kent State University Kent OH 44242‐0001 USA, Brain Health Research Institute Kent State University Kent OH 44242‐0001 USA
6. Chemical Physics Interdisciplinary Program Advanced Materials and Liquid Crystal Institute Kent State University Kent OH 44242‐0001 USA, Department of Physics and Astronomy Kent State University Kent OH 44242‐0001 USA
7. Chemical Physics Interdisciplinary Program Advanced Materials and Liquid Crystal Institute Kent State University Kent OH 44242‐0001 USA, Brain Health Research Institute Kent State University Kent OH 44242‐0001 USA, Department of Chemistry and Biochemistry Kent State University Kent OH 44242‐0001 USA

Abstract The range of possible morphologies for bent‐core B4 phase liquid crystals has recently expanded from helical nanofilaments (HNFs) and modulated HNFs to dual modulated HNFs, helical microfilaments, and heliconical‐layered nanocylinders. These new morphologies are observed when one or both aliphatic side chains contain a chiral center. Here, the following questions are addressed: which of these two chiral centers controls the handedness (helicity) and which morphology of the nanofilaments is formed by bent‐core liquid crystals with tris‐biphenyl diester core flanked by two chiral 2‐octyloxy side chains? The combined results reveal that the longer arm of these nonsymmetric bent‐core liquid crystals controls the handedness of the resulting dual modulated HNFs. These derivatives with opposite configuration of the two chiral side chains now feature twice as large dimensions compared to the homochiral derivatives with identical configuration. These results are supported by density functional theory calculations and stochastic dynamic atomistic simulations, which reveal that the relative difference between the para ‐ and meta ‐sides of the described series of compounds drives the variation in morphology. Finally, X‐ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) data also uncover the new morphology for B4 phases featuring p 2/ m symmetry within the filaments and less pronounced crystalline character.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1580625
• Journal Information: Small, Journal Name: Small Journal Issue: 4 Vol. 16; ISSN 1613-6810
• Publisher: Wiley Blackwell (John Wiley & Sons)Copyright Statement
• Country of Publication: Germany
• Language: English