Mesogenicity of 4-alkanoyl-4′-alkyloxybiphenyl derivatives

Abstract

Phase transitions of 4-alkanoyl-4′-alkyloxybiphenyl were studied by differential scanning calorimetry and optical microscopy. 4-Acetyl-4′-alkyloxybiphenyl homologues (number of carbon atoms, of n, 4′-alkyloxy group is 4–10) showed S_E phases with good thermal stability, while 4-propionyl-4′-alkyloxybiphenyl homologues (n = 4–10) and 4-pentanoyl-4′-decyloxybiphenyl showed S_A phases with good thermal stability. Moreover changes in the thermal stability by substitution of bulky Br, Cl or CH₃ substituents into the alkanoyl groups were studied for the previously mentioned three homologues. The substitution at the α-position of the alkanoyl group was found to strikingly lower the thermal stability.