We synthesized an optically active 4,4,4-trifluoro-3-{4-(4-methoxyphenyl)phenyl)butanoic acid (5*). New chiral dopants for nematic liquid crystals were derived from (R)-(-)-5*, and their helical twisting power (HTP) values were measured. Their HTP values were largely influenced by the linkage between the asymmetric frame and the core moiety. The chiral dopant, (R)-(+)-4,4,4-trifluoro-1-(4-hexyloxyphenyl)-3-{4-(4-methoxyphenyl)phenyl}-1-butanone ((R)-(+)-7*) showed the largest HTP value (-21.7 mu m(-1)). (C) 2005 Elsevier B.V. All rights reserved.