Selective Anion Binding by a Cofacial Binuclear Zinc Complex of a Schiff-Base Pyrrole Macrocycle

详细信息    查看全文

• 作者：Aline M. J. Devoille ; Patricia Richardson ; Nathan L. Bill ; Jonathan L. Sessler ; Jason B. Love
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：April 4, 2011
• 年：2011
• 卷：50
• 期：7
• 页码：3116-3126
• 全文大小：1162K
• 年卷期：v.50,no.7(April 4, 2011)
• ISSN：1520-510X

文摘

The synthesis of the new cofacial binuclear zinc complex [Zn₂(L)] of a Schiff-base pyrrole macrocycle is reported. It was discovered that the binuclear microenvironment between the two metals of [Zn₂(L)] is suited for the encapsulation of anions, leading to the formation of [K(THF)₆][Zn₂(渭-Cl)(L)]路2THF and [Buⁿ₄N][Zn₂(渭-OH)(L)] which were characterized by X-ray crystallography. Unusually obtuse Zn鈭扻鈭抁n angles (X = Cl: 150.54(9)掳 and OH: 157.4(3)掳) illustrate the weak character of these interactions and the importance of the cleft preorganization to stabilize the host. In the absence of added anion, aggregation of [Zn₂(L)] was inferred and investigated by successive dilutions and by the addition of coordinating solvents to [Zn₂(L)] solutions using NMR spectroscopy as well as isothermal microcalorimetry (ITC). On anion addition, evidence for deaggregation of [Zn₂(L)], combined with the formation of the 1:1 host鈭抔uest complex, was observed by NMR spectroscopy and ITC titrations. Furthermore, [Zn₂(L)] binds to Cl^{鈭?/sup> selectively in THF as deduced from the ITC analyses, while other halides induce only deaggregation. These conclusions were reinforced by density functional theory (DFT) calculations, which indicated that the binding energies of OH鈭?/sup> and Cl鈭?/sup> were significantly greater than for the other halides.}