Actinide-MOF chemistry and applications

Actinide metal-organic frameworks (An-MOFs) have garnered considerable attention in recent years.1 Yet, this class of compounds remains understudied compared with their transition metal or lanthanide homologues and this, despite a wide range of interesting properties, which may be turned into promising applications, from radiation detection to tailor-made nuclear waste forms. Moreover, this novel group of metal-organic compounds allows for straightforward comparison with molecular complexes, which have been the target of fundamental studies in actinide science for some time.
We will discuss a series of isoreticular MOFs based on mononuclear An(IV) (Th, U, Np, Pu) primary building units in which each actinide is coordinated by six molecules of 9,10-anthracenedicarboxylic acid (ADC).2 This arrangement leads to an unusually large coordination number of 12 in icosahedral symmetry. Quantum chemical calculations indicate that this large coordination number is only feasible in the high-symmetry environment provided by the An-MOFs. Moreover, these MOFs not only demonstrate autoluminescence but also wide-bandgap (2.89 eV) semiconducting properties. In addition, we will present recent findings, illustrating how selective crystallization from mixed-metal solutions may present a viable pathway for the production of actinide waste forms from specialized waste streams. As an example we will present the formation of Th-MOFs containing isonicotinic acid linkers in the presence of a wide range of metals representative of fission products.3

REFERENCES
[1] K. Lv et al., Coord. Chem. Rev. 446, 214011 (2021) and references therein.
[2] K. Lv et al., J. Am. Chem. Soc. 144, 2879 (2022).
[3] K. Lv et al., ACS Mater. Lett. 5, 536 (2023).