A study on mesophase behavior of Schiff’s base liquid crystalline benzal-amino benzothiazole derivatives of 3-methoxy cinnamoyl ester

In the current synthetic approach, the cinnamoyl ester of Schiff base containing 4’-benzal-2’’-amino benzothiazole functionality has been synthesised to investigate its mesophase characteristics. The newly synthesised homologous series (I1 to I16) possesses varying alkoxy chains, which impact the mesophase properties. The synthesised compounds were characterised using elemental analysis (CHN), spectral analysis (FT-IR, 1H-NMR and Mass spectrometry), thermal analysis (differential scanning calorimetry) and surface texture analysis (polarising optical microscopy). As a result, these materials exhibited liquid crystalline behaviour (except I1), displaying both nematic and SmecticA phases, which were influenced by the variation in alkyl chain lengths. The smectogenic and nematogenic homologues exhibiting mesophases below 80°C can be suitable for liquid crystal device fabrication due to their suitability for low-temperature operation. Furthermore, minimum inhibitory concentration (MIC) revealed that compound I14 exhibited the most potent antimicrobial activity among the synthesised compounds, with the MIC value of 50 µg∙mL−1 against E. coli and 250 µg∙mL−1 against C. Albicans and A. Niger demonstrating its superior antibacterial and antifungal efficacy compared to the other compounds.