IntroductionSuccessful crystal engineering of organic materials1requires access to a large number of synthons and a detailed understanding of the subtle interplay of relatively weak interactions which can become important in the solid state. Desiraju and others2have described a wide variety of intermolecular contacts which can be used to control the architecture of organic solids. Despite the considerable interest in the use of 2,6­disubstituted pyridines in the organisation of molecular architecture,3the Cambridge Structural Database4contains only one example of a free pyridine ring bearing an ester functionality at both C­2 and C­6,5and even in that case all other positions about the pyridine ring are also substituted. All other ‘hits’ incorporating the 2,6­dicarboxylato unit are either concerned with situationsin which the pyridine ring is part of a macrocyclic skeleton, or cases where strong electrostatic interactions dominate,e.g.in metal­ion complexes6or in the parent diacid and its salts.4,7We now report preliminary results of a study of the solid­state behaviour of a number of simple pyridine-2,6­dicarboxylate esters1a–fand a 3,5­disubstituted analogue2.