Article
Chemistry, Physical
Sivaranjani Kottaipalayam Somasundaram, Ana Guilherme Buzanich, Franziska Emmerling, Sangameswaran Krishnan, Kittusamy Senthilkumar, Raphael Justin Joseyphus
Summary: Chemically synthesized iron is in demand for biomedical applications due to its large saturation magnetization compared to iron oxides. The polyol process, suitable for obtaining Co and Ni particles and their alloys, is laborious in synthesizing Fe. This study shows that a vicinal polyol, such as 1,2-propanediol, is suitable for obtaining Fe rather than 1,3-propanediol owing to the formation of a reducible Fe intermediate complex. X-ray absorption spectroscopy analysis reveals the ferric octahedral geometry and tetrahedral geometry in the ferrous state of the reaction intermediates in 1,2-propanediol and 1,3-propanediol, respectively. The final product obtained using a vicinal polyol is Fe with a γ-Fe2O3 shell, while the terminal polyol is favourable for Fe3O4. The distinct Fe-Fe and Fe-O bond lengths suggest the presence of a carboxylate group and a terminal alkoxide ligand in the intermediate of 1,2-propanediol. A large Fe-Fe bond distance suggests diiron complexes with bidentate carboxylate bridges. Prominent high-spin and low-spin states indicate the possibility of transition, which favors the reduction of iron ions in the reaction using 1,2-propanediol.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Norimasa Sasabe, Motoi Kimata, Tetsuya Nakamura
Summary: In this study, XMCD signal was observed from compensated two-dimensional triangle AFM structures on a Kagome lattice, based on the different absorption coefficients of the three sublattices and the sign of the spin chirality. This XMCD signal is only present when the spin chirality is negative, reflecting the unique charge density anisotropies and directions of spin and orbital magnetic moments in the system.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
Tomoki Kanazawa, Shunta Nishioka, Shuhei Yasuda, Daichi Kato, Toshiyuki Yokoi, Shunsuke Nozawa, Hiroshi Kageyama, Kazuhiko Maeda
Summary: The local structure dependence of BaTiO3-xHx on the doped H- amount was investigated using Raman and X-ray absorption fine-structure (XAFS) spectroscopy measurements. It was found that the tetragonal phase transforms into the cubic phase when the doped H- amount is relatively large (x ≥ 0.2). XAFS measurements revealed that the TiO6 octahedral symmetry in BaTiO3-xHx is strongly affected by the doped H- amount, where an increase of H- relaxes the local distortion of the Ti [111] displacement and causes the tetragonal-to-cubic structural change.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Tihana Cizmar, Ivana Panzic, Ivana Capan, Andreja Gajovic
Summary: The study investigated the role of Cu(II) ions in Cu-modified immobilized nanostructured TiO2 photocatalysts, showing that Cu(II) cations can reduce the recombination rate of photo generated charge carriers and improve the photocatalytic activity.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Young Choon Park, Ajith Perera, Rodney J. Bartlett
Summary: In this work, the time-independent and time-dependent EOM-CC oscillator strengths were implemented beyond the dipole approximation, including contributions beyond the quadrupole moment. This allows for the calculation of intensities for dipole inactive transitions, such as pre-edge transitions in metal K-edge spectra. The use of second-order oscillator strengths is demonstrated through TI-EOM-CCSD and TD-EOM-CCSD spectra of Ti4+ atoms.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Review
Energy & Fuels
Brittany Kerr, Hannah J. King, C. Felipe Garibello, P. Ronali Dissanayake, Alexandr N. Simonov, Bernt Johannessen, Daniel S. Eldridge, Rosalie K. Hocking
Summary: X-ray absorption spectroscopy (XAS) plays a critical role in characterizing energy materials and can target distinct chemical environments within a material. This review outlines key questions that XAS experiments can answer, shows the complementarity of XAS with other analytical techniques, and discusses the future role of XAS in energy material innovations.
Article
Multidisciplinary Sciences
Abhijit H. Phakatkar, Tolou Shokuhfar, Reza Shahbazian-Yassar
Summary: By utilizing electron energy loss spectroscopy, the oxidation state of solid solution polyelemental transition metal oxide nanoparticles was studied, revealing that random mixing in solid solution phase not only enhances entropy stabilization but also leads to stable oxidation states in transition metals ranging from binary to quinary transition metal oxides.
Article
Chemistry, Multidisciplinary
Augustin Braun, Leland B. Gee, Michael W. Mara, Ethan A. Hill, Thomas Kroll, Dennis Nordlund, Dimosthenis Sokaras, Pieter Glatzel, Britt Hedman, Keith O. Hodgson, A. S. Borovik, Michael L. Baker, Edward I. Solomon
Summary: Fe K-edge XAS is widely used for studying high-valent iron intermediates in catalysts. The 4p-mixing into the 3d orbitals complicates the analysis, but understanding it correctly enables deeper insights into the structure and reactivity. This study reveals that the loss of inversion in the equatorial plane leads to 4p mixing into the 3dx2-y2,xy orbitals, providing structural insights for distinguishing 6- vs 5-coordinate active sites. Furthermore, the study investigates the electronic structure of Fe(IV)=O active sites and their reactivity selectivity through O K-edge XAS.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Patrick Frank, Maurizio Benfatto
Summary: The structure of aqueous Cu(II)-bis-thiosemicarbazide, [Cu(tsc)(2)](2+), was analyzed using EXAFS and MXAN, showing a high Cu-S covalence of 0.66 e(-) indicating Cu1.34+. The study contradicts the need for a protein rack to explain the unique structure of the blue copper active site and presents a revised solvation model for aqueous Cu(II).
JOURNAL OF PHYSICAL CHEMISTRY B
(2021)
Article
Chemistry, Inorganic & Nuclear
Maria Haimerl, Martin Piesch, Gabor Balazs, Piero Mastrorilli, Werner Kremer, Manfred Scheer
Summary: The article investigates the reaction of nacnac Cu(I) compound with complexes containing aromatic cyclo-E-n ligands, resulting in the formation of various heterometallic complexes. These complexes were characterized comprehensively and their dynamic behavior in solution was studied using VT NMR spectroscopy, with electronic structures elucidated by DFT calculations.
INORGANIC CHEMISTRY
(2021)
Article
Materials Science, Ceramics
Angelo P. Rillera, Mayrene A. Uy, Keito Shinohara, Melvin John F. Empizo, Toshihiko Shimizu, Hideki Yoshida, Nobuhiko Sarukura, Hitoshi Abe
Summary: The structural properties of Fe in celadon glazes provide information about its production process and coloration mechanism. In this study, we used depth-resolved Fe K-edge X-ray absorption spectroscopy to explore the Fe properties of reduction-fired celadon glazes from a spatial perspective. Our results show a typical reduction-firing profile with surface oxidation occurring. We observed a transition region between two Fe valency proportions near the surface and the glaze interior. The analysis of fluorescence XAS spectra collected from glaze surfaces is limited by the possibility of surface oxidation in synthetic glazes or ceramic artifacts.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2023)
Article
Chemistry, Physical
Mikael Scott, Mickael G. G. Delcey
Summary: This article presents novel developments for the efficient evaluation of complex linear response functions of a multiconfigurational self-consistent field (MCSCF) wave function. The direct evaluation of linear response properties using the complex polarization propagator (CPP) approach is implemented within both the Tamm-Dancoff approximation (TDA) and the random phase approximation (RPA). The code's performance is illustrated with numerical examples, demonstrating its capability to handle large-scale MC-CPP calculations as well as the effect of including or excluding core orbitals in X-ray spectroscopy for small covalent metal complexes.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Multidisciplinary
Shaoyao Tian, Zhihao Sun, Han Ding, Zihao Guo, Peng Wang, Yu Qiu, Benli Du, Jingyu Bi, Guangshen Li, Lei Qian
Summary: This study investigates the correlation between coordination environments/configurations and microwave absorption (MA) performance using S-doped composites. The results show that S-doped CoP can significantly improve absorption performance, while S-doped Co2P is less effective in improving MA performance due to the hindered conductive loss.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Sana Mehmood, M. F. Natiq, M. Anis-ur-Rehman
Summary: Magnetolpumbite nanoparticles of Cr-doped strontium hexaferrites were synthesized using the sol-gel method, with XRD showing hexagonal structure and some composition containing hematite phase alpha-Fe2O3. The study revealed changes in lattice parameters and vibrations due to Cr doping, further analyzed using XAFS to confirm the presence of hematite not detected by XRD spectrum.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
A. A. Guda, S. A. Guda, A. Martini, A. N. Kravtsova, A. Algasov, A. Bugaev, S. P. Kubrin, L. V. Guda, P. Sot, J. A. van Bokhoven, C. Coperet, A. V. Soldatov
Summary: X-ray absorption near-edge structure (XANES) spectra can be analyzed using machine learning algorithms to establish the relationship between intuitive descriptors of spectra and local atomic and electronic structures, providing a simple and fast tool for extracting structural parameters, successfully demonstrated high prediction quality on experimental data.
NPJ COMPUTATIONAL MATERIALS
(2021)
Article
Chemistry, Inorganic & Nuclear
Wiebke Drescher, Daniel Schmitt-Monreal, Christoph R. Jacob, Christian Kleeberg
Article
Chemistry, Physical
Matteo De Santis, Leonardo Belpassi, Christoph R. Jacob, Andre Severo Pereira Gomes, Francesco Tarantelli, Lucas Visscher, Loriano Storchi
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2020)
Article
Multidisciplinary Sciences
Marcel M. Willich, Lucas Wegener, Johannes Vornweg, Manuel Hohgardt, Julia Nowak, Mario Wolter, Christoph R. Jacob, Peter Jomo Walla
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2020)
Article
Chemistry, Physical
Mario Wolter, Moritz von Looz, Henning Meyerhenke, Christoph R. Jacob
Summary: The study introduces a systematic partitioning scheme aimed at minimizing the fragmentation error of a local target quantity for a given maximum fragment size by constructing a weighted graph representation of the protein. This graph-based scheme consistently improves upon the commonly employed naive approach of using fixed-size fragments for large protein treatments in quantum-chemical fragmentation methods.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Multidisciplinary
Simon Kolb, Martin Petzold, Felix Brandt, Peter G. Jones, Christoph R. Jacob, Daniel B. Werz
Summary: The first electrochemical activation of D-A cyclopropanes and D-A cyclobutanes leading to the formation of highly reactive radical cations is described. Molecular oxygen is formally inserted after direct or DDQ-assisted anodic oxidation of the strained carbocycles, delivering beta- and gamma-hydroxy ketones and 1,2-dioxanes electrocatalytically. Insights into the mechanism of the oxidative process are obtained experimentally and by additional quantum-chemical calculations, demonstrating the synthetic potential of the reaction products through diverse derivatizations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Daniel Schmitt-Monreal, Christoph R. Jacob
Summary: Fragmentation methods based on many-body expansion are attractive for quantum-chemical treatment of large molecular systems. Traditionally, energy-based many-body expansion may suffer from slow convergence, especially in systems with strong polarization effects. Density-based many-body expansion offers a promising alternative, taking into account higher-order polarization effects and showing accurate predictions for water cluster systems.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Felix Brandt, Christoph R. Jacob
Summary: QM/MM studies of enzymatic reactions are subject to uncertainty, and the effect of different choices by the simulation scientist when setting up QM/MM calculations is often unclear. This study quantifies uncertainties in QM/MM calculations by assessing the sensitivity of QM/MM reaction energies with respect to variations of the MM point charges. A protocol is devised to systematically construct QM regions that minimize this uncertainty.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Multidisciplinary
Felix Kaspar, Felix Brandt, Sarah Westarp, Lea Eilert, Sebastian Kemper, Anke Kurreck, Peter Neubauer, Christoph R. R. Jacob, Anett Schallmey
Summary: Biocatalytic nucleoside (trans-)glycosylations catalyzed by nucleoside phosphorylases have become a practical method for preparing modified nucleosides, which are important in treating cancer and viral infections. However, the reaction yield is limited by the thermodynamic properties of the nucleosides, hindering access to desired target nucleosides. This study introduces a new approach by using inorganic borate to bias the esterification of nucleosides and ribosyl phosphates, thus affecting the apparent equilibrium in phosphorolysis and glycosylation reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Julia Brueggemann, Mario Wolter, Christoph R. Jacob
Summary: We present an efficient quantum-chemical protocol for predicting static 2D IR spectra without the need for empirical parameters. By calculating anharmonic vibrational energy levels and transition dipole moments, we can reliably predict 2D IR spectra of metal carbonyl complexes and dipeptides. Furthermore, we demonstrate how to extract the parameters of vibrational exciton models from these calculations.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Stefanie Schuermann, Johannes R. Vornweg, Mario Wolter, Christoph R. Jacob
Summary: The many-body expansion (MBE) is an efficient quantum-chemical method for molecular clusters, but its convergence can be slow for clusters with large intermolecular polarization effects. This study assesses the accuracy of the energy-based MBE and the density-based MBE for ion-water clusters, and finds that the density-based two-body expansion outperforms the energy-based three-body expansion. The results suggest that accurate and efficient quantum-chemical calculations for large ion-water clusters and condensed-phase systems are possible.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Johannes R. Vornweg, Mario Wolter, Christoph R. Jacob
Summary: The MFCC method is a widely used fragmentation method for quantum-chemical treatment of proteins. However, it lacks consideration of interactions between amino acid fragments. In this study, we propose a combination of MFCC fragmentation with second-order many-body expansion (MBE) to include all fragment-fragment, fragment-cap, and cap-cap interactions, while maintaining the simplicity and chemical meaningfulness of MFCC. With the MFCC-MBE(2) scheme, we demonstrate a significant reduction in energy errors and accurate prediction of relative energies of protein conformers.
JOURNAL OF COMPUTATIONAL CHEMISTRY
(2023)
Article
Chemistry, Physical
Felix Brandt, Christoph R. Jacob
Summary: The construction of a suitable QM region is crucial in QM/MM simulations for enzymatic reactions. Most existing methods are based on distance or electrostatic effect, which may miss non-electrostatic and long-range interactions. In this study, we propose using protein network analysis and find that protein network centralities can be a useful descriptor for systematic QM region construction. Combined with point charge variation analysis, they can identify important residues missed by purely electrostatic approaches.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Felix Brandt, Christoph R. Jacob
Summary: The setup of QM/MM calculations is a complex task that requires careful decision-making to achieve accurate and consistent results. The main challenge is to construct the QM region, taking into account the relevant parts of the environment while excluding less important ones.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Julia Brueggemann, Christoph R. Jacob
FARADAY DISCUSSIONS
(2020)
Article
Chemistry, Multidisciplinary
Tobias G. Bergmann, Michael O. Welzel, Christoph R. Jacob