MOFs with 12-Coordinate 5f-Block Metal Centers

Abstract

We have constructed an unprecedented MOF platform that accommodates a range of 5f-block metal ions (Th 4+ , U 4+ , Np 4+ , Pu 4+ ) as the primary building block. The isoreticular actinide metal−organic frameworks (An-MOFs) exhibit periodic trends in the 12-coordinate metal environment, ligand configuration, and resulting ultramicroporosity. It holds potential in distinguishing neighboring tetravalent actinides. The metal ionic radius, carboxylate bite angle, anthracene plane twisting, interligand interactions, and countercation templating collectively determine an interplay between solvation, modulation, and complexation, resulting in a coordination saturation of the central actinide, while lanthanide counterparts are stabilized by the formation of a dimer-based motif. Quantum chemical calculations indicate that this large coordination number is only feasible in the high-symmetry environment provided by the An-MOFs. This category of MOFs not only demonstrates autoluminescence (4.16 × 10 4 counts per second per gram) but also portends a wide-bandgap (2.84 eV) semiconducting property with implications for a multitude of applications such as hard radiation detection.

Metal–organic framework (MOF)-based fluorescence “turn-on” sensors

“…The construction of MOFs is possible using ligands and a variety of metal ions such as s/p block elements, 50 d block metals 51 and lanthanide metal ions. 52 MOFs synthesized using d block elements particularly d10 metal ions play a vital role in the photoluminescent properties. 53,54 The d10 metal ions contain a closed shell electronic configuration, and thus the d-d electronic transition is very difficult.…”

f‐block MOFs: A Pathway to Heterometallic Transuranics

“…At the same time, fundamental aspects including relativistic effects through mixing of excited and ground states, f-f transitions in crystal fields, or pronounced spinorbit coupling are cornerstones of inorganic, physical, and materials chemistry which could lead to coordination environments that are uncommon in transition metal systems, resulting in unique physicochemical properties or unusual structural motifs. [41][42][43][44][45][46][47][48][49] Another area which has not been explored yet is preparation of actinide-based frameworks containing actinides with mixed metal oxidation states. [50] Currently, reports on f-block MOFs, especially those containing transuranic elements, mainly focus on detailed structural analysis, while studies toward material properties have only very recently emerged (Scheme 1).…”

Adjusting the match-degree between electron library and surface-active sites and forming surface polarization in MOF-based photo-cocatalysts for accelerating electron transfer

“…Many researchers have re-constructed metal centers from crystal strategies, coordination environments, heteroatom substitution strategies and so on. 18,19 For instance, the heteroatom substitution can be modified in terms of catalyst intrinsic properties, 20 where from the microscopic point of view it could re-construct the electron cloud distribution in the system and from the macroscopic aspect the morphology of catalytic materials is changed. Therefore, we may substitute a small number of metal centers with heteroatoms of similar atomic radius size, which will lead to rearrangement of electrons in the system, leading to the occurrence of asymmetry breaking its original symmetry in the catalytic system which results in the surface polarization phenomenon.…”