Mesomorphic properties and X-ray diffraction studies of 4-alkanoyloxybenzylidene-4′-fluoroaniline

A new homologous series of Schiff base esters comprising a terminal fluoro substituent was studied. Molecular polarizability is enhanced by the presence of fluoro substituent, subsequently, affecting intermolecular interactions and resulting in smectic molecular arrangement. All members can be differed from the number of carbons at the alkanoyloxy chain (C_n-1H_2n-1COO^-, n = 10, 12, 14, 16, 18). The structure of the title compound was confirmed by spectroscopic (IR and NMR) techniques along with mass spectrometric analysis. Their mesomorphic properties were studied by using differential scanning calorimetry and optical polarizing microscopy techniques. Early members (n = 10, 12 and 14) exhibited monotropic smectic A phase while the longer chain members (n = 16 and 18) are non mesogenic compounds. X-ray diffraction analysis was used and confirmed monolayer of smectic A phase in n-dodecanoyloxy derivative.