Prolonged glyoxylation of pyrenyl-1-glyoxylic acid ethyl ester leads to a mixture of isomers with polar pyreny- lene-1,8-diglyoxylic acid as the main product, whereas the centrosymmetric 1,6-isomer is obtained in good yield from the corresponding dibromopyrene. Perkin condensations fol- lowed by Pd-catalyzed cyclizations lead to isomeric dinaph- thopyrene-tetracarboxdiimides that self-assemble into col- umnar liquid crystals of hexagonal and rectangular symme- try, of which the rectangular mesophases have unusually elongated unit cells. The cisoid diimides with both alkylimide substituents on the same side of the oblong arene system show a much greater tendency to self-assemble into fluid stacks of disks than their centrosymmetric isomers. With rac- emically branched alkyl substituents, uniform vertical surface alignment of the columns in the high-temperature hexago- nal mesophase is resilient to cycling through the lower-tem- perature rectangular and crystalline phases.