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Khan RK, Mohiuddin G, Begum N, Turlapati S, Nandiraju RVS, Debbarma BK, Ghosh S. Extremely High Kerr Constant and Low Operating Voltage in a Stable Room-Temperature Blue Phase III Derived from Three-Ring-Based Bent-Core Molecules. ACS APPLIED MATERIALS & INTERFACES 2022; 14:42628-42634. [PMID: 36082439 DOI: 10.1021/acsami.2c09392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this study, we used a new series of highly polar three-ring-based bent-core liquid crystals (BCLCs) to stabilize a wide temperature range of blue phase III (BPIII), including room temperature. A significant finding is the implementation of electro-optical (E-O) switching at room temperature in the current BPIII system. The observed Kerr constant (K) has an extraordinarily high value (K ≈ 9.2 × 10-9m V-2) that exceeds all previously reported values in the category of BPIII materials. The extremely high value of K realizes the lowest operating voltage (Von ≈ 3.3 Vrms/μm) for BPIII. The measured values of K and Von in BPIII set a new limit for the experimentalist. The millisecond (ms) order response times are explained based on rotational viscosity. The present binary system of BPIII materials is an excellent choice for device application.
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Affiliation(s)
- Raj Kumar Khan
- Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009, India
- Soft Condensed Matter Laboratory, Raman Research Institute, Bangalore 560080, India
| | - Golam Mohiuddin
- Department of Chemistry, University of Science & Technology Meghalaya, Ri-Bhoi, Meghalaya 793101, India
| | - Nazma Begum
- Department of Chemistry, Assam University, Silchar, Assam-788011, India
| | | | - Rao V S Nandiraju
- Department of Chemistry, Assam University, Silchar, Assam-788011, India
| | | | - Sharmistha Ghosh
- Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009, India
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Imine-based highly polar achiral unsymmetrical four-ring bent shaped liquid crystals: Design, Synthesis and Characterization. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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3
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Kanth P, Shankar Rao D, Krishna Prasad S, Singh B. Investigation of mesomorphic, photophysical and gelation behavior in aroylhydrazone based liquid crystals: Observation of mesophase crossover phenomena. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.117084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yu JS, Kim JH. Hacking detection based on the elastic properties of liquid crystals in different phases. OPTICS EXPRESS 2021; 29:39352-39361. [PMID: 34809301 DOI: 10.1364/oe.441941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 10/31/2021] [Indexed: 06/13/2023]
Abstract
We present a security device that can detect and block hacking using the characteristics of liquid crystals. This device is based on a liquid crystal cell consisting of a uniformly aligned layer and a photo-alignment layer. To inscribe a pattern, the device is illuminated when the liquid crystal is in the smectic phase. The resulting image is invisible after light irradiation. Heating to the nematic phase improves this alignment and reveals the recorded pattern. Returning to the smectic phase distorts the pattern. Because the pattern is not shown without heating and the trace of the pattern does not disappear once viewed, it is possible to detect whether data has been hacked. The device is easy to fabricate, cost-effective, and sensitive to outside intrusion.
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Kaur S, Begum N, Mohiuddin G, Kumar Pal S. Photo-Responsive Behavior of Azobenzene Based Polar Hockey-Stick-Shaped Liquid Crystals. Chemphyschem 2021; 22:1361-1370. [PMID: 33956388 DOI: 10.1002/cphc.202100215] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 05/05/2021] [Indexed: 11/08/2022]
Abstract
A study on the photoswitching behavior of azobenzene-based polar hockey-stick-shaped liquid crystals (HSLCs) has been presented. Two new series of five phenyl rings based polar HSLCs have been designed and synthesized. Solution state photoisomerization of the synthesized materials was investigated thoroughly via UV-visible and 1 H NMR spectroscopic techniques, whereas solid-state photochromic behavior was elucidated via physical color change of the materials, solid-state UV-visible study, powder XRD, and FE-SEM techniques. The materials exhibited decent photochromic behavior for different potential applications. The thermal phase behavior of the superstructural assembly has been characterized via polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and temperature-dependent small and wide-angle X-ray scattering (SAXS/WAXS) studies. Depending upon the length of the terminal alkyl chain, nematic (N) and partially bilayer smectic A (SmAd ) phases were observed. DFT calculations revealed the favorable anti-parallel arrangement of the polar molecules that substantiate the formation of SmAd phase.
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Affiliation(s)
- Supreet Kaur
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector-81, Knowledge City, Manauli, 140306, India
| | - Nazma Begum
- 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
| | - 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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Punjani V, Mohiuddin G, Kaur S, Choudhury AR, Paladugu S, Dhara S, Ghosh S, Pal SK. Chiral Bent-Shaped Molecules Exhibiting Unusually Wide Range of Blue Liquid-Crystalline Phases and Multistimuli-Responsive Behavior. Chemistry 2020; 26:5859-5871. [PMID: 32083772 DOI: 10.1002/chem.201905707] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/02/2020] [Indexed: 11/11/2022]
Abstract
Recently, an unprecedented observation of polar order, thermochromic behavior, and exotic mesophases in new chiral, bent-shaped systems with a -CH3 moiety placed at the transverse position of the central core was reported. Herein, a homologous series of compounds with even-numbered carbon chains from n=4 to 18 were synthesized, in which -Cl was substituted for -CH3 at the kink position and a drastic modification in the phase structure of the bent-shaped molecule was observed. An unusual stabilization of the cubic blue phase (BP) over a wide range of 16.4 °C has been witnessed. Two homologues in this series (1-12 and 1-14) exhibit an interesting phase sequence consisting of BPI/II, chiral nematic, twist grain boundary, smectic A, and smectic X (SmX) phases. The higher homologues (1-16 and 1-18) stabilize the SmX phase enantiotropically over the entire temperature range. Crystal structure analysis confirmed the bent molecular architecture, with a bent angle of 148°, and revealed the presence of two different molecular conformations in an asymmetric unit of compound 1-4. A DFT study corroborated that the -Cl moiety at the central core of the molecule led to an increase in the dipole moment along the transverse direction, which, in turn, facilitated the unusual stabilization of frustrated structures. Crystal polymorphism has been evidenced in three homologues (1-10, 1-12, and 1-14) of the series. On the application of mechanical pressure through grinding, compound 1-10 transformed from a bright yellow crystalline solid to a dark orange-green amorphous solid, which reversed upon dropwise addition of dichloromethane, indicating reversible mechanochromism in this class of compounds. In addition, excellent thermochromic behavior has been observed for compound 1-10 with a controlled temperature-color combination.
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Affiliation(s)
- Vidhika Punjani
- 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
| | - Supreet Kaur
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli, 140306, India
| | - Angshuman Roy Choudhury
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Knowledge City, Manauli, 140306, India
| | | | - Surajit Dhara
- School of Physics, University of Hyderabad, Hyderabad, 500046, India
| | - Sharmistha Ghosh
- Department of Physics, University of Calcutta, 92 Acharyya Prafulla Chandra Road, Kolkata, 700009, 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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Jain V, Mohiuddin G, Pal SK. Design, synthesis and application of 2-chloro-3-nitrobenzoic acid based three-ring bent-core molecules with a terminal halogen moiety. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.127383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Kaur S, Mohiuddin G, Punjani V, Khan RK, Ghosh S, Pal SK. Structural organization and molecular self-assembly of a new class of polar and non-polar four-ring based bent-core molecules. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111687] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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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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Cybotactic nematic phase of achiral unsymmetrical bent-core liquid crystals – Quelling of polar ordering and the influence of terminal substituent moiety. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.02.097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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11
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Vinodha M, Senthilkumar K. Counter anion effect on structural, opto-electronic and charge transport properties of fused π-conjugated imidazolium compound. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1414965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- M. Vinodha
- Department of Physics, Bharathiar University, Coimbatore, India
| | - K. Senthilkumar
- Department of Physics, Bharathiar University, Coimbatore, India
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