Absorption spectra of two pentadentate Schiff base type systems in ordinary organic solvents and liquid crystal (LC) media have been measured as a function of temperature, between 25 and 60 degrees C. The interactions between solute and LC molecules were investigated on the basis of their spectral properties in both isotropic and nematic phases of the LC. The results revealed strong interactions between the ligand and LC molecules, which are probably due to the specific or non specific intermolecular forces. Moreover, the influence of the presence of the solutes on the phase transition temperature of 4-cyano-4'-n-pentyl-biphenyl (5CB) and 4-cyano-4'-n-heptyl-biphenyl (7CB) has been studied and a correlation between the chemical structure of the solutes and their spectroscopic behaviour has also been discussed.