New homologous FLCs (I similar to II-n [n=1 similar to4]) derived from optically active 5-alkyl-6-valerolactones were synthesized. Their mesomorphic properties were systematically investigated with respect to their molecular structures, which were different in terms of the length of an alkyl group attached to a chiral centre and the direction of phenylpyrimidyl group. For compounds type I-n, with pyrimidyl group conjugated to the terminal position carrying chiral 5-fluoro-alkyloxy tail, elongation of the attached alkyl groups enhanced the stability of the chiral smectic C phase, while the other type, with pyrimidyl group conjugated to the terminal position carrying achiral alkyloxy tail, showed no remarkable alteration in the stability of the phase. Short optical response time (22 mus, 80 degreesC[Tc-T=10K]) was found for the FLC II-3 that has almost the same magnitude of spontaneous polarization (25nCcm(-2), 80 degreesC[Tc-T=10K]) with that of 11-4.