Crystal polymorphs of 6‐[(phenylcarbamoyl)oxy]hexa‐2,4‐diyn‐1‐yl isonicotinate

The title compound, C19H14N2O4, was found to have two crystal polymorphs, in which the mol­ecular structures of the di­acetyl­enic compound are broadly similar. The main structural difference between the polymorphs concerns the inter­molecular hydrogen-bonding motifs adopted, namely a one-dimensional zigzag polymer linked by N—H⋯N(py) (py is pyridine) inter­actions in polymorph I and a centrosymmetric dimeric motif formed by N—H⋯O=C inter­actions in polymorph II. The di­acetyl­ene cores of the mol­ecules stack along the a and b axes in polymorphs I and II, respectively. It was found that only the mol­ecular arrangement in polymorph II satisfies Baughman's criterion to afford polydi­acetyl­enes (PDAs) by thermal annealing or irradiation with light. This predicted polymerization activity was confirmed by experiment.