McCusker Thomas L, Roseborough Alexander, McDonald Morgan A, Jackson Sabrina A, Redeker Frenio A, Nyman May, Knope Karah E
Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington, District of Columbia 20057, United States.
Department of Chemistry, 153 Gilbert Hall, Oregon State University, Corvallis, Oregon 97331, United States.
Inorg Chem. 2025 Aug 25;64(33):16789-16797. doi: 10.1021/acs.inorgchem.5c01730. Epub 2025 Aug 11.
Nitrate-decorated hexamers with a [Ln(μ-O)(μ-OH)] core have been reported for nearly every lanthanide ion and are used as precursors for the assembly of functional metal-organic frameworks. Yet, few studies have examined the correlation between the solution and solid-state species, and the formation of mixed-metal clusters. Toward this end, a series of homo- and heterometal lanthanide nitrate hexamers was prepared via pH adjustment of aqueous lanthanide nitrate solutions. Examination of the homometallic europium solutions using Small Angle X-ray Scattering and ESI-MS showed that lower order complexes dominate lanthanide speciation in nitrate media. Yet, powder X-ray diffraction data of the precipitated phase confirmed the formation of [Ln(μ-O)(μ-OH)(NO)(HO)]·2(NO)·(HO), , for Ln = Eu and Tb. For heterometal systems, analysis of the solid-state product by ICP-MS showed the selective incorporation of the heavier rare earths into . Selectivity was quantified by calculating an average separation factor, which is defined as the ratio of recovery factors of both metals. Further examination of the luminescence behavior of mixed metal [TbEu(μ-O)(μ-OH)(NO)(HO)]·2(NO)·(HO), with = 1.1-3.6, showed that the relative intensities of the peaks at 489 nm (terbium, D → F) and 690 nm (europium, D → F) trend with the percent incorporation of europium and terbium into the cluster.
几乎每种镧系离子都有报道过具有[Ln(μ-O)(μ-OH)]核心的硝酸盐修饰六聚体，它们被用作组装功能性金属有机框架的前驱体。然而，很少有研究考察溶液和固态物种之间的相关性以及混合金属簇的形成。为此，通过调节硝酸镧水溶液的pH值制备了一系列同金属和异金属镧系硝酸盐六聚体。使用小角X射线散射和电喷雾电离质谱对同金属铕溶液进行研究表明，在硝酸盐介质中，低阶络合物主导着镧系元素的物种形成。然而，沉淀相的粉末X射线衍射数据证实了对于Ln = Eu和Tb，形成了[Ln(μ-O)(μ-OH)(NO)(H₂O)]·2(HNO₃)·(H₂O)。对于异金属体系，通过电感耦合等离子体质谱对固态产物进行分析表明，较重的稀土元素选择性地掺入到[Ln(μ-O)(μ-OH)(NO)(H₂O)]·2(HNO₃)·(H₂O)中。通过计算平均分离因子对选择性进行了量化，平均分离因子定义为两种金属的回收因子之比。对混合金属[TbₓEu₁₋ₓ(μ-O)(μ-OH)(NO)(H₂O)]·2(HNO₃)·(H₂O)（其中x = 1.1 - 3.6）的发光行为进行进一步研究表明，489 nm（铽，⁵D₄→⁷F₅）和690 nm（铕，⁵D₀→⁷F₂）处峰的相对强度随铕和铽掺入簇中的百分比而变化。
