Spectrophotometric study of liquid crystals containing pentadentate Schiff base type systems

The visible and ultraviolet absorption spectra of the pentadentate Schiff base 1,3-Bis (2-hydroxy-1-naphthylideneamino)-2propanol and its copper (II) and nickel (II) complexes in isotropic and anisotropic solvents have been studied. The red and the blue shifts observed in the spectra lead to the assumption that different interactions may occur between solute species or between solute and liquid crystal molecules. Such phenomenon are probably due to the specific or non specific intermolecular forces. Moreover, the effect of the solutes on the phase transition of two liquid crystals, 4-cyano-4’-n-pentyl-biphenyl (5CB) and 4cyano-4’-n-heptyl-biphenyl (7CB), has been studied as a function of temperature, between 25 and 60 ∘C. An attempt was made to correlate the chemical structures of the solutes with their spectroscopical behaviour.