scholarly journals Anticorrelation between the Evolution of Molecular Dipole Moments and Induced Work Function Modifications

2013 ◽  
Vol 4 (20) ◽  
pp. 3521-3526 ◽  
Author(s):  
David A. Egger ◽  
Egbert Zojer
Keyword(s):  
Work Function ◽  
Dipole Moments ◽  
Molecular Dipole

Precise measurement of molecular dipole moments with a tunable far-infrared Stark spectrometer: application to HOCl

1996 ◽  
Vol 13 (8) ◽  
pp. 1645 ◽  
Author(s):  
G. Modugno ◽  
P. De Natale ◽  
M. Bellini ◽  
M. Inguscio ◽  
G. Di Lonardo ◽  
...  
Keyword(s):  
Precise Measurement ◽  
Dipole Moments ◽  
Far Infrared ◽  
Molecular Dipole

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>

scholarly journals Deep insight into reasons for the mechanoluminescence phenomenon of triphenylamine-substituted imidazoles and their distinct mechano-fluorochromic behaviours

RSC Advances ◽  
2020 ◽  
Vol 10 (39) ◽  
pp. 23187-23195 ◽  
Author(s):  
Xiao-Jing Liu ◽  
Guan-Lei Gao ◽  
Hao Jiang ◽  
Yan-Rong Jia ◽  
Min Xia
Keyword(s):  
Dipole Moments ◽  
Deep Insight ◽  
Molecular Dipole ◽  
Insight Into

Three imidazole crystals with high molecular dipole moments exhibit remarkable ML effects that are attributed to the formation of polar molecular couples in crystals. Imidazole and benzimidazole crystals are MFC-active, but phenanthrimidazole one is MFC-inactive.

scholarly journals Conformational preferences of fluorine-containing agrochemicals and their implications for lipophilicity prediction

2020 ◽  
Vol 16 ◽  
pp. 2469-2476
Author(s):  
Daniela Rodrigues Silva ◽  
Joyce K Daré ◽  
Matheus P Freitas
Keyword(s):  
Organic Chemistry ◽  
Partition Coefficients ◽  
Molecular Conformation ◽  
Dipole Moments ◽  
Biological Properties ◽  
Molecular Dipole ◽  
Conformational Preferences ◽  
Environmental Properties ◽  
Physicochemical And Biological Properties ◽  
Lipophilicity Prediction

Molecular polarity governs lipophilicity, which in turn determines important agrochemical and environmental properties, such as soil sorption and bioconcentration of organic compounds. Since the C–F bond is the most polar in organic chemistry, the orientation of fluorine substituents originating from the rotation around C–C(F) bonds should affect the polarity and, consequently, the physicochemical and biological properties of fluorine-containing agrochemicals. Accordingly, this study aims to determine the most likely conformers of some fluorine-containing agrochemicals and to correlate their molecular dipole moments with the respective n-octanol/water partition coefficients (log P), in order to investigate the dependence of the lipophilicity with the molecular conformation.

A large deuterium isotope effect on molecular dipole moments

1984 ◽  
Vol 80 (7) ◽  
pp. 3497-3498 ◽  
Author(s):  
David M. Hanson ◽  
Irwin C. Winkler
Keyword(s):  
Isotope Effect ◽  
Dipole Moments ◽  
Deuterium Isotope Effect ◽  
Molecular Dipole
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