Phase Transitions and Pre-transitional Effects in N-(p-n-Pentylbenzylidene)-p-n-pentylaniline (5.5) and its Oxygen Derivatives – A Dilatometric Study

Abstract

The density of N-(p-n-pentylbenzylidene)-p-n-pentylaniline (5.5) and its two oxygen derivatives, viz. N-(p-n-pentylbenzylidene)-p-n-pentyloxyaniline (5.O5) and N-(p-n-pentyloxybenzylidene)-p-npentyloxyaniline (5O.O5), is reported for the isotropic (I), nematic (N), smectic-G (SG) and crystalline (K) phases. Dilatometric results reveal the first order nature of the I-N, N-SG and N-K transitions. A rare occurrence of the N-K transition is found for the compound 5O.O5 at a considerably higher temperature. From the observed density data pre-transitional effects are estimated for the isotropic to the first mesomorphic phase. The results are discussed in the light of data reported on other Schiff base benzylidene anilines