Dr. Alexander Schnegg - EPR Research Group

Vita
Dipl.-Phys.Free University Berlin (1998)
Dr. rer. nat.Institut für Experimentalphysik, Free University Berlin (1999-2003)
PostdocMax Planck Institute for Bioinorganic Chemistry; today: MPI CEC (2004-2005)
PostdocHelmholtz Zentrum Berlin für Materialien und Energie (HZB) (2006-2013)
Staff ScientistHZB's EPR lab (2013-2018)
Adjunct ProfessorMonash University, Melbourne, Australia (2016-2021)
Research group leaderMPI CEC (since 2018)
  
Publications

Full publications list

Publications at MPI CEC

[1] N. Frank; M. B. Chaudhari; M. Leutzsch; B. Helmich-Paris; P. C. Bruzzese; D. Nater; N. Nöthling; A. Schnegg; S. R. Waldvogel; B. List, The photohydrolysis of furans. Science 2026, 391, 267, https://doi.org/10.1126/science.aec6532.

[2] M. Amann; M. Drosou; T. Al Said; A. Allgaier; Y. Kutin; P. W. Antoni; J. J. Holstein; M. Kasanmascheff; J. van Slageren; A. Schnegg; D. A. Pantazis; M. M. Hansmann, Triplet Metallovinylidenes of Palladium and Platinum Based on a Chelating P/Diazoalkene Ligand. Angew. Chem., Int. Ed. 2026, 65, e16032, https://doi.org/10.1002/anie.202516032.

[3] K. Abdiaziz; L. Ni; D. Demirbas; H. Haak; E. Reijerse; P. Theis; W. Jiang; S. Chabbra; T. Lunkenbein; U. I. Kramm; A. Schnegg, Reversibly Redox-Active Iron Oxide Structures in FeNC Catalysts Identified by Microscopy and Spectroelectrochemical EPR and Mössbauer Methods. J. Am. Chem. Soc. 2026, 148, 3995, https://doi.org/10.1021/jacs.5c12396.

[4] W. Wan; L. Kang; A. Schnegg; O. Ruediger; Z. Chen; C. S. Allen; L. Liu; S. Chabbra; S. DeBeer; S. Heumann, Carbon-Supported Single Fe/Co/Ni Atom Catalysts for Water Oxidation: Unveiling the Dynamic Active Sites. Angew. Chem., Int. Ed. 2025, 64, e202424629, https://doi.org/10.1002/anie.202424629.

[5] C. Van Stappen; E. Reijerse; S. Chabbra; A. Schnegg; Y. Lu, Contrasting secondary coordination sphere effects on spin density distribution in Red vs. Blue Cu azurin. J Biol Inorg Chem 2025, https://doi.org/10.1007/s00775-025-02116-x.

[6] D. Schellenburg; T. Bihnam; C. Placke-Yan; G. Bendt; O. Prymak; T. Sato; D. Jennings; C. Leiva-Leroy; D. Zhang; M. Nachev; K. Dhaka; F. Nkou; U. Hagemann; M. Heidelmann; S. Kenmoe; K. S. Exner; B. Sures; M. Muhler; C. H. Liebscher; A. Schnegg; S. Schulz; S. Barcikowski; S. Reichenberger, Mechanistic Understanding of Laser-Induced Defect Engineering of Anisotropic Cobalt Oxide Spinel Platelets in Water. ChemCatChem 2025, n/a, e01054, https://doi.org/10.1002/cctc.202501054.

[7] Z. Qiu; P. C. Bruzzese; Z. Wang; H. Deng; M. Leutzsch; C. Farès; S. Chabbra; F. Neese; A. Schnegg; C. N. Neumann, 3-Center-3-Electron σ-Adduct Enables Silyl Radical Transfer below the Minimum Barrier for Silyl Radical Formation. J. Am. Chem. Soc. 2025, 147, 12024, https://doi.org/10.1021/jacs.4c18445.

[8] M. C. Neben; N. Wegerich; T. A. Al Said; R. R. Thompson; S. Demeshko; K. Dollberg; I. Tkach; G. P. Van Trieste, III; H. Verplancke; C. von Hänisch; M. C. Holthausen; D. C. Powers; A. Schnegg; S. Schneider, Transient Triplet Metallopnictinidenes M–Pn (M = PdII, PtII; Pn = P, As, Sb): Characterization and Dimerization. J. Am. Chem. Soc. 2025, 147, 5330, https://doi.org/10.1021/jacs.4c16830.

[9] A. Mateos-Calbet; P. C. Bruzzese; M. A. Mermigki; A. Schnegg; D. A. Pantazis; J. Cornella, Rapid Oxygen Atom Transfer at a Catalysis-Relevant Ni(I)–Alkyl Complex with N2O. J. Am. Chem. Soc. 2025, 147, 19438, https://doi.org/10.1021/jacs.5c03351.

[10] M. Magott; M. Arczyński; L. Malec; M. Rams; M. Rouzières; A. Rogalev; F. Wilhelm; I. Oyarzabal; T. Lohmiller; A. Schnegg; C. de Graaf; C. Mathonière; R. Clérac; D. Pinkowicz, Reversible single crystal photochemistry and spin state switching in a metal-cyanide complex. Nat. Commun. 2025, 16, 8377, https://doi.org/10.1038/s41467-025-63523-x.

[11] Y. Kutin; T. Koike; M. Drosou; A. Schnegg; D. A. Pantazis; M. Kasanmascheff; M. M. Hansmann, Ph3PC – A Monosubstituted C(0) Atom in Its Triplet State. Angew. Chem., Int. Ed. 2025, 64, e202424166, https://doi.org/10.1002/anie.202424166.

[12] A. Hareendran; T. Sato; M. Dreyer; A. Rabe; S. Salamon; N. Sülzner; U. Hagemann; C. Leiva-Leroy; N. Cosanne; K. Ravi; D. Zhang; G. W. Busser; M. Behrens; C. Hättig; H. Wende; A. Schnegg; M. Muhler, Mechanistic and Structural Insights into the Liquid-Phase Oxidation of Cyclohexane over LaCo0.7Fe0.3O3 Perovskite Nanoparticles. ACS Catal. 2025, 15, 12773, https://doi.org/10.1021/acscatal.5c02919.

[13] T. M. Diederich; T. Wehland; M. Schrodt; N. Kochetov; A. Schnegg; C. M. Jimenez-Muñoz; V. Krewald; L. Ni; N. S. Salas; U. I. Kramm; J. Ballmann; M. Enders, Electronic and Magnetic Properties of Ferrous Iron in a True Square-Planar Molecular Environment. Chemistry – A European Journal 2025,31, e202501474, https://doi.org/10.1002/chem.202501474.

[14] W. Chen; N. Kochetov; T. Lohmiller; Q. Liu; L. Deng; A. Schnegg; S. Ye, A Spectroscopic Criterion for Identifying the Degree of Ground-Level Near-Degeneracy Derived from Effective Hamiltonian Analyses of Three-Coordinate Iron Complexes. JACS Au2025, 5, 1016, https://doi.org/10.1021/jacsau.4c01256.

[15] A. Bera; S. Bimmermann; P. Gerschel; D. J. Barman; L. Gerndt; T. Lohmiller; K. Abdiaziz; A. Schnegg; M. Orio; D. G. H. Hetterscheid; K. L. Bren; M. Roemelt; U.-P. Apfel; K. Ray, Mechanistic Promiscuity in Cobalt Mediated CO2 Reduction Reaction: One- versus Two-Electron Reduction Process. Angew. Chem., Int. Ed.2025, n/a, e202503705, https://doi.org/10.1002/anie.202503705.

[16] T. Al Said; D. Spinnato; K. Holldack; F. Neese; J. Cornella; A. Schnegg, Direct Determination of a Giant Zero-Field Splitting of 5422 cm–1 in a Triplet Organobismuthinidene by Infrared Electron Paramagnetic Resonance. J. Am. Chem. Soc. 2025, 147, 84, https://doi.org/10.1021/jacs.4c14795.

[17] M. H. Pohle; T. Lohmiller; M. Böhme; M. Rams; S. Ziegenbalg; H. Görls; A. Schnegg; W. Plass, THz-EPR-based Magneto-Structural Correlations for Cobalt(II) Single-Ion Magnets With Bis-Chelate Coordination. Chemistry – A European Journal 2024, 30, e202401545, https://doi.org/10.1002/chem.202401545.

[18] J. Mateos; T. Schulte; D. Behera; M. Leutzsch; A. Altun; T. Sato; F. Waldbach; A. Schnegg; F. Neese; T. Ritter, Nitrate reduction enables safer aryldiazonium chemistry. Science2024, 384, 446, https://doi.org/10.1126/science.adn7006.

[19] M. F. Lukman; P. C. Bruzzese; W. Böhlmann; A. Schnegg; A. Pöppl, Spin Density Studies of Tetrahedral Cu(II) Ions Doped into Porous Zeolitic Imidazolate Frameworks. The Journal of Physical Chemistry C 2024,128, 9130, https://doi.org/10.1021/acs.jpcc.4c01261.

[20] Q. Jin; P. C. Bruzzese; A. Vetere; C. Weidenthaler; E. Budiyanto; M. Henglin; N. Noethling; A. Schnegg; C. N. Neumann, Programmable Metal Arrangements in Metal-Organic Polyhedra and Frameworks. ChemRxiv 2024, https://doi.org/10.26434/chemrxiv-2024-h09tl.

[21] A. Hareendran; M. Dreyer; T. Sato; N. Cosanne; C. L. Leroy; B. Peng; M. Behrens; A. Schnegg; M. Muhler, Aerobic Oxidation of Cyclohexane over LaCoxFe1-xO3 Perovskites in the Liquid Phase. Molecular Catalysis 2024, 569, 114615, https://doi.org/10.1016/j.mcat.2024.114615.

[22] M. Deitermann; T. Sato; Y. Haver; A. Schnegg; M. Muhler; B. T. Mei, Mechanistic understanding of the thermal-assisted photocatalytic oxidation of methanol-to-formaldehyde with water vapor over Pt/SrTiO3. Phys Chem Chem Phys 2024, 26, 14960, https://doi.org/10.1039/D4CP01106F.

[23] C. de Lichtenberg; L. Rapatskiy; M. Reus; E. Heyno; A. Schnegg; M. M. Nowaczyk; W. Lubitz; J. Messinger; N. Cox, Assignment of the slowly exchanging substrate water of nature’s water-splitting cofactor. Proceedings of the National Academy of Sciences 2024, 121, e2319374121, https://doi.org/10.1073/pnas.2319374121.

[24] A. Bogdanov; V. Frydman; M. Seal; L. Rapatskiy; A. Schnegg; W. Zhu; M. Iron; A. M. Gronenborn; D. Goldfarb, Extending the Range of Distances Accessible by 19F Electron–Nuclear Double Resonance in Proteins Using High-Spin Gd(III) Labels. J. Am. Chem. Soc. 2024, https://doi.org/10.1021/jacs.3c13745.

[25] X. Yang; E. J. Reijerse; N. Nöthling; D. J. SantaLucia; M. Leutzsch; A. Schnegg; J. Cornella, Synthesis, Isolation, and Characterization of Two Cationic Organobismuth(II) Pincer Complexes Relevant in Radical Redox Chemistry. J. Am. Chem. Soc. 2023, 145, 5618−5623, https://doi.org/10.1021/jacs.2c12564.

[26] S. Tretiakov; M. Lutz; C. J. Titus; F. de Groot; J. Nehrkorn; T. Lohmiller; K. Holldack; A. Schnegg; M. F. X. Tarrago; P. Zhang; S. Ye; D. Aleshin; A. Pavlov; V. Novikov; M.-E. Moret, Homoleptic Fe(III) and Fe(IV) Complexes of a Dianionic C3-Symmetric Scorpionate. Inorganic Chemistry 2023,62, 10613, https://doi.org/10.1021/acs.inorgchem.3c00871.

[27] V. A. Tran; M. Teucher; L. Galazzo; B. Sharma; T. Pongratz; S. M. Kast; D. Marx; E. Bordignon; A. Schnegg; F. Neese, Dissecting the Molecular Origin of g-Tensor Heterogeneity and Strain in Nitroxide Radicals in Water: Electron Paramagnetic Resonance Experiment versus Theory. J. Phys. Chem. A 2023, 127, 6447, https://doi.org/10.1021/acs.jpca.3c02879.

[28] S. L. Schumann; S. Kotnig; Y. Kutin; M. Drosou; L. M. Stratmann; Y. Streltsova; A. Schnegg; D. A. Pantazis; G. H. Clever; M. Kasanmascheff, Structure and Flexibility of Copper-Modified DNA G-Quadruplexes Investigated by 19F ENDOR Experiments at 34 GHz**. Chemistry – A European Journal 2023,29, e202302527, https://doi.org/10.1002/chem.202302527.

[29] M. Rams; T. Lohmiller; M. Böhme; A. Jochim; M. Foltyn; A. Schnegg; W. Plass; C. Näther, Weakening the Interchain Interactions in One Dimensional Cobalt(II) Coordination Polymers by Preventing Intermolecular Hydrogen Bonding. Inorganic Chemistry 2023, 62, 10420, https://doi.org/10.1021/acs.inorgchem.3c01324.

[30] M. H. Pohle; M. Böhme; T. Lohmiller; S. Ziegenbalg; L. Blechschmidt; H. Görls; A. Schnegg; W. Plass, Magnetic Anisotropy and Relaxation of Pseudotetrahedral [N2O2] Bis-Chelate Cobalt(II) Single-Ion Magnets Controlled by Dihedral Twist Through Solvomorphism. Chemistry – A European Journal 2023, 29, e202202966, https://doi.org/10.1002/chem.202202966.

[31] M. Mato; P. C. Bruzzese; F. Takahashi; M. Leutzsch; E. J. Reijerse; A. Schnegg; J. Cornella, Oxidative Addition of Aryl Electrophiles into a Red-Light-Active Bismuthinidene. J. Am. Chem. Soc. 2023, 145, 18742, https://doi.org/10.1021/jacs.3c06651.

[32] S. Lima; M. H. Pohle; M. Böhme; H. Görls; T. Lohmiller; A. Schnegg; R. Dinda; W. Plass, Kink distortion of the pseudo-S4 axis in pseudotetrahedral [N2O2] bis-chelate cobalt(ii) single-ion magnets leads to increased magnetic anisotropy. Dalton Transactions 2023, 52, 9787, https://doi.org/10.1039/D3DT01604H.

[33] K. Lau; F. Niemann; K. Abdiaziz; M. Heidelmann; Y. Yang; Y. Tong; M. Fechtelkord; T. C. Schmidt; A. Schnegg; R. K. Campen; B. Peng; M. Muhler; S. Reichenberger; S. Barcikowski, Differentiating between Acidic and Basic Surface Hydroxyls on Metal Oxides by Fluoride Substitution: A Case Study on Blue TiO2 from Laser Defect Engineering. Angew. Chem., Int. Ed. 2023,62, e202213968, https://doi.org/10.1002/anie.202213968.

[34] E. M. H. Larsen; N. A. Bonde; H. Weihe; J. Ollivier; T. Vosch; T. Lohmiller; K. Holldack; A. Schnegg; M. Perfetti; J. Bendix, Experimental assignment of long-range magnetic communication through Pd & Pt metallophilic contacts. Chem. Sci.2023, 14, 266, http://dx.doi.org/10.1039/D2SC05201F.

[35] X. Yang; E. J. Reijerse; K. Bhattacharyya; M. Leutzsch; M. Kochius; N. Nöthling; J. Busch; A. Schnegg; A. A. Auer; J. Cornella, Radical Activation of N–H and O–H Bonds at Bismuth(II). J. Am. Chem. Soc. 2022, 144, 16535, https://doi.org/10.1021/jacs.2c05882.

[36] M. Teucher; J. W. Sidabras; A. Schnegg, Milliwatt three- and four-pulse double electron electron resonance for protein structure determination. Phys Chem Chem Phys 2022, 24, 12528, 10.1039/D1CP05508A.

[37] M. K. Sharma; S. Chabbra; C. Wölper; H. M. Weinert; E. J. Reijerse; A. Schnegg; S. Schulz, Modulating the frontier orbitals of L(X)Ga-substituted diphosphenes [L(X)GaP]2 (X = Cl, Br) and their facile oxidation to radical cations. Chem. Sci.2022, 13, 12643, 10.1039/D2SC04207J.

[38] T. Lohmiller; C.-J. Spyra; S. Dechert; S. Demeshko; E. Bill; A. Schnegg; F. Meyer, Antisymmetric Spin Exchange in a μ-1,2-Peroxodicopper(II) Complex with an Orthogonal Cu–O–O–Cu Arrangement and S = 1 Spin Ground State Characterized by THz-EPR. JACS Au 2022, 2, 1134, 10.1021/jacsau.2c00139.

[39] S. Chatterjee; I. Harden; G. Bistoni; R. G. Castillo; S. Chabbra; M. van Gastel; A. Schnegg; E. Bill; J. A. Birrell; B. Morandi; F. Neese; S. DeBeer, A Combined Spectroscopic and Computational Study on the Mechanism of Iron-Catalyzed Aminofunctionalization of Olefins Using Hydroxylamine Derived N–O Reagent as the “Amino” Source and “Oxidant”. J. Am. Chem. Soc. 2022, 144, 2637, 10.1021/jacs.1c11083.

[40] M. Tarrago; C. Römelt; J. Nehrkorn; A. Schnegg; F. Neese; E. Bill; S. Ye, Experimental and Theoretical Evidence for an Unusual Almost Triply Degenerate Electronic Ground State of Ferrous Tetraphenylporphyrin. Inorganic Chemistry2021, 60, 4966, 10.1021/acs.inorgchem.1c00031.

[41] J. C. Ott; E. A. Suturina; I. Kuprov; J. Nehrkorn; A. Schnegg; M. Enders; L. H. Gade, Observability of Paramagnetic NMR Signals at over 10 000 ppm Chemical Shifts. Angew. Chem., Int. Ed. 2021, 60, 22856, https://doi.org/10.1002/anie.202107944.

[42] J. Nehrkorn; I. A. Valuev; M. A. Kiskin; A. S. Bogomyakov; E. A. Suturina; A. M. Sheveleva; V. I. Ovcharenko; K. Holldack; C. Herrmann; M. V. Fedin; A. Schnegg; S. L. Veber, Easy-plane to easy-axis anisotropy switching in a Co(ii) single-ion magnet triggered by the diamagnetic lattice. Journal of Materials Chemistry C2021, 9, 9446, 10.1039/D1TC01105G.

[43] J. Nehrkorn; S. M. Greer; B. J. Malbrecht; K. J. Anderton; A. Aliabadi; J. Krzystek; A. Schnegg; K. Holldack; C. Herrmann; T. A. Betley; S. Stoll; S. Hill, Spectroscopic Investigation of a Metal–Metal-Bonded Fe6 Single-Molecule Magnet with an Isolated S = 19/2 Giant-Spin Ground State. Inorganic Chemistry 2021, 60, 4610, 10.1021/acs.inorgchem.0c03595.

[44] C. Liu; A. M. Geer; C. Webber; C. B. Musgrave; S. Gu; G. Johnson; D. A. Dickie; S. Chabbra; A. Schnegg; H. Zhou; C.-J. Sun; S. Hwang; W. A. Goddard; S. Zhang; T. B. Gunnoe, Immobilization of “Capping Arene” Cobalt(II) Complexes on Ordered Mesoporous Carbon for Electrocatalytic Water Oxidation. ACS Catal. 2021, 11, 15068, 10.1021/acscatal.1c04617.

[45] S. Künstner; A. Chu; K. P. Dinse; A. Schnegg; J. E. McPeak; B. Naydenov; J. Anders; K. Lips, Rapid-scan electron paramagnetic resonance using an EPR-on-a-Chip sensor. Magnetic Resonance 2021, 2, 673, 10.5194/mr-2-673-2021.

[46] J. Büker; B. Alkan; S. Chabbra; N. Kochetov; T. Falk; A. Schnegg; C. Schulz; H. Wiggers; M. Muhler; B. Peng, Liquid-Phase Cyclohexene Oxidation with O2 over Spray-Flame-Synthesized La1-xSrxCoO3 Perovskite Nanoparticles. Chemistry - A European Journal 2021, 27, 16912, DOI: 10.1002/chem.202103381.

[47] S. A. Bonke; T. Risse; A. Schnegg; A. Brückner, In situ electron paramagnetic resonance spectroscopy for catalysis. Nature Review Methods Primers 2021, 1, 33, 10.1038/s43586-021-00031-4.

[48] A. N. Bone; C. N. Widener; D. H. Moseley; Z. Liu; Z. Lu; Y. Cheng; L. L. Daemen; M. Ozerov; J. Telser; K. Thirunavukkuarasu; D. Smirnov; S. M. Greer; S. Hill; J. Krzystek; K. Holldack; A. Aliabadi; A. Schnegg; K. R. Dunbar; Z. L. Xue, Applying Unconventional Spectroscopies to the Single-Molecule Magnets, Co(PPh(3) )(2) X(2) (X=Cl, Br, I): Unveiling Magnetic Transitions and Spin-Phonon Coupling. Chemistry2021, 27, 11110, 10.1002/chem.202100705.

[49] M. Viciano-Chumillas; G. Blondin; M. Clémancey; J. Krzystek; M. Ozerov; D. Armentano; A. Schnegg; T. Lohmiller; J. Telser; F. Lloret; J. Cano, Single-Ion Magnetic Behaviour in an Iron(III) Porphyrin Complex: A Dichotomy Between High Spin and 5/2–3/2 Spin Admixture. Chemistry – A European Journal 2020, 26, 14242, https://doi.org/10.1002/chem.202003052.

[50] M. Rams; A. Jochim; M. Böhme; T. Lohmiller; M. Ceglarska; M. M. Rams; A. Schnegg; W. Plass; C. Näther, Single-Chain Magnet Based on Cobalt(II) Thiocyanate as XXZ Spin Chain. Chemistry - A European Journal 2020,26, 2837, 10.1002/chem.201903924.

[51] A. A. Pavlov; J. Nehrkorn; S. V. Zubkevich; M. V. Fedin; K. Holldack; A. Schnegg; V. V. Novikov, A Synergy and Struggle of EPR, Magnetometry and NMR: A Case Study of Magnetic Interaction Parameters in a Six-Coordinate Cobalt(II) Complex. Inorganic Chemistry 2020, 59, 10746, 10.1021/acs.inorgchem.0c01191.

[52] Y. Ma; Y. Pang; S. Chabbra; E. J. Reijerse; A. Schnegg; J. Niski; M. Leutzsch; J. Cornella, Radical C‒N Borylation of Aromatic Amines Enabled by a Pyrylium Reagent. Chemistry – A European Journal 2020, n/a, 10.1002/chem.202000412.

[53] Y.-H. Lin; Y. Kutin; M. van Gastel; E. Bill; A. Schnegg; S. Ye; W.-Z. Lee, A Manganese(IV)-Hydroperoxo Intermediate Generated by Protonation of the Corresponding Manganese(III)-Superoxo Complex. J. Am. Chem. Soc. 2020, 142, 10255, 10.1021/jacs.0c02756.

[54] J. Li; J. Chen; R. Sang; W.-S. Ham; M. B. Plutschack; F. Berger; S. Chabbra; A. Schnegg; C. Genicot; T. Ritter, Photoredox catalysis with aryl sulfonium salts enables site-selective late-stage fluorination. Nat. Chem. 2020, 12, 56, 10.1038/s41557-019-0353-3.

[55] J. Krzystek; A. Schnegg; A. Aliabadi; K. Holldack; S. A. Stoian; A. Ozarowski; S. D. Hicks; M. M. Abu-Omar; K. E. Thomas; A. Ghosh; K. P. Caulfield; Z. J. Tonzetich; J. Telser, Advanced Paramagnetic Resonance Studies on Manganese and Iron Corroles with a Formal d4 Electron Count. Inorganic Chemistry 2020, 59, 1075, 10.1021/acs.inorgchem.9b02635.

[56] A. Jochim; T. Lohmiller; M. Rams; M. Böhme; M. Ceglarska; A. Schnegg; W. Plass; C. Näther, Influence of the Coligand onto the Magnetic Anisotropy and the Magnetic Behavior of One-Dimensional Coordination Polymers. Inorganic Chemistry 2020, 59, 8971, 10.1021/acs.inorgchem.0c00815.

[57] M. Böhme; A. Jochim; M. Rams; T. Lohmiller; S. Suckert; A. Schnegg; W. Plass; C. Näther, Variation of the Chain Geometry in Isomeric 1D Co(NCS)2 Coordination Polymers and Their Influence on the Magnetic Properties. Inorganic Chemistry 2020, 59, 5325, 10.1021/acs.inorgchem.9b03357.

[58] G. Zhao; G. W. Busser; C. Froese; B. Hu; S. A. Bonke; A. Schnegg; Y. Ai; D. Wei; X. Wang; B. Peng; M. Muhler, Anaerobic Alcohol Conversion to Carbonyl Compounds over Nanoscaled Rh-Doped SrTiO3 under Visible Light. The Journal of Physical Chemistry Letters 2019, 10, 2075, 10.1021/acs.jpclett.9b00621.

[59] J. W. Sidabras; J. Duan; M. Winkler; T. Happe; R. Hussein; A. Zouni; D. Suter; A. Schnegg; W. Lubitz; E. J. Reijerse, Extending electron paramagnetic resonance to nanoliter volume protein single crystals using a self-resonant microhelix. Science Advances 2019, 5, eaay1394, 10.1126/sciadv.aay1394 %J Science Advances.

[60] J. Nehrkorn; S. A. Bonke; A. Aliabadi; M. Schwalbe; A. Schnegg, Examination of the Magneto-Structural Effects of Hangman Groups on Ferric Porphyrins by EPR. Inorganic Chemistry 2019, 58, 14228, 10.1021/acs.inorgchem.9b02348.

[61] Y. Kutin; N. Cox; W. Lubitz; A. Schnegg; O. Rüdiger, In Situ EPR Characterization of a Cobalt Oxide Water Oxidation Catalyst at Neutral pH. Catalysts 2019, 9, 926, 10.3390/catal9110926.

[62] J. Cheng; J. Liu; X. Leng; T. Lohmiller; A. Schnegg; E. Bill; S. Ye; L. Deng, A Two-Coordinate Iron(II) Imido Complex with NHC Ligation: Synthesis, Characterization, and Its Diversified Reactivity of Nitrene Transfer and C–H Bond Activation. Inorganic Chemistry 2019, 58, 7634, 10.1021/acs.inorgchem.9b01147.

[63] W. Riedel; L. Thum; J. Möser; V. Fleischer; U. Simon; K. Siemensmeyer; A. Schnegg; R. Schomäcker; T. Risse; K.-P. Dinse, Magnetic Properties of Reduced and Reoxidized Mn–Na2WO4/SiO2: A Catalyst for Oxidative Coupling of Methane (OCM). The Journal of Physical Chemistry C 2018,122, 22605, 10.1021/acs.jpcc.8b07386.

[64] J. Nehrkorn; S. L. Veber; L. A. Zhukas; V. V. Novikov; Y. V. Nelyubina; Y. Z. Voloshin; K. Holldack; S. Stoll; A. Schnegg, Determination of Large Zero-Field Splitting in High-Spin Co(I) Clathrochelates. Inorganic Chemistry 2018, 57, 15330, 10.1021/acs.inorgchem.8b02670.

[65] M. Böhme; S. Ziegenbalg; A. Aliabadi; A. Schnegg; H. Görls; W. Plass, Magnetic relaxation in cobalt(ii)-based single-ion magnets influenced by distortion of the pseudotetrahedral [N2O2] coordination environment. Dalton Transactions 2018, 47, 10861, 10.1039/C8DT01530A.

Group members

laboratory coordinator

Dr. Leonid Rapatskiy

Postdocs

Dr. Kaltum Abdiaziz
Dr. Takuma Sato

Guests

Nikolai Kochetov

EPR Research Group @ MPI CEC

The EPR Research Group at MPI CEC employs electron paramagnetic resonance (EPR) spectroscopy to identify and characterise paramagnetic states relevant to energy conversion and storage processes. Special focus is devoted to catalytically active transition-metals and main group compounds as well as organic radicals. We develop and utilise state-of-the-art EPR spectrometers ranging from GHz to THz frequencies. Our spectrometers are capable of a wide repertoire of CW/pulsed multi-resonance and multi-frequency EPR methods for powder, crystal, solution and in-situ experiments.

Currently we are working in the following fields of research:

In-situ EPR

An understanding of catalyst function enables rational modification and improvement. Yet, the most reactive and catalytically active states are typically only formed under operational conditions. This motivates our group to develop methodology for in situ / operando studies that allow EPR characterisation of catalysts for energy conversion reactions. These studies require electrochemical measurements to be undertaken within the constraints of specific spectroscopic equipment, which we design and develop to ensure the conditions of analysis are truly relevant to the operational catalytic activity.
The applicability of EPR to any electrochemically derived/analysed species is that single electron redox steps frequently involve paramagnetic states. The exceptional sensitivity of spectro-electrochemical EPR (SEC EPR) to these states makes it powerful in examining the subtle, yet crucial, electronic effects that enable catalysis. EPR also allows selective analysis of paramagnetic oxidation states independent of diamagnetic species, thus providing selectivity that is unavailable with many other techniques - especially if the catalyst ground state is diamagnetic. In-situ EPR spectra are interpreted with extensive experiment-simulation comparisons and then correlated with catalytic measurements as well as with results from other techniques. SEC EPR is employed within DFG collaborative research centre (CRC) 247 for studies in paramagnetic states in Co oxide catalysts for alcohol oxidation reactions and within CRC 1487 for the characterization of high spin iron states in single atom catalysts for the oxygen reduction reactions. 

K. Abdiaziz; L. Ni; D. Demirbas; H. Haak; E. Reijerse; P. Theis; W. Jiang; S. Chabbra; T. Lunkenbein; U. I. Kramm; A. Schnegg, Reversibly Redox-Active Iron Oxide Structures in FeNC Catalysts Identified by Microscopy and Spectroelectrochemical EPR and Mössbauer Methods. J. Am. Chem. Soc. 2026, 148, 3995, https://doi.org/10.1021/jacs.5c12396.

Contact: Dr. Kaltum Abdiaziz 

 

High-spin transition metal ion states

EPR characterisation of mono- and multi-nuclear high-spin states (electron spin, S > 1/2) in transition-metal ions targets the determination of their spin coupling parameters, in particular zero-field splittings and exchange couplings. The latter are sensitive probes of the metal ion’s coordination environment and electronic structure. In the case of a catalytically active ion, spin couplings provide unique information on its structure-function relationship. However, the highly desired spin couplings are oftentimes not accessible with standard 9.5 GHz EPR spectrometers. To bridge this gap we develop and apply advanced field and frequency domain EPR methods, covering the GHz to THz EPR-excitation energy range.

T. Al Said; D. Spinnato; K. Holldack; F. Neese; J. Cornella; A. Schnegg, Direct Determination of a Giant Zero-Field Splitting of 5422 cm–1 in a Triplet Organobismuthinidene by Infrared Electron Paramagnetic Resonance. J. Am. Chem. Soc. 2025, 147, 84, https://doi.org/10.1021/jacs.4c14795.

Lohmiller, T.; Spyra, C.-J.; Dechert, S.; Demeshko, S.; Bill, E.; Schnegg, A.; Meyer, F. (2022) Antisymmetric Spin Exchange in a μ-1,2-Peroxodicopper(II) Complex with an Orthogonal Cu–O–O–Cu Arrangement and S = 1 Spin Ground State Characterized by THz-EPR. JACS Au, https://doi.org/10.1021/jacsau.2c00139

Contact: Dr. Alexander Schnegg

  

EPR-on-a-Chip (EPRoC)

EPRoC are mm-sized sensors that incorporate a microwave source and detector on a surface array allowing for a fundamental paradigm shift in EPR spectroscopy by facilitating in situ measurements of paramagnetic samples in miniaturized setups in a cost-efficient way. We are interested in integrating the EPRoC sensors, designed in the Anders Group (Universität Stuttgart), in an electrode for electrochemical experiments, alongside the characterization of paramagnetic states in liquid solutions, e.g. in electrochemical cells, batteries or reactors. Research with EPRoC sensors is funded by the Federal Ministry of Education and Research (Grant reference number: 03SF0565A).

Contact: Dr. Takuma Sato

Bonke, S. A.; Risse, T.; Schnegg, A.; Brückner, A. (2021) In situ electron paramagnetic resonance spectroscopy for catalysis. Nature Review Methods Primershttps://doi.org/10.1038/s43586-021-00031-4 

 

Active Site Characterization by Multi-frequency EPR and Hyperfine Spectroscopy

The identification and characterization of catalytically active sites occupy a central place in the study of catalysis. As the active sites often involve paramagnetic states, EPR spectroscopy is the method of choice to obtain exquisite details on their geometric and electronic structure. In our group, high-resolution multi-frequency (S-, X-, Q- and W-band) and multi-resonance EPR techniques are employed to provide such functional information in the different branches of catalysis ranging from homogenous, heterogeneous and single-site heterogeneous catalysis. By using hyperfine spectroscopies (HYSCORE, ENDOR and EDNMR) we monitor the nuclear spins from the first and second coordination sphere of the paramagnetic active sites. This allows us to shed light on the intimate features of the chemical bonding, which is crucial to understand the catalytic potential of active species. The calculation of the EPR parameters with state-of-the-art electronic structure quantum chemical methods translates the spectroscopic findings into microscopic structure of the catalyst's active site enabling structure–property correlations.

Z. Qiu; P. C. Bruzzese; Z. Wang; H. Deng; M. Leutzsch; C. Farès; S. Chabbra; F. Neese; A. Schnegg; C. N. Neumann, 3-Center-3-Electron σ-Adduct Enables Silyl Radical Transfer below the Minimum Barrier for Silyl Radical Formation. J. Am. Chem. Soc. 2025, 147, 12024, https://doi.org/10.1021/jacs.4c18445.

X. Yang; E. J. Reijerse; N. Nöthling; D. J. SantaLucia; M. Leutzsch; A. Schnegg; J. Cornella, Synthesis, Isolation, and Characterization of Two Cationic Organobismuth(II) Pincer Complexes Relevant in Radical Redox Chemistry. J. Am. Chem. Soc. 2023, 145, 5618−5623, https://doi.org/10.1021/jacs.2c12564.

Contact: Dr. Alexander Schnegg und Dr. Leonid Rapatskiy