The structures of three iodochalcones, functionalized with fluorine or a nitro group, have been investigated to explore the impact of different molecular electrostatic distributions on the halogen bonding within each crystal structure. The strongly withdrawing nitro group presented a switch of the halogen bond from a lateral to a linear motif. Surprisingly, this appears to be influenced by a net positive shift in charge distribution around the lateral edges of the σ-hole, making the lateral I…I bonding motif less preferable. A channel of amphoteric I…I type II halogen bonds is observed for a chalcone molecule, which was not previously reported in chalcones, alongside an example of the common synthon involving extended linear chains of I…O₂N donor–acceptor halogen bonds. This work shows that halogenated chalcones may be an interesting target for developing halogen bonding as a significant tool within crystal engineering, a thus far underexplored area for this common structural motif.

中文翻译：

---

碘查耳酮中卤素键的结构效应

已经研究了用氟或硝基官能化的三种碘查耳酮的结构，以探索不同分子静电分布对每个晶体结构内卤素键的影响。强烈撤回的硝基呈现了卤素键从横向到线性基序的转换。令人惊讶的是，这似乎受到 σ 孔横向边缘周围电荷分布的净正偏移的影响，使得横向 I…I 键合基序不太可取。在查耳酮分子中观察到两性 I…I 型 II 型卤素键的通道，这在查耳酮分子中之前没有报道过，同时还有一个常见合成子的例子，其中包括 I…O _{2 的}延伸线性链N 供体 - 受体卤素键。这项工作表明，卤化查耳酮可能是开发卤素键合作为晶体工程中的重要工具的一个有趣目标，迄今为止，对于这种常见的结构基序，这是一个尚未得到充分探索的领域。