Effects of chain branching and lateral fluorine substitution on mesomorphism of cholesteryl benzoates

Abstract

The mesogenic cholesteryl 4′-alkoxyphenyl-4-carboxylates possessing terminal normal/branched/saturated/unsaturated alkyl chains with laterally ortho/meta substituted electronegative fluorine atom are described. All the homologues exhibited enantiotropic mesomorphism. Smectic A phase, chiral nematic, blue phase (BP) and TGB A phases were observed in different homologues. All the novel compounds were characterised by spectroscopic and elemental analysis. Thermal investigations and mesophase characterisations for all the compounds were carried out by the combination of DSC, POM and X-ray analysis. The effects of the various terminal normal/branched/ saturated/unsaturated alkyl chains and the position of the substituted fluorine atom with its structurally related compounds have been discussed.

Synthesis and mesomorphic characterization of novel amphotropic steroidal esters

“…8 Cholesterol-based mesogens have been reported to form diverse mesophases ranging from cholesteric to smectic to a wide variety of fluid frustrated phases (TGB, Blue phases, etc.). [16][17][18][19][20][21][22][23][24] Based on their exceptional optical properties, cholesteric mesogens find numerous applications. They are useful as thermal sensors (e.g.…”

“…). 16–24 Based on their exceptional optical properties, cholesteric mesogens find numerous applications. They are useful as thermal sensors ( e.g.…”

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

“…Additionally, it is well known that the introduction of fluoro-substituent into conventional LCs could bring unusual properties to the resulting material, such as optical and chemical stability, low viscosity, good solubility as well as low conductivity. [34][35][36][37][38][39] Furthermore, the role of fluoro-substituent is not certainly evident in H-bonded self-assembly of bentshape mesogens. Therefore, the number of fluorosubstituents and the length of the terminal chains are also considered in this study ( Figure 1).…”

Phase polymorphism and thermal stability of new cholesterol thioesters derivatives

“…[4,5] The studies of these substances have intensified during the last years. For example, imidazolium-based ionic liquid crystals bearing a cholesteryl mesogenic group were synthesised and characterised [6], effects of chain branching and lateral fluorine substitution on mesomorphism of cholesteryl benzoates has been investigated [7], as well influence of chemical structure on the optical properties of new side-chain polymers containing cholesterol was identified. [8] Cholesterol-based dimeric liquid crystals have also been studied in terms of mesomorphic properties of their frustrated phases.…”