Synthese und DNP verstärkte Festkörper-NMR-Untersuchung von immobilisierten enantioselektiven Katalysatoren.
Zusammenfassung der Projektergebnisse
The main results of this project can be summarized as follows: (1) A novel synthetic route to obtain benzophenone functionalized cellulose has been proposed that can be further used to prepare self-standing polymer films. The success of the functionalization was monitored by 1D and 2D solid state NMR techniques including the use of natural abundance DNP enhanced 15N solid-state NMR that proves the coupling of benzophenone to amine-functionalized cellulose via an amide bond. (2) The binding of dirhodium complexes on functionalized porous silica material has been studied by DNP enhanced 15N and 13C solid-state NMR that prove the binding of the complex in axial position via an amine coordination and via the carboxy function in equatorial position. The number of active sites was quantified by 19F MAS NMR and correlates well with the data from catalytic experiments of the model cyclopropanation of styrene. A mechanism for the immobilization of the complex has been proposed based on thermodynamic data from DFT calculations and is in excellent agreement with the obtained results from solid-state NMR experiments. (3) Multinuclear Solid-state NMR is evaluated as an efficient tool to identify the composition of commercially available epoxy raisin-based thermosets doped with phosphorous containing flame retardants. (4) The DNP methodology was extended to novel radicals with high efficiency to generate enhancement as well as to systems containing immobilized radicals that can be used for solvent free DNP experiments. (5) Selective DNP signal enhancement has been introduced for polymer functionalized cellulose/paper substrates as powerful tool to separate signals of the polymer from the cellulose/paper material by tuning the DNP sample preparation. This approach is applied to identify the structure of the shell independent of the core in complex core-shell nanoparticle architectures.
Projektbezogene Publikationen (Auswahl)
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Coherent manipulation of nonthermal spin order in optical nuclear polarization experiments. J. Chem. Phys. (2017), 146, 114501
G. Buntkowsky, K.L. Ivanov, H. Zimmermann, H.-M. Vieth
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Dynamic Nuclear Polarization Signal Amplification as a Sensitive Probe for Specific Functionalization of Complex Paper Substrates. J.Phys.Chem. C, 2017, 121, 3896-3903
Gutmann, T.; Kumari, B.; Zhao, L.; Breitzke, H.; Schöttner, S.; Rüttiger, C.; Gallei, M.
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Revealing Structure Reactivity Relationships in heterogenized Dirhodium Catalysts by Solid State NMR Techniques. J.Phys.Chem. C, (2017), 121, 17409–17416
J Liu, P. Braga-Groszewicz, Q. Wen, A.S. Lilly Thankamony, B.Zhang, U. Kunz, G. Sauer, Y. Xu, T. Gutmann, G. Buntkowsky
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Thermo-reversible self-assembly of perfluorinated corecoronas cellulose-nanoparticles in dry state. Advanced Materials, (2017), 1702473
Y. Wang, P.B. Groszewicz, S. Rosenfeldt, H. Schmidt, C. A. Volkert, P. Vana, T. Gutmann, G. Buntkowsky, K. Zhang
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Efficient, self‐terminating isolation of cellulose nanocrystals via periodate oxidation in Pickering emulsions. Chem.Sus.Chem. (2018), 11, 3581-3585
P. Liu, B. Pang, L. Tian, T. Schäfer, T. Gutmann, H. Liu, C. A. Volkert, G. Buntkowsky, K. Zhang
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Gallei, M., Preceramic Core-Shell Particles for the Preparation of Hybrid Colloidal Crystal Films by Melt- Shear Organization and Conversion into Porous Ceramics. Materials & Design, 2018, 160, 926-935
Vowinkel, S.; Boehm, A.; Schäfer, T.; Gutmann, T.; Ionescu, E.; Gallei, M.
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Selective DNP Signal Amplification to Probe Structures of Core–Shell Polymer Hybrid Nanoparticles.; J.Phys.Chem. C, 2019, 123, 644-652
Schäfer, T.; Vowinkel, S.; Breitzke, H.; Gallei, M.; Gutmann, T.
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Trityl-Aryl-Niroxide Based Genuinely g-Engineered Biradicals, as Studied by DNP, Multi-Frequency ESR/ENDOR, AWG Pulse MW Spectroscopy and Quantum Chemical Calculations. J.Phys.Chem.A, (2019), 123, 7507-7517
K. Sato; R. Hirao; I, Timofeev; O. Krumkacheva; E. Zaytseve; O. Rogozhnikova; V. Tormyshev; D. Trukhin; E. Bagryanskaya; T. Gutmann; V. Klimavicius; G. Buntkowsky; K. Sugisaki; S. Nakazawa; H. Matsuoka; K. Toyota; D. Shiomi; T. Takui
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Dynamics and Proton Transport in Imidazole-Doped Nanocrystalline Cellulose Revealed by High-Resolution Solid-State NMR. J.Phys.Chem.C (2020),124,18886- 18893
M. Bielejewski; M. Pinto-Salazar; L. Lindner; R. Pankiewicz; G. Buntkowsky; J.Tritt-Goc
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N- Hydroxysuccinimide-activated esters as a functionalization agent for amino cellulose: synthesis and solid-state NMR characterization. Cellulose (2020) 27,1239- 1254
P. B. Groszewicz, P.Mendes, B. Kumari, M. Biesalski, T. Gutmann, G. Buntkowsky
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Solid-State NMR as versatile tool to identify the main chemical components of epoxy-based thermosets. ACS Omega (2020), 5, 5412-5420
T. Schäfer, G. Buntkowsky, T. Gutmann
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Direct Observation of Carbonate Formation in Partly Hydrated Tricalcium Silicate by DNP Enhanced NMR Spectroscopy. J. Phys.Chem. C, (2021), 125, 7321–7328
V. Klimavicius, H. Hilbig, T. Gutmann, G. Buntkowsky
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Mechanism of Heterogenization of Dirhodium Catalysts: Insights from DFT calculations. Inorganic Chemistry (2021)
Pietruschka, D.; Kumari, B.; Buntkowsky, G.; Gutmann, T. Mollenhauer, D.
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Surface reactions of ammonia on ruthenium nanoparticles revealed by 15N and 13C solid-state NMR. Catal. Sci. Technol., 2021
Rothermel, N., Limbach, H.-H., del Rosal, I., Poteau, R., Mencia, G., Chaudret, B., Buntkowsky, G., Gutmann, T.
