Estimation of thermodynamic parameters and molecular free length in liquid crystalline N-(p-n-alkoxybenzylidene)-p-n-pentyloxy aniline (nO.O5) compounds

Different thermodynamic parameters such as Sharma parameter (So), Huggins parameter (F), reduced volume (V∼), reduced compressibility (V∼ C1) etc., are estimated from the volume expansion coefficient (α) for N-(p-n-alkoxybenzylidene)-p-n-pentyloxy aniline (nO.O5) compounds in isotropic and liquid crystalline phases. The parameters like intermolecular free length (Lf) and molecular radius (mr) are also computed from density and refractive index for these nO.O5 compounds. The results are discussed in the light of these parameter variations with temperature in a particular phase, in a liquid crystal molecule and in a homologous series. The thermodynamic parameter So exhibits a constant characteristic value (1.15 ± 0.05) in all the compounds like other reported liquid crystalline compounds and liquids. The variation of other thermodynamic parameters in all the phases of these compounds with temperature is discussed in the light the body of the data available.