---
_id: '63974'
abstract:
- lang: eng
  text: A versatile strategy for synthesizing tailored peptide based biradicals is
    presented. By labeling the protected amino acid hydroxyproline with PROXYL via
    the OH functionality and using this building block in solid phase peptide synthesis
    (SPPS), the obtained peptides become polarization agents for DNP enhanced solid-state
    NMR in biotolerant media. To analyze the effect of the radical position on the
    enhancement factor, three different biradicals are synthesized. The PROXYL spin-label
    is inserted in a collagen inspired artificial peptide sequence by binding through
    the OH group of the hydroxyproline moieties at specific position in the chain.
    This labeling strategy is universally applicable for any hydroxyproline position
    in a peptide sequence since solid-phase peptide synthesis is used to insert the
    building block. High performance liquid chromatography (HPLC) and mass spectrometry
    (MS) analyses show the successful introduction of the spin label in the peptide
    chain and electron paramagnetic resonance (EPR) spectroscopy confirms its activity.
    Dynamic nuclear polarization (DNP) enhanced solid-state nuclear magnetic resonance
    (NMR) experiments performed on frozen aqueous glycerol-d8 solutions containing
    these peptide radicals show significantly higher enhancement factors of up to
    45 in 1H→13C cross polarization magic angle spinning (CP MAS) experiments compared
    to an analogous mono-radical peptide including this building block (ε ≈ 14). Compared
    to commercial biradicals such as AMUPol for which enhancement factors {\textgreater}
    100 have been obtained in the past and which have been optimized in their structure,
    the obtained enhancement up to 45 for our biradicals presents a significant progress
    in radical design.
author:
- first_name: Kevin
  full_name: Herr, Kevin
  last_name: Herr
- first_name: Mark V.
  full_name: Höfler, Mark V.
  last_name: Höfler
- first_name: Henrike
  full_name: Heise, Henrike
  last_name: Heise
- first_name: Fabien
  full_name: Aussenac, Fabien
  last_name: Aussenac
- first_name: Felix
  full_name: Kornemann, Felix
  last_name: Kornemann
- first_name: David
  full_name: Rosenberger, David
  last_name: Rosenberger
- first_name: Martin
  full_name: Brodrecht, Martin
  last_name: Brodrecht
- first_name: Marcos
  full_name: Oliveira, Marcos
  last_name: Oliveira
- first_name: Gerd
  full_name: Buntkowsky, Gerd
  last_name: Buntkowsky
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
citation:
  ama: Herr K, Höfler MV, Heise H, et al. Biradicals based on PROXYL containing building
    blocks for efficient dynamic nuclear polarization in biotolerant media. <i>Journal
    of Magnetic Resonance Open</i>. 2024;20:100152. doi:<a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>
  apa: Herr, K., Höfler, M. V., Heise, H., Aussenac, F., Kornemann, F., Rosenberger,
    D., Brodrecht, M., Oliveira, M., Buntkowsky, G., &#38; Gutmann, T. (2024). Biradicals
    based on PROXYL containing building blocks for efficient dynamic nuclear polarization
    in biotolerant media. <i>Journal of Magnetic Resonance Open</i>, <i>20</i>, 100152.
    <a href="https://doi.org/10.1016/j.jmro.2024.100152">https://doi.org/10.1016/j.jmro.2024.100152</a>
  bibtex: '@article{Herr_Höfler_Heise_Aussenac_Kornemann_Rosenberger_Brodrecht_Oliveira_Buntkowsky_Gutmann_2024,
    title={Biradicals based on PROXYL containing building blocks for efficient dynamic
    nuclear polarization in biotolerant media}, volume={20}, DOI={<a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>},
    journal={Journal of Magnetic Resonance Open}, author={Herr, Kevin and Höfler,
    Mark V. and Heise, Henrike and Aussenac, Fabien and Kornemann, Felix and Rosenberger,
    David and Brodrecht, Martin and Oliveira, Marcos and Buntkowsky, Gerd and Gutmann,
    Torsten}, year={2024}, pages={100152} }'
  chicago: 'Herr, Kevin, Mark V. Höfler, Henrike Heise, Fabien Aussenac, Felix Kornemann,
    David Rosenberger, Martin Brodrecht, Marcos Oliveira, Gerd Buntkowsky, and Torsten
    Gutmann. “Biradicals Based on PROXYL Containing Building Blocks for Efficient
    Dynamic Nuclear Polarization in Biotolerant Media.” <i>Journal of Magnetic Resonance
    Open</i> 20 (2024): 100152. <a href="https://doi.org/10.1016/j.jmro.2024.100152">https://doi.org/10.1016/j.jmro.2024.100152</a>.'
  ieee: 'K. Herr <i>et al.</i>, “Biradicals based on PROXYL containing building blocks
    for efficient dynamic nuclear polarization in biotolerant media,” <i>Journal of
    Magnetic Resonance Open</i>, vol. 20, p. 100152, 2024, doi: <a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>.'
  mla: Herr, Kevin, et al. “Biradicals Based on PROXYL Containing Building Blocks
    for Efficient Dynamic Nuclear Polarization in Biotolerant Media.” <i>Journal of
    Magnetic Resonance Open</i>, vol. 20, 2024, p. 100152, doi:<a href="https://doi.org/10.1016/j.jmro.2024.100152">10.1016/j.jmro.2024.100152</a>.
  short: K. Herr, M.V. Höfler, H. Heise, F. Aussenac, F. Kornemann, D. Rosenberger,
    M. Brodrecht, M. Oliveira, G. Buntkowsky, T. Gutmann, Journal of Magnetic Resonance
    Open 20 (2024) 100152.
date_created: 2026-02-07T15:42:00Z
date_updated: 2026-02-17T16:17:22Z
doi: 10.1016/j.jmro.2024.100152
extern: '1'
intvolume: '        20'
keyword:
- solid-state nmr
- dynamic nuclear polarization
- peptides
- Biradicals
- Spin labeling
language:
- iso: eng
page: '100152'
publication: Journal of Magnetic Resonance Open
status: public
title: Biradicals based on PROXYL containing building blocks for efficient dynamic
  nuclear polarization in biotolerant media
type: journal_article
user_id: '100715'
volume: 20
year: '2024'
...
---
_id: '63969'
abstract:
- lang: eng
  text: A number of Ir-N-heterocyclic carbene (Ir-NHC) complexes with asymmetric N-heterocyclic
    carbene (NHC) ligands have been prepared and examined for signal amplification
    by reversible exchange (SABRE). Pyridine was chosen as model compound for hyperpolarization
    experiments. This substrate was examined in a solvent mixture using several Ir-NHC
    complexes, which differ in their NHC ligands. The SABRE polarization was created
    at 6mT and the H-1 nuclear magnetic resonancesignals were detected at 7T. We show
    that asymmetric NHC ligands, because of their favorable chemistry, can adapt the
    SABREactive complexes to different chemical scenarios.
author:
- first_name: S.
  full_name: Hadjiali, S.
  last_name: Hadjiali
- first_name: R.
  full_name: Savka, R.
  last_name: Savka
- first_name: M.
  full_name: Plaumann, M.
  last_name: Plaumann
- first_name: U.
  full_name: Bommerich, U.
  last_name: Bommerich
- first_name: S.
  full_name: Bothe, S.
  last_name: Bothe
- first_name: Torsten
  full_name: Gutmann, Torsten
  id: '118165'
  last_name: Gutmann
- first_name: T.
  full_name: Ratajczyk, T.
  last_name: Ratajczyk
- first_name: J.
  full_name: Bernarding, J.
  last_name: Bernarding
- first_name: H. H.
  full_name: Limbach, H. H.
  last_name: Limbach
- first_name: H.
  full_name: Plenio, H.
  last_name: Plenio
- first_name: G.
  full_name: Buntkowsky, G.
  last_name: Buntkowsky
citation:
  ama: Hadjiali S, Savka R, Plaumann M, et al. Substituent Influences on the NMR Signal
    Amplification of Ir Complexes with Heterocyclic Carbene Ligands. <i>Applied Magnetic
    Resonance</i>. 2019;50(7):895–902. doi:<a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>
  apa: Hadjiali, S., Savka, R., Plaumann, M., Bommerich, U., Bothe, S., Gutmann, T.,
    Ratajczyk, T., Bernarding, J., Limbach, H. H., Plenio, H., &#38; Buntkowsky, G.
    (2019). Substituent Influences on the NMR Signal Amplification of Ir Complexes
    with Heterocyclic Carbene Ligands. <i>Applied Magnetic Resonance</i>, <i>50</i>(7),
    895–902. <a href="https://doi.org/10.1007/s00723-019-01115-x">https://doi.org/10.1007/s00723-019-01115-x</a>
  bibtex: '@article{Hadjiali_Savka_Plaumann_Bommerich_Bothe_Gutmann_Ratajczyk_Bernarding_Limbach_Plenio_et
    al._2019, title={Substituent Influences on the NMR Signal Amplification of Ir
    Complexes with Heterocyclic Carbene Ligands}, volume={50}, DOI={<a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>},
    number={7}, journal={Applied Magnetic Resonance}, author={Hadjiali, S. and Savka,
    R. and Plaumann, M. and Bommerich, U. and Bothe, S. and Gutmann, Torsten and Ratajczyk,
    T. and Bernarding, J. and Limbach, H. H. and Plenio, H. and et al.}, year={2019},
    pages={895–902} }'
  chicago: 'Hadjiali, S., R. Savka, M. Plaumann, U. Bommerich, S. Bothe, Torsten Gutmann,
    T. Ratajczyk, et al. “Substituent Influences on the NMR Signal Amplification of
    Ir Complexes with Heterocyclic Carbene Ligands.” <i>Applied Magnetic Resonance</i>
    50, no. 7 (2019): 895–902. <a href="https://doi.org/10.1007/s00723-019-01115-x">https://doi.org/10.1007/s00723-019-01115-x</a>.'
  ieee: 'S. Hadjiali <i>et al.</i>, “Substituent Influences on the NMR Signal Amplification
    of Ir Complexes with Heterocyclic Carbene Ligands,” <i>Applied Magnetic Resonance</i>,
    vol. 50, no. 7, pp. 895–902, 2019, doi: <a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>.'
  mla: Hadjiali, S., et al. “Substituent Influences on the NMR Signal Amplification
    of Ir Complexes with Heterocyclic Carbene Ligands.” <i>Applied Magnetic Resonance</i>,
    vol. 50, no. 7, 2019, pp. 895–902, doi:<a href="https://doi.org/10.1007/s00723-019-01115-x">10.1007/s00723-019-01115-x</a>.
  short: S. Hadjiali, R. Savka, M. Plaumann, U. Bommerich, S. Bothe, T. Gutmann, T.
    Ratajczyk, J. Bernarding, H.H. Limbach, H. Plenio, G. Buntkowsky, Applied Magnetic
    Resonance 50 (2019) 895–902.
date_created: 2026-02-07T15:40:18Z
date_updated: 2026-02-17T16:17:34Z
doi: 10.1007/s00723-019-01115-x
extern: '1'
intvolume: '        50'
issue: '7'
keyword:
- dynamic nuclear-polarization
- hyperpolarization
- enhancement
- hydrogen induced polarization
- olefin-metathesis catalysts
- parahydrogen-induced polarization
- peptides
- Physics
- sabre
- spectroscopy
language:
- iso: eng
page: 895–902
publication: Applied Magnetic Resonance
publication_identifier:
  issn:
  - 1613-7507
status: public
title: Substituent Influences on the NMR Signal Amplification of Ir Complexes with
  Heterocyclic Carbene Ligands
type: journal_article
user_id: '100715'
volume: 50
year: '2019'
...