Mesogenic quinazolone derivatives: synthesis and characterisation

Abstract

Two new mesogenic homologous series of quinazolone derivatives have been synthesised by condensation of 4-n-alkoxybenzoyloxy benzaldehyde (for series I) / 4-n-alkoxy-3-methoxybenzoyloxy benzaldehyde (for series II) with 3-amino-2-methyl quinazolone in alcohol. The synthesised compounds are characterised by a combination of elemental analysis and standard spectroscopic methods. In series I, all the synthesised members exhibit the nematic mesophase. An enantiotropic smectic A phase is observed from the n-decyloxy derivative onward to the last homologue synthesised. Methoxy to n-propyloxy derivatives of series II are non-mesogenic, whereas the rest of the members exhibit a monotropic nematic mesophase. The mesomorphic properties of the present series I and II are compared with each other and with the other structurally related mesogenic homologous series to evaluate the effect of lateral methoxy substituent and quinazolone moiety on mesomorphism.

Keywords:

• quinazolone derivatives
• Schiff's base ester
• smectic A
• nematic

Acknowledgements

The authors are thankful to the Dean, Faculty of Technology and Engineering, and Head, Applied Chemistry Department, for providing the research facilities.

Notes

This paper was presented at the 15^th National Conference on Liquid Crystals (NCLC-2008) held at the Department of Organic Chemistry, Indian Institute of Science, Bangalore, India, 13–15 October 2008.