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Dissertation
Structural and spectroscopic properties of actinide and lanthanide polyoxometalate complexes
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2025
Abstract
Qubits are the basic processing unit for a quantum computer constructed out of a two-level quantum system. One of the most promising qubit platforms is based on molecular spins, which produces its two-level quantum system from, commonly, electron spins of paramagnetic molecules. The Na9Ho(W5O18)2•35H2O (Na9[HoW10]) lanthanide polyoxometalate complex is a model molecular spin qubit with accessible atomic clock transitions. The performance of molecular spin-qubits are assessed by the duration superposition of the two-level system can be maintained dubbed the coherence time, T2. Clock transition provides protection for the coherent state from magnetic noises that enhances T2 values in magnetically noisy environments. Na9[HoW10] possess a T2 of 8.2 µs, which is relatively long for molecular spin qubit, yet it is well short of the 100 µs threshold that has been outlined for practical use in quantum computing applications. To further improve T2 in Na9[HoW10] and other related molecules, a strategy to minimize the vibrational noise of the system is required; however, there is a gap within the literature regarding how to deal with this issue. The work contained here aims to elaborate on how structural and vibrational properties can be leveraged to reduce vibrational noise within f-element polyoxometalate (POM) complexes, which has been explored in a series of systematic fundamental investigations aimed at addressing the following overarching research question. If vibrational noise is minimized in f-element complexes possessing clock transitions, can extremely long T2 be realized? The first chapter of this thesis is the Introduction covering relevant topics addressed throughout the following chapters. The second chapter covers the Materials and Methods which contain expositions and technical details regarding experimental protocols used in this work. The third chapter covers the investigation into the Structural and Vibrational Properties of Lanthanide Lindqvist Polyoxometalate Complexes. In this chapter we uncover the importance of secondary lattice packing towards the distortion around the primary sphere of the f-element cations within the Na9Ln(W5O18)2•χH2O system. The fourth chapter in this thesis is Delineating the Effects of Counterions on the Structural and Vibrational Properties of U(IV) Lindqvist Polyoxometalate Complexes. This chapter builds on our discovery from the third chapter and saw us directly manipulating the secondary lattice of the [U(IV)(W5O18)2]8- complex by changing the counterion configurations which confirms the importance of secondary lattice in both structural and vibrational properties of this system. The fifth chapter covers the Effects of Counterion Configurations on the Spin and Vibrational Manifolds of [Ho(III)(W5O18)2]9- Molecular Qubit. This chapter provide direct evidence of the spin states in the [Ho(III)(W5O18)2]9- to be affected by change in counterion configurations through EPR measurements. The sixth chapter saw us focus on the Isolation and Characterization of Tb(IV) in Aqueous Media via Polyoxometalate Encapsulation. In this chapter, we provided strong evidences for the presence of Tb(IV) in the [Tb(III/IV)(P2W17O61)2]17/16- complex through SCXRD, XANES, EPR, and SQUID measurements. The final experimental chapter covers the Structural and Vibrational Characterization of Plutonium Polyoxometalate Complexes which contains information regarding our effort in isolating five plutonium polyoxometalate complexes as well as their crystal structures and Raman spectra. The final chapter of this thesis is the Conclusions which summarizes the accomplishments of the previous experimental chapters.
Details
- Title: Subtitle
- Structural and spectroscopic properties of actinide and lanthanide polyoxometalate complexes
- Creators
- Primadi Joseph Subintoro
- Contributors
- Korey P. Carter (Advisor)Scott R. Daly (Committee Member)Tori Z. Forbes (Committee Member)Edward G. Gillan (Committee Member)Florence J. Williams (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Chemistry
- Date degree season
- Autumn 2025
- Publisher
- University of Iowa
- Number of pages
- xx, 515 pages
- Copyright
- Copyright 2025 Primadi Joseph Subintoro
- Grant note
This work was funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Early Career Research Program under Award DE-SC0024035, Nuclear Regulatory Commission Faculty Development Grant (NRC 31310018M0042)
- Comment
- This thesis has been optimized for improved web viewing. If you require the original version, contact the University Archives at the University of Iowa: https://www.lib.uiowa.edu/sc/contact/
- Language
- English
- Date submitted
- 11/26/2025
- Description illustrations
- illustrations (some color)
- Description bibliographic
- Includes bibliographical references (page 270-293)
- Public Abstract (ETD)
Qubits are the basic information processing unit for a quantum computer and current qubit candidates are still lacking in their performance. In this thesis, I investigate the viability of felement (rare-earth elements and actinides) molecules as molecular spin qubits. From our investigations, we have found new routes to tune the structural and vibrational properties of these f-element materials to potentially improve their qubit properties. We have also uncovered ways to stabilize terbium, one of the rare earth elements, in a unique oxidation state which could potentially open new approaches toward more efficient rare earth separations. We have also stood up the first plutonium lab at the University of Iowa, which enabled the synthesis of novel plutonium materials with potentially interesting properties for qubit applications.
- Academic Unit
- Chemistry
- Record Identifier
- 9985135345102771
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