Molecular Crystals and Liquid Crystals, Vol.625, No.1, 38-46, 2016
Mesomorphism dependence on molecular rigidity and flexibility
A novel homologous series of mesogens was synthesized and studied with a view to understanding and establishing the relations between molecular structure and liquid crystal properties. Eleven members of the series were synthesized. Mesogenic behavior commences from the C-6 member and continues up to the C-14 member. The rest of the members, C-1 to C-5 and C-16, are non-mesogenic. Mesogenic homologues (C-6 to C-14) are enantiotropically nematogenic. Textures of nematic phase are threaded or Schlieren. Transition temperatures were determined by an optical polarizing microscope equipped with a heating stage. Analytical and structural data confirm the molecular structures of homologues. Thermal stability for nematic phase is 198.0 degrees C. Mesomorphic phase length ranges from 11.0 degrees C to 50.0 degrees C. Cr-I/N and N-I transition curves of a phase diagram behave in normal manner from C-1 to C-12 members, and higher members C-14 and C-16 deviated from normal behavior. Mesogenic properties of present novel ester series are compared with the structurally similar series. Odd-even effect is missing for the N-I transition curve. Thus, the present series is partly nematogenic without exhibition of smectic property whose transition temperatures vary between 153 degrees C and 210 degrees C.