NEW FLUORESCENT MESOGENS WITH BENZOPYRAN-4[H] ONE HETEROCYCLIC MOIETY

We have reported on isoflavone derivatives as potential mesogens. Few mesogens of chromone and flavone derivatives are found in the literatu re. Chromones are fluorescent in character. In the present study, a ho mologous series of 2-methyl-6-(4'-n-alkoxybenzoyloxy)benzopyran-4[H] o ne, was synthesized by condensing 2-methyl-6-hydroxybenzopyran-4[H] on e with thirteen different 4'-n-alkoxybenzoyl chlorides. The lower memb ers of the series are not mesogenic in character. The decyloxy to hexa decyloxy derivatives do exhibit liquid crystalline mesophases. The dec yloxy member exhibited only the monotropic nematic phase. The dodecylo xy to hexadecyloxy of benzopyran-4[H] one derivatives exhibit smectic mesophases. DSC studies served the dual purpose of confirming the micr oscopic transition temperatures. The synthesized compounds are charact erized by elemental analysis and spectroscopy. The thermal stabilities of the homologous series were compared with those of corresponding fl avones and isoflavones.