Dissolution dynamic nuclear polarization of deuterated molecules

• Main Author: Jhajharia, Aditya
• Other Authors: Physico-Chimie-Curie (PCC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut Curie Paris -Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres, Geoffrey Bodenhausen, Dennis Kurzbach
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2017
• Subjects: Nuclear magnetic resonance (NMR); Dynamic nuclear polarization (DNP); Cross-polarization (CP); Dissolution-dynamic nuclear polarization (D-DNP); Long-lived states (LLS); Microwave irradiation; Résonance magnétique nucléaire (RMN); Polarisation nucléaire dynamique (DNP); Polarisation croisée (CP); Polarisation nucléaire dynamique par dissolution (DDNP); Longue durée de vie (LLS); Irradiation micro-ondes; [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry; sami
• Online Access: https://tel.archives-ouvertes.fr/tel-01818363; https://tel.archives-ouvertes.fr/tel-01818363/document; https://tel.archives-ouvertes.fr/tel-01818363/file/Jhajharia-2017-These.pdf

Nowadays, Nuclear Magnetic Resonance (NMR) has become an inevitable spectroscopic technique that can be applied in many fields of science and medicine. However it is limited by low sensitivity due to the low nuclear polarization, defined by the difference of populations between the energy levels involved, thus leading to long experimental times. This drawback can be overcome by using the huge polarization of unpaired electrons compared to nuclear spins and its transfer to nuclear spins at low temperatures (using microwave irradiation) to achieve a large nuclear magnetization - a method know as dynamic nuclear polarization (DNP). Sami Jannin and co-workers have recently combined the cross-polarization (CP) method with DNP at very low temperatures to polarize low γ nuclei faster by transferring the electron polarization to protons and then to low γ nuclei like ¹³C. This thesis demonstrates that the efficiency of the CP method can be improved by switching the microwave irradiation off for a few hundred milliseconds prior to CP. By performing these microwave gating experiments, ¹³C polarizations for sodium [1-¹³C]acetate as high as 64% could be achieved with a polarization build-up time constant as short as 160 s. The hyperpolarized sample can subsequently be rapidly dissolved to achieve NMR signal enhancement in the liquid state at ambient temperature. This method has been developed by Ardenkjaer-Larsen and co-workers in 2003 and became known as dissolution-dynamic nuclear polarization (D-DNP). It can provide signal enhancements by a factor of up to four orders of magnitude in liquid state at room temperature. Combining D-DNP with CP techniques from ¹H to ¹³C can be used to create to create long-lived states (LLS) in deuterated molecules like ethanol-d₆ and DMSO-d₆, which can have much longer life times than conventional Zeeman magnetization. These LLS can be detected indirectly via the asymmetric multiplets in ¹³C NMR spectra in solution state at room temperature after dissolution due to scalar couplings between ...