Synthesis and Mesomorphic Properties of 4-(Methylthio)benzylidene-4'-n-alkanoyloxyanilines

Abstract

A homologous series of Schiff base esters, 4-(methylthio)benzylidene-4'-n-alkanoyloxyanilines possessing even number of carbon atoms at the alkanoyloxy chain (C_n-1H_2n-1COO^-, n = 2 to 18) was synthesized. The structure of the 4-(methylthio)benzylidene-4'-n-alkanoyloxyanilines was confirmed by elemental analysis and spectroscopic techniques including FT-IR, ¹H and ¹³C NMR and EI-MS. Mesomorphic properties were evaluated by differential scanning calorimetry and polarizing optical microscopy techniques. Whilst n-butanoyloxy to n-octanoyloxy derivatives exhibited monotropic nematic phase, n-ethanoyloxy and n-decanoyloxy to n-octadecanoyloxy derivatives were non-mesogenic compounds. The mesomorphic properties of the present series were compared with other structurally related series to establish the chemical structure-mesomorphic property relationship.