Efficient and practical method for the synthesis of hydrophobic azines as liquid crystalline materials

ABSTRACT

A series of hydrophobic symmetrical azines: 1,2-bis[4-(n-alkoxy)benzylidene]hydrazine (where, n-alkoxy: O(CH₂)_nH, n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, or 18) have been prepared following an efficient and practical method. These compounds have been synthesized via the condensation reaction of hydrazine hydrate and appropriately 4-(n-alkoxy) benzaldehydes in acidic medium under ambient conditions. The prepared organic compounds have been characterized and their structures were elucidated depending upon micro-elemental analysis and spectral data (IR, UV-Vis, ¹HNMR, ¹³C{¹H}NMR, 2D ¹H-¹H-cozy, 2D ¹H-¹³C-HSQC, and mass spectra). Liquid crystalline behavior of the prepared compounds was studied using polarized light optical microscopy and differential scanning calorimetry techniques. This study revealed that all the compounds displayed enantiotropic liquid crystal properties, exhibiting smectic and nematic mesophases.

KEYWORDS:

• Hydrophobic symmetrical azines
• enantiotropic liquid crystal
• mesogenic compounds

Acknowledgments

We thank Dr. Adnan Ibraheem Al-Saadi, Kerbala University, and Dr Dhafir Tamween Al-Hetemi, Baghdad University, for their help. We are indebted to Arab Science of Technology Foundation (ASTF) for their support.