Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin—a mammalian metal transporter—in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)–ligand–protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.

中文翻译：

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氧化态+ IV的的螯合和稳定化

铍（Bk）被认为是唯一能够在溶液中同时表现出+ III和+ IV氧化态的跨p元素，但是到目前为止，仍然没有一种稳定的氧化Bk螯合物的证据。在这里，我们描述了使用铁载体衍生物在温和的水性条件下稳定周期表中最重的4+离子的过程。所得的Bk（IV）配合物通过分子内天线效应通过敏化而显示出发光。与用邻近的三价act系元素a，cur和（Cf）获得的带负电荷的物质相比，这种中性的Bk（IV）配位化合物不会被铁蛋白佛得林（一种哺乳动物的金属转运蛋白）隔离。对应的Cf（III）-配体-蛋白质三元加合物通过X射线衍射分析进行了表征。结合理论预测，这些数据为跨p化学领域增添了重要见识，并可能导致创新性的Bk分离和纯化工艺。