New Liquid Crystalline Compound with 1, 3, 5- Trisubstituted Pyrazole in the Mesogenic Core: Synthesis, Characterization and Mesomorphic Behavior

Abstract

Two new homologous series of 1,3,5-tri substituted pyrazole derivatives derived from 1-X 3-methyl 5-pyrazolone (X = phenyl or tollyl), p- amino acetophenone and alkoxy aldehyde have been synthesized, viz. 4-(4′-n-alkoxy propenoyl) imine-4″-(1-phenyl-3-methyl 5-one) pyrazole and 4-(4′-n-alkoxy propenoyl) imine-4″-(1-tollyl-3-methyl 5-one)pyrazole. The compounds of both the series have been characterized by elemental analyses, FT-IR, ¹H-NMR, Mass spectrometry methods. Their liquid crystalline properties have been investigated by optical polarizing microscopy and DSC studies. All the derivatives are mesomorphic in nature showing nematic phase. The use of phenyl and tollyl substituted pyrazole core has a very dramatic effect on the melting clearing points. The mesomorphic behavior has been analyzed in terms of structure property relationship.

Keywords:

• mesophase
• nematic phase
• schiff base -- chalcone
• thermal behavior
• tri substituted pyrazole

Acknowledgments

We thank full to IIT (Indian Institute of Technology) Bombay, CDRI Lucknow, and Punjab University Chandigar for providing the facility of Elemental analysis, FTIR, Mass spectra and ¹H-NMR experiments. We also thankful to Applied Chemistry Department, Faculty of technology & engineering, M.S. University of Baroda, for providing the polarizing microscopic studies .We specially grateful to Mr. Hemant Patel at Garda chemicals Ltd., Ankleshwar for providing DSC studies of our compounds.