Influence of the position and number of fluorine atoms and of the chiral moiety on a newly synthesized series with anticlinic properties

A series of trifluoro-substituted benzoate derivatives: (S)-1-ethylheptyl 4 -[ 4-(4-alkyloxy-3-fluorobenzoyloxy)- 3-fluorobenzoyloxy]- 2-fluorobenzoate s is reported. The short chain members (n = 8 to n = 11) display a direct S mCA*-SmA transition, whereas for longer chains a SmC* phase appears, but no ferrielectric phases are present, and a direct SmCA*-SmC* transition is ob tained. The mesomorphic properties were studied by optical microscopy and D SC, and by electro-optical, helical pitch and optical rotatory power measur ements. The effect of the number and position of the fluoro substituents, a nd the influence of the chiral moiety on the mesomorphic behaviour are disc ussed.