Trifluoromethoxy-Schiff base vanilloxyl mesogens: phase transitions and bioactivity

The homologous series of 4-(((4-(trifluoromethoxy)phenyl)imino)methyl)phenyl 4-alkoxy-3-methoxybenzoate has been developed and analysed for structural elucidation using spectral analysis (FT-IR, 1H- and 13C-NMR, UV-visible), mass spectrometry (ESI-MS) and X-ray diffraction. Thermal stability and liquid crystalline (LC) phases have been determined by DSC and polarised optical microscopy analysis, respectively. The studied samples (except K1 and K2) display a nematic mesophase with moderate thermal stability, showing an average transition temperature of ~ 142°C. Computational calculations were employed to discuss energy and relevant parameters like polarisability, dipole moment, aspect ratio, etc. The energy gap and anticipated thermal stabilities for titled molecules, K4 show the considerable gap and maximum stability, followed by other samples which have approximately equal values. Among the tested samples, K12 and K18 showed notable potency against the bacterial strains used in the experimental study, with activity comparable to standard drugs. Following a similar performance trend, samples K12 and K18 demonstrated higher binding affinities, suggesting their potential effectiveness as precursors for inhibiting protein receptor activity. The findings indicate that the synthesised LC molecules hold promise as potential bacterial inhibitors, though further optimisation and validation in preclinical trials are required.