Leake Gebresilassie Feven, Ji Kim Min, Castellanos Daniela, Broderick Conor H, Ngo Steven M, Young Victor G, Cao Dennis D
Chemistry Department, Macalester College, 1600 Grand Avenue, Saint Paul, MN, 55105, USA.
Department of Chemistry, University of Minnesota, 207 Pleasant St. S.E., Minneapolis, MN, 55455, USA.
Chemistry. 2024 Oct 11;30(57):e202402791. doi: 10.1002/chem.202402791. Epub 2024 Sep 23.
The incorporation of cationic groups onto electron-poor compounds is a viable strategy for achieving potent electron acceptors, as evidenced by reports of air-stable radical forms of large aromatic diimides such as naphthalene and perylene diimides. These ions have also been observed to exhibit anion-π interaction tendencies of interest in molecular recognition applications. The benefits of phosphonium incorporation, however, have not yet been extended to the smallest benzene diimides. Here, we report that dibrominated pyromellitic diimide and mellophanic diimide both readily undergo substitution reactions with phosphine sources to yield bisphosphonium compounds. In the single crystalline form, these dications display anion-π interactions and, in the case of mellophanic diimide, the stabilization of a bromide-water H-bonding ring pattern. The reaction of these dications with chemical reductants readily provides the singly and doubly reduced redox states, which were characterized by UV-vis spectroscopy and found to exhibit intense absorptions extending into the near-IR region. Taken together, this work demonstrates that phosphonium incorporation onto congested aromatic diimide scaffolds is synthetically viable and produces unusual electron-poor compounds.
将阳离子基团引入缺电子化合物是获得强电子受体的一种可行策略，萘和苝二亚胺等大型芳香族二亚胺的空气稳定自由基形式的报道证明了这一点。这些离子在分子识别应用中也表现出了令人感兴趣的阴离子-π相互作用倾向。然而，鏻离子引入的益处尚未扩展到最小的苯二亚胺。在此，我们报道二溴化均苯四甲酸二亚胺和蜜石酸二亚胺都能与膦源轻松发生取代反应，生成双鏻化合物。在单晶形式下，这些双阳离子表现出阴离子-π相互作用，对于蜜石酸二亚胺而言，还存在溴化物-水氢键环模式的稳定化。这些双阳离子与化学还原剂的反应很容易提供单还原和双还原的氧化还原状态，通过紫外-可见光谱对其进行了表征，发现它们表现出延伸至近红外区域的强吸收。综上所述，这项工作表明将鏻离子引入拥挤的芳香族二亚胺支架在合成上是可行的，并能产生不同寻常的缺电子化合物。
