Chiral Symmetry Breaking in Bent-Core Liquid Crystals

By molecular modeling we demonstrate that the nematic long-range order discovered in bent-core liquid crystal systems should reveal further spatially homogeneous phases. Two of them are identified as a tetrahedratic nematic ($N_T$) phase with $D_{2d}$ symmetry and a chiral tetrahedratic nematic ($N_T^{\ast }$) phase with $D_2$ symmetry. These new phases were found for a lattice model with quadrupolar and octupolar anisotropic interactions using Mean Field theory and Monte Carlo simulations. The phase diagrams exhibit tetrahedratic ($T$), $N_T$ and $N_T^{\ast }$ phases, in addition to ordinary isotropic ($I$), uniaxial nematic ($N_U$) and biaxial nematic ($N_B$) phases. To our knowledge, this is the first molecular model with spontaneous chiral symmetry breaking in non-layered systems.