Effects of the direction of the tropone carbonyl group on the mesogenic properties

摘要

Recently, we have reported the measogenic properties of troponoid liquid crystals, in which the tropone carbonyl group played an impotant role to exhibit mesogenic properties. In this paper, we report the effects of the direction of the tropone carbonyl group on the measogenic properties of twin-type troponoids. Compared with the properties between twin-type troponoid liquid crystals 1 and the corresponding benzenoid 2, the former showed a monotropic smectic C phase~2 whereas the latter was not mesogenic becasue benzensoid 2 has a higher melting point than 1. On the other hand, twin-type troponoid 3a, in which both carbonyl groups oriented outwards, was not measogenic. COmpound 3b with a shorter inner alkylene chain, however, showed a monotropic smectic C phase with higher transition temperatures than 1. This indicated that the distance between the two core cores weas also important to induce measogenic properties.