Synthesis and Mesomorphic Properties of Azo Compounds Derived from Phenyl-and Thienyl-1,3,4-Thiadiazole

Abstract

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 higher homologues (n = 9 - 10) also show a monotropic smectic C phase. Series 5b show dimorphism SC - N (for n = 5 - 7 the SC is monotropic). These series are compared with the Schiff’s bases analogues, the imine bond gives rise to similar liquid crystals phase but larger mesomorphic range.

Liquid Crystals Investigation Behavior on Azo-Based Compounds: A Review

“…A study was conducted in 1997 by Parra et al on the structure–properties relationship of azo-based compounds [ 19 ]. In this study, Parra and her co-worker synthesized two azo compounds, 1 (a–f) and 2 (a–f).…”

Preliminary communication: The synthesis of new mesogenic 1,3,4‐thiadiazole‐2‐carboxylate esters via a novel ring‐closure

“…Substituents that have been incorporated at the 2-and 5-positions of the 1,3,4-thiadiazole ring include: (a) two aryl units, (b) an alkyl (or cycloalkyl) and an aryl unit, (c) two cycloalkyl units, (d) an alkyl and an amino-based unit (azo, amide or Schiff's base), (e) a perfluoroalkyl and an aryl unit and (f) an aryl and an amino unit (azo, amide or Schiff's base). Examples of such mesogens [1][2][3][4][5][6][7][8][9][10] are shown in figure 1 (I-V).…”

“…1,3,4-Thiadiazoles with nitrogen-based linkers (amides, Schiff's bases or azo groups) at the 2-position have been recently synthesized by Parra and co-workers [6][7][8][9][10]. These materials are derived from 2-amino-1,3,4-thiadiazoles that are obtained via cyclization of the requisite thiosemicarbazides using either sulphuric acid or acetyl chloride in combination with HCl.…”

Symmetric esters derived from 1,3,4-oxadiazole: synthesis, mesomorphic properties and structural study by semi-empirical calculations

“…The homothiadiazole or thiophene rings can be incorporated into logues series of diesters were synthesized by using the principal structure of calamitic mesogens [7][8][9][10][11][12]. In 4-hydroxy-phenylhydrazide as precursor.…”