The interaction of N-(p-methoxy-o-hydroxybenzylidene)-p-aminopyridine (I) and N-(p-methoxy-o-hydroxybenzylidene)-m-aminopyridine (II) with certain p-alkoxybenzoic acids results in the formation of liquid crystals. Specifically, as established by optical microscopy, DSC and X-ray diffraction studies, complexes of I with short-chain acids afford nematic phases while smectic and nematic phases are induced with acids of long alkyl chain. In the complexes derived from anil II only the acids with long alkyl chains induce the formation of nematic and smectic phases.