Liquid Crystalline Properties of 3-[4-(4′-Alkoxybenzoyloxybenzylidene) amino]-1,2,4-triazines: Synthesis and Characterization

Abstract

A new series of 3-[4-(4′-alkoxybenzoyloxybenzylidene)amino]-1,2,4-triazines, C₃H₂N₃N˭CHC₆H₄OCOC₆H₄OC_mH_2m + 1 where m = 6, 7, 8, 9, 10, 11, 12, 14, and 16 have been synthesized. These compounds have been characterized by elemental analyses, FT-IR, UV-visible, ¹H, and ¹³C NMR spectroscopy. Mesomorphic properties of these compounds were studied by differential scanning calorimetry and polarizing microscopy. The mesomorphic nature of these compounds is dependent on the alkoxy chain length. The compounds (m = 6, 7) do not exhibit mesomorphism while the compounds (m = 8, 9, 11, 12, 14) show a monotropic nematic mesophase in cooling cycle. The 3-[4-(4′-decyloxybenzoyloxybenzylidene)amino]-1,2,4-triazine displays an enantiotropic nematic mesophase and the hexadecyloxy compound exhibits the smectic A mesophase.

Keywords:

• Differential scanning calorimetry
• enantiotropic nematic mesophase
• monotropic nematic mesophase
• polarizing microscopy
• smectic A mesophase

Acknowledgment

The authors thank the Head, Department of Chemistry, BHU, Varanasi for providing laboratory facilities. One of the authors (AP) thanks UGC for financial support as Project Fellow and BHU for research scholarship. Thanks are also due to Mr. Satish Tiwari for CHN and DSC analyses, Mr. R. C. P. Bipin for NMR and Mr. V. N. Pandey for IR and electronic spectral data.