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Novel types of liquid crystal phases: tetrahedratic smectic C and nematic mesophases in unsymmetrically 1,1’-bis substituted ferrocene
Oleg N Kadkin
,Eun Ho Kim
,Young Joon Rha
,So Yeon Kim
An unsymmetrically 1,1’-bis substituted mesogenic ferrocene derivative exhibiting non-conventional thermotropic liquid crystal phases have been synthesized. The mesophases were characterized by POM, DSC and X-ray scattering methods. The formation of helical superstructures and spontaneous resolution into chiral macroscopic domains occurred in the lamellar mesophase. The nematic mesophase showed non-textured dark appearance, optical biaxiality and chiral nematic droplets. During nematic-to-isotropic liquid and reverse transitions the regular nematic mesophase appeared for a short period, which was identified by observation of a schlieren texture and birefringent droplets. In view of unusual thermooptical behavior and XRD diffraction patterns, and basing on computational molecular models a tetrahedratic order was suggested for the observed liquid crystal phases.