New fluorescent mesogens with benzopyran-4[H] one heterocyclic moiety

Abstract

We have reported on isoflavone derivatives as potential mesogens. Few mesogens of chromone and flavone derivatives are found in the literature. Chromones are fluorescent in character. In the present study, a homologous series of 2-methy 1-6-(4′-n alkoxybenzoyloxy) benzopyran-4[H] one, was synthesized by condensing 2-methy 1-6-hydroxybenzopyran-4[H] one with thirteen different 4′-n-alkoxybenzoyl chlorides. The lower members of the series are not mesogenic in character. The decyloxy to hexadecyloxy derivatives do exhibit liquid crystalline mesophases. The decyloxy member exhibited only the monotropic nematic phase. The dodecyloxy to hexadecyloxy of benzopyran-4[H] one derivatives exhibit smectic mesophases. DSC studies served the dual purpose of confirming the microscopic transition temperatures. The synthesized compounds are characterized by elemental analysis and spectroscopy. The thermal stabilities of the homologous series were compared with those of corresponding flavones and isoflavones.