Maciej Damian Korzynski


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Korzynski

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Maciej Damian

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0000-0002-6577-1821

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2021 - 20247
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Publications 1 - 7 of 7
  • Leveraging Surface Siloxide Electronics to Enhance the Relaxation Properties of a Single-Molecule Magnet
    Item type: Journal Article
    Korzynski, Maciej Damian; Berkson, Zachariah J.; Le Guennic, Boris; et al. (2021)
    Journal of the American Chemical Society
    Single-molecule magnets (SMMs) hold promise for unmatched information storage density as well as for applications in quantum computing and spintronics. To date, the most successful SMMs have been organometallic lanthanide complexes. However, their surface immobilization, one of the requirements for device fabrication and commercial application, remains challenging due to the sensitivity of the magnetic properties to small changes in the electronic structure of the parent SMM. Thus, finding controlled approaches to SMM surface deposition is a timely challenge. In this contribution we apply the concept of isolobality to identify siloxides present at the surface of partially dehydroxylated silica as a suitable replacement for archetypal ligand architectures in organometallic SMMs. We demonstrate theoretically and experimentally that isolated siloxide anchoring sites not only enable successful immobilization but also lead to a 2 orders of magnitude increase in magnetization relaxation times.
  • Solid-state NMR spectra of protons and quadrupolar nuclei at 28.2 T: Resolving signatures of surface sites with fast magic angle spinning
    Item type: Journal Article
    Berkson, Zachariah J.; Björgvinsdóttir, Snædís; Yakimov, Alexander; et al. (2022)
    JACS Au
    Advances in solid-state nuclear magnetic resonance (NMR) methods and hardware offer expanding opportunities for analysis of materials, interfaces, and surfaces. Here, we demonstrate the application of a very high magnetic field strength of 28.2 T and fast magic-angle-spinning rates (MAS, >40 kHz) to surface species relevant to catalysis. Specifically, we present as case studies the 1D and 2D solid-state NMR spectra of important catalyst and support materials, ranging from a well-defined silica-supported organometallic catalyst to dehydroxylated γ-alumina and zeolite solid acids. The high field and fast-MAS measurement conditions substantially improve spectral resolution and narrow NMR signals, which is particularly beneficial for solid-state 1D and 2D NMR analysis of 1H and quadrupolar nuclei such as 27Al at surfaces.
  • Orientation-Driven Large Magnetic Hysteresis of Er(III) Cyclooctatetraenide-Based Single-Ion Magnets Adsorbed on Ag(100)
    Item type: Journal Article
    Romankov, Vladyslav; Bernhardt, Moritz; Heinrich, Martin; et al. (2024)
    Small Science
    The molecular self-assembly and the magnetic properties of two cyclooctatetraenide (COT)-based single-ion magnets (SIM) adsorbed on Ag(100) in the sub-monolayer (ML) range are reported. Our study combines scanning-tunneling microscopy, X-ray photoemission spectroscopy and polarized X-ray absorption spectroscopy to show that Cp*ErCOT (Cp* = 1,2,3,4,5-pentamethylcyclopentadienide anion) SIMs self-assemble as alternating compact parallel rows including standing-up and lying-down conformations, following the main crystallographic directions of the substrate. Conversely, K[Er(COT)2], obtained from subliming the [K(18-c-6)][Er(COT)2]·2THF salt, forms uniaxially ordered domains with the (COT)2− rings perpendicular to the substrate plane. The polarization-dependent X-ray absorption spectra reproduced by the multiX simulations suggest that the strong in-plane magnetic anisotropy of K[Er(COT)2]/Ag(100) and the weak out-of-plane anisotropy of Cp*ErCOT/Ag(100) can be attributed to the strikingly different surface ordering of these two complexes. Compared to the bulk phase, surface-supported K[Er(COT)2] exhibits a similarly large hysteresis opening, while the Cp*ErCOT shows a rather small opening. This result reveals that despite structural similarities, the two organometallic SMMs have strongly different magnetic properties when adsorbed on the metal substrate, attributed to the different orientations and the resulting interactions of the ligand rings with the surface.
  • Cyclooctatetraenide-based single-ion magnets featuring bulky cyclopentadienyl ligand
    Item type: Journal Article
    Korzynski, Maciej Damian; Bernhardt, Moritz; Romankov, Vladyslav; et al. (2022)
    Chemical Science
    We report a family of organometallic rare-earth complexes with the general formula (COT)M(Cp-ttt) (where (COT)(2-) = cyclooctatetraenide, (Cp-ttt)(-) = 1,2,4-tri(tert-butyl)cyclopentadienide, M = Y(iii), Nd(iii), Dy(iii) and Er(iii)). Similarly to the prototypical Er(iii) analog featuring pentamethylcyclopentadienyl ligand (Cp*)(-), (COT)Er(Cp-ttt) behaves as a single-ion magnet. However, the introduction of the sterically demanding (Cp-ttt)(-) imposes geometric constraints that lead to a simplified magnetic relaxation behavior compared to the (Cp*)(-) containing complexes. Consequently, (COT)Er(Cp-ttt) can be viewed as a model representative of this organometallic single-ion magnet architecture. In addition, we demonstrate that the increased steric profile associated with the (Cp-ttt)(-) ligand permits preparation, structural characterization and interrogation of magnetic properties of the early-lanthanide complex, (COT)Nd(Cp-ttt). Such a mononuclear derivative could not be obtained when a (Cp*)(-) ligand was employed, a testament to larger ionic radius of this early lanthanide ion.
  • Tailored Lewis Acid Sites for High-Temperature Supported Single-Molecule Magnetism
    Item type: Journal Article
    Bernhardt, Moritz; Korzynski, Maciej Damian; Berkson, Zachariah J.; et al. (2023)
    Journal of the American Chemical Society
    Generating or even retaining slow magnetic relaxationin surfaceimmobilized single-molecule magnets (SMMs) from promising molecularprecursors remains a great challenge. Illustrative examples are organolanthanidecompounds that show promising SMM properties in molecular systems,though surface immobilization generally diminishes their magneticperformance. Here, we show how tailored Lewis acidic Al-(III) siteson a silica surface enable generation of a material with SMM characteristicsvia chemisorption of (Cp-ttt)(2)DyCl ((Cp-ttt)(-) = 1,2,4-tri-(tert-butyl)-cyclopentadienide).Detailed studies of this system and its diamagnetic Y analogue indicatethat the interaction of the metal chloride with surface Al sites resultsin a change of the coordination sphere around the metal center inducingfor the dysprosium-containing material slow magnetic relaxation upto 51 K with hysteresis up to 8 K and an effective energy barrier(U (eff)) of 449 cm(-1),the highest reported thus far for a supported SMM.
  • Surface organometallic and coordination chemistry approach to formation of single site heterogeneous catalysts
    Item type: Encyclopedia Entry
    Copéret, Christophe; Korzynski, Maciej Damian (2023)
    Comprehensive Inorganic Chemistry III (Third Edition). Volume 6: Heterogeneous Inorganic Catalysis
    Surface Organometallic Chemistry (SOMC), an approach to generate molecularly defined surface sites on solids, has opened possibilities to understand heterogeneous catalysis with atomic-level precision. Treating the surface of traditional supports as defined (albeit complex) ligands and applying the rules of molecular inorganic chemistry allowed for formation of countless examples of well-defined surface moieties, some of which were shown to display remarkable catalytic performances for variety of chemical transformations, surpassing their homogeneous analogs, and behaving as single-site catalysts. Additionally, the ability to precisely design the coordination environment of the metal center brought us closer to elucidation of the nature of active sites in more complex industrial catalysts. The aim of this article is to familiarize the reader with the logic behind and the techniques involved in the SOMC approach. We will begin by outlining the complexity of heterogeneous catalysis and how SOMC enters its realm, followed by description of the methodology and its defining features. Finally, we will discuss some of the success stories in using SOMC approach in single-site heterogeneous catalysis.
  • Single sites in heterogeneous catalysts: separating myth from reality
    Item type: Review Article
    Korzynski, Maciej Damian; Copéret, Christophe (2021)
    Trends in Chemistry
    Heterogeneous catalytic processes are a staple of the sustainable chemical industry. One of the holy grails of contemporary catalysis science is the formation of the so-called single-site catalysts. The single-site character implies that the catalytically active species are structurally uniform, do not interact with each other, and exhibit identical affinity towards the substrates in the desired transformation. Achieving such characteristics in real-life materials is a challenge due to the complex nature of chemical transformations at surfaces. Surface organometallic chemistry (SOMC) has emerged as a powerful approach to form well-defined species on the surface of materials. In this short review, we discuss the myth and reality of single-site heterogeneous catalyst formation, with a primary focus on application of SOMC methodology. © 2021 Elsevier Inc.
Publications 1 - 7 of 7