Article
Chemistry, Physical
Rabia Malik, Yuxiang Bu
Summary: This work computationally designed trans and cis forms of photochromic azobenzene-bridged diradicals and studied the modulation of magnetic coupling characteristics through intramolecular proton transfer. The results showed that proton transfer significantly regulated the magnetic spin coupling constants and allowed magnetic conversion between antiferromagnetic and ferromagnetic coupling. The study also found that the position of nitroxide radicals had a significant impact on the magnetic spin coupling characteristics.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Biochemical Research Methods
Whylder Moore, Ru Yao, Yangping Liu, Sandra S. Eaton, Gareth R. Eaton
Summary: Trityl-nitroxides exhibit potential as polarizing agents in solid state dynamic nuclear polarization. Understanding the impact of spin-spin interactions on relaxation times is crucial for optimization. Analysis of EPR spectra reveals the influence of exchange interaction on different regions of the spectra, with observations of two conformations for each diradical with varying J values. The nitroxide is shown to effectively enhance the relaxation of the trityl, even with relatively small values of J.
JOURNAL OF MAGNETIC RESONANCE
(2021)
Article
Chemistry, Physical
Suranjan Shil, Debojit Bhattacharya, Anirban Misra, Yenni P. Ortiz, Douglas J. Klein
Summary: The impact of heteroatoms on exchange coupling pathways and the presence of multiple coupling paths were explored. The lone pairs of sp(2)-hybridized heteroatoms contribute to aromaticity but have no significant role in spin coupling between two centers. A conceptual model, the heteroatom blocking effect, was proposed to explain this behavior of heteroatoms. With the occurrence of two pi-orbital exchange coupling pathways (ECPs) via bridgehead heteroatoms (B-, N-, O-, or S-), the magnetic exchange coupling constants (J) can be understood as the sum of different individual pathways. The effect of sigma-electron coupling was also investigated.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Hui Zhang, Maren Pink, Ying Wang, Suchada Rajca, Andrzej Rajca
Summary: High-spin aminyl triradicals with near-planar triphenylene backbones were reported. The effective overlap within the cross-conjugated pi-system leads to a well-separated quartet ground state. The thermal populations of the low-spin excited states were detectable, and the primary mechanism for the decay of triradicals is hydrogen atom abstraction from the solvent.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Biochemistry & Molecular Biology
Surendra N. Mahapatro, Tanden A. Hovey, Thacien Ngendahimana, Sandra S. Eaton, Gareth R. Eaton
Summary: Manganate ion MnO42- plays important roles in catalysis and water treatment. EPR spectra of MnO(4)(2-) in different solutions were studied, revealing its sensitive response to geometry and relaxation behavior at different temperatures.
JOURNAL OF INORGANIC BIOCHEMISTRY
(2022)
Article
Chemistry, Physical
Daeheum Cho, Jin Yong Lee
Summary: Single-molecule magnetic junctions are versatile platforms for manipulating spin-polarized currents through fine-tuning of the electronic properties. We used simulations to study the performance of high-spin organic oligoradicals as spin filters sandwiched between gold electrodes. By varying the number of magnetic units, the spin filtering efficiency could be tuned. Analysis revealed how the magnetic exchange interaction in a molecule modulates electron conducting channels and spin filtering efficiency. This tunable organic magnetic molecular junction system may be promising for spintronic devices.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Physics, Multidisciplinary
A. Signoles, T. Franz, R. Ferracini Alves, M. Gaerttner, S. Whitlock, G. Zuern, M. Weidemueller
Summary: This study observed anomalous relaxation dynamics in disordered quantum systems, where relaxation originates from the buildup of nonclassical correlations. The research found that the evolution towards a randomized state is independent of the strength of disorder, hinting towards a unifying description of relaxation dynamics in disordered isolated quantum systems.
Article
Chemistry, Physical
Samuel M. Jahn, Elizabeth R. Canarie, Stefan Stoll
Summary: Long electron spin coherence lifetimes are crucial for applications in quantum information science and electron paramagnetic resonance. In this study, the decoherence dynamics of an organic radical were experimentally investigated, revealing the role of proton concentration and clustering in the decoherence process. Simulations using molecular dynamics and many-body spin quantum dynamics showed excellent agreement with the experimental results and provided a predictive tool for designing molecular systems with long electron spin coherence times.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Junpei Sonehara, Michael Kammermeier, Dai Sato, Daisuke Iizasa, Ulrich Zulicke, Shutaro Karube, Junsaku Nitta, Makoto Kohda
Summary: The anisotropic spin dynamics in wires based on a [001]-oriented semiconductor quantum well were investigated, revealing that the spin relaxation time is longest for the in-plane magnetic field perpendicular to the spin-orbit field, while the shortest for the parallel configuration. The precession frequency exhibits opposite symmetry, allowing for the evaluation of spin-orbit coefficients and a greater understanding of quantum and topological information in semiconductor one-dimensional wires.
Article
Chemistry, Physical
Nathan A. Prisco, Arthur C. Pinon, Lyndon Emsley, Bradley F. Chmelka
Summary: By analogy to heat and mass transfer film theory, a general approach is introduced for determining hyperpolarization transfer rates between dilute electron spins and a surrounding nuclear ensemble. The empirical DNP polarization-transfer coefficient measured as a function of the bulk matrix H-1 spin density indicates the presence of two distinct kinetic regimes. The quantitative analyses closely agree with experimental measurements for the accumulation, propagation, and dissipation of hyperpolarization in solids, providing evidence for kinetically-limited transfer associated with a spin-diffusion barrier.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
A. Ceferino, S. J. Magorrian, V Zolyomi, D. A. Bandurin, A. K. Geim, A. Patane, Z. D. Kovalyuk, Z. R. Kudrynskyi, I. Grigorieva, V. Fal'ko
Summary: The paper demonstrates the tunability of spin-orbit coupling strength in few-layer gamma-InSe films, potentially enabling electrically switchable spintronic devices. Theoretical calculations and experimental measurements show good agreement in terms of Dyakonov-Perel spin relaxation due to SOC.
Article
Chemistry, Multidisciplinary
Pei Jing, Lu Xi, Jiao Lu, Jing Han, Xiaohui Huang, Chaoyi Jin, Junfang Xie, Licun Li
Summary: Four biradical-Ln complexes with different transition metal ions were prepared and characterized. The different coordination spheres of the Dy ions in complex 2 and 4 result in distinct magnetic relaxation behaviors, providing new insights for improving the properties of Ln-biradical based SMMs.
CHEMISTRY-AN ASIAN JOURNAL
(2021)
Article
Physics, Applied
Kohei Etou, Satoshi Hiura, Soyoung Park, Kazuya Sakamoto, Junichi Takayama, Agus Subagyo, Kazuhisa Sueoka, Akihiro Murayama
Summary: The spin-transport properties in an In0.5Ga0.5As quantum dot (QD) spin LED are affected by temperature and bias voltage, influencing spin polarization and spin relaxation. Spin polarization increases with temperature, but may decrease at higher temperatures and voltages. The electric field and temperature can enhance spin relaxation in the undoped GaAs barrier.
PHYSICAL REVIEW APPLIED
(2021)
Article
Chemistry, Physical
Krzysztof Tadyszak, Radoslaw Mrowczynski, Raanan Carmieli
Summary: A comprehensive electron paramagnetic resonance investigation of polydopamine radicals revealed the presence of two distinct paramagnetic species in the PDA structure, with different electron spin relaxation behaviors due to various couplings to local phonons, confirming spatial distancing between the two radical types. These findings shed new light on the radical structure of PDA, enhancing our understanding of their properties and potential applications in materials science and biomedicine.
JOURNAL OF PHYSICAL CHEMISTRY B
(2021)
Article
Physics, Applied
Koichi Nakanishi, Ayuki Arikawa, Yasuhito Saito, Daisuke Iizasa, Satoshi Iba, Yuzo Ohno, Nobuhide Yokota, Makoto Kohda, Yoshihiro Ishitani, Ken Morita
Summary: The study reveals the unique out-of-plane and in-plane spin-orbit (SO) magnetic fields in slightly misoriented (110) InGaAs QWs, using spatially resolved diffusion-driven spin precession dynamics and a diagonally applied external magnetic field. Through the scan position dependence of the spin precession frequency induced by the SO magnetic field, simultaneous observations of the out-of-plane and in-plane components are achieved, with the Dresselhaus SO parameter extracted to be 1.9 x 10(-12) eV m.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Atomic, Molecular & Chemical
Whylder Moore, Justin L. Huffman, Benoit Driesschaert, Sandra S. Eaton, Gareth R. Eaton
Summary: This study characterized a perchlorotriarylmethyl tricarboxylic acid radical enriched in C-13 at the central carbon, and investigated its properties under different solution conditions. The findings shed light on the potential applications of this compound in oximetry and distance measurements.
APPLIED MAGNETIC RESONANCE
(2022)
Article
Biochemistry & Molecular Biology
Andrzej Rajca, Chan Shu, Hui Zhang, Sheng Zhang, Hua Wang, Suchada Rajca
Summary: This study reports on the properties of thiophene-based double helices, including oxidation potentials, spin density localization, and computational findings on spin density distribution. The radical cations exhibit unique characteristics like low g-value and violation of the Aufbau principle, while the closed-shell neutral species show more stability in terms of EPR peak intensity.
PHOTOCHEMISTRY AND PHOTOBIOLOGY
(2021)
Article
Chemistry, Multidisciplinary
Kamalon Amrutha, Velavan Kathirvelu
Summary: In this study, EPR and optical absorption spectra of Ni(II) ions diluted in different hosts were investigated to analyze their properties and understand the coordination symmetry. The EPR spectra of Ni/MMPC and Ni/ZPN were studied, showing different transitions and revealing the spin Hamiltonian parameters. Optical absorption spectra were deconvoluted to determine the coordination environment symmetry of the complexes.
MAGNETIC RESONANCE IN CHEMISTRY
(2022)
Article
Chemistry, Physical
Cassidy E. Jackson, Thacien Ngendahimana, Chun-Yi Lin, Gareth R. Eaton, Sandra S. Eaton, Joseph M. Zadrozny
Summary: This study investigates the impact of different counterions on the spin relaxation of V(IV) complexes and finds that the methyl groups in the counterions play a dominant role in dictating the spin relaxation. The experimental results show that the methyl groups in the counterions are bound to the complex unit via hydrogen bonding. Additionally, the study reveals that the shot repetition time in spin echo measurements has a significant impact on the shape of the decay curve and the measured relaxation times. Furthermore, the spin-lattice relaxation times are independent of cations and remain the same in different systems.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
Shuyang Zhang, Maren Pink, Tobias Junghoefer, Wenchao Zhao, Sheng-Ning Hsu, Suchada Rajca, Arrigo Calzolari, Bryan W. Boudouris, Maria Benedetta Casu, Andrzej Rajca
Summary: This study reports an organic diradical composed of two Blatter radicals that has a triplet ground state and a small singlet-triplet energy gap. The diradical exhibits robust thermal stability and shows conformational equilibrium in different environments. In crystals and a polystyrene matrix, the diradical demonstrates good electrical conductivity. Additionally, the diradical can form stable thin films that remain stable in air for a significant period of time.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Review
Engineering, Electrical & Electronic
Kurugundla Gopi Krishna, Saidireddy Parne, Nagaraju Pothukanuri, Velavan Kathirvelu, Suman Gandi, Dhananjay Joshi
Summary: This article reviews the synthesis methods and sensing properties of nanostructured metal oxide semiconductor-based gas sensors, and summarizes the novel gas sensors and their characteristics under environmental pollution. Prospects for future research on the gas sensing mechanism of metal oxide semiconductors are proposed.
SENSORS AND ACTUATORS A-PHYSICAL
(2022)
Article
Chemistry, Multidisciplinary
Hui Zhang, Maren Pink, Ying Wang, Suchada Rajca, Andrzej Rajca
Summary: High-spin aminyl triradicals with near-planar triphenylene backbones were reported. The effective overlap within the cross-conjugated pi-system leads to a well-separated quartet ground state. The thermal populations of the low-spin excited states were detectable, and the primary mechanism for the decay of triradicals is hydrogen atom abstraction from the solvent.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Physics, Atomic, Molecular & Chemical
Thacien Ngendahimana, Whylder Moore, Autumn Canny, Sandra S. Eaton, Gareth R. Eaton
Summary: The electron spin relaxation rates of the boron-oxygen hole center (BOHC) formed by irradiation of boron oxides vary significantly in different samples. The concentration of defects in practical grade B2O3 affects the spin echo dephasing and spin lattice relaxation, resulting in sample-dependent behavior.
APPLIED MAGNETIC RESONANCE
(2023)
Article
Physics, Atomic, Molecular & Chemical
Georgina Amassah, Deborah G. Mitchell, Tanden A. Hovey, Sandra S. Eaton, Gareth R. Eaton
Summary: Electron spin relaxation times were studied for the SO2- radical in solid Na2S2O4 and K2S2O5, as well as the SO3- radicals in Na2S2O5 and K2S2O5. Echo envelope modulation was observed for the radicals in the Na+ salts and characterized by HYSCORE. T-m and T-1 were measured using spin echo methods and long-pulse saturation recovery. In each lattice, there is a distribution of spin lattice relaxation times that may be attributed to distributions in interspin distances.
APPLIED MAGNETIC RESONANCE
(2023)
Article
Chemistry, Multidisciplinary
Wyatt B. Larrinaga, Joseph A. Cotruvo, Brady T. Worrell, Sandra S. Eaton, Gareth R. Eaton
Summary: This study systematically investigates the electron paramagnetic resonance (EPR) properties of lanthanide(III) ions when bound to natural lanthanide-binding protein and synthetic small-molecule chelator. The results show that the EPR spectra and relaxation times of lanthanide(III) ions are sensitive to coordination environment, which is of great importance for characterizing the interactions between small molecules/biomolecules and lanthanide ions.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Physical
Lukas B. Woodcock, Eric A. Legenzov, Nathaniel D. A. Dirda, Joseph P. Y. Kao, Gareth R. Eaton, Sandra S. Eaton
Summary: Glutathione (GSH) is the main antioxidant in cells and its concentration serves as an indicator of the redox state. Researchers designed a cyclic disulfide-linked dinitroxide to monitor GSH using electron-paramagnetic resonance (EPR) spectroscopy. The reaction between the disulfide and GSH was shown to be first order, and the equilibrium ratio of the cleaved and intact disulfide can be used to measure the redox state. The feasibility of using EPR spectroscopy and imaging to study the disulfide and its cleavage product was demonstrated.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Radiology, Nuclear Medicine & Medical Imaging
Rhia M. Martin, Samantha Diaz, Martin Poncelet, Benoit Driesschaert, Eugene Barth, Mrignayani Kotecha, Boris Epel, Gareth R. Eaton, Joshua R. Biller
Summary: This article describes the progress in developing a novel encapsulated nanoparticle EPR imaging agent for determining pO(2) in tumors, and verifies its effectiveness in a mouse model, indicating its potential for guiding radiotherapy in a clinical setting.
MOLECULAR IMAGING AND BIOLOGY
(2023)
Article
Biochemical Research Methods
Sandra S. Eaton, Gareth R. Eaton
Summary: X-band EPR absorption spectra were measured for lanthanide ions in a glassy acidic water:ethanol solution. The power required for a p/2 pulse in the EPR transition was found to be consistent with theoretical calculations for some ions, but larger than predicted for others. The discrepancy in power requirement was attributed to mixing of energy levels and overlapping transitions with varying magnetic quantum numbers.
JOURNAL OF MAGNETIC RESONANCE
(2023)
Article
Chemistry, Multidisciplinary
Zhimin Yang, Richard A. Stein, Maren Pink, Peter Madzelan, Thacien Ngendahimana, Suchada Rajca, Mark A. Wilson, Sandra S. Eaton, Gareth R. Eaton, Hassane S. Mchaourab, Andrzej Rajca
Summary: We report complex formation between the chloroacetamide 2,6-diazaadamantane nitroxide radical (ClA-DZD) and cucurbit[7]uril (CB-7), which significantly immobilizes the radical and allows for reliable measurement of interspin distances. These findings have important implications for supramolecular recognition-enabled long-distance DEER measurements at near physiological temperatures.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Analytical
Martin Poncelet, Thacien Ngendahimana, Teresa D. Gluth, Emily H. Hoblitzell, Timothy D. Eubank, Gareth R. Eaton, Sandra S. Eaton, Benoit Driesschaert
Summary: This article describes the synthesis and application of a unique spin probe for measuring tissue microviscosity using EPR, which has high sensitivity and biocompatibility.