Two novel series of pyrazine-containing esters, together with an analogous phenyl system have been prepared, and their liquid crystalline phase behaviour compared in order to establish how the replacement of a phenyl ring by a pyrazine ring affects the liquid crystal behaviour of these esters. Both of the heterocyclic-containing ester series show significant suppression of the smectic phases, and some suppression of the nematic phase, when compared with the non-heterocyclic series.