Exploring chemical and photochemical reactivity in metal-free parahydrogen-induced polarization

The thesis investigates metal-free parahydrogen-induced polarization (PHIP) as a method to enhance the sensitivity in NMR spectroscopy. It focuses on parahydrogen activation using ansa-aminoboranes and phosphorus biradicaloids as sustainable alternatives to metal catalysts. NMR spectroscopy was used to examine spin hyperpolarization with respect to the kinetic and thermodynamic behavior of these systems. The research delivers multiple novel contributions to metal-free PHIP. It shows the influence of solvent polarity on hyperpolarization using labeled ansa-aminoboranes. It also investigates the water tolerance of those compounds in parahydrogen activation, allowing for broadening the scope of the metal-free catalysis. Finally, it introduces metal-free light-controlled PHIP by using visible-light photoswitching of a pnictogen biradicaloid for precise reaction control. Together, these findings deepen understanding of metal-free PHIP and pave the way for more versatile NMR techniques.