Palladium(II) Modulation Enhances the Water Stability and Aqueous 99 TcO 4 - /ReO 4 - Removal Performance of Metal-Organic Frameworks.

Improving the water stability of metal-organic frameworks (MOFs) is essential for their use in water pollution treatment and environmental remediation, though it remains technically challenging. Herein, we report a novel cationic MOF constructed with [Th 6 O 4 (OH) 4 (COO) 12 ] units and [CoN 4 ·Cl 2 ] units possessing a ftw-type topology (denoted as 1-Th-Co ). 1-Th-Co itself exhibited poor water stability but excellent stability following a palladium(II) modulation strategy. Experimental studies reveal that Co(II) ions in 1-Th-Co were replaced by Pd(II) ions through cation exchange in N,N-diethylformamide (yielding 1-Th-Pd ). The planar PdN 4 units in 1-Th-Pd were responsible for improving the water stability of the framework. As a result, 1-Th-Pd offered excellent stability, fast adsorption kinetics, and high removal ratios for 99 TcO 4 - and ReO 4 - (as a 99 TcO 4 - surrogate) in contaminated water. When used in packed columns, 1-Th-Pd can dynamically capture ReO 4 - from groundwater. This work provides a new avenue for improving the water stability of MOFs, offering new vistas for the decontamination of aqueous solutions containing 99 TcO 4 - and ReO 4 - .