ABSTRACT
A novel homologous series of liquid crystal (LC) derivatives of general structure: RO·C6H4·COO·C6H3·OCH3(ortho)CH = CH·COO·(n)C5H11 was synthesized and studied with a view to understanding the effect of molecular structure on liquid crystal behavior with reference to lateral –OCH3 and terminal end group. Homologous series consists of 12 derivatives (C1–C16), the first five (C1–C5), and the last (C16) members are not liquid crystals and the rest of the homologs (C6–C14) are enantiotropically smectogenic without exhibition of the nematic phase. The textures of the smectic phases are focal conic fan shaped or batonets of smectic-A or smectic-C. Average thermal stability for smectic is 81.8°C and mesophase length ranges from 9°C to 31°C. Transition curves of a phase diagram (Sm-I and Cr-Sm/I) behave in a normal manner. The Sm-I transition curve exhibits an odd-even effect. Analytical and spectral data support the molecular structures. The series is smectogenic of a middle ordered melting type. LC properties of the present series are compared with structurally similar known homologous series. Transition temperatures were determined by an optical polarizing microscope equipped with a heating stage.
Acknowledgments
The authors are especially thankful to management, principal and HOD (chemistry dept.) of Shree M. & N. Virani Sc. College, Rajkot and Kamani Sc. College & Prataprai Arts College, Amreli for their valuable cooperation to facilitate present research work, and IR spectra. The authors are also thankful to the authorities of Saurashtra University for analytical services.