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.
研究发现,标题化合物
C19H14N2O4 有两种晶体多形态,其中二
乙炔化合物的分子结构大致相似。多晶型之间的主要结构差异与所采用的分子间氢键结构有关,即在多晶型 I 中是由 N-H...N(py)(py 为
吡啶)相互作用连接的一维之字形聚合物,而在多晶型 II 中则是由 N-H...O=C 相互作用形成的中心对称二聚体结构。在多晶体 I 和 II 中,分子的双
乙炔核分别沿 a 轴和 b 轴堆积。研究发现,只有多晶体 II 中的分子排列符合鲍曼标准,才能通过热退火或光照产生聚二
乙烯(
PDA)。实验证实了这一预测的聚合活性。