Chiral Smectic *C Mesogens Having Ester and Amide Central Linkages
摘要:
Ten members of a chiral homologous series 4-(4'-n-alkoxy benzoyloxy benzoyl)4''- S- (+) 2-methyl butoxy anilides were synthesized in multiple step synthesis. Series exhibits chiral smectic *C and cholesteric mesophases. In this series, n-propyl to n-dodecyl derivatives exhibit smectic *C and cholesteric mesophases. n-Tetradecyl and n-hexadecyl derivatives exhibit only smectic *C phases. The plot of transition temperatures versus number of carbon atoms in alkoxy chain exhibits odd-even effect for cholestric-isotropic transition temperatures. The effect of amide linkage and chirality is discussed in detail. High-temperature cholestric phases exhibit vivid colors. Two compounds were analyzed by calorimetric study (C12 and C14) to confirm the transition temperatures of which was observed under polarizing microscope. The mesogenic behavior of the series compared with other series where amide central linkage differs in its position. The mesogenic thermal stability is compared with other related homologous series. The result indicates that amide linkage enhances smectic as well as cholesteric thermal stability but enhancement in smectic phase is much higher. Compounds are characterized by elemental analysis, IR spectral data, Mass spectral data, DSC, NMR, and microscopic study.
New hockey stick shaped amino allylidene (‒N˭CH‒CH˭CH) based compounds: Effect of linkage group on mesomorphic properties
作者:Vinay. S. Sharma、Rajesh. H. Vekariya、Anuj. S. Sharma、R. B. Patel
DOI:10.1080/15421406.2017.1357430
日期:2017.7.24
GRAPHICAL ABSTRACT ABSTRACT Two nonlinear hockey stick shaped homologous series based on three linking groups have been synthesized and characterized by elemental analyses and spectroscopic techniques. The mesomorphic properties of these compounds were observed by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). In this present investigation, we have synthesized two
New chalcone based liquid crystals with allylidene amino linking unit: Synthesis and characterization
作者:Vinay S. Sharma、Anuj S. Sharma、Upendra H. Jadeja、Deepak Suthar
DOI:10.1080/15421406.2018.1499697
日期:2018.4.13
In this study, the synthesis, structural characterization and mesomorphic properties of newly thirteen calamitic shaped compounds derived from allylidene amino chalcone and 4-n-alkoxy benzoyloxy benzoic acid. Comp.H-1 to H-3 exhibited nonliquid crystalline nature, while comp.H-4 to comp.H-18 displayed enantiotropical smectic C phase. Phase transition temperatures of present synthesised compounds were determined by optical polarising microscopy (POM), differential scanning calorimetric (DSC) and powder X-ray diffraction (PXRD) techniques. Thermal stabilities of smectic to isotropic phase are 150.0 degrees C and temperature range of mesophase is in decreasing order from comp.H-3 to comp.H-18 respectively. The presences of SmC phase are the type of broken fan and needle type in present synthesized series. It is also shown that presence of chalcone amino allylidene central linking group favors a calamitic liquid crystalline behaviour in molecules with lower member to higher member aliphatic side chain in alkoxy group (-OR).