ine compound, at least one of R1, R2 and R3 is an optically active substituent mentioned in Examplification 1, and n is an integer of 1-18, preferably 3-14. ##STR3## wherein R1, R2 and R3 are independently a linear or branched alkyl group having the formula Cn H2n+1 or a substituent group selected from the substituent groups mentioned in Examplification 1, in the case of a discotic liquid crystall