Porphyrins having alkyl chains, each of which contains a diacetylene unit, were prepared to examine their self-assembled structures at the liquid/solid interface on graphite. The porphyrins with the longest alkyl chains form a face-on arrangement on the surface, while those with shorter alkyl chains form highly ordered one-dimensional columns. This work demonstrates that introducing a structural perturbation in the alkyl chain is a useful strategy to obtain novel surface assemblies.