Sibert John W, Forshee Philip B, Hundt Greg R, Sargent Andrew L, Bott Simon G, Lynch Vincent
Department of Chemistry, The University of Texas at Dallas, Richardson, Texas 75083, USA. sibertj@ utdallas.edu
Inorg Chem. 2007 Dec 10;46(25):10913-25. doi: 10.1021/ic701560n. Epub 2007 Nov 13.
Two series of isomeric, redox-responsive azacrown ethers based on ortho- and para-phenylenediamine (Wurster's crowns) have been synthesized and their properties explored through 13C NMR spectroscopy, electrospray ionization mass spectrometry, cyclic voltammetry, and X-ray crystallography. These crowns display strong affinity for alkali metal cations while maintaining comparable selectivity profiles to the parent crown ethers from which they are derived. Like Wurster's reagent (N,N,N',N'-tetramethyl-p-phenylenediamine or para-TMPD), the para-Wurster's crowns undergo two reversible one-electron oxidations. The integrity of the alkali metal ion complexes is maintained in the neutral and singly oxidized ligand states but not after removal of two electrons. In contrast, the oxidation of ortho-Wurster's crowns is scan rate dependent, occurring at potentials substantially higher than their para counterparts, with their complexes oxidizing irreversibly. X-ray crystal structures of representative complexes show, in all cases, participation of the redox-active phenylenediamine subunits in complex formation via direct bonding to the guest cation.
基于邻苯二胺和对苯二胺（沃斯特冠醚）合成了两系列异构的、氧化还原响应型氮杂冠醚，并通过13C核磁共振光谱、电喷雾电离质谱、循环伏安法和X射线晶体学对其性质进行了探索。这些冠醚对碱金属阳离子表现出强烈的亲和力，同时保持与其衍生的母体冠醚相当的选择性。与沃斯特试剂（N,N,N',N'-四甲基对苯二胺或对-TMPD）一样，对沃斯特冠醚经历两次可逆的单电子氧化。碱金属离子配合物的完整性在中性和单氧化配体状态下得以保持，但在失去两个电子后则不然。相比之下，邻沃斯特冠醚的氧化取决于扫描速率，发生在比其对位对应物高得多的电位下，其配合物不可逆地氧化。代表性配合物的X射线晶体结构在所有情况下都表明，氧化还原活性的苯二胺亚基通过与客体阳离子直接键合参与配合物的形成。
