Synthesis, Characterization and Texture Observations of Calamitic Liquid Crystalline Compounds

Abstract

Several divinylic mesogenic monomers were synthesized based on coupling the monomer 4-(4-pentenyloxy)benzoic acid with chlorohydroquinone, 2,5-dihydroxy- acetophenone, methylhydroquinone or 2-methoxyhydroquinone. This resulted in novel mesogens of phenylene esters with different lateral substituent groups. The effect of the lateral substituent group on the thermotropic phase behavior for these liquid crystalline compounds was investigated using DSC and optical polarized microscopy. All the mesogens proved to have a wide nematic liquid crystalline range. Only the phenylene ester, which has a methoxy lateral substituent, exhibited both nematic and smectic phases. Structural confirmation of all new derivatives was accomplished by 1H- and 13C-NMR spectroscopic analysis, along with CH elemental analysis.

Poly(l-Lactide) Liquid Crystals with Tailor-Made Properties Toward a Specific Nematic Mesophase Texture

“… 5 The schlieren texture of an N phase is observed for a flat sample between crossed polarizers, showing a network of black brushes connecting centers of point and line defects ( Figures 1 E,F and S4 in the Supporting Information). 36 , 37 This texture is observed in a planar cell, where the director aligns parallel to the surface and is organized around point disclinations, surface disclination lines, and inversion walls. 38…”

“…5 The schlieren texture of an N phase is observed for a flat sample between crossed polarizers, showing a network of black brushes connecting centers of point and line defects (Figures 1E,F and S4 in the Supporting Information). 36,37 This texture is observed in a planar cell, where the director aligns parallel to the surface and is organized around point disclinations, surface disclination lines, and inversion walls. 38 In the case of the N* mesophase under POM, interference colors of the planar texture, also called Grandjean texture of the N* mesophase (the most stable and that with the lowest energy state), were visible (Figures 1C and S9 in the Supporting Information).…”

Probing the Texture of the Calamitic Liquid Crystalline Dimer of 4-(4-Pentenyloxy)benzoic Acid

“…the smectic X2 (see Figure 5 e and Figure 6 k) which is also consistent with the smectic B texture reported in the literature (see Figure 8 ). Moreover, in structures similar to alkoxybenzoic acid, similar work confirmed the possibility of induction of such smectic B phase [ 34 ], in addition to other phases like smectic E [ 34 ], smectic A [ 35 , 36 , 37 , 38 ], and crystal G [ 39 ].…”

Cytotoxic Anti-Cancer Activity of Certain Thermotropic Liquid Crystalline Poly (Ester-Amides) Containing 2, 6-Bis (Benzylidene)Cyclohexanone Moiety in the Main Chain

“…The poly(ester-amides) exhibited high birefringence when it analyzed with a HOPM. 15 In Figure 5(a), crystalline phases of the mesogens has been shown. By increasing the temperature, crystal to crystal transition was observed.…”