Thermotropic Liquid Crystals Formed by Intermolecular Hydrogen Bonding Interactions

Abstract

The role of hydrogen bonding in the formation or stabilization of liquid crystalline phases has only recently been appreciated. Following the first. wellestablished examples of liquid crystal formation from the dimerization of aromatic carboxylic acids, through hydrogen bonding, several classes of compounds have recently been synthesized, the liquid crystalline behavior of which is also dependent on intermolecular hydrogen bonds between similar or dissimilar molecules. In this review the main classes of compounds exhibiting liquid crystallinity due to hydrogen bonding are presented to show the diversity of organic compounds that can be used as building elements in liquid crystals. The molecules are either of the rigid-rod anisotropic or amphiphilic types such as molecules appropriately functionalized with pyridyl and carboxyl groups, whose interaction leads to the formation of liquid crystals; amphiphilic carhohydrates and amphiphilic and bolaamphiphilic compounds with multiple hydroxyl groups whose dimerization or association is indispensable for the formation of liquid crystals; and certain amphiphilic carboxylic acids with monomeric or polymeric mesogens and amphiphilic-type compounds bearing different moieties, whose interaction may lead to the formation of mesomorphic compounds. Associated with the macroscopic display of liquid crystalline phases is the supramolecular structure, and therefore rather extended discussion of these structures are included in this review.

Side chain functionalized liquid crystalline polymers and blends, 1. Reentrant nematic phase formation in hydrogen-bonded blends of liquid crystalline functionalized copolymers with a low molecular weight non-mesogeic dopant

“…In recent years great attention has been devoted to the synthesis and investigation of polymer systems capable of specific non-covalent interactions [1][2][3][4][5][6][7][8][9] . These interactions influence in a specific way the phase behavior of the macromolecules.…”

Physical Gelation of Nematic Liquid Crystals with Amino Acid Derivatives Leading to the Formation of Soft Solids Responsive to Electric Field.

“…[ 1,2] Recently, hydrogenbonded mesogenic materials have been developed. [3][4][5][6][7] These materials exhibit thermally stable liquid-crystalline phases by the formation of various types of self-organized structures. [3][4][5][6][7] On the other hand, physical gelation of common organic solvents has been reported.…”

“…[3][4][5][6][7] These materials exhibit thermally stable liquid-crystalline phases by the formation of various types of self-organized structures. [3][4][5][6][7] On the other hand, physical gelation of common organic solvents has been reported. [8][9][10][11][12][13] Those organic physical gels are microphase-separated materials consisting of organic solvents and fibrous aggregates of low molecular weight gelling agents.…”

Hydrogen Bonding for Supramolecular Liquid Crystals

“…The topic of hydrogen bonded liquid crystalline materials has been reviewed by several groups [2,27,[29][30][31]. Herein only the important and recent development on hydrogen bonded supramolecular low molecular weight LCs will be introduced.…”