Journal of rare earths vol:22 issue:2 pages:193-196
The 4-alkoxybenzoic acids are well-known liquid crystals showing several mesophases (nematic, smectic C phase or both) depending on the alkoxy chain length and whereby the rigid core of the mesogen is formed by intermolecular hydrogen bonds. In this paper it is shown that the thermal behaviour of lanthanide salts of 4-hexyloxybenzoic acids depends on the lanthanide ion (Ln = La, Pr, Nd, Sm, Eu). The lanthanum (III) and praseodymium (III) 4-hexyloxybenzoates exhibit a smectic A mesophase. No mesophase is found for the corresponding compounds of heavier lanthanides. The thermal properties of the lanthanide(III) 4-hexyloxybenzoates were investigated by differential scanning calorimetry (DSC), polarising thermo-optical microscopy and synchrotron X-ray radiation.