Synthesis of 4-Chloro-1,3-Diazobenzene Bent-Cores Liquid Crystal and Characterizations of Its Mesogenic Behaviors and Photosensitivity

2020 ◽  
Author(s):  
Jinying Lu ◽  
Zelong Zhang ◽  
Daoren Yan ◽  
Zhiyong Zhang ◽  
Jintao Guan ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Nematic Phase ◽  
Density Functional ◽  
Optical Switching ◽  
Density Functional Theory Calculations ◽  
Acetate Solution ◽  
Photochromic Properties ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
Practical Applications

<p></p><p>Azobenzene-based bent-core liquid crystals demonstrate a variety of mesomorphic behaviors and photochromic properties which are desirable for optical switching. In this study, a novel compound was synthesized by adding azo functional groups and chlorine substituent to the central bent-cores to form a 4-chloro-1,3-dizaophenylene bent-core. This compound was characterized by fourier-transform infrared spectroscopy (FTIR), <sup>1</sup>H and <sup>13</sup>C nuclear magnetic resonance (NMR), mass spectrometry (MS), differential scanning calorimetry (DSC), polarized optical microscopy (POM), ultraviolet–visible spectroscopy (UV-Vis) to evaluate its structure, mesogenic properties, and photosensitivity. The experimental results show that compound <b>4c</b> exhibits a broad temperature window of 63.8 °C for nematic phase, rapid photoisomerization in seconds, and high <i>cis</i> fraction 0.81. At room temperature, compound <b>4c </b>dissolved in ethyl acetate solution can reach photostationary state in 10 seconds. At 95 °C, compound <b>4c</b> in nematic phase became isotropic liquid under UV-irradiation in 3 seconds due to the forward <i>trans – cis</i> photoisomerization and can be restored to be nematic under natural visible light in 5 seconds because of the backward <i>cis – trans</i> photoisomerization. Density functional theory calculations confirm that the diazo as the central linkages instead of esters can effectively reduce the molecular dipole moment, which promotes these favorable characteristics. This study provides valuable insights to improve future design of azobenzene bent-core liquid crystals for practical applications especially in photonic applications.</p><p></p>

scholarly journals Synthesis of 4-Chloro-1,3-Diazobenzene Bent-Cores Liquid Crystals and Characterizations of Their Mesogenic Behaviors and Photoisomerization Phenomena

2020 ◽  
Author(s):  
Jinying Lu ◽  
Zelong Zhang ◽  
Daoren Yan ◽  
Zhiyong Zhang ◽  
Jintao Guan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Nematic Phase ◽  
Dipole Moments ◽  
Intermolecular Forces ◽  
Acetate Solution ◽  
Molecular Dipole ◽  
Practical Applications ◽  
Nematic Phases ◽  
Terminal Chain

<p></p><p>Azobenzene-based bent-core liquid crystals demonstrate a variety of mesomorphic behaviors and photochromic properties which are desirable for optical switching. Nowadays azobenzene-based bent-core liquid crystal (ABLC) compounds usually exhibit at least one of the following traits which are unfavorable for practical applications: (1) narrow temperature windows of nematic phases, (2) high phase transition temperature, and (3) long period of light stimulation to reach photostationary states. In this study, a series of ABLC compounds <b>4a–4g</b> were synthesized by adding azo functional groups and chlorine substituent to the central bent-cores to form 4-chloro-1,3-dizaophenylene bent-cores. These ABLC compounds were characterized by i. fourier-transform infrared spectroscopy (FTIR), <sup>1</sup>H and <sup>13</sup>C nuclear magnetic resonance (NMR), and mass spectrometry (MS) for their structures, ii. differential scanning calorimetry (DSC) and polarized optical microscopy (POM) for their mesogenic properties, and iii. ultraviolet–visible spectroscopy (UV-Vis) and POM for their photosensitivity. The experimental results show that all compounds exhibited broad temperature windows of mesogenic phases. In particular, compound <b>4c</b> showed a broad temperature window of 63.8 °C for nematic phase. Molecular simulations indicate that the molecular dipole moments of compounds <b>4a–4g</b> are closely associated with the temperatures of Sm – N phase transition and temperature ranges of nematic phases. In addition, simulation results reveal that the terminal alkyl chains exhibit a diphasic effect on the molecular polarity: extending the terminal chain can initially reduce and then increase the molecular dipole moments due to the severe structural disorder of overly extended terminal chain. These findings indicate that the intermolecular forces play a vital role in shaping the mesogenic behavior of ABLCs. Comprehensive characterizations of photochromatic properties show that <b>4c</b> was highly photosensitive and displayed rapid photoisomerization processes. At room temperature, compound <b>4c </b>dissolved in ethyl acetate solution can reach photostationary state in 10 seconds. At 95 °C, compound <b>4c</b> in nematic phase became isotropic liquid under UV-irradiation in 3 seconds due to the forward <i>trans – cis</i> photoisomerization and can be restored to be nematic under natural visible light in 5 seconds because of the backward <i>cis – trans</i> photoisomerization. This study linking the mechanistic details with mesogenic properties provides valuable insights to improve future design of azobenzene bent-core liquid crystals for practical applications especially in photonic applications.</p><p><br></p><p>Pertinent molecular structure files (mol2) can be downloaded from</p><p><a href="https://github.com/er1czz/ABLC">https://github.com/er1czz/ABLC</a><br></p><p></p>

Synthesis of 4-Chloro-1,3-Diazobenzene Bent-Cores Liquid Crystal and Characterizations of Its Mesogenic Behaviors and Photosensitivity

2020 ◽  
Author(s):  
Jinying Lu ◽  
Zelong Zhang ◽  
Daoren Yan ◽  
Zhiyong Zhang ◽  
Jintao Guan ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Optical Switching ◽  
Room Temperature ◽  
Visible Spectroscopy ◽  
Photochromic Properties ◽  
Scanning Calorimetry ◽  
Photostationary State ◽  
Synergistic Approach ◽  
Chlorine Substituent ◽  
Temperature Window

<p></p><p>Azobenzene-based bent-core liquid crystals demonstrate a variety of mesomorphic behaviours and photochromic properties which are desirable for optical switching. In this study, a novel compound <b>4c</b> was synthesised by adding azo functional groups and chlorine substituent to the central bent-core. The structure, mesogenic properties, and photosensitivity of <b>4c</b> was characterised by fourier-transform infrared spectroscopy (FTIR), <sup>1</sup>H and <sup>13</sup>C nuclear magnetic resonance (NMR), mass spectrometry (MS), differential scanning calorimetry (DSC), polarised optical microscopy (POM), and ultraviolet–visible spectroscopy (UV-Vis). The experimental results show that <b>4c</b> exhibited a broad temperature window of nematic phase (63.8 °C), rapid <i>trans – cis</i> photoisomerisation in seconds, and high <i>cis</i> fraction of 0.81. At room temperature, <b>4c </b>dissolved in ethyl acetate can reach photostationary state in 10 seconds. At 95 °C, nematic <b>4c</b> became isotropic under UV irradiation in 3 seconds and can be restored to be nematic under natural visible light in 5 seconds. Quantum mechanics calculations confirm that using azos instead of esters as the central linkages can effectively reduce the molecular dipole moment and enhance the overall molecular polarisabilities, which promotes favourable mesogenic and photonic behaviours. This study provides novel synthesis route and synergistic approach to advance the design of azobenzene bent-core liquid crystals.</p><p></p>

scholarly journals Synthesis of 4-Chloro-1,3-Diazobenzene Bent-Cores Liquid Crystal and Characterizations of Its Mesogenic Behaviors and Photosensitivity

2020 ◽  
Author(s):  
Jinying Lu ◽  
Zelong Zhang ◽  
Daoren Yan ◽  
Zhiyong Zhang ◽  
Jintao Guan ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Optical Switching ◽  
Room Temperature ◽  
Visible Spectroscopy ◽  
Photochromic Properties ◽  
Scanning Calorimetry ◽  
Photostationary State ◽  
Synergistic Approach ◽  
Chlorine Substituent ◽  
Temperature Window

<p></p><p>Azobenzene-based bent-core liquid crystals demonstrate a variety of mesomorphic behaviours and photochromic properties which are desirable for optical switching. In this study, a novel compound <b>4c</b> was synthesised by adding azo functional groups and chlorine substituent to the central bent-core. The structure, mesogenic properties, and photosensitivity of <b>4c</b> was characterised by fourier-transform infrared spectroscopy (FTIR), <sup>1</sup>H and <sup>13</sup>C nuclear magnetic resonance (NMR), mass spectrometry (MS), differential scanning calorimetry (DSC), polarised optical microscopy (POM), and ultraviolet–visible spectroscopy (UV-Vis). The experimental results show that <b>4c</b> exhibited a broad temperature window of nematic phase (63.8 °C), rapid <i>trans – cis</i> photoisomerisation in seconds, and high <i>cis</i> fraction of 0.81. At room temperature, <b>4c </b>dissolved in ethyl acetate can reach photostationary state in 10 seconds. At 95 °C, nematic <b>4c</b> became isotropic under UV irradiation in 3 seconds and can be restored to be nematic under natural visible light in 5 seconds. Quantum mechanics calculations confirm that using azos instead of esters as the central linkages can effectively reduce the molecular dipole moment and enhance the overall molecular polarisabilities, which promotes favourable mesogenic and photonic behaviours. This study provides novel synthesis route and synergistic approach to advance the design of azobenzene bent-core liquid crystals.</p><p></p>

scholarly journals Photosensitive Bent-Core Liquid Crystals with Laterally Substituted Azobenzene Unit

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1265
Author(s):  
Diana Jágerová ◽  
Michal Šmahel ◽  
Anna Poryvai ◽  
Jan Macháček ◽  
Vladimíra Novotná ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Nematic Phase ◽  
Uv Light ◽  
Rapid Development ◽  
Functional Materials ◽  
Scanning Calorimetry ◽  
Isotropic Liquid ◽  
Relative Configuration ◽  
Azo Group ◽  
Optical Polarizing Microscopy

Photosensitive liquid crystals represent an important class of functional materials that experience rapid development. Hereby, we present novel bent-core liquid crystals bearing a lateral substitution on the central core and in the vicinity of the photosensitive unit—an azo group. The azo group enables fast (E)-to-(Z)-isomerization upon irradiation with UV-light and visible light, while the substitution facilitates the high stability of the photochemically formed (Z)-isomer. The effectiveness of the irradiation and the composition of photostationary states was determined by UV/Vis and 1H NMR spectroscopy. A nematic phase formed by the materials was characterized by differential scanning calorimetry and optical polarizing microscopy. We show that the materials easily change their relative configuration of the N=N double bond not only in solution, but also in the mesophase, which leads to fast isothermal phase transition from the nematic phase to isotropic liquid.

scholarly journals Highly active and selective oxygen reduction to H2O2 on boron-doped carbon for high production rates

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yang Xia ◽  
Xunhua Zhao ◽  
Chuan Xia ◽  
Zhen-Yu Wu ◽  
Peng Zhu ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Density Functional ◽  
High Selectivity ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Production Rates ◽  
Practical Applications ◽  
Highly Active ◽  
Boron Doped ◽  
Oxidized Carbon

AbstractOxygen reduction reaction towards hydrogen peroxide (H2O2) provides a green alternative route for H2O2 production, but it lacks efficient catalysts to achieve high selectivity and activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm−2) while maintaining high H2O2 selectivity (85–90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H2O2 activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H2O2 solutions with high selectivity (up to 95%) and high H2O2 partial currents (up to ~400 mA cm−2), illustrating the catalyst’s great potential for practical applications in the future.

scholarly journals Nitrogen-rich covalent organic frameworks with multiple carbonyls for high-performance sodium batteries

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruijuan Shi ◽  
Luojia Liu ◽  
Yong Lu ◽  
Chenchen Wang ◽  
Yixin Li ◽  
...  
Keyword(s):  
High Performance ◽  
Density Functional ◽  
Specific Capacity ◽  
Density Functional Theory Calculations ◽  
Rechargeable Batteries ◽  
High Rate ◽  
Ex Situ ◽  
Covalent Organic Frameworks ◽  
Rate Performance ◽  
Practical Applications

AbstractCovalent organic frameworks with designable periodic skeletons and ordered nanopores have attracted increasing attention as promising cathode materials for rechargeable batteries. However, the reported cathodes are plagued by limited capacity and unsatisfying rate performance. Here we report a honeycomb-like nitrogen-rich covalent organic framework with multiple carbonyls. The sodium storage ability of pyrazines and carbonyls and the up-to twelve sodium-ion redox chemistry mechanism for each repetitive unit have been demonstrated by in/ex-situ Fourier transform infrared spectra and density functional theory calculations. The insoluble electrode exhibits a remarkably high specific capacity of 452.0 mAh g−1, excellent cycling stability (~96% capacity retention after 1000 cycles) and high rate performance (134.3 mAh g−1 at 10.0 A g−1). Furthermore, a pouch-type battery is assembled, displaying the gravimetric and volumetric energy density of 101.1 Wh kg−1cell and 78.5 Wh L−1cell, respectively, indicating potentially practical applications of conjugated polymers in rechargeable batteries.

scholarly journals Ultrahigh sensitive Raman spectroscopy for subnanoscience: Direct observation of tin oxide clusters

2019 ◽  
Vol 5 (12) ◽  
pp. eaax6455 ◽  
Author(s):  
Akiyoshi Kuzume ◽  
Miyu Ozawa ◽  
Yuansen Tang ◽  
Yuki Yamada ◽  
Naoki Haruta ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Tin Oxide ◽  
Density Functional ◽  
Rational Design ◽  
High Sensitivity ◽  
Density Functional Theory Calculations ◽  
Surface Enhanced Raman Spectroscopy ◽  
Atomic Scale ◽  
Practical Applications ◽  
Surface Enhanced Raman

Subnanometric metal clusters exhibit anomalous catalytic activity, suggesting innovative applications as next-generation materials, although identifying and characterizing these subnanomaterials in atomic detail remains a substantial challenge because of the severely weak signal intensity for the conventional analytical methods. Here, we report a subnanosensitive vibrational technique established based on the surface-enhanced Raman spectroscopy, demonstrating the first-ever detailed vibrational characterization of subnanomaterials. Furthermore, combining with density functional theory calculations, we reveal that inherent surface structures of the tin oxide subnanoclusters determine the size-specific spectral and catalytic characteristics of these clusters. The high-sensitivity characterization methodology elaborated here can provide a comprehensive understanding of the chemical and structural natures of subnanomaterials, which facilitate the rational design of subnanomaterials on the atomic scale for practical applications, such as in catalysts, biosensors, and electronics.

scholarly journals Polymer selective laser curing for integrated optical switches

2017 ◽  
Vol 9 (1) ◽  
pp. 32
Author(s):  
Manuel Gil-Valverde ◽  
Manuel Cano-García ◽  
Rodrigo Delgado ◽  
Tianyi Zuo ◽  
José Manuel Otón ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Optical Switching ◽  
Optical Switch ◽  
Single Mode ◽  
Multimode Waveguide ◽  
Direct Writing ◽  
Isotropic Liquid ◽  
Direct Laser ◽  
Laser Curing

A simple in-layer electro optical switch has been prepared by selectively curing a photocurable optical polymer with a UV laser. The core of the device is a NOA-81 multimode waveguide grown by selective laser curing. The cladding is a positive calamitic liquid crystal, which allows tunability and switching of the waveguide by external driving electric signals. The effective refractive index in the guide changes upon switching the liquid crystal. Depending on the geometry, this setup leads to an electrooptical modulator or a switch between two levels of transmitted light. Full Text: PDF ReferencesT. Ako, A. Hope, T. Nguyen, A. Mitchell, W. Bogaerts, K. Neyts, and J. Beeckman, "Electrically tuneable lateral leakage loss in liquid crystal clad shallow-etched silicon waveguides", Opt. Express 23, 2846 (2015). CrossRef K. Kruse, C. Middlebrook, "Laser-direct writing of single mode and multi-mode polymer step index waveguide structures for optical backplanes and interconnection assemblies", Photon. Nanostruct. - Fundamentals and Appl. 13, 66 (2015). CrossRef A. Günther, A.B. Petermann, M. Rezem, M. Rahlves, M. Wollweber, and B. Roth, European Conf. Lasers and Electro-Optics - European Quantum Electronics Conference, Munich, Germany (2015).C. Florian, S. Piazza, A. Diaspro, P. Serra, M. Duocastella, "Direct Laser Printing of Tailored Polymeric Microlenses", ACS Appl. Mater. Interfaces, 8(27), 17028 (2016). CrossRef F. Costache, M. Blasl, "Optical switching with isotropic liquid crystals", Opt. Photonik 6, 29 (2011). CrossRef M. Cano-Garcia, R. Delgado, T. Zuo, M.A. Geday, X. Quintana, Jose M. Otón, 16th OLC Topical Meeting on the Optics of Liquid Crystals, Sopot, Poland (2015).S. Ishihara, H. Wakemoto, K. Nakazima, Y. Matsuo, "The effect of rubbed polymer films on the liquid crystal alignment", Liq. Cryst. 4(6), 669 (1989). DirectLink

Modeling Reaction Kinetics of Twin Polymerization via Differential Scanning Calorimetry

2018 ◽  
Vol 43 (4) ◽  
pp. 347-357
Author(s):  
Janett Prehl ◽  
Robin Masser ◽  
Peter Salamon ◽  
Karl Heinz Hoffmann
Keyword(s):  
Reaction Mechanism ◽  
Density Functional ◽  
Reaction Rate ◽  
Density Functional Theory Calculations ◽  
Scanning Calorimetry ◽  
Functional Theory ◽  
Reaction Rate Constants ◽  
Acid Catalyzed ◽  
Kinetics Of ◽  
Derivatives Of

Abstract We present a kinetic model for the reaction mechanism of acid-catalyzed twin polymerization. Our model characterizes the reaction mechanism not by the reactants, intermediate structures, and products, but via reaction-relevant moieties. We apply our model for three different derivatives of 2,2’-Spirobi[4H-1,3,2-benzodioxasiline] and determine activation energies, reaction enthalpies, and reaction rate constants for the reaction steps in our mechanism. We compare our findings to previously reported values obtained from density functional theory calculations. Furthermore, with this approach we are also able to follow the time development of the concentrations of the reaction-relevant moieties.

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