Cristais líquidos calamíticos baseados em iminas: estudos de propriedades mesomórficas e estruturais.

Abstract

Liquid crystal (LC) is the name given to describe materials that have an intermediary behavior between the three-dimensionally organized solid and the liquid state. Thermotropic LCs are capable of presenting characteristic mesophases, which vary in shape and molecular arrangement, as a function of temperature. The present work investigates the types of mesophases that can be obtained from the variation of alkyl groups in the (E)-4-((phenylimino)methyl)phenyl benzoate system. Eight novel imines were studied to determine the temperature ranges of mesomorphism, thermal stabilities and structural organizations. All intermediates and final products were characterized using the techniques of Melting Point, Infrared Spectrometry, ¹H and ¹³C Nuclear Magnetic Resonance. The thermal properties of the final molecules were studied by differential scanning calorimetry (DSC), polarized light optical microscopy (MOLP) and thermogravimetric analysis (TGA) techniques, revealing that all target compounds had high thermal stability (decomposition temperature) above 280°C) and liquid-crystalline phases characteristic of calamitic LC. The textures observed for the compounds indicate the presence of nematic and smectic C mesophases.