Mesogenic Schiff's base ester with chloroethyl tail

Two new mesogenic homologous series of Schiff's base ester with chloroethyl tail having the following general formula have been synthesized. The molecular structures of the synthesized compounds were characterized by the standard spectroscopic methods and elemental analysis. The mesomorphic behaviour of these new Schiff's base esters was mainly investigated with the help of optical polarizing microscope. For some representative compounds differential scanning calorimetric study was carried out to support the optical observation of transition temperatures and associated enthalpies. In series I, lower members are non-mesogenic, whereas higher members exhibit smectic mesophase. In series II, methoxy to n -hexyloxy derivatives exhibit nematic mesophase, while the smectic A phase commences from n -propyloxy derivative and persists up to the last member synthesized. The mesomorphic properties of these two series of compounds are compared with each other and with structurally related systems.