64328-65-0Relevant academic research and scientific papers
Nonsymmetrical cholesterol dimers constituting regioisomeric oxadiazole and thiadiazole cores: an investigation of the structure-property correlation
Pradhan, Balaram,Chakraborty, Nirmalangshu,Gupta, Ravindra Kumar,Shanker,Achalkumar, Ammathnadu S.
, p. 879 - 888 (2017/02/05)
Three series of chiral nonsymmetrical dimers were prepared by connecting promesogenic cholesterol to a bent structure derived from a substituted 1,3,4-oxadiazole or 1,2,4-oxadiazole or 1,3,4-thiadiazole moiety. These two mesogenic segments are interconnected through spacers of varying lengths and parity. The structures of the bent achiral unit were systematically varied with different central heterocyclic cores to understand the influence of bent angles on the thermal and gelation behavior. The bent angle of the achiral unit, which is determined by the heterocyclic core, has a major role in the stabilization of frustrated phases. Dimers based on the 1,3,4-oxadiazole unit with a more bent structure stabilized frustrated phases like blue phases and twist grain boundary phases. The bent system with a wider bent angle preferred to stabilize chiral nematic and smectic A phases. It is interesting to note that an increased bent structure reduced the mesophase stability as in the case of dimers based on the 1,3,4-oxadiazole unit, where many compounds exhibited monotropic phases. In the case of dimers with a wider bent angle, enantiotropic mesomorphism was observed. All the compounds showed blue light emission in the solution. Among these chiral dimers, only the compounds based on the 1,3,4-oxadiazole unit showed the gelation ability, which emphasizes how small structural changes like bent angle, dipole moment and the type of heteroatom in the heterocyclic unit affect the macroscopic self-assembly.
Liquid crystals derived from semifluorinated alkoxybenzoyl hydrazines
Khairuddean, Melati,Twieg, Robert J.
experimental part, p. 3 - 31 (2012/08/13)
A variety of liquid crystals with semifluorinated tails including 4-alkoxybenzoic acids (1d-h), 4-alkoxybenzoyl hydrazines (2d-h), and N,N0-bis(4-alkoxybenzoyl) hydrazines (3d-m) have been synthesized, and their properties are compared with their perhydrogenated analogs. Semifluorination in compounds 1d-h suppressed nematic phases, and semifluorinated compounds 2d-h exhibit mesogenic behavior where none is found in their perhydrogenated counterparts. Compounds 3a-c with perhydrogenated chains display Cub and SmC phases. Introduction of one semifluorinated chain, 3d-h suppresses the Cub phase but induces a SmA phase, with lower melting but higher clearing temperatures compared to compounds with two semifluorinated chains, 3i-m. The mesogenic properties of some selected binary mixtures of these compounds 3a-d and some lateral fluoro substituted N,N'-bis (4-alkoxybenzoyl) hydrazines 7-9 are also discussed. Copyright Taylor & Francis Group, LLC.
Synthesis and mesomorphic properties of azo compounds derived from phenyl- and thienyl-1,3,4-thiadiazole
Parra,Villouta,Vera,Belmar,Zú?iga,Zunza
, p. 1533 - 1538 (2007/10/03)
The synthesis and mesomorphic behaviour of new series of liquid crystals containing 1,3,4-thiadiazole and thiophene rings with azo central bond are reported (series 5a and 5b). All compounds of series 5a exhibit enantiotropic nematic mesophase and the hig
