Liquid crystals with a 5-cyanotropone skeleton: 2-(4-alkoxybenzoyloxy)-5-cyanotropones and 2-(4-alkoxybenzoylamino)-5-cyanotropones

New troponoid liquid crystals with an electron-withdrawing cyano group at the C-5 position of tropolone and 2- aminotropone rings were prepared. Tropolone derivatives had nematic phases with lower thermal stabilities and smectic A phases with higher thermal stabilities than the corresponding benzenoids while thermal stabilities of the aminotropone derivatives were better than those of the benzenoids. The X-ray diffraction studies indicated that the ratios of the layer spacing measured in the smectic A phase and the calculated molecular length are 1.3 for a tropolone derivative and 1.45 for an aminotropone derivative. They formed interdigitated bilayers.