Synthesis and characterization of cholesterol-based nonsymmetric dimers terminated with ferrocenyl core

The molecular design, synthesis, and thermal behavior of cholesterol-based nonsymmetric dimers, which can also be regarded as metallomesogens, consisting of either two- or three-ring aromatic cores terminated with ferrocenyl unit are reported. The spacer length connecting the cholesterol and aromatic cores is held constant while the length of the spacer connecting ferrocene and aromatic cores has been varied. The occurrence of the enantiotropic mesomorphism in these compounds has been adjudged by optical, calorimetric, and X-ray diffraction studies. In particular these systems exhibit liquid crystal phases such as chiral nematic, twist grain boundary, and smectic A phases. Of these, the chiral nematic phase commonly occurs in all the synthesized compounds.