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ABSTRACT
A novel homologous series of ethylene derivatives of thermotropic liquid crystals has been synthesized. The methoxy to octyloxy derivatives are nematogenic, the decyloxy to tetradecyloxy derivatives are smectogenic, in addition to nematogenic, and the hexadecyloxy homologue is smectogenic only. All the members of the series are enantiotropically mesogenic. Thermotropic behavior was determined by an optical polarizing microscope equipped with a heating stage and Differential Scanning Calorimetry (DSC) study. Analytical and spectral data confirm the molecular structures of homologues (infrared, nuclear magnetic resonance, mass spectra, X-ray, and DSC data). Textures of the nematic phase are threaded or Schlieren and that of smectic phase are focal conic fan-shaped of smectic A or C. Transition curves of the phase diagram behave in a normal manner except one or two deviations from the normal trend. The mesophase range (Sm+N) varies from 3°C to 44°C. The average thermal stability for smectic is 93°C and that for nematic 117.4°C. The LC behavior of the novel series is compared with a structurally similar known series.
Acknowledgments
Authors acknowledge thanks to the Department of Chemistry (DST-FIST funded & UGC-SAP sponsored), Saurashtra University, Rajkot, for research work. Authors are also thankful to Dr. A. V. Doshi, Ex. Principal, M.V.M. Science and Home Science College, Rajkot, for his valuable cooperation during the present investigation as and when needed. Also, thanks are due to the National Facility for Drug Discovery through New Chemical Entities (NCEs), for analysis of samples.