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Nakasugi S, Kang S, Chang TFM, Manaka T, Ishizaki H, Sone M, Watanabe J. Spontaneous Polarization Characteristics in Polar Smectic Phases of Fluoro-Substituted Bent-Shaped Dimeric Molecules. J Phys Chem B 2022; 126:8119-8127. [PMID: 36194857 DOI: 10.1021/acs.jpcb.2c05813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three kinds of bent-shaped dimeric molecules are synthesized by fluorine substitution of C16 molecules, and influences of the substitution on the polar smectic phases are examined. The fluorine-substituted C16 molecules form the SmAPF and SmCAPA phases. The transition temperatures decrease by 20-30 °C without significantly changing the temperature span of the smectic phase, and the switching rates to the ferroelectric state become 5-10 μs, which are fairly shorter than 250 μs of C16. These behaviors are considered to be caused by the decrease in the intermolecular force and the decrease in the viscosity. The anchoring behavior also appears to be different. On the indium tin oxide (ITO)-coated cell, the fluorine-substituted molecules are homogeneously aligned with the bent (polar) axes perpendicular to the surface, while the bent axes of ordinary bent-shaped molecules lie parallel to the surface. This may be attributable to the repulsion between the fluorine and ITO electrodes. Further, the fluorine substitution can increase the dipole moment of the molecule. The largest dipole moment obtained is 7.94 D, and this leads to a huge reversal polarization of 2.42 μC cm-2, which is much higher compared to those reported in the bent-shaped molecules.
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Affiliation(s)
- Shigemasa Nakasugi
- Advanced Technology Research Department, LG Japan Lab Inc., 1-2-13, Takashima, Nishi-ku, Yokohama, Kanagawa220-0011, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa226-8503, Japan
| | - Sungmin Kang
- Advanced Technology Research Department, LG Japan Lab Inc., 1-2-13, Takashima, Nishi-ku, Yokohama, Kanagawa220-0011, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa226-8503, Japan
| | - Tso-Fu Mark Chang
- Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa226-8503, Japan
| | - Takaaki Manaka
- Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo152-8552, Japan
| | - Hiroki Ishizaki
- Advanced Technology Research Department, LG Japan Lab Inc., 1-2-13, Takashima, Nishi-ku, Yokohama, Kanagawa220-0011, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa226-8503, Japan
| | - Masato Sone
- Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa226-8503, Japan
| | - Junji Watanabe
- Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa226-8503, Japan
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Madhusudana NV. Two-state model for the SmAP_{R} phase with randomized layer polarization exhibited by some compounds with bent-core molecules. Phys Rev E 2022; 106:034702. [PMID: 36266904 DOI: 10.1103/physreve.106.034702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 08/17/2022] [Indexed: 06/16/2023]
Abstract
One of the unusual liquid crystalline phases exhibited by some compounds with bent-core (BC) molecules is designated as SmAP_{R}, in which transverse polarization (P) of smectic layers with upright molecules has a random orientational distribution. Most of such compounds undergo a transition to the SmAP_{A} phase with antiferroelectric order of adjacent layers as the temperature is lowered. Second harmonic studies have shown that the medium consists of polarized domains with only a few hundred molecules, the number increasing at lower temperatures. This is in contrast to the random orientations of entire layers predicted by a few phenomenological models which have been proposed for the SmAP_{R} phase. In this paper we show that the two-state model, developed earlier by us to describe modulated phases found in compounds with BC molecules, can successfully account for all the experimental results on the SmAP_{R} phase. It is proposed that polarized domains which are made of ground state conformers, with a large bend of the aromatic cores, nucleate as circular disks in a first order transition from the isotropic phase. Excited state conformers (with a smaller bend) freely rotate about their long axes and surround the disks. The polarization in the disk has a spontaneous splay distortion which generates a texture with an expelled center of a partial disclination. The interdisk electrostatic energy is lower than the thermal energy and the disks are subject to significant rotational fluctuations, resulting in the uniaxial symmetry of the medium. Calculated equilibrium properties of the medium as functions of temperature and electric field reflect the trends seen in experiments. The model overestimates properties such as the radius of the disks as the transition to a lower temperature uniform phase is approached, and physical arguments are given to show that interlayer interactions ignored in the model become important in that regime, and should be included for an improved description of the medium.
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Affiliation(s)
- N V Madhusudana
- Raman Research Institute, C. V. Raman Avenue, Bengaluru 560080, India
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Nakasugi S, Kang S, Chang TFM, Ishizaki H, Sone M, Watanabe J. Electric Switching Behaviors and Dielectric Relaxation Properties in Ferroelectric, Antiferroelectric, and Paraelectric Smectic Phases of Bent-Shaped Dimeric Molecules. J Phys Chem B 2022; 126:4967-4976. [PMID: 35749271 DOI: 10.1021/acs.jpcb.2c01938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study reports the electric switching behaviors and dielectric properties of the ferroelectric smectic-A (SmAPF), anti-ferroelectric smectic-A (SmAPA), anti-ferroelectric SmCAPA, and smectic-A (SmA) phases formed by mixing the bent-shaped dimeric molecules, α,ω-bis(4-alkoxyanilinebenzylidene-4'-carbonyloxy)pentanes. These four phases each show characteristic features. The SmAPF shows a low threshold electric field for ferroelectric switching and a large dielectric strength due to the collective fluctuation mode of dipoles at around 500 Hz. Both the threshold electric field and dielectric strength are strongly dependent on the cell thickness. The threshold field decreases to 0.1 V μm-1, and the dielectric strength increases up to a huge value of 10,000 as the cell thickness increases up to 80 μm. The SmAPA also shows a similar collective mode at around 2 kHz with a relatively small dielectric strength (around 200), which may be induced by the anti-phase rotation of dipoles in adjacent layers. In these collective modes, the dielectric strength is found to be inversely proportional to the switching threshold field. On the other hand, another anti-ferroelectric SmCAPA as well as the paraelectric SmA show only the non-collective mode (i.e., rotational relaxation of individual molecules around their short axes) at a high frequency of around 100 kHz.
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Affiliation(s)
- Shigemasa Nakasugi
- Advanced Technology Research Department, LG Japan Lab Inc., 1-2-13, Takashima, Nishi-ku, Yokohama, Kanagawa 220-0011, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Sungmin Kang
- Advanced Technology Research Department, LG Japan Lab Inc., 1-2-13, Takashima, Nishi-ku, Yokohama, Kanagawa 220-0011, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Tso-Fu Mark Chang
- Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Hiroki Ishizaki
- Advanced Technology Research Department, LG Japan Lab Inc., 1-2-13, Takashima, Nishi-ku, Yokohama, Kanagawa 220-0011, Japan.,Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Masato Sone
- Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
| | - Junji Watanabe
- Institute of Innovative Research, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503, Japan
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Upadhyaya K, Ghosh S, Khan RK, Pratibha R, Rao NV. Development of nematic and orthogonal smectic phases in short-core fluorinated hockey-stick shaped liquid crystal compounds. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.111989] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Alaasar M, Prehm M, Poppe S, Tschierske C. Development of Polar Order by Liquid‐Crystal Self‐Assembly of Weakly Bent Molecules. Chemistry 2017; 23:5541-5556. [DOI: 10.1002/chem.201606035] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Indexed: 01/23/2023]
Affiliation(s)
- Mohamed Alaasar
- Institute of Chemistry Martin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
- Department of Chemistry Faculty of Science Cairo University Giza Egypt
| | - Marko Prehm
- Institute of Chemistry Martin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
| | - Silvio Poppe
- Institute of Chemistry Martin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
| | - Carsten Tschierske
- Institute of Chemistry Martin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
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Kaur S, Punjani V, Mohiuddin G, Pal SK. Orthogonal smectic and nematic ordering in three-ring polar bent-core molecules with anti-parallel arrangement. NEW J CHEM 2017. [DOI: 10.1039/c7nj00272f] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three-ring based BLCs exhibiting orthogonal smectic and nematic phases with antiparallel arrangement as derived from SCXRD and X-ray scattering results.
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Affiliation(s)
- Supreet Kaur
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
| | - Vidhika Punjani
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
| | - Golam Mohiuddin
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
| | - Santanu Kumar Pal
- Department of Chemical Sciences
- Indian Institute of Science Education and Research (IISER) Mohali
- Manauli-140306
- India
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7
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Alaasar M, Prehm M, Tamba MG, Sebastián N, Eremin A, Tschierske C. Development of Polar Order in the Liquid Crystal Phases of a 4-Cyanoresorcinol-Based Bent-Core Mesogen with Fluorinated Azobenzene Wings. Chemphyschem 2015; 17:278-87. [DOI: 10.1002/cphc.201500891] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Indexed: 01/17/2023]
Affiliation(s)
- Mohamed Alaasar
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
- Department of Chemistry; Faculty of Science; Cairo University; Giza Egypt
| | - Marko Prehm
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
| | - Maria-Gabriela Tamba
- Institute for Experimental Physics; Otto-von-Guericke University Magdeburg; Universitätsplatz 2 39106 Magdeburg Germany
| | - Nerea Sebastián
- Institute for Experimental Physics; Otto-von-Guericke University Magdeburg; Universitätsplatz 2 39106 Magdeburg Germany
| | - Alexey Eremin
- Institute for Experimental Physics; Otto-von-Guericke University Magdeburg; Universitätsplatz 2 39106 Magdeburg Germany
| | - Carsten Tschierske
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
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Romiszewski J, Puterová-Tokarová Z, Mieczkowski J, Gorecka E. Optical properties of thiophene-containing liquid crystalline and hybrid liquid crystalline materials. NEW J CHEM 2014. [DOI: 10.1039/c4nj00298a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mesogenic and optical properties of thiophene-based stilbenes and azobenzenes were investigated. A new hybrid material built of AuNPs coated with a thiophene-containing ligand is presented.
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Affiliation(s)
| | - Zita Puterová-Tokarová
- Department of Chemistry
- Warsaw University
- 02-093 Warsaw, Poland
- Department of Chemistry
- University of SS Cyril and Methodius
| | | | - Ewa Gorecka
- Department of Chemistry
- Warsaw University
- 02-093 Warsaw, Poland
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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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Guo L, Gorecka E, Pociecha D, Vaupotič N, Čepič M, Reddy RA, Gornik K, Araoka F, Clark NA, Walba DM, Ishikawa K, Takezoe H. Ferroelectric behavior of orthogonal smectic phase made of bent-core molecules. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:031706. [PMID: 22060389 DOI: 10.1103/physreve.84.031706] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Indexed: 05/31/2023]
Abstract
Ferroelectric behavior in the recently reported orthogonal ferroelectric Sm-A(d)P(F) phase in an unsymmetric bent-core molecule with a carbosilane terminal group was studied. The ferroelectricity of the Sm-A(d)P(F) phase was unambiguously confirmed by optical second-harmonic generation activity in the absence of an electric field, ferroelectric response, and high dielectric strength. The long-range polar order is a consequence of weakened interlayer coupling due to the formation of carbosilane sublayers, which allows for the parallel order of dipole moments of bent-core molecules in the neighboring layers. It develops in the system gradually through the second-order phase transition from the orthogonal Sm-A(d) phase. In the Sm-A(d)P(F) phase the strong surface anchoring results in the splay of polarization across the sample thickness. The polar surface anchoring also brings about strongly thickness-dependent polar fluctuations, as proved by the dielectric measurements (Goldstone-like mode). The relaxation frequency and dielectric strength vary more than one order of magnitude with cell thickness; in particular the dielectric strength attains more than 2000 in a 25 μm-thick cell and continues to increase for thicker cells. Simple theory developed qualitatively explains the experimental results, supporting the polarization splay model proposed.
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Affiliation(s)
- Lingfeng Guo
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-S8-42 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
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Gomola K, Guo L, Pociecha D, Araoka F, Ishikawa K, Takezoe H. An optically uniaxial antiferroelectric smectic phase in asymmetrical bent-core compounds containing a 3-aminophenol central unit. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm01241f] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Guo L, Dhara S, Sadashiva BK, Radhika S, Pratibha R, Shimbo Y, Araoka F, Ishikawa K, Takezoe H. Polar switching in the smectic- A(d)P(A) phase composed of asymmetric bent-core molecules. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:011703. [PMID: 20365387 DOI: 10.1103/physreve.81.011703] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Indexed: 05/29/2023]
Abstract
We have studied mesogenic properties in the smectic- A(d)P(A) phase of an asymmetric bent-core liquid crystal by means of polarizing optical microscopy, second-harmonic generation (SHG), electro-optical (EO), and dielectric measurements. In homeotropically aligned cells, EO switching is clearly observed from a schlieren texture with both four- and two-brush defects to a uniform bright domain under the application of very low in-plane electric field below 1 V/microm. The phase is SHG active under an electric field, i.e., SHG gradually increases without a threshold and saturates with the increasing field. In homogeneous cells, by applying triangular wave field at saturated voltage, the splitting of the polarization switching current peak is observed, indicating that the mesophase is antiferroelectric. The dielectric studies indicate a Debye-type relaxation of the transverse dipoles associated with the rotation of the molecules about their long axis. The dc bias-dependent dielectric relaxation time and the dielectric strength suggest that a field-induced antiferroelectric-ferroelectric phase transition occurs continuously beyond 1.2 V/microm and is reversible. The field-dependent texture observation is consistent with the dielectric measurements. Two possible models are proposed to interpret the continuous phase transition.
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Affiliation(s)
- Lingfeng Guo
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan
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Weissflog W, Pelzl G, Kresse H, Baumeister U, Brand K, Schröder MW, Tamba MG, Findeisen-Tandel S, Kornek U, Stern S, Eremin A, Stannarius R, Svoboda J. In search of a new design strategy for solid single-component organic ferroelectrics: Polar crystalline phases formed by bent-core molecules. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm00322k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gomola K, Guo L, Gorecka E, Pociecha D, Mieczkowski J, Ishikawa K, Takezoe H. First symmetrical banana compounds exhibiting SmAPR mesophase and unique transition between two orthogonal polar phases. Chem Commun (Camb) 2009:6592-4. [DOI: 10.1039/b912150a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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