Synthesis and mesomorphic properties of oxadiazole esters derived from (R)‐2‐octanol, (S)‐2‐n‐octyloxypropanol and (2S,3S)‐2‐chloro‐3‐methylpentanol

Abstract

A novel series of chiral liquid crystalline materials based on 1,3,4‐ and 1,2,4‐oxadiazole derivatives were synthesised. These compounds contain a chiral chain derived from (R)‐2‐octanol (Ia–Ic), (S)‐ethyl lactate (IIa–IIc) or (S)‐isoleucine (IIIa–IIIc). Their liquid crystalline properties were studied by polarizing optical microscopy and differential scanning calorimetry. With the exception of compounds IIa and IIb, all of the new compounds exhibit an enantiotropic chiral nematic (cholesteric) phase. A monotropic chiral smectic C phase (ferroelectric) was also found in compounds Ia, IIa and IIb, whereas in compound IIIa an enantiotropic chiral smectic C phase was observed. Compounds Ic, IIc, IIIb and IIIc are purely chiral nematic (cholesteric) in character. In addition, a monotropic blue phase was observed in compounds Ib and IIIa.