Thermal Stability of Liquid Crystalline Hydroxamic Acid Derivatives

The liquid crystalline behaviour of five newly synthesized N-4-alkoxyphenyl-4'-n-butoxycinnamohydroxamic acids was systematically studied using optical microscopy and differential scanning calorimetry. These compounds demonstrated a variety of mesophases, including smectic and schlieren nematic phases. Among the synthesized compounds, N-4-n-butoxyphenyl-4'-n-butoxycinnamohydroxamic acid exhibited the highest thermal stability. In contrast, N-4-isopropoxyphenyl-4'-n-butoxycinnamohydroxamic acid showed comparatively lower thermal stability. This investigation provides valuable insights into the relationship between molecular structure and liquid crystalline behaviour, highlighting the influence of terminal alkoxy groups on the thermal properties of hydroxamic acids.