Abstract
In liquid, temperature affects the structures of lanthanide complexes in multiple ways that depend upon complex interactions between ligands, anions, and solvent molecules. The relative simplicity of lanthanide aqua ions (Ln3+) make them well suited to determine how temperature induces structural changes in lanthanide complexes. We performed a combination of ab initio molecular dynamics (AIMD) simulations and extended X-ray absorption fine structure (EXAFS) measurements, both at 25 and 90 °C, to determine how temperature affects the first-and second-coordination spheres of three Ln3+ (Ce3+, Sm3+, and Lu3+) aqua ions. AIMD simulations show first lanthanide coordination spheres that are similar at 25 and 90 °C, more so for the Lu3+ ion that remains as eight-coordinate than for the Ce3+ and Sm3+ ions that change their preferred coordination number from nine (at 25 °C) to eight (at 90 °C). The measured EXAFS spectra are very similar at 25 and 90 °C, for the Ce3+, Sm3+, and Lu3+ ions, suggesting that the dynamical disorder of the Ln3+ ions in liquid water is sufficient such that temperature-induced changes do not clearly manifest changes in the structure of the three ions. Both AIMD simulations and EXAFS measurements show very similar structures of the first coordination sphere of the Lu3+ ion at 25 and 90 °C.
| Original language | English |
|---|---|
| Pages (from-to) | 287-294 |
| Number of pages | 8 |
| Journal | Inorganic Chemistry |
| Volume | 61 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 10 2022 |
Funding
The authors thank Cailin Buchanan and Nirala Singh, from the University of Michigan, for providing Ln salt samples. R.C.S. and D.C.C. acknowledge support from the donors of the American Chemical Society Petroleum Research Fund. Work by J.L.F. was supported under project 16248, funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated by Battelle for the U.S. DOE under Contract no. DE-AC05-76RL01830. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract no. DE-AC02-06CH11357. Calculations were performed in Pronghorn, the High-Performance Computing cluster of the University of Nevada, Reno. 3+