1
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Phase Equilibria and Critical Behavior in Nematogenic MBBA-Isooctane Monotectic-Type Mixtures. Int J Mol Sci 2023; 24:ijms24032065. [PMID: 36768388 PMCID: PMC9916662 DOI: 10.3390/ijms24032065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/16/2023] [Accepted: 01/18/2023] [Indexed: 01/21/2023] Open
Abstract
The transition from the isotropic (I) liquid to the nematic-type (N) uniaxial phase appearing as the consequence of the elongated geometry of elements seems to be a universal phenomenon for many types of suspensions, from solid nano-rods to biological particles based colloids. Rod-like thermotropic nematogenic liquid crystalline (LC) compounds and their mixtures with a molecular solvent (Sol) can be a significant reference for this category, enabling insights into universal features. The report presents studies in 4'-methoxybenzylidene-4-n-butylaniline (MBBA) and isooctane (Sol) mixtures, for which the monotectic-type phase diagram was found. There are two biphasic regions (i) for the low (TP1, isotropic liquid-nematic coexistence), and (ii) high (TP2, liquid-liquid coexistence) concentrations of isooctane. For both domains, biphasic coexistence curves' have been discussed and parameterized. For TP2 it is related to the order parameter and diameter tests. Notable is the anomalous mean-field type behavior near the critical consolute temperature. Regarding the isotropic liquid phase, critical opalescence has been detected above both biphasic regions. For TP2 it starts ca. 20 K above the critical consolute temperature. The nature of pretransitional fluctuations in the isotropic liquid phase was tested via nonlinear dielectric effect (NDE) measurements. It is classic (mean-field) above TP1 and non-classic above the TP2 domain. The long-standing problem regarding the non-critical background effect was solved to reach this result.
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2
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Patranabish S, Sinha A, Kanakala MB, Yelamaggad CV. Nematic twist-bend phase of a bent liquid crystal dimer: field-induced deformations of the helical structure and macroscopic polarization. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:465101. [PMID: 36067787 DOI: 10.1088/1361-648x/ac8fd3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 09/06/2022] [Indexed: 06/15/2023]
Abstract
The twist-bend nematic (Ntb) phase is a recent addition to the family of nematic (N) phases of liquid crystals (LCs). A net polar order in the Ntbphase under an external electric field is interesting and it was predicted in several recent theoretical studies. We investigated the field-induced polarization behaviour, dielectric, and electro-optic properties of a bent LC dimer CB7CB in the N and Ntbphases. A threshold-dependent polarization current response was obtained in both the phases under triangular and square-wave input electric fields, existing till frequencies as high as 150 Hz. The polarization switching times were found in ∼1 ms region, especially in the N phase. In the Ntbphase, electric field-induced deformation of the helical structure was observed, like ferroelectric LCs. Dielectric measurements revealed the presence of cybotactic clusters via collective relaxations. The dielectric anisotropy (Δϵ) is negative at the frequencies of polarization measurements. The net polarization resulted from field-induced reorientation of cybotactic clusters and additionally from the field-induced deformation of helical structures in the Ntbphase. We explored the possibility of ionic contributions to the net polarization by synthesizing TiO2nanoparticles (NPs) dispersed CB7CB LC nanocomposite. Incorporation of the NPs resulted in reduction of the collective order, increase in the ionic impurity content and conductivity, but an extinction of the field-induced polarization response. Our results demonstrate that the net polarization has competing contributions from both ferroelectric-like and ionic origin (up to ∼10 Hz) in the LC phases, but it becomes dominantly ferroelectric-like at higher frequencies.
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Affiliation(s)
- Sourav Patranabish
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Aloka Sinha
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Madhu B Kanakala
- Centre for Nano and Soft Matter Sciences, Survey No. 7, Shivanapura, Dasanapura Hobli, Bengaluru 562162, India
| | - C V Yelamaggad
- Centre for Nano and Soft Matter Sciences, Survey No. 7, Shivanapura, Dasanapura Hobli, Bengaluru 562162, India
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3
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Arakawa Y, Inui S, Tsuji H. Synthesis, phase transitions, and liquid crystal behavior of alkylthio azobenzenes. Tetrahedron 2022. [DOI: 10.1016/j.tet.2022.132958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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4
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Guan Z, Wang L, Bae J. Advances in 4D printing of liquid crystalline elastomers: materials, techniques, and applications. MATERIALS HORIZONS 2022; 9:1825-1849. [PMID: 35504034 DOI: 10.1039/d2mh00232a] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Liquid crystalline elastomers (LCEs) are polymer networks exhibiting anisotropic liquid crystallinity while maintaining elastomeric properties. Owing to diverse polymeric forms and self-alignment molecular behaviors, LCEs have fascinated state-of-the-art efforts in various disciplines other than the traditional low-molar-mass display market. By patterning order to structures, LCEs demonstrate reversible high-speed and large-scale actuations in response to external stimuli, allowing for close integration with 4D printing and architectures of digital devices, which is scarcely observed in homogeneous soft polymer networks. In this review, we collect recent advances in 4D printing of LCEs, with emphases on synthesis and processing methods that enable microscopic changes in the molecular orientation and hence macroscopic changes in the properties of end-use objects. Promising potentials of printed complexes include fields of soft robotics, optics, and biomedical devices. Within this scope, we elucidate the relationships among external stimuli, tailorable morphologies in mesophases of liquid crystals, and programmable topological configurations of printed parts. Lastly, perspectives and potential challenges facing 4D printing of LCEs are discussed.
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Affiliation(s)
- Zhecun Guan
- Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA.
| | - Ling Wang
- School of Materials Science and Engineering, Tianjin University, Tianjin 300350, P. R. China.
| | - Jinhye Bae
- Department of Nanoengineering, University of California San Diego, La Jolla, CA 92093, USA.
- Chemical Engineering Program, University of California San Diego, La Jolla, CA 92093, USA
- Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92093, USA
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5
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Jabar MA, H. Karam N. Synthesis and characterization of azo liquid crystal compounds based on 5H-Thiazolo [3,4-b][1,3,4]thiadiazole unit. BIONATURA 2022. [DOI: 10.21931/rb/2022.07.02.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
A calamitic symmetric liquid crystalline consisting of an azo group containing 5H-Thiazolo[3,4-b][1,3,4]thiadiazole moiety compound[III] was synthesized via sequence reactions starting from reaction terephthaldehyde with mercaptoacetic acid and thiosemicarbazide in the presence of concentrated sulfuric acid to synthesized 5,5'-(1,4-phenylene)bis(5H-thiazolo[4,3-b][1,3,4]thiadiazol-2-amine)[I] then the azo compound [II] synthesized by coupling between diazonium salt of the compound [I] with phenol at(0-4) ̊C., after that the compound [III] was synthesized by the reaction of the compound [II] with methyl bromide in alkaline media. The compounds are characterized by melting points, FTIR and 1HNMR spectroscopy. The mesomorphic behavior was studied by using polarized optical microscopy POM.
Keywords. Azo compounds, liquid crystal, mesomorphic properties
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Affiliation(s)
- Maha A. Jabar
- Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad/ Iraq
| | - Nisreen H. Karam
- Department of Chemistry, College of Education for Pure Science (Ibn-Al-Haitham), University of Baghdad/ Iraq
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6
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A Ten-Year Perspective on Twist-Bend Nematic Materials. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092689. [PMID: 35566040 PMCID: PMC9102178 DOI: 10.3390/molecules27092689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/20/2022] [Accepted: 04/20/2022] [Indexed: 11/16/2022]
Abstract
The discovery of the twist-bend nematic phase (NTB) is a milestone within the field of liquid crystals. The NTB phase has a helical structure, with a repeat length of a few nanometres, and is therefore chiral, even when formed by achiral molecules. The discovery and rush to understand the rich physics of the NTB phase has provided a fresh impetus to the design and characterisation of dimeric and oligomeric liquid crystalline materials. Now, ten years after the discovery of the NTB phase, we review developments in this area, focusing on how molecular features relate to the incidence of this phase, noting the progression from simple symmetrical dimeric materials towards complex oligomers, non-covalently bonded supramolecular systems.
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7
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Alaasar M, Cai X, Kraus F, Giese M, Liu F, Tschierske C. Controlling ambidextrous mirror symmetry breaking in photosensitive supramolecular polycatenars by alkyl-chain engineering. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118597] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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8
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Li J, Alfares A, Zheng Y. Optical Manipulation and Assembly of Micro/Nanoscale Objects on Solid Substrates. iScience 2022; 25:104035. [PMID: 35313687 PMCID: PMC8933704 DOI: 10.1016/j.isci.2022.104035] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2022] Open
Abstract
Many light-based technologies have been developed to manipulate micro/nanoscale objects such as colloidal particles and biological cells for basic research and practical applications. While most approaches such as optical tweezers are best suited for manipulation of objects in fluidic environments, optical manipulation on solid substrates has recently gained research interest for its advantages in constructing, reconfiguring, or powering solid-state devices consisting of colloidal particles as building blocks. Here, we review recent progress in optical technologies that enable versatile manipulation and assembly of micro/nanoscale objects on solid substrates. Diverse technologies based on distinct physical mechanisms, including photophoresis, photochemical isomerization, optothermal phase transition, optothermally induced surface acoustic waves, and optothermal expansion, are discussed. We conclude this review with our perspectives on the opportunities, challenges, and future directions in optical manipulation and assembly on solid substrates.
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9
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Thioether-Linked Liquid Crystal Trimers: Odd-Even Effects of Spacers and the Influence of Thioether Bonds on Phase Behavior. MATERIALS 2022; 15:ma15051709. [PMID: 35268942 PMCID: PMC8911043 DOI: 10.3390/ma15051709] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/18/2022] [Accepted: 02/20/2022] [Indexed: 02/04/2023]
Abstract
We report the synthesis, phase-transition behavior, and mesophase structures of the first homologous series of thioether-linked liquid crystal (LC) trimers, 4,4′-bis[ω-(4-cyanobiphenyl-4′-ylthio)alkoxy]biphenyls (CBSnOBOnSCB with a wide range of spacer carbon numbers, n = 3–11). All CBSnOBOnSCB homologs exhibited LC phases. Interestingly, even-n and odd-n homologs showed monotropic layered smectic A (SmA) and pseudo-layered twist-bend nematic (NTB) phases, respectively, below a nematic (N) phase. This alternate formation, which depends on spacer chain parity, is attributed to different average molecular shapes, which are associated with the relative orientations of the biphenyl moieties: linear and bent shapes for even-n and odd-n homologs, respectively. In addition, X-ray diffraction analysis indicated a strong cybotactic N phase tendency, with a triply intercalated structure. The phase-transition behavior and LC phase structures of thioether-linked CBSnOBOnSCB were compared with those of the all-ether-linked classic LC trimers CBOnOBOnOCB. Overall, thioether linkages endowed CBSnOBOnSCB with a monotropic LC tendency and lowered phase-transition temperatures, compared to those of CBOnOBOnOCB, for the same n. This is attributed to enhanced flexibility and bending (less molecular anisotropy) of the molecules, caused by the greater bond flexibility and smaller inner bond angles of the C–S–C bonds, compared to those of the C–O–C bonds.
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10
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Li J, Cong Y, Huang H, Shi Q, Jia Y, Zhang B. Liquid crystalline dimers containing a cholesteryl benzoate unit: smectic phase, chiral nematic phase and blue phase. NEW J CHEM 2022. [DOI: 10.1039/d2nj00386d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multiple mesophases, including the smectic A phase (Sm A), chiral nematic phase (N*), and blue phase (BP I), were seen in a series of non-symmetric bent mesogenic dimers containing a cholesteryl benzoate group.
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Affiliation(s)
- Jun Li
- College of Sciences, Northeastern University, Shenyang, China
| | - Yuehua Cong
- College of Sciences, Northeastern University, Shenyang, China
| | - Haozhou Huang
- College of Sciences, Northeastern University, Shenyang, China
| | - Qiankun Shi
- College of Sciences, Northeastern University, Shenyang, China
| | - Yinggang Jia
- College of Sciences, Northeastern University, Shenyang, China
| | - Baoyan Zhang
- College of Sciences, Northeastern University, Shenyang, China
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11
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Aleksandriiskii V, Novikov I, Monakhov L, Pakhomov S, Burmistrov V, Koifman O. Role of local intermolecular contacts in the physical properties of induced helical phases based on nematic disubstituted azobenzene. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Photo-driven effects in twist-bend nematic phases: Dynamic and memory response of liquid crystalline dimers. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117680] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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13
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Thapa K, Iadlovska OS, Bisoyi HK, Paterson DA, Storey JMD, Imrie CT, Li Q, Shiyanovskii SV, Lavrentovich OD. Combined electric and photocontrol of selective light reflection at an oblique helicoidal cholesteric liquid crystal doped with azoxybenzene derivative. Phys Rev E 2021; 104:044702. [PMID: 34781517 DOI: 10.1103/physreve.104.044702] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 09/16/2021] [Indexed: 11/07/2022]
Abstract
An oblique helicoidal cholesteric liquid crystal Ch_{OH} represents a unique optical material with a single-harmonic periodic modulation of the refractive index and a pitch that can be tuned by an electric or magnetic field in a broad range from submicrometers to micrometers. In this work, we demonstrate that the oblique helicoidal cholesteric doped with azoxybenzene molecules can be tuned by both the electric field and light irradiation. The tuning mechanism is explained by the kinetics of trans-cis photoisomerization of the azoxybenzene molecules. At a fixed voltage, UV irradiation causes a redshift of the reflection peak by more than 200 nm. The effect is caused by an increase of the bend elastic constant of Ch_{OH} under irradiation. The demonstrated principle has the potential for applications such as smart windows, sensors, tunable lasers, and filters.
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Affiliation(s)
- Kamal Thapa
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA.,Department of Physics, Kent State University, Kent, Ohio 44242, USA
| | - Olena S Iadlovska
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA.,Department of Physics, Kent State University, Kent, Ohio 44242, USA
| | - Hari Krishna Bisoyi
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA
| | - Daniel A Paterson
- Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, AB24 3UE Scotland, United Kingdom
| | - John M D Storey
- Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, AB24 3UE Scotland, United Kingdom
| | - Corrie T Imrie
- Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, AB24 3UE Scotland, United Kingdom
| | - Quan Li
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA.,Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, USA
| | - Sergij V Shiyanovskii
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA.,Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, USA
| | - Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA.,Department of Physics, Kent State University, Kent, Ohio 44242, USA.,Materials Science Graduate Program, Kent State University, Kent, Ohio 44242, USA
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14
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Alamro FS, Ahmed HA, El-Atawy MA, Al-Zahrani SA, Omar AZ. Induced Nematic Phase of New Synthesized Laterally Fluorinated Azo/Ester Derivatives. Molecules 2021; 26:4546. [PMID: 34361699 PMCID: PMC8347854 DOI: 10.3390/molecules26154546] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 01/04/2023] Open
Abstract
A new series of laterally fluorinated mesomorphic compounds, namely 2-fluoro-4-((4-(alkyloxy)phenyl)diazenyl)phenyl 4-substitutedbenzoate (Inx) were prepared and evaluated for their mesophase behavior. The synthesized series constitutes five members that possess different terminally attached polar groups (X). Their molecular structures were confirmed by elemental analyses and both FT-IR and NMR spectroscopy. Examination of the prepared derivatives was conducted via experimental and theoretical tools. Mesomorphic investigations were carried by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). DSC and POM measurements indicated that except for the un-substituted analogue, all other derivatives were purely nematogenic, possessing their nematic (N) mesophase enantiotropically. This is to say that insertions of terminal polar substituents on their mesogenic structures induced the N phase. In addition, the location of lateral and terminal polar moieties played a considerable role in achieving good thermal N stability. Computational calculations were investigated to determine the deduced optimized molecular structures. Theoretical data indicated that both size and polarity of the terminal substituent (X) have essential impact on the thermal parameters and optical properties of possible geometries.
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Affiliation(s)
- Fowzia S. Alamro
- Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia;
| | - Hoda A. Ahmed
- Department of Chemistry, Faculty of Science, Cairo University, Cairo 12613, Egypt
- Chemistry Department, Faculty of Science, Taibah University, Yanbu 46423, Saudi Arabia
| | - Mohamed A. El-Atawy
- Chemistry Department, Faculty of Science, Taibah University, Yanbu 46423, Saudi Arabia
- Chemistry Department, Faculty of Science, Alexandria University, P.O. Box 426 Ibrahemia, Alexandria 21321, Egypt;
| | - Salma A. Al-Zahrani
- Department of Chemistry, College of Sciences, University of Ha’il, Ha’il 2440, Saudi Arabia;
| | - Alaa Z. Omar
- Chemistry Department, Faculty of Science, Alexandria University, P.O. Box 426 Ibrahemia, Alexandria 21321, Egypt;
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15
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Synthesis, Optical and DFT Characterizations of Laterally Fluorinated Phenyl Cinnamate Liquid Crystal Non-Symmetric System. Symmetry (Basel) 2021. [DOI: 10.3390/sym13071145] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A new laterally fluorinated unsymmetric liquid crystalline homologous series, based on cinnamate linkage, named 2-fluoro-4-(4-(alkoxy)phenyl)diazenyl)phenyl cinnamate (In), was synthesized and evaluated via different experimental and computational tools. The series had different terminal alkoxy-chain lengths with a lateral F atom in the meta position with respect to the azo moiety. The experimental mesomorphic and optical investigations were carried out using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Theoretical calculations and geometrical parameter predictions were conducted using the DFT program method at B3LYP/6-311G** level of theory. The results revealed that all the designed compounds exhibited the nematic (N) mesophase enantiotropically. The nematic stability and temperature range were impacted by the terminal alkoxy chain length. Compounds with the shortest chains (I6 and I8) showed a monotropic smectic A (SmA) phase, while the longest chain derivative, I16, possessed enantiotropic Sm A phase. Theoretical density functional theory (DFT) predictions were correlated with the practically observed data from the mesomorphic investigations. Data revealed that the terminal alkoxy and lateral F groups had an essential impact on the total energy of possible geometrical structures and their physical and thermal parameters.
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16
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Alaasar M, Schmidt JC, Cai X, Liu F, Tschierske C. Controlling liquid and liquid crystalline network formation by core-fluorination of hydrogen bonded supramolecular polycatenars. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115870] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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Arakawa Y, Komatsu K, Ishida Y, Igawa K, Tsuji H. Carbonyl- and thioether-linked cyanobiphenyl-based liquid crystal dimers exhibiting twist-bend nematic phases. Tetrahedron 2021. [DOI: 10.1016/j.tet.2020.131870] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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18
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A new light-responsive resistive random-access memory device containing hydrogen-bonded complexes. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2020.112914] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Forsyth E, Paterson DA, Cruickshank E, Strachan GJ, Gorecka E, Walker R, Storey JM, Imrie CT. Liquid crystal dimers and the twist-bend nematic phase: On the role of spacers and terminal alkyl chains. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114391] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Yoo GY, Lee S, Ko M, Kim H, Lee KN, Kim W, Do YR. Diphylleia grayi-Inspired Intelligent Hydrochromic Adhesive Film. ACS APPLIED MATERIALS & INTERFACES 2020; 12:49982-49991. [PMID: 33079523 DOI: 10.1021/acsami.0c13185] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Diphylleia grayi-inspired hydrochromic nano/microstructured films have received much attention for its promising smart hydrochromic applications owing to their simple and low-cost but energy-effective strategy. A new type of water-switchable glazing film patterned with various nano/micro air-hole inverse opal arrays is introduced by selectively removing nano/microsphere polystyrene arrays embedded in the surface of polydimethylsiloxane (PDMS) films. Using the significant contrast ratio of the bleaching and the scattering states, we have optimized the switching properties of Mie scattered patterns. As a result, we obtained a single inverse opal layer-embedded PDMS adhesive film with hexagonally close-packed 1 μm air-hole arrays as an optimum scattered film. The differences of diffusive transmittance and optical haze values between the dry and the wet states of the best scattered film reached 44.93% (ΔTD.T = 59.11-14.18%) and 54.88% (ΔH = 69.42-14.54%), respectively. In addition, using the best-optimized inverse opal layer-embedded PDMS film, we fabricated a perfectly imitated Diphylleia grayi structure for camouflage application and an intelligent hydrochromic window device. The dynamic water modulation of the scattered opaque and nonscattered transparent state of the inverse opal-patterned PDMS adhesive film can provide an advanced platform structure in the area of hydrochromic technology for smart windows, camouflage, and clear umbrellas for rainy days.
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Affiliation(s)
- Gang Yeol Yoo
- Department of Materials Science and Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - SeungJe Lee
- Department of Chemistry, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Minji Ko
- Department of Chemistry, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Hyunjin Kim
- Department of Chemistry, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Keyong Nam Lee
- Department of Chemistry, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
| | - Woong Kim
- Department of Materials Science and Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Young Rag Do
- Department of Chemistry, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
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21
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2,3,4-Trihydroxy benzonitrile-based liquid crystals: Fiber forming room temperature nematic phases. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114244] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Walker R. The twist-bend phases: structure–property relationships, chirality and hydrogen-bonding. LIQUID CRYSTALS TODAY 2020. [DOI: 10.1080/1358314x.2020.1771841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Rebecca Walker
- Department of Chemistry, University of Aberdeen, Aberdeen, UK
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23
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Goulet-Hanssens A, Eisenreich F, Hecht S. Enlightening Materials with Photoswitches. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905966. [PMID: 31975456 DOI: 10.1002/adma.201905966] [Citation(s) in RCA: 209] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/28/2019] [Indexed: 05/05/2023]
Abstract
Incorporating molecular photoswitches into various materials provides unique opportunities for controlling their properties and functions with high spatiotemporal resolution using remote optical stimuli. The great and largely still untapped potential of these photoresponsive systems has not yet been fully exploited due to the fundamental challenges in harnessing geometrical and electronic changes on the molecular level to modulate macroscopic and bulk material properties. Herein, progress made during the past decade in the field of photoswitchable materials is highlighted. After pointing to some general design principles, materials with an increasing order of the integrated photoswitchable units are discussed, spanning the range from amorphous settings over surfaces/interfaces and supramolecular ensembles, to liquid crystalline and crystalline phases. Finally, some potential future directions are pointed out in the conclusion. In view of the exciting recent achievements in the field, the future emergence and further development of light-driven and optically programmable (inter)active materials and systems are eagerly anticipated.
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Affiliation(s)
- Alexis Goulet-Hanssens
- Department of Chemistry & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany
| | - Fabian Eisenreich
- Department of Chemistry & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany
| | - Stefan Hecht
- Department of Chemistry & IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489, Berlin, Germany
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany
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Lehmann A, Alaasar M, Poppe M, Poppe S, Prehm M, Nagaraj M, Sreenilayam SP, Panarin YP, Vij JK, Tschierske C. Stereochemical Rules Govern the Soft Self-Assembly of Achiral Compounds: Understanding the Heliconical Liquid-Crystalline Phases of Bent-Core Mesogens. Chemistry 2020; 26:4714-4733. [PMID: 31859404 PMCID: PMC7186843 DOI: 10.1002/chem.201904871] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/15/2019] [Indexed: 11/16/2022]
Abstract
A series of bent-shaped 4-cyanoresorcinol bisterephthalates is reported. Some of these achiral compounds spontaneously form a short-pitch heliconical lamellar liquid-crystalline phase with incommensurate 3-layer pitch and the helix axis parallel to the layer normal. It is observed at the paraelectric-(anti)ferroelectric transition, if it coincides with the transition from random to uniform tilt and with the transition from anticlinic to synclinic tilt correlation of the molecules in the layers of the developing tilted smectic phase. For compounds with long chains the heliconical phase is only field-induced, but once formed it is stable in a distinct temperature range, even after switching off the field. The presence of the helix changes the phase properties and the switching mechanism from the naturally preferred rotation around the molecular long axis, which reverses the chirality, to a precession on a cone, which retains the chirality. These observations are explained by diastereomeric relations between two coexisting modes of superstructural chirality. One is the layer chirality, resulting from the combination of tilt and polar order, and the other one is the helical twist evolving between the layers. At lower temperature the helical structure is replaced by a non-tilted and ferreoelectric switching lamellar phase, providing an alternative non-chiral way for the transition from anticlinic to synclinic tilt.
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Affiliation(s)
- Anne Lehmann
- Department of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
| | - Mohamed Alaasar
- Department of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
- Department of ChemistryCairo University12613GizaEgypt
| | - Marco Poppe
- Department of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
| | - Silvio Poppe
- Department of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
| | - Marko Prehm
- Department of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
| | - Mamatha Nagaraj
- Department of Electronic and Electrical EngineeringTrinity College, Dublin, The University of DublinDublin2Ireland
| | - Sithara P. Sreenilayam
- Department of Electronic and Electrical EngineeringTrinity College, Dublin, The University of DublinDublin2Ireland
| | - Yuri P. Panarin
- Department of Electronic and Electrical EngineeringTrinity College, Dublin, The University of DublinDublin2Ireland
| | - Jagdish K. Vij
- Department of Electronic and Electrical EngineeringTrinity College, Dublin, The University of DublinDublin2Ireland
| | - Carsten Tschierske
- Department of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
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25
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Thermal and Photophysical Studies of Binary Mixtures of Liquid Crystal with Different Geometrical Mesogens. CRYSTALS 2020. [DOI: 10.3390/cryst10030223] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Three binary systems were prepared by mixing of two different mesogenic derivatives, homologues, the first is azo/ester, namely 4-alkoxyphenylazo-4′-phenyl-4″-alkoxybenzoates (IIn+m) and the second is Schiff base/ester, namely 4-(arylideneamino)phenyl-4″-alkoxy benzoates (In+m). The two corresponding analogues from both series in the binary mixtures investigated are of the same terminal alkoxy chain length. Mesomorphic properties were investigated by differential scanning calorimetry (DSC) and phases identified by polarized optical microscope (POM). Photophysical studies were investigated by UV spectroscopy connected to a hot stage. Results were discussed based on constructed binary phase diagrams. All mixtures were found to exhibit eutectic compositions, with linear or slightly linear nematic and smectic A stability/composition dependences. Geometrical parameters were predicted applying density functional theory (DFT) calculations. Twist angle (θ), aspect ratio, dipole moment and the polarizability of the individual compounds were discussed and correlated with the experimental results to illustrate the enhanced the mesophase stability and the mesophase range of the mixture at the eutectic composition compared with those of their individual components.
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26
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Tsuei M, Shivrayan M, Kim YK, Thayumanavan S, Abbott NL. Optical “Blinking” Triggered by Collisions of Single Supramolecular Assemblies of Amphiphilic Molecules with Interfaces of Liquid Crystals. J Am Chem Soc 2020; 142:6139-6148. [DOI: 10.1021/jacs.9b13360] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Michael Tsuei
- Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Manisha Shivrayan
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Young-Ki Kim
- Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
| | - S. Thayumanavan
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Nicholas L. Abbott
- Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
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27
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Color tuning in thermo-sensitive chiral photonic liquid crystals based on the pseudo-dielectric heating effect. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.112082] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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28
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Zhao K, Xiao Y, Chang Q, Zhang D, Cheng X. Azobenzene-based asymmetric bolaamphiphiles: Formation of LC phases with honeycomb structures and gels with helical structures. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111417] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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29
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Yuan CL, Huang W, Zheng ZG, Liu B, Bisoyi HK, Li Y, Shen D, Lu Y, Li Q. Stimulated transformation of soft helix among helicoidal, heliconical, and their inverse helices. SCIENCE ADVANCES 2019; 5:eaax9501. [PMID: 31620560 PMCID: PMC6777971 DOI: 10.1126/sciadv.aax9501] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 09/09/2019] [Indexed: 05/21/2023]
Abstract
Dynamic modulation of soft helix in terms of the molecular organization, handedness, and pitch length could result in a sophisticated control over its functions, opening numerous possibilities toward the exploration of previously unidentified applications. Here, we report a dynamic and reversible transformation of a soft helical superstructure among the helicoidal (molecules orthogonal to helical axis), heliconical (molecules oblique to the helical axis, i.e., oblique helicoidal), and their inverse helices, together with a tunability on the helical pitch, by combining electrical and optical manipulations. This multistate transformation depends on a matching of the temperature, the strength of external stimuli, and the bend and twist elastic effects of the system. A laser emission with tunable wavelength and polarization, and prescribed micropatterns formed by any aforementioned architectures were achieved.
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Affiliation(s)
- Cong-long Yuan
- Department of Physics, East China University of Science and Technology, Shanghai 200237, China
| | - Wenbin Huang
- Department of Physics, East China University of Science and Technology, Shanghai 200237, China
- School of Optoelectronic Science and Engineering and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China
| | - Zhi-gang Zheng
- Department of Physics, East China University of Science and Technology, Shanghai 200237, China
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
- Corresponding author. (Z.-g.Z.); (Y.Lu); (Q.L.)
| | - Binghui Liu
- Department of Physics, East China University of Science and Technology, Shanghai 200237, China
| | - Hari Krishna Bisoyi
- Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA
| | - Yannian Li
- Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA
| | - Dong Shen
- Department of Physics, East China University of Science and Technology, Shanghai 200237, China
| | - Yanqing Lu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
- Corresponding author. (Z.-g.Z.); (Y.Lu); (Q.L.)
| | - Quan Li
- Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA
- Corresponding author. (Z.-g.Z.); (Y.Lu); (Q.L.)
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30
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Begum N, Kaur S, Mohiuddin G, Nandi R, Gupta SP, Rao NVS, Pal SK. Structural Understanding, Photoswitchability, and Supergelation of a New Class of Four Ring-Based Bent-Shaped Liquid Crystal. J Phys Chem B 2019; 123:4443-4451. [PMID: 31042387 DOI: 10.1021/acs.jpcb.9b01456] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Herein, we report a new type of azobenzene-based unsymmetrical bent-core molecules exhibiting photoswitchability in the liquid crystalline state, solid state, and solution state and in mixture upon UV irradiation and intense visible light. The compounds exhibited solid-state photochromism upon exposure to UV light, whereas in liquid crystalline state, reversible phase transitions were observed via both UV irradiation and intense visible light exposure. Crystal structure analysis reveals the basic structural understanding such as nonplanar bent molecular shape, antiparallel arrangement of the polar bent molecules, intra- and intermolecular hydrogen bonding, and different π-π interactions and interdigitation of long alkyl chains. The compounds are also found to act as supergelator toward various organic solvents. Hence, this is an excellent example of such potential bent-shaped liquid crystals that promise an immense perspective for device applications such as optical storage, molecular switches, etc.
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Affiliation(s)
- Nazma Begum
- Department of Chemistry , Assam University , Silchar 788011 , Assam , India.,Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81 , Knowledge City, Manauli 140306 , India
| | - Supreet Kaur
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81 , Knowledge City, Manauli 140306 , India
| | - Golam Mohiuddin
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81 , Knowledge City, Manauli 140306 , India
| | - Rajib Nandi
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81 , Knowledge City, Manauli 140306 , India
| | | | - Nandiraju V S Rao
- Department of Chemistry , Assam University , Silchar 788011 , Assam , India
| | - Santanu Kumar Pal
- Department of Chemical Sciences , Indian Institute of Science Education and Research (IISER) Mohali , Sector-81 , Knowledge City, Manauli 140306 , India
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31
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Alaasar M, Prehm M, Belau S, Sebastián N, Kurachkina M, Eremin A, Chen C, Liu F, Tschierske C. Polar Order, Mirror Symmetry Breaking, and Photoswitching of Chirality and Polarity in Functional Bent‐Core Mesogens. Chemistry 2019; 25:6362-6377. [DOI: 10.1002/chem.201806180] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/21/2019] [Indexed: 01/06/2023]
Affiliation(s)
- Mohamed Alaasar
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
- Department of Chemistry, Faculty of ScienceCairo University Giza Egypt
| | - Marko Prehm
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
| | - Sebastian Belau
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Nerea Sebastián
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Marharyta Kurachkina
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Changlong Chen
- State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong University Xi'an 710049 P. R. China
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong University Xi'an 710049 P. R. China
| | - Carsten Tschierske
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
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32
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Walker R, Pociecha D, Strachan GJ, Storey JMD, Gorecka E, Imrie CT. Molecular curvature, specific intermolecular interactions and the twist-bend nematic phase: the synthesis and characterisation of the 1-(4-cyanobiphenyl-4'-yl)-6-(4-alkylanilinebenzylidene-4'-oxy)hexanes (CB6O.m). SOFT MATTER 2019; 15:3188-3197. [PMID: 30892369 DOI: 10.1039/c9sm00026g] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The syntheses and characterisation of the first ten homologues of the 1-(4-cyanobiphenyl-4'-yl)-6-(4-alkylanilinebenzylidene-4'-oxy)hexanes (CB6O.m) are reported. All ten members of the series exhibit an enantiotropic nematic, N, phase, and a monotropic twist-bend nematic, NTB, phase. Only CB6O.10 shows a smectic phase. The assignment of both nematic phases was confirmed using X-ray diffraction. For short chain lengths (m = 1-6) the local packing in both nematic phases is an intercalated arrangement, for intermediate chain lengths a frustrated local structure is seen and for the longest chain length, a bilayer arrangement is observed. This change in the local structure on increasing m has no apparent effect on the stability of either nematic phase, and TNTBN and TNI show a regular dependence on m. Specifically, TNTBN and TNI decrease on increasing m and superimposed upon this is a weak odd-even effect in which the odd members show the higher values. TNI decreases more rapidly than TNTBN on increasing m such that the ratio TNTBN/TNI increases. The lower temperature liquid crystal phase shown by 1-(4-cyanobiphenyl-4'-yloxy)-5-(4-butylanilinebenzylidene-4'-oxy)pentane (CBO5O.4) is reassigned as a twist-bend nematic phase. The transitional properties of the CB6O.m, CB6O.Om and CBO5O.m series are compared.
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Affiliation(s)
- Rebecca Walker
- Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen, AB24 3UE Scotland, UK.
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33
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Yoshioka J, Salamon P, Paterson DA, Storey JMD, Imrie CT, Jákli A, Araoka F, Buka A. Spherical-cap droplets of a photo-responsive bent liquid crystal dimer. SOFT MATTER 2019; 15:989-998. [PMID: 30657150 DOI: 10.1039/c8sm01751d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Using a photo-responsive dimer exhibiting the transition between nematic (N) and twist-bend nematic (NTB) phases, we prepared spherical cap-shaped droplets on solid substrates exposed to air. The internal director structures of these droplets vary depending on the phase and on the imposed boundary conditions. The structural switching between the N and NTB phases was successfully performed either by temperature control or by UV light-irradiation. The N phase is characterized by an extremely small bend elastic constant K3, and surprisingly, we found that the droplet-air interface induces a planar alignment, in contrast to that seen for typical calamitic liquid crystals. As a consequence, the director configuration was stabilized in a structure substantially different from that normally found in conventional nematic liquid crystalline droplets. In the twist-bend nematic droplets characteristic structures with macroscopic length scales were formed, and they were well controlled by the droplet size. These results indicated that a continuum theory is effective in describing the stabilization mechanism of the macroscopic structure even in the twist-bend nematic liquid crystal droplets exhibiting director modulations on a scale of several molecular lengths.
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Affiliation(s)
- Jun Yoshioka
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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34
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Zep A, Pruszkowska K, Dobrzycki Ł, Sektas K, Szałański P, Marek PH, Cyrański MK, Sicinski RR. Cholesterol-based photo-switchable mesogenic dimers. Strongly bent molecules versus an intercalated structure. CrystEngComm 2019. [DOI: 10.1039/c9ce00013e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A homologous series of cholesterol-based liquid crystalline dimers were synthesized and characterized by polarizing optical microscopy, DSC, and powder and single-crystal XRD.
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Affiliation(s)
- Anna Zep
- Laboratory of Stereocontrolled Organic Synthesis
- Faculty of Chemistry
- University of Warsaw
- 02-089 Warsaw
- Poland
| | - Kamila Pruszkowska
- The Czochralski Laboratory of Advanced Crystal Engineering
- Faculty of Chemistry
- University of Warsaw
- 02-089 Warsaw
- Poland
| | - Łukasz Dobrzycki
- The Czochralski Laboratory of Advanced Crystal Engineering
- Faculty of Chemistry
- University of Warsaw
- 02-089 Warsaw
- Poland
| | - Katarzyna Sektas
- Laboratory of Stereocontrolled Organic Synthesis
- Faculty of Chemistry
- University of Warsaw
- 02-089 Warsaw
- Poland
| | - Piotr Szałański
- Faculty of Chemistry
- Rzeszow University of Technology
- Rzeszow
- Poland
| | - Paulina H. Marek
- The Czochralski Laboratory of Advanced Crystal Engineering
- Faculty of Chemistry
- University of Warsaw
- 02-089 Warsaw
- Poland
| | - Michał K. Cyrański
- The Czochralski Laboratory of Advanced Crystal Engineering
- Faculty of Chemistry
- University of Warsaw
- 02-089 Warsaw
- Poland
| | - Rafal R. Sicinski
- Laboratory of Stereocontrolled Organic Synthesis
- Faculty of Chemistry
- University of Warsaw
- 02-089 Warsaw
- Poland
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35
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Salamończyk M, Mandle RJ, Makal A, Liebman-Peláez A, Feng J, Goodby JW, Zhu C. Double helical structure of the twist-bend nematic phase investigated by resonant X-ray scattering at the carbon and sulfur K-edges. SOFT MATTER 2018; 14:9760-9763. [PMID: 30484465 DOI: 10.1039/c8sm01215f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The mesogenic dimer displaying nematic and NTB phases was investigated by resonant X-ray scattering at both C and S absorption K-edges and supported by single X-ray crystallography. In the crystal resonant studies revealed the forbidden reflection in non-resonant diffraction similar to that found in the NTB phase. The lack of a second harmonic in both C and S resonant X-ray scattering supports the double helical structure of the twist-bend nematic phase.
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Affiliation(s)
- Mirosław Salamończyk
- Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720, USA
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36
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Vanti L, Mohd Alauddin S, Zaton D, Aripin NFK, Giacinti-Baschetti M, Imrie CT, Ribes-Greus A, Martinez-Felipe A. Ionically conducting and photoresponsive liquid crystalline terpolymers: Towards multifunctional polymer electrolytes. Eur Polym J 2018. [DOI: 10.1016/j.eurpolymj.2018.08.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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37
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Moran MJ, Magrini M, Walba DM, Aprahamian I. Driving a Liquid Crystal Phase Transition Using a Photochromic Hydrazone. J Am Chem Soc 2018; 140:13623-13627. [DOI: 10.1021/jacs.8b09622] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Mark J. Moran
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Mitchell Magrini
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - David M. Walba
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Ivan Aprahamian
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
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38
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Mandle RJ, Goodby JW. A Nanohelicoidal Nematic Liquid Crystal Formed by a Non-Linear Duplexed Hexamer. Angew Chem Int Ed Engl 2018; 57:7096-7100. [PMID: 29673016 PMCID: PMC6033141 DOI: 10.1002/anie.201802881] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/04/2018] [Indexed: 01/06/2023]
Abstract
The twist-bend modulated nematic liquid-crystal phase exhibits formation of a nanometre-scale helical pitch in a fluid and spontaneous breaking of mirror symmetry, leading to a quasi-fluid state composed of chiral domains despite being composed of achiral materials. This phase was only observed for materials with two or more mesogenic units, the manner of attachment between which is always linear. Non-linear oligomers with a H-shaped hexamesogen are now found to exhibit both nematic and twist-bend modulated nematic phases. This shatters the assumption that a linear sequence of mesogenic units is a prerequisite for this phase, and points to this state of matter being exhibited by a wider range of self-assembling structures than was previously envisaged. These results support the double helix model of the TB phase as opposed to the simple heliconical model. This new class of materials could act as low-molecular-weight surrogates for cross-linked liquid-crystalline elastomers.
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39
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Mandle RJ, Goodby JW. A Nanohelicoidal Nematic Liquid Crystal Formed by a Non-Linear Duplexed Hexamer. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201802881] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | - John W. Goodby
- Department of Chemistry; University of York; York YO10 5DD UK
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40
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Walker R, Pociecha D, Abberley JP, Martinez-Felipe A, Paterson DA, Forsyth E, Lawrence GB, Henderson PA, Storey JMD, Gorecka E, Imrie CT. Spontaneous chirality through mixing achiral components: a twist-bend nematic phase driven by hydrogen-bonding between unlike components. Chem Commun (Camb) 2018; 54:3383-3386. [PMID: 29552681 DOI: 10.1039/c8cc00525g] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The spontaneous formation of a chiral phase via molecular recognition in a system consisting of achiral components is reported. Specifically, the liquid crystalline behaviour of two molecular complexes assembled by hydrogen bonding between a stilbazole-based template and alkoxybenzoic acids has been characterised. The complexes exhibit the heliconical twist-bend nematic phase (NTB) over a broad temperature range despite the hydrogen-bond acceptor not being liquid crystalline and the donor exhibiting the conventional achiral nematic phase.
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Affiliation(s)
- R Walker
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
| | - D Pociecha
- Department of Chemistry, University of Warsaw, ul. Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - J P Abberley
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
| | - A Martinez-Felipe
- Chemical and Materials Engineering Group, School of Engineering, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK
| | - D A Paterson
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
| | - E Forsyth
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
| | - G B Lawrence
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
| | - P A Henderson
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
| | - J M D Storey
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
| | - E Gorecka
- Department of Chemistry, University of Warsaw, ul. Zwirki i Wigury 101, 02-089 Warsaw, Poland
| | - C T Imrie
- Department of Chemistry, King's College, University of Aberdeen, Aberdeen, AB24 3UE, UK.
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41
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Sasaki H, Takanishi Y, Yamamoto J, Yoshizawa A. Photo-Driven Chirality Switching in a Dark Conglomerate Phase of an Achiral Liquid Crystal Trimer. ChemistrySelect 2018. [DOI: 10.1002/slct.201800067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Haruna Sasaki
- Department of Frontier Materials Chemistry; Graduate School of Science and Technology; Hirosaki University; 3 Bunkyo-cho Hirosaki 036-8561 Japan
| | - Yoichi Takanishi
- Department of Physics; Graduate School of Science; Kyoto University; Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
| | - Jun Yamamoto
- Department of Physics; Graduate School of Science; Kyoto University; Oiwake-cho, Kitashirakawa, Sakyo-ku Kyoto 606-8502 Japan
| | - Atsushi Yoshizawa
- Department of Frontier Materials Chemistry; Graduate School of Science and Technology; Hirosaki University; 3 Bunkyo-cho Hirosaki 036-8561 Japan
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42
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Wu Z, Xue R, Xie M, Wang X, Liu Z, Drechsler M, Huang J, Yan Y. Self-Assembly-Triggered Cis-to-Trans Conversion of Azobenzene Compounds. J Phys Chem Lett 2018; 9:163-169. [PMID: 29266959 DOI: 10.1021/acs.jpclett.7b03060] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cis-to-trans transition of azobenzene compounds usually occurs under appropriate light irradiation or slow thermal relaxation, and one can hardly obtain complete cis-to-trans transition of azos due to the overlap of the n-π* transition of the trans and the cis isomers. We show that by viewing the photostationary state as a chemical equilibrium between the cis and trans isomers, triggered self-assembly of the trans isomers can promote the cis-to-trans transition, and trans azos with spectrum-grade purity can even be achieved using an elegantly designed coordinating azo. This work establishes a new paradigm for manipulating the cis-to-trans transition of azo compounds, which may inspire designs for various azo-based advanced materials.
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Affiliation(s)
- Zheng Wu
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Rongrong Xue
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Mengqi Xie
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Xuejiao Wang
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Zihao Liu
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Markus Drechsler
- Bavarian Polymer Institute (BPI), Key Lab of Electron and Optical Microscopy, University of Bayreuth , Universitaetsstr. 30, D-95440 Bayreuth, Germany
| | - Jianbin Huang
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
| | - Yun Yan
- Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, China
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43
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Mandle RJ, Cowling SJ, Goodby JW. Combined Microscopy, Calorimetry and X-ray Scattering Study of Fluorinated Dimesogens. Sci Rep 2017; 7:13323. [PMID: 29042568 PMCID: PMC5645320 DOI: 10.1038/s41598-017-12799-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 09/15/2017] [Indexed: 11/09/2022] Open
Abstract
The material FDO11DFCB3 (compound 2 in this work) remains the only example of a liquid-crystalline material to exhibit a phase transition from the heliconical twist-bend phase into a lamellar smectic A mesophase, additionally this material exhibits a previously unidentified mesophase. We have prepared and characterised several homologues of this compound, with each material subjected to an in-depth analysis by optical microscopy, calorimetry and small angle X-ray scattering studies. Despite FDO11DFCB3 being similar in chemical structure to the novel materials presented herein its liquid-crystalline behaviour is rather different, indicating an unexpected sensitivity of the twist-bend phase to molecular structure.
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Affiliation(s)
- Richard J Mandle
- Department of Chemistry, University of York, Heslington, YO10 5DD, UK.
| | - Stephen J Cowling
- Department of Chemistry, University of York, Heslington, YO10 5DD, UK
| | - John W Goodby
- Department of Chemistry, University of York, Heslington, YO10 5DD, UK
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44
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Alaasar M, Poppe S, Dong Q, Liu F, Tschierske C. Isothermal Chirality Switching in Liquid-Crystalline Azobenzene Compounds with Non-Polarized Light. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201705559] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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; P.O. 12613 Giza Egypt
| | - Silvio Poppe
- Institute of Chemistry; Martin-Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
| | - Qingshu Dong
- State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 P.R. China
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of Materials; Xi'an Jiaotong University; Xi'an 710049 P.R. China
| | - Carsten Tschierske
- Institute of Chemistry; Martin-Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
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45
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Isothermal Chirality Switching in Liquid-Crystalline Azobenzene Compounds with Non-Polarized Light. Angew Chem Int Ed Engl 2017; 56:10801-10805. [DOI: 10.1002/anie.201705559] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/10/2017] [Indexed: 12/31/2022]
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46
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Mandle RJ. The Shape of Things To Come: The Formation of Modulated Nematic Mesophases at Various Length Scales. Chemistry 2017; 23:8771-8779. [PMID: 28453914 PMCID: PMC5518215 DOI: 10.1002/chem.201701167] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Indexed: 11/22/2022]
Abstract
The twist-bend nematic (NTB ) phase is a recently discovered liquid-crystalline phase that exhibits macroscopic chirality even when formed from achiral materials, and as such presents a unique testbed for studies concerning the spontaneous breaking of mirror symmetry in soft matter. It is primarily exhibited by materials for which the molecular structure is composed of two rigid aromatic units (such as biphenyl connected by a flexible spacer). The local structure of the NTB phase is nematic-like-with molecules having an average orientational order but no positional order-with a nanoscale helix in which the pitch (i.e., the repeat distance of the helix) is of the order of several nanometres. A helix is chiral, and so the bulk NTB phase-in the absence of a biasing chiral environment-spontaneously separates into macroscopic domains of opposite handedness. After discussing the structure of this mesophase and its elucidation, this concept article presents the molecular factors that determine its incidence. The apparent dependency primarily on molecular shape and bend angle rather than particular functional group combinations manifests in this mesophase being exhibited on length scales far beyond those of simple liquid-crystalline dimers, not only in oligomers and polymers, but also in aqueous suspensions of micron sized helical particles.
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47
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Kishikawa K, Yamamoto Y, Watanabe G, Kawamura A, Kohri M, Taniguchi T. Shape-Assisted Self-Organization in Highly Disordered Liquid Crystal Phases. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201700809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Keiki Kishikawa
- Department of Applied Chemistry and Biotechnology; Graduate School of Engineering; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Yusuke Yamamoto
- Department of Applied Chemistry and Biotechnology; Graduate School of Engineering; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Go Watanabe
- Department of Physics; School of Science; Kitasato University; 1-15-1 Kitasato, Minami-ku, Sagamihara Kanagawa 252-0373 Japan
| | - Ayaka Kawamura
- Department of Applied Chemistry and Biotechnology; Graduate School of 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
| | - Tatsuo Taniguchi
- Department of Applied Chemistry and Biotechnology; Graduate School of Engineering; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
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48
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Kishikawa K, Yamamoto Y, Watanabe G, Kawamura A, Kohri M, Taniguchi T. Shape-Assisted Self-Organization in Highly Disordered Liquid Crystal Phases. Angew Chem Int Ed Engl 2017; 56:4598-4602. [DOI: 10.1002/anie.201700809] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 02/23/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Keiki Kishikawa
- Department of Applied Chemistry and Biotechnology; Graduate School of Engineering; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Yusuke Yamamoto
- Department of Applied Chemistry and Biotechnology; Graduate School of Engineering; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
| | - Go Watanabe
- Department of Physics; School of Science; Kitasato University; 1-15-1 Kitasato, Minami-ku, Sagamihara Kanagawa 252-0373 Japan
| | - Ayaka Kawamura
- Department of Applied Chemistry and Biotechnology; Graduate School of 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
| | - Tatsuo Taniguchi
- Department of Applied Chemistry and Biotechnology; Graduate School of Engineering; Chiba University; 1-33 Yayoi-cho, Inage-ku Chiba 263-8522 Japan
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49
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Parthasarathi S, Shankar Rao DS, Palakurthy NB, Yelamaggad CV, Krishna Prasad S. Effect of Pressure on Dielectric and Frank Elastic Constants of a Material Exhibiting the Twist Bend Nematic Phase. J Phys Chem B 2017; 121:896-903. [PMID: 28068107 DOI: 10.1021/acs.jpcb.6b10563] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the first investigation on the effect of applied pressure on the now well-known dimer α,ω bis(4,4'-cyanobiphenyl)heptane (CB7CB) that exhibits two types of nematic: the regular uniaxial nematic (N) and the recently discovered twist-bend nematic (NTB) phase. At atmospheric pressure, the thermal behavior of ε⊥, the permittivity normal to the director in the N phase decreases on entering the NTB wherein the value represents permittivity orthogonal to the helical axis. Application of pressure initially decreases the magnitude of the change in ε⊥ and with further increase in pressure exhibits an increase in the value. Such a change in the feature of ε⊥ is similar to that obtained at room pressure when the monomeric heptyloxy cyanobiphenyl (7OCB) is doped to CB7CB at a high concentration of 50%. The dielectric anisotropy exhibits a trend reversal with temperature, the extent of which is affected at high pressures. Another salient feature of the study is the effect that pressure has on the Frank bend elastic constant K33. Over the pressure range studied K33 enhances by a large factor of 5. In contrast, the splay elastic constant exhibits a much smaller change of only 70%. The pressure-temperature phase boundary has a much smaller slope for the N-NTB transformation than for the isotropic-N transition. We propose that all these features can be understood in terms of the relative population of the more energetic horseshoe and lower energy extended conformer adopted by the CB7CB molecule. The extended conformer is favored at lower temperatures or at higher pressures. This argument is validated by X-ray diffraction experiments at atmospheric pressure on the binary mixture of CB7CB and 7OCB, mentioned above.
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Affiliation(s)
| | - D S Shankar Rao
- Centre for Nano and Soft Matter Sciences , Jalahalli, Bangalore 560013, India
| | | | - C V Yelamaggad
- Centre for Nano and Soft Matter Sciences , Jalahalli, Bangalore 560013, India
| | - S Krishna Prasad
- Centre for Nano and Soft Matter Sciences , Jalahalli, Bangalore 560013, India
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50
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Al-Janabi A, Mandle RJ, Goodby J. Isomeric trimesogens exhibiting modulated nematic mesophases. RSC Adv 2017. [DOI: 10.1039/c7ra10261e] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A simple deprotection/etherification strategy enables us to prepare oligomeric liquid-crystalline materials with ease, and unearth a potentially new mesophase.
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