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Zirconium-based metal–organic framework nanosheet assembled hydrangea-like architectures were reported and an enhanced iodine capture capacity was achieved. [ABSTRACT FROM AUTHOR]

Designability is an attractive feature for metal–organic frameworks (MOFs) and essential for reticular chemistry, and many ideas are significantly useful in the carboxylate system. Bi‐, tri‐, and tetra‐topic phosphonate ligands are used to achieve framework structures. However, an efficient method for designing phosphonate MOFs is still on the way, especially for uranyl phosphonates, owing to the complicated coordination modes of the phosphonate group. Uranyl phosphonates prefer layer or pillar‐layered structures as the topology extension for uranyl units occurs in the plane perpendicular to the linear uranium‐oxo bonds and phosphonate ligands favor the formation of compact structures. Therefore, an approach that can construct three‐dimensional (3D) uranyl phosphonate MOFs is desired. In this paper, a sterically hindered phosphonate ligand method (SHPL) is described and is successfully used to achieve 3D framework structures of uranyl phosphonates. Four MOF compounds ([AMIM]2(UO2)(TppmH4)⋅H2O (UPF‐101), [BMMIM]2(UO2)3(TppmH4)2⋅H2O (UPF‐102), [Py14]2(UO2)3(TppmH4)2⋅3 H2O (UPF‐103), and [BMIM](UO2)3(TppmH3)F2⋅2 H2O (UPF‐104); [AMIM]=1‐allyl‐3‐methylimidazolium, [BMMIM]=1‐butyl‐2,3‐dimethylimidazolium, [Py14]=N‐butyl‐N‐methylpyrrolidinium, and [BMIM]=1‐butyl‐3‐methylimidazolium) are obtained by ionothermal synthesis, with zero‐dimensional nodes of uranyl phosphonates linked by steric tetra‐topic ligands, namely tetrakis[4‐(dihyroxyphosphoryl)phenyl]methane (TppmH8), to give 3D framework structures. Characterization by PXRD, UV/Vis, IR, Raman spectroscopy, and thermogravimetry (TG) were also performed. [ABSTRACT FROM AUTHOR]

For the first time, we report intense X-ray scintillation enabled by a series of isotypic lanthanide (Eu and Tb) based metal–organic frameworks, initially showing a very efficient X-ray to visible light luminescence conversion. By systematic adjusting of the molar ratio of Eu3+ and Tb3+ in the same MOF structure as a traditional strategy for color-tuning in lanthanide-based photoluminescent materials, linear multicolor visualization of X-ray radiation from red to green can be facilely achieved, providing a new class of scintillating materials with continuous color tunability that can be customized for desired purposes. Moreover, these lanthanide–organic framework based scintillators exhibit excellent radiation resistance and humidity stability, in comparison with the state of the art and commercially-available X-ray scintillator, CsI:Tl. [ABSTRACT FROM AUTHOR]

• New uranyl uptake strategy with combined complexation and photoreduction is shown. • An ultrahigh uranyl uptake capacity not limited by the sorption site is achieved. • Uranyl can be removed completely regardless of its initial concentration. • Uranyl extraction is not affected by the coexisting metal cations. Uranium enrichment is perhaps the most critical chemical process throughout the nuclear fuel cycle including uranium mining, uranium extraction from seawater, used fuel reprocessing and disposal, and environmental contamination remediation. New uranium extraction technology is still highly desirable at current stage, although a variety of extraction methods have been established and developed in the past several decades but all with clear demerits. Herein we present a new uranium extraction strategy with combined ligand complexation and photocatalytic reduction based on postsynthetically functionalized metal-organic frameworks (MOFs). The highly robust and photoactive MOF PCN-222 is modified with phosphono- and amino groups that can capture U(VI) from solution. Upon visible light irradiation, the photo-induced electrons from the MOF host can efficiently reduce U(VI) pre-enriched in MOF, affording neutral uranium species that evacuate the MOF structure and regenerating the active site readily for capturing additional U(VI). This auto-recycled process offers an ultrahigh uranium extraction capacity not limited by the number of adsorption sites and more importantly an extra uranium uptake selectivity over these non-redox-active competing metal cations, and can be utilized for uranium separation over extremely wide uranium concentrations and pH ranges, showing a powerful application potential. [ABSTRACT FROM AUTHOR]