Novel chiral mesomorphic compounds based on α-amino acid derivatives: synthesis and properties

Abstract

Four novel series of chiral mesogens were prepared from commercially available α-amino acids. The phase behaviour and physical properties of these materials were assessed in order to investigate how the microscopic interactions of the chiral moiety associated with the molecular structure influence the macroscopic physical properties. Some of the materials exhibited unusual phase behaviour, such as the formation of TGB phases, in addition to inversions in helical twist sense in the smectic C* phase. The presence of TGB phases may be explained by the presence of a high degree of ‘molecular chirality’, which can be rationalised to some extent in terms of molecular structure. In addition a microscopic model involving interchanging conformational species is proposed to explain the macroscopic inversion phenomenon encountered in cholesteric and smectic C* phases.