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Open AccessArticle

Characterization of New H-Bonded Liquid Crystalline Complexes Based on Iminophenyl Nicotinate

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Chemistry Department, College of Sciences, Yanbu, Taibah University, Yanbu 30799, Saudi Arabia
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Chemistry Department, Faculty of Science, Alexandria University, Alexandria 21321, Egypt
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Department of Chemistry, Faculty of Science, Cairo University, Cairo 12613, Egypt
4
Chemistry Department, College of Sciences, Al-Madina Al-Munawarah, Taibah University, Al-Madina 30002, Saudi Arabia
*
Authors to whom correspondence should be addressed.
Crystals 2020, 10(6), 499; https://doi.org/10.3390/cryst10060499
Received: 25 April 2020 / Revised: 6 June 2020 / Accepted: 8 June 2020 / Published: 9 June 2020
(This article belongs to the Special Issue Photosensitive Liquid Crystals)
Two new 1:2 supramolecular H-bonded liquid crystalline complexes (SMHBCs) were prepared through double H-bond interactions between either isophthalic acid (A) or terephthalic acid (B) and a nicotinate Schiff base (I6). The formed complexes were thermally investigated by differential scanning calorimetry (DSC), and their phases were identified by polarized optical microscopy (POM) and UV-spectroscopy. The formation of 1:2 hydrogen-bonded complexes was confirmed through their Fermi-bands observed by FT-IR spectroscopy. The first system (I6/A) was found to possess enantiotropic smectic A and nematic mesophases. Induced broad range of smectic A phase was observed in I6/A complex which is not shown by their individual components. The second complex system (I6/B) was purely nematogenic. Density functional theory (DFT) calculations were applied to predict their geometrical parameters. Theoretical studies revealed that the isophthalic complex adopted the W-shape; while the U-shape was adopted by the terephthalic acid complex (I6/B). The linear geometry of the complex based on the isophthalic acid enhanced the mesomorphic behavior observed by the terephthalic complex; I6/B. Actually; the orientation of the two carboxylic groups was shown to highly affect the softness of the derived complex. On the other hand; the mapping orientation of the charge distribution can be used to explain the mesophase behavior. The photophysical characterization of isophthalic complex (I6/A) is also discussed View Full-Text
Keywords: dicarboxylic acid supramolecular H-bonding complexes; mesomorphic behavior; induced phase; molecular geometry; DFT calculations; photophysical studies dicarboxylic acid supramolecular H-bonding complexes; mesomorphic behavior; induced phase; molecular geometry; DFT calculations; photophysical studies
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Alnoman, R.B.; Hagar, M.; Ahmed, H.A.; Abu Al-Ola, K.A.; Naoum, M.M.; Al-Elati, F.; Abdullah Zaid, Y.; Alsharif, A.; Al-Juhani, Y.; Abulrhelh, A. Characterization of New H-Bonded Liquid Crystalline Complexes Based on Iminophenyl Nicotinate. Crystals 2020, 10, 499.

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