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Comprehensive Summary: The second example of tetravalent plutonium carboxyl‐based organic framework, 242Pu(OH)[PO[(C6H4)COO]3]·H2O, termed as PuTPO (TPO = tris(4‐carboxylphenyl)‐phosphineoxide), was reported in this work. A series of characterizations of PuTPO, such as X‐ray crystallography and solid‐state UV‐Vis‐NIR spectroscopy, were carried out to expatiate its structure and physicochemical properties. PuTPO is constructed by dimers of the plutonium‐oxygen subunit of [Pu2O16]. Characteristic peaks located at approximately 1100 nm can be considered to be the fingerprint peaks of tetravalent plutonium. While PuTPO can maintain high crystallinity within several months after synthesis, it exhibits a radiation‐induced swelling effect probed by the expansion of cell parameter of b axis after self‐irradiation from α‐decay of 242Pu. This result enriches the inventory of tetravalent plutonium compounds and provides an insight into the irradiation resistance of metal‐organic frameworks. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZJU-X6 is a 3-fold interlocking cationic MOF and could capture 99TcO 4. • ZJU-X6 exhibited superior sorption ability and reusability toward 99TcO 4. • PDF and crystal structure clearly elucidated the sorption mechanism. Technetium-99 is one of most problematic radionuclides with a long half-life, high environmental mobility and solubility, which exists mainly in the form of anionic pertechnetate (99TcO 4 -). Searching for sorbents that hold efficient and selective elimination of radioactive 99TcO 4 - from aqueous solution is still a big challenge and further visualizing it in the sorbents is extremely difficult. Herein, we utilized an elongated organic neutral pyridyl ligand linked with Ni2+ to yield a novel 3-fold interlocking cationic metal–organic framework (ZJU-X6). Unexpectedly, the structure of ZJU-X6 held unique displaceable water pairs on the Ni2+ node in comparison to cationic metal–organic framework constructed by Ni2+. Attainable Ni2+ nodes distinctly improved the positive charge density of the framework, affording high sorption capacity, excellent selectivity, and removal depth toward 99TcO 4 -. Pair distribution functions (PDF) were applied to analyze the changes of atom distances in materials before and after capturing ReO 4 -, clearly showing that ReO 4 - entered into the body of ZJU-X6. More detailed sorption mechanism was atomically elucidated by obtaining the single crystal structure of 99TcO 4 --incorporated ZJU-X6. It is found that the water pairs were replaced by 99TcO 4 - and each Ni2+ coordinated with two 99TcO 4 - through oxygen atoms. In addition, each 99TcO 4 - engaged in multiple C–H...O hydrogen bonding with H atoms of aromatic rings that enhanced the trapping of 99TcO 4 -. [ABSTRACT FROM AUTHOR]