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Ogura Y, Akiyama A, Kohri M, Kishikawa K. Positions of Chiral Alkoxy Groups Responsible for Ferroelectricity in a Columnar Liquid Crystal Phase of Diphenylureas with Six Alkoxy Groups. J Phys Chem B 2024; 128:3775-3783. [PMID: 38569005 DOI: 10.1021/acs.jpcb.4c00642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
The columnar polarization direction of ferroelectric columnar liquid crystals can be switched by applying an external electric field, and the polarization direction can be maintained, even after the electric field is removed. If the polarization direction of each column in ferroelectric columnar liquid crystals can be switched and maintained, then ultrahigh-density memory devices can be generated. Recently, we found that the columnar phase of N,N'-bis(3,4,5-tri(S)-citronellyloxyphenyl)urea (Urea-(S)-cit) shows ferroelectricity, whereas that of N,N'-bis(3,4,5-tridecyloxyphenyl)urea (Urea-10) does not. However, the mechanisms by which the six chiral alkoxy groups in Urea-(S)-cit generate ferroelectricity have not been determined. In this study, we regioselectively synthesized four diphenylurea compounds containing (S)-citronellyloxy and decyloxy groups, i.e., N,N'-bis(3,5-di((S)-citronellyloxy)-4-decyloxyphenyl)urea (1), N,N'-bis(4-((S)-citronellyloxy)-3,5-didecyloxyphenyl)urea (2), N,N'-bis(3-((S)-citronellyloxy)-4,5-didecyloxyphenyl)urea (3), and N,N'-bis(3,4-di((S)-citronellyloxy)-5-decyloxyphenyl)urea (4), and investigated which chiral alkoxy group at which position is strongly responsible for the ferroelectricity. The chiral alkoxy groups at 3- and 5-positions of the phenyl groups were clarified to play a significant role in the generation of ferroelectricity. Furthermore, a comparison of these four compounds based on circular dichroism spectroscopy and second harmonic generation experiments revealed the relationship between the helical structure order and the stability of the polarized structure.
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Affiliation(s)
- Yoshiki Ogura
- Division of Advanced Science and Engineering, Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Azumi Akiyama
- Division of Advanced Science and Engineering, Graduate School of Science and Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Michinari Kohri
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Keiki Kishikawa
- Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
- Molecular Chirality Research Center, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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Sambe K, Takeda T, Hoshino N, Matsuda W, Miura R, Tsujita K, Maruyama S, Yamamoto S, Seki S, Matsumoto Y, Akutagawa T. Ferroelectric Organic Semiconductor: [1]Benzothieno[3,2- b][1]benzothiophene-Bearing Hydrogen-Bonding -CONHC 14H 29 Chain. ACS APPLIED MATERIALS & INTERFACES 2023; 15:58711-58722. [PMID: 38055344 DOI: 10.1021/acsami.3c14476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
An alkylamide-substituted [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivative of BTBT-CONHC14H29 (1) and C8H17-BTBT-CONHC14H29 (2) were prepared to design the multifunctional organic materials, which can show both ferroelectric and semiconducting properties. Single-crystal X-ray structural analyses of short-chain (-CONHC3H7) derivatives revealed the coexistence of two-dimensional (2D) electronic band structures brought from a herringbone arrangement of the BTBT π core and the one-dimensional (1D) hydrogen-bonding chains of -CONHC3H7 chains. The thin films of 1 and 2 fabricated on the Si/SiO2 substrate surface have monolayer and bilayer structures, respectively, resulting in conducting layers parallel to the substrate surface, which is suitable for a channel layer of organic field-effect transistors (OFETs). The thin film of 1 indicated a hole mobility μFET = 2.4 × 10-5 cm2 V-1 s-1 and threshold voltage VTh = - 29 V, whereas that of 2 showed a μFET = 2.1 × 10-2 cm2 V-1 s-1 and threshold voltage VTh = -9.7 V. Both 1 and 2 formed the smectic E (SmE) phase above 410 and 369 K, respectively, where the existence of a hole transport pathway was confirmed in the SmE phase. The ferroelectric hysteresis behavior was observed in bulk 1 and 2 in the polarization-electric field (P-E) curves at the SmE phase. 1 showed the remanent polarization Pr = 2.3 μC cm-2 and coercive electric field Ec = 5.2 V μm-1, whereas the Pr and Ec of 2 were 3.4 μC cm-2 and 7.0 V μm-1 at the conditions of 453 K and 1 Hz. Introduction of alkylamide units into the BTBT π core has the potential to develop the external stimulus-responsive organic semiconductors brought from both ferroelectricity and semiconducting properties.
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Affiliation(s)
- Kohei Sambe
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Takashi Takeda
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Department of Chemistry, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan
| | - Norihisa Hoshino
- Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi-2, Niigata 9050-2181, Japan
| | - Wakana Matsuda
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Riku Miura
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Kanae Tsujita
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Shingo Maruyama
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Shunsuke Yamamoto
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Shu Seki
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yuji Matsumoto
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
| | - Tomoyuki Akutagawa
- Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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Yuan G, Kimura Y, Kobayashi T, Takeda T, Hoshino N, Akutagawa T. Ion polarisation-assisted hydrogen-bonded ferroelectrics in liquid crystalline domains. Chem Sci 2021; 12:13520-13529. [PMID: 34777772 PMCID: PMC8528045 DOI: 10.1039/d1sc03301h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 09/20/2021] [Indexed: 12/01/2022] Open
Abstract
An alkylamide-substituted (−NHCOC10H21) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Colh) liquid crystal. The introduction of simple M+X− salts such as Na+PF6− and K+I− into the ionic channel of 1 enhanced the ionic conductivity of the Colh phase of the M+·(1)·X− salts, with the highest ionic conductivity reaching ∼10−6 S cm−1 for K+·(1)·I− and Na+·(1)·PF6− at 460 K, which was approximately 5 orders of magnitude higher than that of 1. The introduction of non-ferroelectric 1 into the ferroelectric N,N′,N′′-tri(tetradecyl)-1,3,5-benzenetricarboxamide (3BC) elicited a ferroelectric response from the mixed Colh phase of (3BC)x(1)1−x with x = 0.9 and 0.8. The further doping of M+X− into the ferroelectric Colh phase of (3BC)0.9(1)0.1 enhanced the ferroelectric polarisation assisted by ion displacement in the half-filled ionic channel for the vacant dibenzo[18]crown-6 of (3BC)0.9[(M+)0.5·(1)·(X−)0.5]0.1. An alkylamide-substituted (−NHCOC10H21) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Colh) liquid crystal.![]()
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Affiliation(s)
- Guohao Yuan
- Graduate School of Engineering, Tohoku University Sendai 980-8579 Japan .,Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai 980-8577 Japan
| | - Yuko Kimura
- Graduate School of Engineering, Tohoku University Sendai 980-8579 Japan
| | | | - Takashi Takeda
- Graduate School of Engineering, Tohoku University Sendai 980-8579 Japan .,Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai 980-8577 Japan
| | - Norihisa Hoshino
- Graduate School of Engineering, Tohoku University Sendai 980-8579 Japan .,Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai 980-8577 Japan
| | - Tomoyuki Akutagawa
- Graduate School of Engineering, Tohoku University Sendai 980-8579 Japan .,Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University 2-1-1 Katahira, Aoba-ku Sendai 980-8577 Japan.,National Institute for Material Science (NIMS) 1-2-1 Tsukuba 305-0047 Japan
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Akutagawa T, Takeda T, Hoshino N. Dynamics of proton, ion, molecule, and crystal lattice in functional molecular assemblies. Chem Commun (Camb) 2021; 57:8378-8401. [PMID: 34369489 DOI: 10.1039/d1cc01586a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dynamic molecular processes, such as short- or long-range proton (H+) and ion (M+) motions, and molecular rotations in electrical conducting and magnetic molecular assemblies enable the fabrication of electron-H+ (or M+) coupling systems, while crystal lattice dynamics and molecular conformation changes in hydrogen-bonded molecular crystals have been utilised in external stimuli responsive reversible gas-induced gate opening and molecular adsorption/desorption behavior. These dynamics of the polar structural units are responsible for the dielectric measurements. The H+ dynamics are formed from ferroelectrics and H+ conductors, while the dynamic M+ motions of Li+ and Na+ involve ionic conductors and coupling to the conduction electrons. In n-type organic semiconductors, the crystal lattices are modulated by replacing M+ cations, with cations such as Li+, Na+, K+, Rb+, and Cs+. The use of polar rotator or inversion structures such as alkyl amides, m-fluoroanilinium cations, and bowl-shaped trithiasumanene π-cores enables the formation of ferroelectric molecular assemblies. The host-guest molecular systems of ESIPT fluorescent chromic molecules showed interesting molecular sensing properties using various bases, where the dynamic transformation of the crystal lattice and the molecular conformational change were coupled to each other.
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Affiliation(s)
- Tomoyuki Akutagawa
- Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
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Moriya M, Kohri M, Kishikawa K. Chiral Self-Sorting and the Realization of Ferroelectricity in the Columnar Liquid Crystal Phase of an Optically Inactive N, N'-Diphenylurea Derivative Possessing Six (±)-Citronellyl Groups. ACS OMEGA 2021; 6:18451-18457. [PMID: 34308076 PMCID: PMC8296585 DOI: 10.1021/acsomega.1c02534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 06/25/2021] [Indexed: 06/13/2023]
Abstract
An axially polar-ferroelectric columnar liquid crystal (AP-FCLC) phase that exhibits both switching and maintenance of the macro-polarity in the column axis direction has been achieved in an N,N'-bis(3,4,5-trialkoxyphenyl)urea compound (rac-1) prepared from (±)-citronellyl bromide. Although it had been thought that chirality is necessary to achieve the AP-FCLC phase from our previous study, the optically inactive compound which is a mixture of 21 stereoisomers, generated an AP-FCLC phase. We confirmed its ferroelectricity and investigated the mechanism for realizing the AP-FCLC phase using optoelectronic experiments, X-ray diffraction, and circular dichroism spectroscopy. As a result, it was suggested that chiral self-sorting occurs in the columnar liquid crystal phase, in which molecules with a similar stereochemistry form a one-handed helical column, and columns with the same helicity gather together to form a chiral domain. Accordingly, we conclude that the optically inactive compound rac-1 also indicates ferroelectricity similar to that of an optically pure urea compound because of chiral self-sorting.
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Affiliation(s)
- Miyu Moriya
- Department
of Applied Chemistry and Biotechnology, Graduate School of Science
and Engineering, Chiba University, 1-33 Yayoi-cho,
Inage-ku, Chiba 263-8522, Japan
| | - Michinari Kohri
- Department
of Applied Chemistry and Biotechnology, Graduate School of Engineering
and Molecular Chirality Research Center, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
| | - Keiki Kishikawa
- Department
of Applied Chemistry and Biotechnology, Graduate School of Engineering
and Molecular Chirality Research Center, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
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