Abstract
Signal Amplification By Reversible Exchange (SABRE) is gaining increased attention as a tool to enhance weak Nuclear Magnetic Resonance (NMR) signals. In SABRE, spin order is transferred from parahydrogen (H2 in its nuclear singlet spin state) to a substrate molecule in a transient Ir-based complex. In recent years, SABRE polarization of biologically active substrates has been demonstrated, notably of metronidazole – an antibiotic and antiprotozoal drug. In this work, we study 15N SABRE polarization of metronidazole at natural isotope abundance. We are able to demonstrate significant 15N polarization reaching 15 %, which corresponds to a signal enhancement of 46,000 at 9.4 T for the nitrogen atom with lone electron pair. Additionally, the other two N-atoms can be polarized, although less efficiently. We present a detailed study of the field dependence of polarization and explain the maxima in the field dependence using the concept of coherent polarization transfer at level anti-crossings in the SABRE complex. A study of spin relaxation phenomena presented here enables optimization of the magnetic field for efficient storage of non-thermal polarization.
Original language | English |
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Pages (from-to) | 1470-1477 |
Number of pages | 8 |
Journal | ChemPhysChem |
Volume | 22 |
Issue number | 14 |
Early online date | 19 May 2021 |
DOIs | |
Publication status | Published - 16 Jul 2021 |
Keywords
- metronidazole
- parahydrogen
- SABRE method
- spin hyperpolarization
OECD FOS+WOS
- 1.03 PHYSICAL SCIENCES AND ASTRONOMY
- 1.04 CHEMICAL SCIENCES
- 1.04.EI CHEMISTRY, PHYSICAL
- 1.03.UH PHYSICS, ATOMIC, MOLECULAR & CHEMICAL