Effect of bent-shape and calamitic-shape of hydrogen-bonded mesogens on the liquid crystalline properties

Abstract

2015): Effect of bentshape and calamitic-shape of hydrogen-bonded mesogens on the liquid crystalline properties, Liquid Crystals, Six series of hydrogen-bonded (H-bonded) liquid crystals (LCs) were synthesised to study the effect of H-bonded mesogens with calamitic-shape or bent-shape structure on mesogenic behaviours by using isonicotinate and nicotinate derivatives as proton acceptors. The lateral fluoro-substituent and the length of the terminal chains were also studied in detail. When the structure of H-bonded LCs changed from calamitic-shape to bent-shape, the length to breadth ratio reduced greatly, which led to the temperature range of mesophases narrowed and a decrease in melting point and clear point. Although the introduction of fluorine substituent could reduce the length to breadth ratio and lead to the mesophase range narrowed, even disappeared, it could effectively inhibit the emergence of the smectic A phase and obviously enhance the strength of H-bond self-assembly. Additionally, it could help reduce the phase transition points to increase the length of terminal chains.

Mesophase behaviour of azobenzene-based angular supramolecular hydrogen-bonded liquid crystals

“…[27][28][29][30][31][32][33] Alteration of the binding sites of the supramolecules is simple and effective way to change the shape of SMHBLCs [34][35][36][37] in order to design new materials with new mesomorphic properties. Herein, we extend our systematic study to investigate the effect of introducing additional azobenzene unit to the angular supramolecular complexes previously reported by us [36] through hydrogen-bond formation between 4-alkoxyphenylazo benzoic acids (In) [38,39] as proton donors and 4-(3ʹ-pyridylazo)-4ʹʹ-alkoxybenzoates (IIm) as proton acceptors (see Figure 1).…”

Synthesis of urea‐containing ABA triblock copolymers: Influence of pendant hydrogen bonding on morphology and thermomechanical properties

“…A commonly utilized noncovalent interaction is hydrogen bonding due to its potential for specificity, directionality, and reversibility. Thus, researchers invoke thermo‐reversible hydrogen bonding as a means to improve mechanical properties, induce microphase separation, impart self‐healing performance, and facilitate liquid crystal formation …”

Recent synthetic advances in pyridine-based thermotropic mesogens

“…He et al 21 synthesized nicotinate and isonicotinate derivatives (27a and 27b, respectively) as proton acceptors and studied the effects of bent-shape or calamitic-shape structures on their mesogenic behavior. During the synthesis, nicotinic acid and DMF as solvent were combined and stirred.…”