ABSTRACT In order to investigate the effect of replacing the azo group with the azomethine in the previously investigated four-ring azo/ester/azo compounds, 4-alkoxy phenylazo phenyl 4ʹ-(4′′-alkoxyphenylazo) benzoates (II m/n) on… Click to show full abstract
ABSTRACT In order to investigate the effect of replacing the azo group with the azomethine in the previously investigated four-ring azo/ester/azo compounds, 4-alkoxy phenylazo phenyl 4ʹ-(4′′-alkoxyphenylazo) benzoates (II m/n) on their mesophase behaviour, 24 different homologues of the formula 4-alkoxy phenyl azomethine phenyl 4ʹ-(4′′-alkoxyphenylazo) benzoates (I m/n) were prepared and investigated for their mesophase behaviour. In these compounds, the length of the terminal alkoxy group attached to phenyl azomethine (m) varies between 6 and 12 carbons, while the length of the other alkoxy group, attached to the phenylazo moiety (n), varies between 6 and 16 carbons. Compounds prepared were structurally characterised and their mesophases transition temperatures determined by DSC, and the phases identified by PLM. A comparative study was made once between the prepared compounds (I m/n) and their previously investigated four-ring azo/ester/azo analogues (II m/n), aiming to investigate the effect of replacing the azo group with an azomethine one. Another two comparisons were made individually between the prepared series of compounds (I m/n) and their corresponding three-ring azo/ester analogues, namely, 4-alkoxyphenyl 4ʹ-(4′′-alkoxyphenylazo) benzoates (III m/n), and the three-ring analogues 4-alkoxyphenyl 4ʹ-(4′′-alkoxyphenylazomethine) benzoates (IV m/n) aiming to investigate the effect of inclusion of the extra phenyl azomethine and phenylazo moieties to series III and IV, respectively. GRAPHICAL ABSTRACT
               
Click one of the above tabs to view related content.