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Chang JJ, Huang JW, Lin CF, Liu SW, Chen CH. Enhancing the signal contrast ratio and stability of liquid crystal-based sensors by using fine grids made by photolithography of photoresists. Analyst 2021; 146:3834-3840. [PMID: 33913955 DOI: 10.1039/d1an00332a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We prepared fine grid patterns on a glass substrate through photolithography of photoresists; we filled photoresist grids with liquid crystals (LCs) to construct LC-based sensors. Scanning electron microscopy images revealed that the photoresist grids were flat, smooth, and 3.0-8.0 μm thick. In contrast to conventional LC-based sensors, in which LCs are filled in metal grids placed on glass substrates, our results proved that LC-based sensors constructed using photoresist grids exhibited a larger signal contrast ratio, better signal stability in aqueous solutions and lower limit of detection for mercuric ions. All these characteristics enhanced the performance of the LC-based sensors.
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Affiliation(s)
- Jung-Jung Chang
- Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan. and Department of Electronic Engineering and Organic Electronics Research Center, Ming Chi University of Technology, New Taipei City 24301, Taiwan.
| | - Jhih-Wei Huang
- Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
| | - Chun-Feng Lin
- Department of Electronic Engineering and Organic Electronics Research Center, Ming Chi University of Technology, New Taipei City 24301, Taiwan.
| | - Shun-Wei Liu
- Department of Electronic Engineering and Organic Electronics Research Center, Ming Chi University of Technology, New Taipei City 24301, Taiwan.
| | - Chih-Hsin Chen
- Department of Chemistry, Tamkang University, New Taipei City 25137, Taiwan.
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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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Gude V, Karmakar M, Dey A, Datta PK, Biradha K. Is the origin of green fluorescence in unsymmetrical four-ring bent-core liquid crystals single or double proton transfer? Phys Chem Chem Phys 2020; 22:4731-4740. [DOI: 10.1039/c9cp06307b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The origin of green fluorescence in unsymmetrical four-ring bent-core liquid crystals (BCLCs) is not understood clearly.
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Affiliation(s)
- Venkatesh Gude
- Department of Chemistry
- Indian Institute of Technology-Kharagpur
- Kharagpur
- India
| | - Manobina Karmakar
- Department of Physics, Indian Institute of Technology-Kharagpur
- Kharagpur
- India
| | - Avishek Dey
- Department of Chemistry
- Indian Institute of Technology-Kharagpur
- Kharagpur
- India
| | | | - Kumar Biradha
- Department of Chemistry
- Indian Institute of Technology-Kharagpur
- Kharagpur
- India
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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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