State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, CAS, Lanzhou, 730000, P.R. China.
Chemistry. 2013 Jul 1;19(27):9034-41. doi: 10.1002/chem.201300275. Epub 2013 May 15.
Three ferrocenyl-functionalized tripodal hexaurea anion receptors with ortho- (L(2)), meta- (L(3)), and para-phenylene (L(4)) bridges, which showed strong binding affinities toward sulfate ions, have been designed and synthesized. In particular, meta-phenylene-bridged ligand L(3), owing to its trigonal bipyramidal structure, can encapsulate two SO4(2-) ions in its "inner" and "outer" tripodal clefts, respectively, as supported by their clearly distinct NMR resonances and by molecular modeling. The sulfate complex of ortho-ligand L(2), (TBA)2[SO4⊂L(2)]·2H2O (1), displays a caged tetrahedral structure with an encapsulated sulfate ion that is hydrogen bonded by the six urea groups of ligand L(2). CV studies showed two types of electrochemical response of the ferrocene/ferrocenium redox couple upon anion binding, that is, a shift of the wave and the appearance of a new peak. Quantitative binding data were obtained from the NMR and CV titrations.
三种具有邻位（L(2)）、间位（L(3)）和对位苯撑（L(4)）桥的三齿六元胍阴离子受体被设计并合成，它们对硫酸根离子具有很强的结合亲和力。特别是间位苯撑桥联配体 L(3)，由于其三角双锥结构，可以分别在其“内”和“外”三齿凹槽中包合两个 SO4(2-)离子，这得到了它们明显不同的 NMR 共振和分子建模的支持。邻位配体 L(2)的硫酸盐配合物（TBA）2[SO4⊂L(2)]·2H2O（1），显示出具有被六个脲基配体 L(2)氢键结合的包封硫酸根离子的笼状四面体形结构。CV 研究表明，在阴离子结合时，铁/铁氧化还原对有两种类型的电化学响应，即波的移动和新峰的出现。从 NMR 和 CV 滴定中获得了定量的结合数据。
