An ionic covalent–organic framework (ICOF-1 containing sp³ hybridized boron anionic centers formed by spiroborate linkage and dimethylammonium ions) is explored as an ion exchanger for the removal of lead (Pb²⁺) ions from aqueous solution. From molecular simulations, the Pb²⁺ ions are observed to exchange with the nonframework DMA⁺ ions in the ICOF-1. At a concentration of 600 ppm, the Pb²⁺ ions are completely exchanged and reside in the ICOF-1, while the DMA⁺ ions are in a dynamic equilibrium with the solution. It is revealed that the exchange between Pb²⁺ and DMA⁺ is governed by the stronger attraction of Pb²⁺ with the negatively charged ICOF-1 framework. The radial distribution functions and mean-squared displacements further show that the exchanged Pb²⁺ ions are in a closer proximity to the ICOF-1 framework with a smaller mobility than DMA⁺ ions. The simulation study provides microscopic insight into the ion-exchange process between Pb²⁺ and DMA⁺, and it suggests that the ICOF-1 might be an intriguing candidate for water purification.

中文翻译：

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离子共价-有机骨架有效去除水溶液中Pb ^2+的分子模拟研究

离子共价-有机框架（包含由螺硼酸酯键和二甲基铵离子形成的sp ³杂化的硼阴离子中心的ICOF-1 ）被用作离子交换剂，用于从水溶液中去除铅（Pb ²⁺）离子。通过分子模拟，观察到Pb ²⁺离子与ICOF-1中的非骨架DMA ⁺离子交换。在600 ppm的浓度下，Pb ²⁺离子被完全交换并保留在ICOF-1中，而DMA ⁺离子则与溶液处于动态平衡状态。揭示了Pb ²⁺与DMA ⁺之间的交换受Pb ²⁺的较强吸引力^支配带有负电荷的ICOF-1框架。径向分布函数和均方位移进一步表明，交换后的Pb ²⁺离子更接近于ICOF-1骨架，迁移率比DMA ⁺离子小。该模拟研究提供了对Pb ²⁺和DMA ⁺之间离子交换过程的微观见解，它表明ICOF-1可能是纯净水的一个吸引人的候选对象。