Conformation of bis-nitroxide polarizing agents by multi-frequency EPR spectroscopy
| Autor: | Chen Yang, Yanchuan Zhao, Janne Soetbeer, Joseph J. Walish, Robert G. Griffin, Christy George, Guinevere Mathies, Peter Gast, Timothy M. Swager |
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| Přispěvatelé: | Massachusetts Institute of Technology. Department of Chemistry, Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology), Soetbeer, Janne Marie, Walish, Joseph John, Zhao, Yanchuan, George, Christy, Yang, Chen, Swager, Timothy M, Griffin, Robert Guy, Mathies, Guinevere |
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Nitroxide mediated radical polymerization
Materials science 010405 organic chemistry Chemical structure General Physics and Astronomy 010402 general chemistry 01 natural sciences Article 0104 chemical sciences law.invention Crystallography Unpaired electron law Glassy matrix ddc:540 Molecule Physical and Theoretical Chemistry Electron paramagnetic resonance Polarization (electrochemistry) |
| Zdroj: | Physical Chemistry Chemical Physics, 20 (39) Royal Society of Chemistry Physical chemistry chemical physics : PCCP Physical Chemistry Chemical Physics |
| ISSN: | 1463-9084 1463-9076 |
| Popis: | The chemical structure of polarizing agents critically determines the efficiency of dynamic nuclear polarization (DNP). For cross-effect DNP, biradicals are the polarizing agents of choice and the interaction and relative orientation of the two unpaired electrons should be optimal. Both parameters are affected by the molecular structure of the biradical in the frozen glassy matrix that is typically used for DNP/MAS NMR and likely differs from the structure observed with X-ray crystallography. We have determined the conformations of six bis-nitroxide polarizing agents, including the highly efficient AMUPol, in their DNP matrix with EPR spectroscopy at 9.7 GHz, 140 GHz, and 275 GHz. The multi-frequency approach in combination with an advanced fitting routine allows us to reliably extract the interaction and relative orientation of the nitroxide moieties. We compare the structures of six bis-nitroxides to their DNP performance at 500 MHz/330 GHz. Physical Chemistry Chemical Physics, 20 (39) ISSN:1463-9084 ISSN:1463-9076 |
| Databáze: | OpenAIRE |
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