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Franzke YJ, Bruder F, Gillhuber S, Holzer C, Weigend F. Paramagnetic Nuclear Magnetic Resonance Shifts for Triplet Systems and Beyond with Modern Relativistic Density Functional Methods. J Phys Chem A 2024; 128:670-686. [PMID: 38195394 DOI: 10.1021/acs.jpca.3c07093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
An efficient framework for the calculation of paramagnetic NMR (pNMR) shifts within exact two-component (X2C) theory and (current-dependent) density functional theory (DFT) up to the class of local hybrid functionals (LHFs) is presented. Generally, pNMR shifts for systems with more than one unpaired electron depend on the orbital shielding contribution and a temperature-dependent term. The latter includes zero-field splitting (ZFS), hyperfine coupling (HFC), and the g-tensor. For consistency, we calculate these three tensors at the same level of theory, i.e., using scalar-relativistic X2C augmented with spin-orbit perturbation theory. Results for pNMR chemical shifts of transition-metal complexes reveal that this X2C-DFT framework can yield good results for both the shifts and the individual tensor contributions of metallocenes and related systems, especially if the HFC constant is large. For small HFC constants, the relative error is often large, and sometimes the sign may be off. 4d and 5d complexes with more complicated structures demonstrate the limitations of a fully DFT-based approach. Additionally, a Co-based complex with a very large ZFS and pronounced multireference character is not well described. Here, a hybrid DFT-multireference framework is necessary for accurate results. Our results show that X2C is sufficient to describe relativistic effects and computationally cheaper than a fully relativistic approach. Thus, it allows use of large basis sets for converged HFCs. Overall, current-dependent meta-generalized gradient approximations and LHFs show some potential; however, the currently available functionals leave a lot to be desired, and the predictive power is limited.
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Affiliation(s)
- Yannick J Franzke
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Florian Bruder
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Sebastian Gillhuber
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 15, 76131 Karlsruhe, Germany
| | - Christof Holzer
- Institute of Theoretical Solid State Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1, 76131 Karlsruhe, Germany
| | - Florian Weigend
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
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Ren P, Zhang T, Jain N, Ching HYV, Jaworski A, Barcaro G, Monti S, Silvestre-Albero J, Celorrio V, Chouhan L, Rokicińska A, Debroye E, Kuśtrowski P, Van Doorslaer S, Van Aert S, Bals S, Das S. An Atomically Dispersed Mn-Photocatalyst for Generating Hydrogen Peroxide from Seawater via the Water Oxidation Reaction (WOR). J Am Chem Soc 2023. [PMID: 37487055 DOI: 10.1021/jacs.3c03785] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
In this work, we have fabricated an aryl amino-substituted graphitic carbon nitride (g-C3N4) catalyst with atomically dispersed Mn capable of generating hydrogen peroxide (H2O2) directly from seawater. This new catalyst exhibited excellent reactivity, obtaining up to 2230 μM H2O2 in 7 h from alkaline water and up to 1800 μM from seawater under identical conditions. More importantly, the catalyst was quickly recovered for subsequent reuse without appreciable loss in performance. Interestingly, unlike the usual two-electron oxygen reduction reaction pathway, the generation of H2O2 was through a less common two-electron water oxidation reaction (WOR) process in which both the direct and indirect WOR processes occurred; namely, photoinduced h+ directly oxidized H2O to H2O2 via a one-step 2e- WOR, and photoinduced h+ first oxidized a hydroxide (OH-) ion to generate a hydroxy radical (•OH), and H2O2 was formed indirectly by the combination of two •OH. We have characterized the material, at the catalytic sites, at the atomic level using electron paramagnetic resonance, X-ray absorption near edge structure, extended X-ray absorption fine structure, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, magic-angle spinning solid-state NMR spectroscopy, and multiscale molecular modeling, combining classical reactive molecular dynamics simulations and quantum chemistry calculations.
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Affiliation(s)
- Peng Ren
- Department of Chemistry, University of Antwerp, Antwerp 2020, Belgium
| | - Tong Zhang
- Department of Chemistry, University of Antwerp, Antwerp 2020, Belgium
| | - Noopur Jain
- EMAT and NANOlab Center of Excellence, Department of Physics, University of Antwerp, Antwerp 2020, Belgium
| | - H Y Vincent Ching
- Department of Chemistry, University of Antwerp, Antwerp 2020, Belgium
| | - Aleksander Jaworski
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm 10691, Sweden
| | - Giovanni Barcaro
- CNR-IPCF, Institute for Chemical and Physical Processes, Area della Ricerca, Pisa I-56124, Italy
| | - Susanna Monti
- CNR-ICCOM, Institute of Chemistry of Organometallic Compounds, Area della Ricerca, Pisa I-56124, Italy
| | | | - Veronica Celorrio
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | - Lata Chouhan
- Department of Chemistry, KU Leuven, Leuven 3001, Belgium
| | - Anna Rokicińska
- Department of Chemical Technology, Jagiellonian University, Krakow 30-387, Poland
| | - Elke Debroye
- Department of Chemistry, KU Leuven, Leuven 3001, Belgium
| | - Piotr Kuśtrowski
- Department of Chemical Technology, Jagiellonian University, Krakow 30-387, Poland
| | | | - Sandra Van Aert
- EMAT and NANOlab Center of Excellence, Department of Physics, University of Antwerp, Antwerp 2020, Belgium
| | - Sara Bals
- EMAT and NANOlab Center of Excellence, Department of Physics, University of Antwerp, Antwerp 2020, Belgium
| | - Shoubhik Das
- Department of Chemistry, University of Antwerp, Antwerp 2020, Belgium
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Pyykkönen A, Vaara J. Computational NMR of the iron pyrazolylborate complexes [Tp 2Fe] + and Tp 2Fe including solvation and spin-crossover effects. Phys Chem Chem Phys 2023; 25:3121-3135. [PMID: 36621831 DOI: 10.1039/d2cp03721a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Transition metal complexes have important roles in many biological processes as well as applications in fields such as pharmacy, chemistry and materials science. Paramagnetic nuclear magnetic resonance (pNMR) is a valuable tool in understanding such molecules, and theoretical computations are often advantageous or even necessary in the assignment of experimental pNMR signals. We have employed density functional theory (DFT) and the domain-based local pair natural orbital coupled-cluster method with single and double excitations (DLPNO-CCSD), as well as a number of model improvements, to determine the critical hyperfine part of the chemical shifts of the iron pyrazolylborate complexes [Tp2Fe]+ and Tp2Fe using a modern version of the Kurland-McGarvey theory, which is based on parameterising the hyperfine, electronic Zeeman and zero-field splitting interactions via the parameters of the electron paramagnetic resonance Hamiltonian. In the doublet [Tp2Fe]+ system, the calculations suggest a re-assignment of the 13C signal shifts. Consideration of solvent via the conductor-like polarisable continuum model (C-PCM) versus explicit solvent molecules reveals C-PCM alone to be insufficient in capturing the most important solvation effects. Tp2Fe exhibits a spin-crossover effect between a high-spin quintet (S = 2) and a low-spin singlet (S = 0) state, and its recorded temperature dependence can only be reproduced theoretically by accounting for the thermal Boltzmann distribution of the open-shell excited state and the closed-shell ground-state occupations. In these two cases, DLPNO-CCSD is found, in calculating the hyperfine couplings, to be a viable alternative to DFT, the demonstrated shortcomings of which have been a significant issue in the development of computational pNMR.
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Affiliation(s)
- Ari Pyykkönen
- NMR Research Unit, University of Oulu, P.O. Box 3000, Oulu FIN-90014, Finland.
| | - Juha Vaara
- NMR Research Unit, University of Oulu, P.O. Box 3000, Oulu FIN-90014, Finland.
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