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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]

Main observation and conclusion: Two new uranium(VI) phosphonate compounds, namely K8[N(C2H5)4]2(UO2)17(H2O)4[CH2(PO3)2]8[CH2(PO3)(PO3H)]4‧16(H2O) (1) and [N(C2H5)4]4(H3O)2(UO2)10[CH2(PO3)2]5[CH2(PO3)(PO3H)]2‧10H2O (2), have been synthesized under mild hydro/solvothermal condition. The structural analysis of the two compounds reveals that they both contain all three typical coordination geometries of the U(VI) ions, including UO6 tetragonal, UO7 pentagonal, and UO8 hexagonal bipyramids. Moreover, compound 1 displays a temperature‐induced single crystal to single crystal phase transformation as confirmed by the Single‐crystal X‐ray diffraction data collected at different temperatures. Temperature‐dependent fluorescence spectra presented herein illustrate the perturbation of the electronic structure of uranyl centers. [ABSTRACT FROM AUTHOR]