88956-32-5Relevant academic research and scientific papers
Mesomorphic Characteristics of Liquid Crystalline Esters p-Methoxyphenyl p-Alkoxycinnamates
Dave, Jayrang S.,Dhake, K. P.
, p. 559 - 561 (1992)
The newly synthesized homologous series p-methoxyphenyl p-alkoxycinnamates (I) can be compared with the series N- p-anisidines (II).All the homologues of both series (I) and (II) from C1 to C18 are mesogens.In series (II) the first five members decompose due to high transitions at about 300 deg C.With decrease in length of the molecules of series (I) than that of series (II), the overall transitions also decrease by about 150 deg C.The first seven members in series (II) are nematogens; polymesomorphism begins from octyloxy homologue with the commencement of smectic mesophase and continues to be exhibited upto the last i.e. octadecyloxy homologue.In series (I) also the nematic phase is exhibited upto the heptyl derivative; the smectic phase commences from C8-member in the form of monotropic phase thereby exhibiting polymesomorphism upto C14 homologue.The last two members of series (II) are smectogens.The odd-even effect is missing in series (II) whereas in series (I), it is seen upto the fifth homologue.In both the series, the N-I curves show a falling tendency - a criterion of high melting series.From textures' point of view both the series have common features, the nematic phase is threaded when it is the only mesophase shown and homeotropic in polymesomorphic region, whereas the smectic mesophase is focal conic fan shaped of smectic-A variety.This series also yields interesting comparison with the series (III) p-nitrophenyl p-alkoxycinnamates and (IV) p-chlorophenyl p-alkoxycinnamates.
Emergence of Smectic Mesophase in Binary Mixtures of Pure Nematogens
Lohar, J. M.,Dave, Jayrang. S.
, p. 181 - 192 (2007/10/02)
Binary mixtures both components of which are liquid crystals are known to form continuous mixed liquid crystals.Most of them do not undergo any change in their mesomorphic textures, though a few have been found to give rise to different textures.We report here a binary system consisting of (A) p-nitrophenyl-p'-n-amyloxycinnamate (90.5-120.5 degC) and (B) p-methoxyphenyl-p'-n-heptyloxycinnamate (91.0-120.5 degC) which transforms the original nematic texture into a mixed smectic A texture over a range of temperature and concentration.Both components individually are nematic liquid crystals.In their binary mixtures, a two dimensional more ordered mixed Smectic A mesophase emerges between 5.0-92.5 molpercent of p-methoxyphenyl-p'-n-heptyloxycinnamate over a temperature range of about 50-105 degC at its maximum.The mixed smectic-nematic transition curve shows a marked rounded concavity, extrapolation of which on either side yields values of latent transition temperatures 77.0 degC and 66.5 degC for the components A and B respectively which could be real in case they were to show polymesomorphism.These values are comparable with those obtained from the study of their homologous series.Besides this unique phenomenon of emergence of the mixed smectic A mesophase out of a mixture of two purely nematic substances, the nematic mesophase also persists continuously in the phase diagram over a range of temperature and concentration.The results are interpreted to account for the unique display of the molecular forces which make such an emergent mixed smectic phase possible.
