Mesogenic Properties of Tricyclic 2,5-Di(4-alkoxybenzoyloxy)tropones. Increasing Smectic Thermal Stabilities by the Lateral Polar Carbonyl Group

2,5-Di(4-alkoxybenzoyloxy)tropones showed similar mesogenic properties to the corresponding benzenoids. The tropone carbonyl group, which behaved as a polar lateral substituent, enhanced the thermal stability of the smectic phases and reduced that of the nematic phases when compared with those of the benzenoids. The tropone carbonyl group induced an intermolecular attractive force.