Thermal behaviour of lanthanum(III) alkanoates

The mesophase behaviour of the lanthanum(III) alkanoates [La(CxH2x+1COO)(3) ] (x = 3-19) has been investigated by hot-stage polarizing optical microsco py, differential scanning calorimetry and high-temperature X-ray diffractio n. Lanthanum(III) butyrate monohydrate shows no mesomorphism, whereas for t he remaining short chain homologues (x = 4-9) a highly viscous mesophase M and a smectic A phase were observed. The longer chain lanthanum(III) soaps (x = 10-19) exhibit only a smectic A phase. However, the chain length has a pronounced effect on the transition temperatures. The thermal behaviour of lanthanum(III) alkanoates is compared with that of other lanthanide(III) a lkanoates.