A homologous series of new Schiff base’s esters, 4-bromobenzylidene-4’-alkanoyloxyanilines were synthesized. The structure of the synthesized compounds was elucidated using IR and NMR spectroscopic techniques along with mass spectrometric method. Nine homologous members were prepared whereby the length of alkanoyloxy chain, C_n-1H_2n-1COO is varied from n = 2, 4, 6, 8, 10, 12, 14, 16 and 18. Their thermotropic properties were analyzed using differential scanning calorimetry and polarized optical microscopy techniques. Whilst short chain members (number of carbons, n = 2, 4) are non-mesogens, member with n = 6 exhibited monotropic smectic A (SmA) phase. As the n increased to 8, this compound becomes the only member that exhibited SmA and SmB as enantiotropic phase. Varying from n = 10 to n = 16, these members displayed enantiotropic SmA and monotropic SmB phases. Longest chain member, n-octadecanoyloxy derivatives exhibited only single mesophase (monotropic SmA). The ester linkage and polar terminal (bromo) group in the present series are essential for the smectic polymorphism in Schiff bases

doi.org/10.32737/0005-2531-2023-3-112-125