1
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Poh YR, Morozov D, Kazmierczak NP, Hadt RG, Groenhof G, Yuen-Zhou J. Alternant Hydrocarbon Diradicals as Optically Addressable Molecular Qubits. J Am Chem Soc 2024; 146:15549-15561. [PMID: 38798142 DOI: 10.1021/jacs.4c04360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
High-spin molecules allow for bottom-up qubit design and are promising platforms for magnetic sensing and quantum information science. Optical addressability of molecular electron spins has also been proposed in first-row transition-metal complexes via optically detected magnetic resonance (ODMR) mechanisms analogous to the diamond-nitrogen-vacancy color center. However, significantly less progress has been made on the front of metal-free molecules, which can deliver lower costs and milder environmental impacts. At present, most luminescent open-shell organic molecules are π-diradicals, but such systems often suffer from poor ground-state open-shell characters necessary to realize a stable ground-state molecular qubit. In this work, we use alternancy symmetry to selectively minimize radical-radical interactions in the ground state, generating π-systems with high diradical characters. We call them m-dimers, referencing the need to covalently link two benzylic radicals at their meta carbon atoms for the desired symmetry. Through a detailed electronic structure analysis, we find that the excited states of alternant hydrocarbon m-diradicals contain important symmetries that can be used to construct ODMR mechanisms leading to ground-state spin polarization. The molecular parameters are set in the context of a tris(2,4,6-trichlorophenyl)methyl (TTM) radical dimer covalently tethered at the meta position, demonstrating the feasibility of alternant m-diradicals as molecular color centers.
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Affiliation(s)
- Yong Rui Poh
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
| | - Dmitry Morozov
- Terra Quantum AG, Kornhausstrasse 25, St. Gallen 9000, Switzerland
| | - Nathanael P Kazmierczak
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ryan G Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Gerrit Groenhof
- Nanoscience Center and Department of Chemistry, University of Jyväskylä, Jyväskylä 40014, Finland
| | - Joel Yuen-Zhou
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
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2
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Subintoro PJ, Carter KP. Structural and vibrational properties of lanthanide Lindqvist polyoxometalate complexes. Dalton Trans 2024; 53:9526-9539. [PMID: 38768267 DOI: 10.1039/d4dt00786g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Molecular spin qubits have demonstrated immense potential in quantum information science research due to the addressability of electron spins using microwave frequencies, and the scalability and tunability of molecular systems. Exemplary in this regard is the holmium polyoxometalate, [Na9Ho(W5O18)2]·35H2O (HoW10), which features an accessible atomic clock transition at 9.4 GHz; however, the coherence time of this molecule is limited by spin-phonon coupling driven decoherence processes. To limit these decoherence pathways, materials need to be designed to reduce energy overlap between spin and phonon states, and this necessitates developing a better understanding on how structural modifications impact the vibrational landscape for classes of complexes. Herein we conducted a full investigation into the fundamental structural and vibrational properties of the lanthanide Lindqvist polyoxometalate series, [Na9Ln(W5O18)2]·xH2O (Ln = La(III)-Lu(III), except Pm(III)) (LnW10), to assess how structural changes effect vibrational characteristics and to elucidate pathways to improve the coherence properties of HoW10. Single crystal X-ray diffraction results revealed four distinct structural polymorphs in complexes 1-14 wherein first coordination spheres were identical, and differences manifested as changes in lattice packing. Interestingly, the subtle changes in packing exhibited by the four polymorphs were found to impact distortions away from ideal D4d symmetry for each of the LnW10 complexes. Raman and far-infrared (FIR) spectra of complexes 1-14 were collected to identify vibrational modes present in low energy regions and peak fitting assignments were made according to literature precedents. Qualitative and Partial least squares (PLS) analysis show correlations between complex structural parameters with the low energy Raman and FIR vibrational modes of interest. Overall, this investigation shows that the second coordination sphere plays an integral role in modulation of the structural and vibrational characteristics of LnW10 complexes, which makes it a viable route for tuning spin and vibrational manifolds of species within this series.
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Affiliation(s)
| | - Korey P Carter
- Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
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3
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Hand AT, Watson-Sanders BD, Xue ZL. Spectroscopic techniques to probe magnetic anisotropy and spin-phonon coupling in metal complexes. Dalton Trans 2024; 53:4390-4405. [PMID: 38380640 DOI: 10.1039/d3dt03609j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Magnetism of molecular quantum materials such as single-molecule magnets (SMMs) has been actively studied for potential applications in the new generation of high-density data storage using SMMs and quantum information science. Magnetic anisotropy and spin-phonon coupling are two key properties of d- and f-metal complexes. Here, phonons refer to both intermolecular and intramolecular vibrations. Direct determination of magnetic anisotropy and experimental studies of spin-phonon coupling are critical to the understanding of molecular magnetism. This article discusses our recent approach in using three complementary techniques, far-IR and Raman magneto-spectroscopies (FIRMS and RaMS, respectively) and inelastic neutron scatterings (INS), to determine magnetic excited states. Spin-phonon couplings are observed in FIRMS and RaMS. DFT phonon calculations give energies and symmetries of phonons as well as calculated INS spectra which help identify magnetic peaks in experimental INS spectra.
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Affiliation(s)
- Adam T Hand
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
| | | | - Zi-Ling Xue
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
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4
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Kazmierczak NP, Lopez NE, Luedecke KM, Hadt RG. Determining the key vibrations for spin relaxation in ruffled Cu(ii) porphyrins via resonance Raman spectroscopy. Chem Sci 2024; 15:2380-2390. [PMID: 38362417 PMCID: PMC10866354 DOI: 10.1039/d3sc05774g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/12/2024] [Indexed: 02/17/2024] Open
Abstract
Pinpointing vibrational mode contributions to electron spin relaxation (T1) constitutes a key goal for developing molecular quantum bits (qubits) with long room-temperature coherence times. However, there remains no consensus to date as to the energy and symmetry of the relevant modes that drive relaxation. Here, we analyze a series of three geometrically-tunable S = ½ Cu(ii) porphyrins with varying degrees of ruffling distortion in the ground state. Theoretical calculations predict that increased distortion should activate low-energy ruffling modes (∼50 cm-1) for spin-phonon coupling, thereby causing faster spin relaxation in distorted porphyrins. However, experimental T1 times do not follow the degree of ruffling, with the highly distorted copper tetraisopropylporphyrin (CuTiPP) even displaying room-temperature coherence. Local mode fitting indicates that the true vibrations dominating T1 lie in the energy regime of bond stretches (∼200-300 cm-1), which are comparatively insensitive to the degree of ruffling. We employ resonance Raman (rR) spectroscopy to determine vibrational modes possessing both the correct energy and symmetry to drive spin-phonon coupling. The rR spectra uncover a set of mixed symmetric stretch vibrations from 200-250 cm-1 that explain the trends in temperature-dependent T1. These results indicate that molecular spin-phonon coupling models systematically overestimate the contribution of ultra-low-energy distortion modes to T1, pointing out a key deficiency of existing theory. Furthermore, this work highlights the untapped power of rR spectroscopy as a tool for building spin dynamics structure-property relationships in molecular quantum information science.
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Affiliation(s)
- Nathanael P Kazmierczak
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology Pasadena California 91125 USA
| | - Nathan E Lopez
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology Pasadena California 91125 USA
| | - Kaitlin M Luedecke
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology Pasadena California 91125 USA
| | - Ryan G Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology Pasadena California 91125 USA
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5
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Mei K, Borrelli WR, Vong A, Schwartz BJ. Using Machine Learning to Understand the Causes of Quantum Decoherence in Solution-Phase Bond-Breaking Reactions. J Phys Chem Lett 2024; 15:903-911. [PMID: 38241152 PMCID: PMC10839908 DOI: 10.1021/acs.jpclett.3c03474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/11/2024] [Accepted: 01/16/2024] [Indexed: 01/21/2024]
Abstract
Decoherence is a fundamental phenomenon that occurs when an entangled quantum state interacts with its environment, leading to collapse of the wave function. The inevitability of decoherence provides one of the most intrinsic limits of quantum computing. However, there has been little study of the precise chemical motions from the environment that cause decoherence. Here, we use quantum molecular dynamics simulations to explore the photodissociation of Na2+ in liquid Ar, in which solvent fluctuations induce decoherence and thus determine the products of chemical bond breaking. We use machine learning to characterize the solute-solvent environment as a high-dimensional feature space that allows us to predict when and onto which photofragment the bonding electron will localize. We find that reaching a requisite photofragment separation and experiencing out-of-phase solvent collisions underlie decoherence during chemical bond breaking. Our work highlights the utility of machine learning for interpreting complex solution-phase chemical processes as well as identifies the molecular underpinnings of decoherence.
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Affiliation(s)
- Kenneth
J. Mei
- Department of Chemistry &
Biochemistry, University of California,
Los Angeles, Los Angeles, California 90095-1569, United States
| | - William R. Borrelli
- Department of Chemistry &
Biochemistry, University of California,
Los Angeles, Los Angeles, California 90095-1569, United States
| | - Andy Vong
- Department of Chemistry &
Biochemistry, University of California,
Los Angeles, Los Angeles, California 90095-1569, United States
| | - Benjamin J. Schwartz
- Department of Chemistry &
Biochemistry, University of California,
Los Angeles, Los Angeles, California 90095-1569, United States
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6
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Vujević L, Karadeniz B, Cindro N, Krajnc A, Mali G, Mazaj M, Avdoshenko SM, Popov AA, Žilić D, Užarević K, Kveder M. Improving the molecular spin qubit performance in zirconium MOF composites by mechanochemical dilution and fullerene encapsulation. Chem Sci 2023; 14:9389-9399. [PMID: 37712041 PMCID: PMC10498684 DOI: 10.1039/d3sc03089j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/12/2023] [Indexed: 09/16/2023] Open
Abstract
Enlarging the quantum coherence times and gaining control over quantum effects in real systems are fundamental for developing quantum technologies. Molecular electron spin qubits are particularly promising candidates for realizing quantum information processing due to their modularity and tunability. Still, there is a constant search for tools to increase their quantum coherence times. Here we present how the mechanochemical introduction of active spin qubits in the form of 10% diluted copper(ii)-porphyrins in the diamagnetic PCN-223 and MOF-525 zirconium-MOF polymorph pair can be achieved. Furthermore, the encapsulation of fullerene during the MOF synthesis directs the process exclusively toward the rare PCN-223 framework with a controllable amount of fullerene in the framework channels. In addition to the templating role, the incorporation of fullerene increases the electron spin-lattice and phase-memory relaxation times, T1 and Tm. Besides decreasing the amount of nuclear spin-bearing solvent guests in the non-activated qubit frameworks, the observed improved relaxation times can be rationalized by modulating the phonon density of states upon fullerene encapsulation.
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Affiliation(s)
- Lucija Vujević
- Ruđer Bošković Institute Bijenička cesta 54 10000 Zagreb Croatia
| | - Bahar Karadeniz
- Ruđer Bošković Institute Bijenička cesta 54 10000 Zagreb Croatia
| | - Nikola Cindro
- Department of Chemistry, University of Zagreb 10000 Zagreb Croatia
| | - Andraž Krajnc
- National Institute of Chemistry Hajdrihova 19 SI-1001 Ljubljana Slovenia
| | - Gregor Mali
- National Institute of Chemistry Hajdrihova 19 SI-1001 Ljubljana Slovenia
| | - Matjaž Mazaj
- National Institute of Chemistry Hajdrihova 19 SI-1001 Ljubljana Slovenia
| | | | - Alexey A Popov
- Leibniz IFW Dresden Helmholtzstrasse 20 D-01069 Dresden Germany
| | - Dijana Žilić
- Ruđer Bošković Institute Bijenička cesta 54 10000 Zagreb Croatia
| | | | - Marina Kveder
- Ruđer Bošković Institute Bijenička cesta 54 10000 Zagreb Croatia
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7
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Kazmierczak NP, Luedecke KM, Gallmeier ET, Hadt RG. T1 Anisotropy Elucidates Spin Relaxation Mechanisms in an S = 1 Cr(IV) Optically Addressable Molecular Qubit. J Phys Chem Lett 2023; 14:7658-7664. [PMID: 37603791 DOI: 10.1021/acs.jpclett.3c01964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Paramagnetic molecules offer unique advantages for quantum information science owing to their spatial compactness, synthetic tunability, room-temperature quantum coherence, and potential for optical state initialization and readout. However, current optically addressable molecular qubits are hampered by rapid spin-lattice relaxation (T1) even at sub-liquid nitrogen temperatures. Here, we use temperature- and orientation-dependent pulsed electron paramagnetic resonance (EPR) to elucidate the negative sign of the ground state zero-field splitting (ZFS) and assign T1 anisotropy to specific types of motion in an optically addressable S = 1 Cr(o-tolyl)4 molecular qubit. The anisotropy displays a distinct sin2(2θ) functional form that is not observed in S = 1/2 Cu(acac)2 or other Cu(II)/V(IV) microwave addressable molecular qubits. The Cr(o-tolyl)4 T1 anisotropy is ascribed to couplings between electron spins and rotational motion in low-energy acoustic or pseudoacoustic phonons. Our findings suggest that rotational degrees of freedom should be suppressed to maximize the coherence temperature of optically addressable qubits.
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Affiliation(s)
- Nathanael P Kazmierczak
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Kaitlin M Luedecke
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Elisabeth T Gallmeier
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ryan G Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
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8
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Fu PX, Zhou S, Liu Z, Wu CH, Fang YH, Wu ZR, Tao XQ, Yuan JY, Wang YX, Gao S, Jiang SD. Multiprocessing Quantum Computing through Hyperfine Couplings in Endohedral Fullerene Derivatives. Angew Chem Int Ed Engl 2022; 61:e202212939. [PMID: 36310119 DOI: 10.1002/anie.202212939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Indexed: 11/06/2022]
Abstract
Magnetic molecules have shown great potential in quantum information processing due to the chemical tunablity of their quantum behaviors. Chemical derivatives of endohedral nitrogen fullerenes with long coherence time and rich energy levels were synthesized and studied to demonstrate the ability of multiprocessing in quantum information using electron magnetic resonance. After initialization of the 12-levelled spin system, subgroups of spin energy levels coursed by the hyperfine couplings can be selectively manipulated. The cooperatively combining of the parallel calculations enabled quantum error correction, increasing the correct rate by up to 17.82 %. Also, different subgroups of transitions divided by hyperfine coupling can be treated as independent qubits, and multi-task quantum computing were realized by performing Z-gate and X-gate simultaneously, which accelerates the overall gating speed.
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Affiliation(s)
- Peng-Xiang Fu
- Beijing National Laboratory of Molecular Science, Beijing Key Laboratory of Magnetoelectric Materials and Devices, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Shen Zhou
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China.,Institute for Quantum Information Science and technology, College of Science, National University of Defense Technology, Changsha, China
| | - Zheng Liu
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China
| | - Cong-Hui Wu
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China
| | - Yu-Hui Fang
- Beijing National Laboratory of Molecular Science, Beijing Key Laboratory of Magnetoelectric Materials and Devices, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Zhi-Rong Wu
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China
| | - Xing-Quan Tao
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China
| | - Jia-Yue Yuan
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China.,Institute for Quantum Information Science and technology, College of Science, National University of Defense Technology, Changsha, China
| | - Ye-Xin Wang
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China
| | - Song Gao
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China.,Beijing National Laboratory of Molecular Science, Beijing Key Laboratory of Magnetoelectric Materials and Devices, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
| | - Shang-Da Jiang
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou, China
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9
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Kazmierczak NP, Hadt RG. Illuminating Ligand Field Contributions to Molecular Qubit Spin Relaxation via T1 Anisotropy. J Am Chem Soc 2022; 144:20804-20814. [DOI: 10.1021/jacs.2c08729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Nathanael P. Kazmierczak
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ryan G. Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
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10
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Lunghi A, Sanvito S. Computational design of magnetic molecules and their environment using quantum chemistry, machine learning and multiscale simulations. Nat Rev Chem 2022; 6:761-781. [PMID: 37118096 DOI: 10.1038/s41570-022-00424-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/15/2022] [Indexed: 11/09/2022]
Abstract
Having served as a playground for fundamental studies on the physics of d and f electrons for almost a century, magnetic molecules are now becoming increasingly important for technological applications, such as magnetic resonance, data storage, spintronics and quantum information. All of these applications require the preservation and control of spins in time, an ability hampered by the interaction with the environment, namely with other spins, conduction electrons, molecular vibrations and electromagnetic fields. Thus, the design of a novel magnetic molecule with tailored properties is a formidable task, which does not only concern its electronic structures but also calls for a deep understanding of the interaction among all the degrees of freedom at play. This Review describes how state-of-the-art ab initio computational methods, combined with data-driven approaches to materials modelling, can be integrated into a fully multiscale strategy capable of defining design rules for magnetic molecules.
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11
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Marcinkowski D, Adamski A, Kubicki M, Consiglio G, Patroniak V, Ślusarski T, Açıkgöz M, Szeliga D, Vadra N, Karbowiak M, Stefaniuk I, Rudowicz C, Gorczyński A, Korabik M. Understanding the effect of structural changes on slow magnetic relaxation in mononuclear octahedral copper(II) complexes. Dalton Trans 2022; 51:12041-12055. [PMID: 35876304 DOI: 10.1039/d2dt01564a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Current advances in molecular magnetism are aimed at the construction of molecular nanomagnets and spin qubits for their utilization as high-density data storage materials and quantum computers. Mononuclear coordination compounds with low spin values of S = ½ are excellent candidates for this endeavour, but knowledge of their construction via rational design is limited. This particularly applies to the single copper(II) spin center, having been only recently demonstrated to exhibit slow relaxation of magnetisation in the appropriate octahedral environment. We have thus prepared a unique organic scaffold that would allow one to gain in-depth insight into how purposeful structural differences affect the slow magnetic relaxation in monometallic, transition metal complexes. As a proof-of-principle, we demonstrate how one can construct two, structurally very similar complexes with isolated Cu(II) ions in an octahedral ligand environment, the magnetic properties of which differ significantly. The differences in structural symmetry effects and in magnetic relaxation are corroborated with a series of experimental techniques and theoretical approaches, showing how symmetry distortions and crystal packing affect the relaxation behaviour in these isolated Cu(II) systems. Our unique organic platform can be efficiently utilized for the construction of various transition-metal ion systems in the future, effectively providing a model system for investigation of magnetic relaxation via targeted structural distortions.
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Affiliation(s)
- Dawid Marcinkowski
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
| | - Ariel Adamski
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
| | - Maciej Kubicki
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
| | - Giuseppe Consiglio
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy
| | - Violetta Patroniak
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
| | - Tomasz Ślusarski
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland. .,Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznańskiego 2, 61-614 Poznań, Poland
| | - Muhammed Açıkgöz
- Department of Science, The State University of New York (SUNY) Maritime College, New York 10465, USA
| | - Daria Szeliga
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.
| | - Nahir Vadra
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland. .,Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física and CONICET - Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Buenos Aires C1428EGA, Argentina
| | - Mirosław Karbowiak
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.
| | - Ireneusz Stefaniuk
- College of Natural Sciences, University of Rzeszow, Rejtana 16a, 35-310 Rzeszow, Poland
| | - Czesław Rudowicz
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
| | - Adam Gorczyński
- Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.
| | - Maria Korabik
- Faculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland.
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12
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Ozvat TM, Rappé AK, Zadrozny JM. Isotopomeric Elucidation of the Mechanism of Temperature Sensitivity in 59Co NMR Molecular Thermometers. Inorg Chem 2022; 61:778-785. [PMID: 34962806 PMCID: PMC9531048 DOI: 10.1021/acs.inorgchem.1c03326] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Understanding the mechanisms governing temperature-dependent magnetic resonance properties is essential for enabling thermometry via magnetic resonance imaging. Herein we harness a new molecular design strategy for thermometry─that of effective mass engineering via deuteration in the first coordination shell─to reveal the mechanistic origin of 59Co chemical shift thermometry. Exposure of [Co(en)3]3+ (1; en = ethylenediamine) and [Co(diNOsar)]3+ (2; diNOsar = dinitrosarcophagine) to mixtures of H2O and D2O produces distributions of [Co(en)3]3+-dn (n = 0-12) and [Co(diNOsar)]3+-dn (n = 0-6) isotopomers all resolvable by 59Co NMR. Variable-temperature 59Co NMR analyses reveal a temperature dependence of the 59Co chemical shift, Δδ/ΔT, on deuteration of the N-donor atoms. For 1, deuteration amplifies Δδ/ΔT by 0.07 ppm/°C. Increasing degrees of deuteration yield an opposing influence on 2, diminishing Δδ/ΔT by -0.07 ppm/°C. Solution-phase Raman spectroscopy in the low-frequency 200-600 cm-1 regime reveals a red shift of Raman-active Co-N6 vibrational modes by deuteration. Analysis of the normal vibrational modes shows that Raman modes produce the largest variation in 59Co δ. Finally, partition function analysis of the Raman-active modes shows that increased populations of Raman modes predict greater Δδ/ΔT, representing new experimental insight into the thermometry mechanism.
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Affiliation(s)
- Tyler M. Ozvat
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Anthony K. Rappé
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Joseph M. Zadrozny
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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13
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Laorenza DW, Kairalapova A, Bayliss SL, Goldzak T, Greene SM, Weiss LR, Deb P, Mintun PJ, Collins KA, Awschalom DD, Berkelbach TC, Freedman DE. Tunable Cr 4+ Molecular Color Centers. J Am Chem Soc 2021; 143:21350-21363. [PMID: 34817994 DOI: 10.1021/jacs.1c10145] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The inherent atomistic precision of synthetic chemistry enables bottom-up structural control over quantum bits, or qubits, for quantum technologies. Tuning paramagnetic molecular qubits that feature optical-spin initialization and readout is a crucial step toward designing bespoke qubits for applications in quantum sensing, networking, and computing. Here, we demonstrate that the electronic structure that enables optical-spin initialization and readout for S = 1, Cr(aryl)4, where aryl = 2,4-dimethylphenyl (1), o-tolyl (2), and 2,3-dimethylphenyl (3), is readily translated into Cr(alkyl)4 compounds, where alkyl = 2,2,2-triphenylethyl (4), (trimethylsilyl)methyl (5), and cyclohexyl (6). The small ground state zero field splitting values (<5 GHz) for 1-6 allowed for coherent spin manipulation at X-band microwave frequency, enabling temperature-, concentration-, and orientation-dependent investigations of the spin dynamics. Electronic absorption and emission spectroscopy confirmed the desired electronic structures for 4-6, which exhibit photoluminescence from 897 to 923 nm, while theoretical calculations elucidated the varied bonding interactions of the aryl and alkyl Cr4+ compounds. The combined experimental and theoretical comparison of Cr(aryl)4 and Cr(alkyl)4 systems illustrates the impact of the ligand field on both the ground state spin structure and excited state manifold, laying the groundwork for the design of structurally precise optically addressable molecular qubits.
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Affiliation(s)
- Daniel W Laorenza
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Arailym Kairalapova
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Sam L Bayliss
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Tamar Goldzak
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Samuel M Greene
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Leah R Weiss
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Pratiti Deb
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.,Department of Physics, University of Chicago, Chicago, Illinois 60637, United States
| | - Peter J Mintun
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| | - Kelsey A Collins
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - David D Awschalom
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.,Department of Physics, University of Chicago, Chicago, Illinois 60637, United States.,Center for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Timothy C Berkelbach
- Department of Chemistry, Columbia University, New York, New York 10027, United States.,Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, United States
| | - Danna E Freedman
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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14
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Kazmierczak NP, Mirzoyan R, Hadt RG. The Impact of Ligand Field Symmetry on Molecular Qubit Coherence. J Am Chem Soc 2021; 143:17305-17315. [PMID: 34615349 DOI: 10.1021/jacs.1c04605] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Developing quantum bits (qubits) exhibiting room temperature electron spin coherence is a key goal of molecular quantum information science. At high temperatures, coherence is often limited by electron spin relaxation, measured by T1. Here we develop a simple and powerful model for predicting relative T1 relaxation times in transition metal complexes from dynamic ligand field principles. By considering the excited state origins of ground state spin-phonon coupling, we derive group theory selection rules governing which vibrational symmetries can induce decoherence. Thermal weighting of the coupling terms produces surprisingly good predictions of experimental T1 trends as a function of temperature and explains previously confounding features in spin-lattice relaxation data. We use this model to evaluate experimental relaxation rates across S = 1/2 transition metal qubit candidates with diverse structures, gaining new insights into the interplay between spin-phonon coupling and molecular symmetry. This methodology elucidates the specific vibrational modes giving rise to decoherence, providing insight into the origin of room temperature coherence in transition metal complexes. We discuss the outlook of symmetry-based modeling and design strategies for understanding molecular coherence.
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Affiliation(s)
- Nathanael P Kazmierczak
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ruben Mirzoyan
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ryan G Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
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15
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Albino A, Benci S, Atzori M, Chelazzi L, Ciattini S, Taschin A, Bartolini P, Lunghi A, Righini R, Torre R, Totti F, Sessoli R. Temperature Dependence of Spin-Phonon Coupling in [VO(acac) 2]: A Computational and Spectroscopic Study. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:22100-22110. [PMID: 34676019 PMCID: PMC8521520 DOI: 10.1021/acs.jpcc.1c06916] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 09/08/2021] [Indexed: 06/13/2023]
Abstract
Molecular electronic spins are good candidates as qubits since they are characterized by a large tunability of their electronic and magnetic properties through a rational chemical design. Coordination compounds of light transition metals are promising systems for spin-based quantum information technologies, thanks to their long spin coherence times up to room temperature. Our work aims at presenting an in-depth study on how the spin-phonon coupling in vanadyl-acetylacetonate, [VO(acac)2], can change as a function of temperature using terahertz time-domain spectroscopy and density functional theory (DFT) calculations. Powder THz spectra were recorded between 10 and 300 K. The temperature dependence of vibrational frequencies was then accounted for in the periodic DFT calculations using unit-cell parameters measured at two different temperatures and the optimized ones, as usually reported in the literature. In this way, it was possible to calculate the observed THz anharmonic frequency shift with high accuracy. The overall differences in the spin-phonon coupling magnitudes as a function of temperature were also highlighted showing that the computed trends have to be ascribed to the anisotropic variation of cell parameters.
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Affiliation(s)
- Andrea Albino
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Universitá degli Studi di Firenze, Via della Lastruccia 3, Sesto
Fiorentino, Florence 50019, Italy
| | - Stefano Benci
- European
Laboratory for Non-Linear Spectroscopy (LENS), Universitá degli Studi di Firenze, Sesto Fiorentino, Florence 50019, Italy
| | - Matteo Atzori
- Laboratoire
National des Champs Magnétiques Intenses (LNCMI), Univ. Grenoble Alpes, INSA Toulouse, Univ. Toulouse
Paul Sabatier, EMFL, CNRS, F38043 Grenoble, France
| | - Laura Chelazzi
- Dipartimento
di Chimica “Ugo Schiff” & Center of Crystallography, Universitá degli Studi di Firenze, Via della Lastruccia 3, Sesto Fiorentino, Florence 50019, Italy
| | - Samuele Ciattini
- Dipartimento
di Chimica “Ugo Schiff” & Center of Crystallography, Universitá degli Studi di Firenze, Via della Lastruccia 3, Sesto Fiorentino, Florence 50019, Italy
| | - Andrea Taschin
- European
Laboratory for Non-Linear Spectroscopy (LENS), Universitá degli Studi di Firenze, Sesto Fiorentino, Florence 50019, Italy
- ENEA,
Agenzia nazionale per le nuove tecnologie, l’energia e lo sviluppo
economico sostenibile, Centro Ricerche Frascati, via Enrico Fermi 45, 00044 Frascati, Roma, Italy
| | - Paolo Bartolini
- European
Laboratory for Non-Linear Spectroscopy (LENS), Universitá degli Studi di Firenze, Sesto Fiorentino, Florence 50019, Italy
| | - Alessandro Lunghi
- School of
Physics, AMBER and CRANN Institute, Trinity
College, Dublin 2, Ireland
| | - Roberto Righini
- European
Laboratory for Non-Linear Spectroscopy (LENS), Universitá degli Studi di Firenze, Sesto Fiorentino, Florence 50019, Italy
| | - Renato Torre
- European
Laboratory for Non-Linear Spectroscopy (LENS), Universitá degli Studi di Firenze, Sesto Fiorentino, Florence 50019, Italy
- Dipartimento
di Fisica ed Astronomia, Universitá
degli Studi di Firenze, Via G. Sansone 1, Sesto Fiorentino, Florence 50019, Italy
| | - Federico Totti
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Universitá degli Studi di Firenze, Via della Lastruccia 3, Sesto
Fiorentino, Florence 50019, Italy
| | - Roberta Sessoli
- Dipartimento
di Chimica “Ugo Schiff” & INSTM RU, Universitá degli Studi di Firenze, Via della Lastruccia 3, Sesto
Fiorentino, Florence 50019, Italy
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