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Open AccessArticle

New Symmetrical U- and Wavy-Shaped Supramolecular H-Bonded Systems; Geometrical and Mesomorphic Approaches

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College of Science, Chemistry Department, Riyadh, Princess Nourah bint Abdulrahman University, Riyadh 11671, Saudi Arabia
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Faculty of Science, Department of Chemistry, Cairo University, Cairo 12613, Egypt
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Chemistry Department, College of Sciences, Yanbu, Taibah University, Yanbu 30799, Saudi Arabia
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Faculty of Science, Chemistry Department, Alexandria University, Alexandria 21321, Egypt
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Chemistry Department, College of Sciences, Al-Madina Al-Munawarah, Taibah University, Al-Madina 30002, Saudi Arabia
*
Authors to whom correspondence should be addressed.
Molecules 2020, 25(6), 1420; https://doi.org/10.3390/molecules25061420
Received: 17 February 2020 / Revised: 10 March 2020 / Accepted: 11 March 2020 / Published: 20 March 2020
(This article belongs to the Special Issue Current Advances in Liquid Crystals)
New mesomorphic symmetrical 2:1 supramolecular H-bonded complexes of seven phenyl rings were prepared between 4-n-alkoxyphenylazobenzoic acids and 4-(2-(pyridin-3-yl)diazenyl)phenyl nicotinate. Mesomorphic studies of the prepared complexes were investigated using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Fermi bands of the formed H-bonded interactions were confirmed by FT-IR spectroscopy. Geometrical parameters for all complexes were performed using the density functional theory (DFT) calculations method. Theoretical results revealed that the prepared H-bonded complexes are in non-linear geometry with U-shaped and wavy-shaped geometrical structures; however, the greater linearity of the wavy-shaped compounds could be the reason for their stability with respect to the U-shaped conformer. Moreover, the stable, wavy shape of supramolecular H-bonded complexes (SMHBCs) has been used to illustrate mesomeric behavior in terms of the molecular interaction. The experimental mesomorphic investigations revealed that all complexes possess enantiotropic smectic C phase. Phases were confirmed by miscibility with a standard smectic C (SmC) compound. A comparison was constructed to investigate the effect of incorporating azophenyl moiety into the mesomeric behavior of the corresponding five-membered complexes. It was found that the addition of the extra phenylazo group to the acid moiety has a great increment of the mesophase stability (TC) values with respect to the monotropic SmC phase of the five aromatic systems to the high stable enantiotropic SmC mesophase. View Full-Text
Keywords: phenyl nicotinate; supramolecular H-bonding complexes; U-shaped; wavy-shaped; smectic phase; DFT calculations phenyl nicotinate; supramolecular H-bonding complexes; U-shaped; wavy-shaped; smectic phase; DFT calculations
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MDPI and ACS Style

Al-Mutabagani, L.A.; Alshabanah, L.A.; Ahmed, H.A.; Hagar, M.; Al-Ola, K.A.A. New Symmetrical U- and Wavy-Shaped Supramolecular H-Bonded Systems; Geometrical and Mesomorphic Approaches. Molecules 2020, 25, 1420.

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