Abstract
We report the synthesis, characterization, and iodine capture application of a novel thorium-organic nanotube, TSN-626, [Th6O4(OH)4(C6H4NO2)7(CHO2)5(H2O)3]·3H2O. The classification as a metal-organic nanotube (MONT) distinguishes it as a rare and reduced dimensionality subset of metal-organic frameworks (MOFs); the structure is additionally hallmarked by low node connectivity. TSN-626 is composed of hexameric thorium secondary building units and mixed O/N-donor isonicotinate ligands that demonstrate selective ditopicity, yielding both terminating and bridging moieties. Because hard Lewis acid tetravalent metals have a propensity to bind with electron donors of rival hardness (e.g., carboxylate groups), such Th-N coordination in a MOF is uncommon. However, the formation of key structural Th-N bonds in TSN-626 cap some of the square antiprismatic metal centers, a position usually occupied by terminal water ligands. TSN-626 was characterized by using complementary analytical and computational techniques: X-ray diffraction, vibrational spectroscopy, N2 physisorption isotherms, and density functional theory. TSN-626 satisfies design aspects for the chemisorption of iodine. The synergy between accessibility through pores, vacancies at the metal-oxo nodes, and pendent N-donor sites allowed a saturated iodine loading of 955 mg g-1 by vapor methods. The crystallization of TSN-626 diversifies actinide-MOF linker selection to include soft electron donors, and these Th-N linkages can be leveraged for the investigation of metal-to-ligand bonding and unconventional topological expressions.
| Original language | English |
|---|---|
| Pages (from-to) | 9480-9492 |
| Number of pages | 13 |
| Journal | Inorganic Chemistry |
| Volume | 61 |
| Issue number | 25 |
| DOIs | |
| State | Published - Jun 27 2022 |
| Externally published | Yes |
Funding
This material is based upon work supported by the Department of Energy, National Nuclear Security Administration under Award DE-NA0003763 and the Arthur J. Schmitt Leadership Fellowship (A.M.H.). S.L.H. acknowledges support from the U.S. Department of Energy National Nuclear Security Administration Stewardship Science Graduate Fellowship (DOE NNSA SSGF) under Award DE-NA0003960. We thank the ND Energy Materials Characterization Facility (MCF) and the assistance of Dr. Ian Lightcap for the use of the XPS and TGA-MS. The MCF is funded by the Sustainable Energy Initiative (SEI), which is part of the Center for Sustainable Energy at Notre Dame (ND Energy). We are also grateful for Dr. Tatyana Orlova and the Notre Dame Integrated Imaging Facility for the use of their sputter coater, Dr. Jay LaVerne for access to DRIFTS, and Dr. Patrick Julien and Dr. Tsuyoshi Kohlgruber for insightful conversations. D.R., W.J., and L.G. acknowledge the Minnesota Supercomputing Institute (MSI) for generous computing resources.