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Patra D, Roy A. Spontaneous breaking of chiral symmetry in achiral bent-core liquid crystals: Excluded volume effect. Phys Rev E 2023; 107:034704. [PMID: 37072988 DOI: 10.1103/physreve.107.034704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/14/2023] [Indexed: 04/20/2023]
Abstract
Bent-Core banana-shaped molecules exhibit tilted polar smectic phases with macroscopically chiral layer order even though the constituent molecules are achiral in nature. Here, we show that the excluded volume interactions between the bent-core molecules account for this spontaneous breaking of chiral symmetry in the layer. We have numerically computed excluded volume between two rigid bent-core molecules in a layer using two types of model structures of them and explored the different possible symmetries of the layer that are favored by the excluded volume effect. For both model structures of the molecule, the C_{2} symmetric layer structure is favored for most values of tilt and bending angle. However, the C_{s} and C_{1} point symmetries of the layer are also possible for one of the model structures of the molecules. We have also developed a coupled XY-Ising model and performed Monte Carlo simulation to explain the statistical origin of spontaneous chiral symmetry breaking in this system. The coupled XY-Ising model accounts for the experimentally observed phase transitions as a function of temperature and electric field.
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Affiliation(s)
- Dipak Patra
- Soft Condensed Matter Group, Raman Research Institute, Bangalore 560080, India
| | - Arun Roy
- Soft Condensed Matter Group, Raman Research Institute, Bangalore 560080, India
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Mishra VD, Srinivasa HT, Roy A. Leaning induced layer undulated tilted smectic phase of asymmetric bent-core liquid crystals. J Chem Phys 2023; 158:074906. [PMID: 36813706 DOI: 10.1063/5.0137990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
We report the synthesis and experimental studies on the liquid crystalline phase of a homologous series of compounds comprised of strongly asymmetric bent-core banana shaped molecules. Our x-ray diffraction studies clearly indicate that the compounds exhibit a frustrated tilted smectic phase with layer undulated structure. The low value of the dielectric constant as well as switching current measurements indicate the absence of polarization in this layer undulated phase. In spite of the absence of polarization, a planar aligned sample can be transformed irreversibly to a higher birefringent texture on the application of a high electric field. The zero field texture can only be retrieved by heating the sample to the isotropic phase and cooling it subsequently to the mesophase. We propose a double tilted smectic structure having layer undulation to account for the experimental observations with the layer undulation arising due to the leaning of the molecules in the layer.
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Affiliation(s)
- Vishnu Deo Mishra
- Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India
| | - H T Srinivasa
- Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India
| | - Arun Roy
- Soft Condensed Matter Group, Raman Research Institute, C. V. Raman Avenue, Sadashivanagar, Bangalore 560 080, India
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Madhusudana NV. Some geometrical aspects of packing of bent-core molecules in the triclinic smectic-C_{g} liquid crystals and simple models of the modulated SmC_{gmod} phase. Phys Rev E 2021; 103:022704. [PMID: 33736059 DOI: 10.1103/physreve.103.022704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/15/2021] [Indexed: 11/07/2022]
Abstract
Organic compounds with bent-core (BC) molecules usually form the layered smectic liquid crystals with tilted molecules and polarization (P) which lies in the plane of the layer. A few such compounds have been found in which P itself tilts out of the plane of the layer, and the medium with general tilt (SmC_{g}) of the molecules has the low chiral triclinic symmetry. We discuss the geometric constraints of molecular packing in this structure to show that projecting groups attached to one of the arms of the BC molecules favors the formation of the SmC_{g} phase. We also extend our model for the modulated phases exhibited by BC molecules to show that the stripe structure made of bilayers shown by a few BC compounds, which is a signature of SmC_{g} layers, is preferentially formed by rotation of the BC molecules about their long axes, rather than about the layer normal. The theoretical results based on the unified model which describes all the modulated phases exhibited by the BC molecules broadly reflect experimental trends.
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Affiliation(s)
- N V Madhusudana
- Raman Research Institute, C.V. Raman Avenue, Bengaluru 560080, India
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The synthesis, mesomorphic and dielectric investigation of new unsymmetrical bent-core mesogens derived from 3-hydroxybenzoic acid. CHEMICAL PAPERS 2020. [DOI: 10.1007/s11696-020-01203-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kondratenko K, Boussoualem Y, Singh DP, Visvanathan R, Duncan AE, Clark NA, Legrand C, Daoudi A. Molecular p-doping in organic liquid crystalline semiconductors: influence of the charge transfer complex on the properties of mesophase and bulk charge transport. Phys Chem Chem Phys 2019; 21:18686-18698. [PMID: 31423509 DOI: 10.1039/c9cp03076j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We explore the molecular nature of doping in organic semiconductors (OSCs) by employing a liquid crystalline organic semiconductor based on phenyl naphthalene as a model. The mesophase nature of composites that include a charge transfer complex (CTC) between the OSC (8-PNP-O12) and an electron acceptor (F4TCNQ) has been investigated by means of differential scanning calorimetry, polarized optical microscopy and X-ray scattering. Optical and vibrational spectroscopies allow us to explore the characteristics and the amount of charge transfer in the CTC and expose some properties that appear only in the complexed state. We have found this system to exhibit partial charge transfer, which manifests itself in all the phase states of the host 8-PNP-O12, as well as in solution. Due to the lowering of molecular symmetry as a result of the charge transfer, one of the previously IR-only vibrational bands of the nitrile group is found to be now active in the Raman spectrum. We have also made an attempt to further investigate the influence of dopant introduction on the bulk hole mobility of 8-PNP-O12. It is found that the presence of the CTC promotes the hole transport in the Smectic B mesophase, however it seems to have a somewhat negative influence in the less ordered smectic A mesophase. This work aims to establish the link between the inevitable change of molecular geometry that occurs on charge transfer with the results obtained by spectroscopic techniques and electronic charge carrier mobility measurements.
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Affiliation(s)
- K Kondratenko
- Univ. Littoral Côte d'Opale, EA 4476 - UDSMM - Unité de Dynamique et Structure de Matériaux Moléculaires, 59140 Dunkerque, France.
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Multi-level chirality in liquid crystals formed by achiral molecules. Nat Commun 2019; 10:1922. [PMID: 31015460 PMCID: PMC6478950 DOI: 10.1038/s41467-019-09862-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/01/2019] [Indexed: 11/22/2022] Open
Abstract
Complex materials often exhibit a hierarchical structure with an intriguing mechanism responsible for the ‘propagation’ of order from the molecular to the nano- or micro-scale level. In particular, the chirality of biological molecules such as nucleic acids and amino acids is responsible for the helical structure of DNA and proteins, which in turn leads to the lack of mirror symmetry of macro-bio-objects. To fully understand mechanisms of cross-level order transfer there is an intensive search for simpler artificial structures exhibiting hierarchical arrangement. Here we present complex systems built of achiral molecules that show four levels of structural chirality: layer chirality, helicity of a basic repeating unit, mesoscopic helix and helical filaments. The structures are identified by a combination of hard and soft x-ray diffraction measurements, optical studies and theoretical modelling. Similarly to many biological systems, the studied materials exhibit a coupling between chirality at different levels. It was previously shown that chiral structures can be formed from achiral bent-shaped mesogens. Here the authors observe hierarchical chiral structures with coupling of chirality at different levels in a system with achiral constituents.
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Abstract
Complexation of biomacromolecules (e.g., nucleic acids, proteins, or viruses) with surfactants containing flexible alkyl tails, followed by dehydration, is shown to be a simple generic method for the production of thermotropic liquid crystals. The anhydrous smectic phases that result exhibit biomacromolecular sublayers intercalated between aliphatic hydrocarbon sublayers at or near room temperature. Both this and low transition temperatures to other phases enable the study and application of thermotropic liquid crystal phase behavior without thermal degradation of the biomolecular components.
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Kovářová A, Světlík S, Kozmík V, Svoboda J, Novotná V, Pociecha D, Gorecka E, Podoliak N. Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core. Beilstein J Org Chem 2014; 10:794-807. [PMID: 24778734 PMCID: PMC3999814 DOI: 10.3762/bjoc.10.75] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 03/19/2014] [Indexed: 12/03/2022] Open
Abstract
Bent-shaped mesogens possessing a biphenyl as a central core have been synthesized and the role of the terminal chain and the orientation of the ester as a linkage group have been investigated. For the studied molecular core we have established that both parameters play an important role for the mesomorphic properties. The polyfluoroalkyl terminal chain supports the formation of mesophases, and the introduction of a chiral lactate terminal chain destabilizes mesophases for the first type of mutual orientation of ester groups, attached to the central core. On the contrary, for the opposite orientation of esters, the terminal chain has no effect on the mesomorphic properties, and columnar phases have been found for all compounds. A unique phase sequence has been found for the mesogen with the fluorinated chain. A generalized tilted smectics, SmCG, have been observed in a temperature interval between two different lamellar SmCP phases and characterized by X-ray and dielectric measurements. The dielectric spectroscopy data are unique and presented for the first time in the SmCG phase providing new information about the molecular dynamics.
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Affiliation(s)
- Anna Kovářová
- Department of Organic Chemistry, Institute of Chemical Technology, CZ-166 28 Prague 6, Czech Republic. ; Tel: +420220444182
| | - Svatopluk Světlík
- Department of Organic Chemistry, Institute of Chemical Technology, CZ-166 28 Prague 6, Czech Republic. ; Tel: +420220444182
| | - Václav Kozmík
- Department of Organic Chemistry, Institute of Chemical Technology, CZ-166 28 Prague 6, Czech Republic. ; Tel: +420220444182
| | - Jiří Svoboda
- Department of Organic Chemistry, Institute of Chemical Technology, CZ-166 28 Prague 6, Czech Republic. ; Tel: +420220444182
| | - Vladimíra Novotná
- Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, CZ-182 21 Prague 8, Czech Republic
| | - Damian Pociecha
- Laboratory of Dielectrics and Magnetics, Chemistry Department, Warsaw University, Al. Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Ewa Gorecka
- Laboratory of Dielectrics and Magnetics, Chemistry Department, Warsaw University, Al. Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Natalia Podoliak
- Institute of Physics, Academy of Science of the Czech Republic, Na Slovance 2, CZ-182 21 Prague 8, Czech Republic
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Deb R, Laskar AR, Sarkar DD, Mohiuddin G, Chakraborty N, Ghosh S, Shankar Rao DS, Rao NVS. Fluorescent unsymmetrical four-ring bent-core mesogens: 2D modulated phases. CrystEngComm 2013. [DOI: 10.1039/c3ce41360h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zhu C, Shao R, Reddy RA, Chen D, Shen Y, Gong T, Glaser MA, Korblova E, Rudquist P, Maclennan JE, Walba DM, Clark NA. Topological Ferroelectric Bistability in a Polarization-Modulated Orthogonal Smectic Liquid Crystal. J Am Chem Soc 2012; 134:9681-7. [DOI: 10.1021/ja3009314] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chenhui Zhu
- Department
of Physics and Liquid
Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
| | - Renfan Shao
- Department
of Physics and Liquid
Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
| | - R. Amaranatha Reddy
- Department of Chemistry and
Biochemistry and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United
States
| | - Dong Chen
- Department
of Physics and Liquid
Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
| | - Yongqiang Shen
- Department
of Physics and Liquid
Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
| | - Tao Gong
- Department of Chemistry and
Biochemistry and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United
States
| | - Matthew A. Glaser
- Department
of Physics and Liquid
Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
| | - Eva Korblova
- Department of Chemistry and
Biochemistry and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United
States
| | - Per Rudquist
- Department of Microtechnology
and Nanoscience, Chalmers University of Technology, S-41269 Göteborg, Sweden
| | - Joseph E. Maclennan
- Department
of Physics and Liquid
Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
| | - David M. Walba
- Department of Chemistry and
Biochemistry and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United
States
| | - Noel A. Clark
- Department
of Physics and Liquid
Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, United States
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Benesch MGK, Mannock DA, Lewis RNAH, McElhaney RN. A Calorimetric and Spectroscopic Comparison of the Effects of Lathosterol and Cholesterol on the Thermotropic Phase Behavior and Organization of Dipalmitoylphosphatidylcholine Bilayer Membranes. Biochemistry 2011; 50:9982-97. [DOI: 10.1021/bi200721j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthew G. K. Benesch
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - David A. Mannock
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Ruthven N. A. H. Lewis
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Ronald N. McElhaney
- Department of Biochemistry, School of Translational
Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Chen WH, Chuang WT, Jeng US, Sheu HS, Lin HC. New SmCG Phases in a Hydrogen-Bonded Bent-Core Liquid Crystal Featuring a Branched Siloxane Terminal Group. J Am Chem Soc 2011; 133:15674-85. [DOI: 10.1021/ja205550b] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wei-Hong Chen
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30049, Taiwan
| | - Wei-Tsung Chuang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - U-Ser Jeng
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Hwo-Shuenn Sheu
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Hong-Cheu Lin
- Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, 30049, Taiwan
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Kohout M, Svoboda J, Novotná V, Pociecha D, Glogarová M, Gorecka E. A nematic-polar columnar phase sequence in new bent-shaped liquid crystals based on a 7-hydroxynaphthalene-2-carboxylic acid core. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b821234a] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Amaranatha Reddy R, Baumeister U, Tschierske C. Self-assembly of bent-core liquid crystals: formation of a modulated smectic phase with p2gg lattice to escape anticlinic tilt. Chem Commun (Camb) 2009:4236-8. [DOI: 10.1039/b907536d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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