Reticular Chemistry of Uranyl Phosphonates: Sterically Hindered Phosphonate Ligand Method is Significant for Constructing Zero‐Dimensional Secondary Building Units

Abstract

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.

Regulating the Porosity of Uranyl Phosphonate Frameworks with Quaternary Ammonium: Structure, Characterization, and Fluorescent Temperature Sensors

“…Therefore, the chemistry of uranium phosphonate may provide more details for understanding the interactions and offering more potential applications . UMOFs based on carboxylic and imidazole ligands can be designed and synthesized following some strategies, , while it is still challenging to obtain phosphonate ligand-based UMOFs with a specific design idea because there are multible coordination modes of a phosphonate group, and mean the while uranyl unit expands the topology only in its equatorial plane, resulting in a relatively smaller number of three-dimensional (3D) porous UPFs compared to that of UMOFs based on carboxylate ligands . The lack of an efficient strategy for the synthesis and functionalization of 3D porous UPFs remains a significant issue, even though many methods have been applied, including doping with heterometals, adding second ligands, and introducing structure-directing agents .…”

Layered Uranyl Phosphonates Encapsulating Co(II)/Mn(II)/Zn(II) Ions: Exfoliation into Nanosheets and Its Impact on Magnetic and Luminescent Properties

“…[15,16] Due to the inert nature of the uranyl oxo atoms, these materials often show 1D chain or 2D layer structures, [1,17] though 3D frameworks are also possible by designing specific phosphonate ligands, introducing co-ligands and changing experimental conditions. [17][18][19][20] While most efforts in this field have been devoted to the control of the dimensionality, topology and porosity of uranyl phosphonate frameworks, the exploration of their physical properties remains far from well-developed. Although photoluminescence of uranyl phosphonates has been investigated in many cases, magnetic studies were limited to a few mixed-valence uranium phosphonates.…”

“…Among them, the uranyl phosphonates are very attractive because of their high thermal and chemical stabilities, unique luminescent properties and potential applications in ion‐exchange, [12,13] gas sorption [14] and luminescent sensor [15,16] . Due to the inert nature of the uranyl oxo atoms, these materials often show 1D chain or 2D layer structures, [1,17] though 3D frameworks are also possible by designing specific phosphonate ligands, introducing co‐ligands and changing experimental conditions [17–20] . While most efforts in this field have been devoted to the control of the dimensionality, topology and porosity of uranyl phosphonate frameworks, the exploration of their physical properties remains far from well‐developed.…”

Anhydrous Superprotonic Conductivity of a Uranyl-Based MOF from Ambient Temperature to 110 °C

“…Notably, uranyl phosphonate 1 was chosen for several reasons: (1) It has an anionic skeleton. (2) It possesses high thermal and water stabilities similar to many other uranyl phosphonates, − and (3) depleted uranium is an abundant radioactive byproduct of the nuclear power industry with an extremely low specific radioactivity of 3.36 × 10 –7 Cig –1 , although the recycling and reuse of this material are still challenges.…”