Halogen hydrogen-bonded organic framework (XHOF) constructed by singlet open-shell diradical for efficient photoreduction of U(VI)

Abstract

Synthesis of framework materials possessing specific spatial structures or containing functional ligands has attracted tremendous attention. Herein, a halogen hydrogen-bonded organic framework (XHOF) is fabricated by using Cl− ions as central connection nodes to connect organic ligands, 7,7,8,8-tetraaminoquinodimethane (TAQ), by forming a Cl−···H3 hydrogen bond structure. Unlike metallic node-linked MOFs, covalent bond-linked COFs, and intermolecular hydrogen bond-linked HOFs, XHOFs represent a different kind of crystalline framework. The electron-withdrawing effect of Cl− combined with the electron-rich property of the organic ligand TAQ strengthens the hydrogen bonds and endows XHOF-TAQ with high stability. Due to the production of excited electrons by TAQ under light irradiation, XHOF-TAQ can efficiently catalyze the reduction of soluble U(VI) to insoluble U(IV) with a capacity of 1708 mg-U g−1-material. This study fabricates a material for uranium immobilization for the sustainability of the environment and opens up a new direction for synthesizing crystalline framework materials.

Enhancing the Photocatalytic Degradation Efficiency of Dyes of Copper-Based Metal–Organic Frameworks through a Dimension-Induced Structural Strategy

“…The low binding energy of 197.5 eV may be attributed to the strong electron-absorbing effect of the Cl − ion, indicating the existence of a weak force related to the Cl − ion. 32 The 3-DPNDI ligand shows two N species peaks corresponding to C�N−C (398.2 eV) and N−C3 (399.9 eV). 33 The N peak of the complex exhibits a higher binding energy (1.3 eV) than that of the ligand (Figure 2b), indicating that the interaction between pyridine N and Cu reduces the electron density at N. As shown in Figure 2c, the typical satellite peak observed at 942 eV in the Cu 2p spectrum indicates the presence of Cu(II).…”

Uranium extraction from seawater: material design, emerging technologies and marine engineering

“…In recent years, a variety of porous framework materials such as MOFs, 301–303 COFs, 83,304 CMPs 92,305 and HOFs 306 have been regarded as new types of photocatalysts for uranium extraction, due to their high specific surface area and multiple reaction sites. Li et al synthesized a post-synthetically functionalized metal–organic framework (MOF PCN-222) by combining ligand complexation and photocatalytic reduction.…”

Multifunctional Porous Hydrogen-Bonded Organic Frameworks: Current Status and Future Perspectives

“…The ease of regeneration and recyclability by simple recrystallization as well as solution processability of HOFs enables them to serve as ideal heterogeneous catalysts. One of the primary strategies for preparing HOF-based catalysts is to choose tectons with the intrinsic catalytic activity for the construction of HOFs. ,− Porphyrins, a class of heterocyclic molecules with four pyrrole subunits and a large π-conjugated system, can coordinate with various metal ions to form metalloporphyrins, which are of extreme importance in many biological functions due to their light-harvesting, electron transfer, oxygen transport, and various catalytic molecular transformations. Remarkably, the rigid and intrinsic catalytic active features of porphyrins permit their ordered arrangement to form HOFs as heterogeneous catalysts.…”

“…The merits of HOFs also enable them as multifunctional materials for many other applications, such as electrochromism, ,, photochromism, environmental applications, ,, chiral separation, structural determination, molecular actuator, etc . Only several representative examples recently reported are shown below since some of them were summarized by ours’ and others’ review articles. , …”