Controlled Formation of the Acid−Pyridine Heterosynthon over the Acid−Acid Homosynthon in 2-Anilinonicotinic Acids

Four substituted 2-anilinonicotinic acids were synthesized, and their crystal structures were analyzed. It was found that by chemically introducing bulky functional groups to the aniline ring of the molecules, it is possible to dislodge the planar conformation due to steric repulsion. As a result, acid−pyridine heterosynthons, not acid−acid homosynthons, are formed in the crystals. The study is believed to offer a refreshing case of how a molecule’s conformation can affect intermolecular interactions and consequent crystal packing.

四种取代的2-安非他酮酸被合成，并对其晶体结构进行了分析。研究发现，通过在分子的苯环上化学引入体积庞大的官能团，可以因位阻排斥作用而移除平面构象。因此，在晶体中形成的是酸-嘧啶杂合物，而非酸-酸同合物。该研究被认为提供了一个新颖的案例，阐述了分子的构象如何影响分子间相互作用以及随之而来的晶体堆积。