Parahydrogen-induced polarization in H2 activations and hydrogenations mediated by metal-free catalysts
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
Auditorium IT115, Linnanmaa, University of Oulu
Topic of the dissertation
Parahydrogen-induced polarization in H2 activations and hydrogenations mediated by metal-free catalysts
Doctoral candidate
Master of Science Danila Zakharov
Faculty and unit
University of Oulu Graduate School, Faculty of Science, NMR Research Unit
Subject of study
Physics
Opponent
Professor Clifford Russell Bowers, University of Florida, USA
Custos
Associate professor Vladimir V. Zhivonitko, University of Oulu, Finland
Parahydrogen-induced polarization in H2 activations and hydrogenations mediated by metal-free catalysts
Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical method utilized in numerous scientific and industrial fields. However, the low sensitivity of NMR often results in insufficient signal strength for reliable analysis. The sensitivity can be enhanced using parahydrogen-induced polarization (PHIP) based hyperpolarization techniques. PHIP is based on chemical transformations of parahydrogen (a spin isomer of H2), which are typically mediated by metal complexes as catalysts. However, metal-free catalysts can be used in this process as non-toxic alternatives.
In the present thesis, we investigated hydrogenations of various alkynes and imines with parahydrogen over metal-free ansa-aminoborane-based catalysts. We observed enhanced signals of catalytic intermediates and, most importantly, hydrogenation products. This study presents the first example of PHIP effects for hydrogenation products using metal-free catalysts. We studied the reaction mechanisms and showed that PHIP can provide valuable mechanistic insights into metal-free hydrogenations. In addition to ansa-aminoboranes, we significantly extended the range of biradicaloid-based metal-free activators for parahydrogen. These compounds revealed substantial NMR signal enhancements exceeding three orders of magnitude, which is a particularly high level for metal-free systems.
Altogether, these studies provided several novel insights into metal-free PHIP. The results of this thesis can be heavily employed in the development of efficient metal-free catalytic systems for sensitivity enhancement in NMR and MRI.
In the present thesis, we investigated hydrogenations of various alkynes and imines with parahydrogen over metal-free ansa-aminoborane-based catalysts. We observed enhanced signals of catalytic intermediates and, most importantly, hydrogenation products. This study presents the first example of PHIP effects for hydrogenation products using metal-free catalysts. We studied the reaction mechanisms and showed that PHIP can provide valuable mechanistic insights into metal-free hydrogenations. In addition to ansa-aminoboranes, we significantly extended the range of biradicaloid-based metal-free activators for parahydrogen. These compounds revealed substantial NMR signal enhancements exceeding three orders of magnitude, which is a particularly high level for metal-free systems.
Altogether, these studies provided several novel insights into metal-free PHIP. The results of this thesis can be heavily employed in the development of efficient metal-free catalytic systems for sensitivity enhancement in NMR and MRI.
Last updated: 23.1.2024