Dynamic nuclear polarization (DNP) upgrade for solid-state NMR spectrometer (400 MHz)

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Dynamic nuclear polarization enables a tremendous signal enhancement for NMR spectroscopy of up to 3 orders of magnitude. This allows on the one hand to perform experiments within minutes or hours which otherwise would take weeks or months of time. On the other hand, completely new fields of application are opened for NMR spectroscopy which would not be accessible without DNP. Our planned research aims towards the investigation of basic principles as well as the developments of novel DNP methods. This will allow for new techniques to structurally characterize biomolecules and materials.By the installation of a DNP upgrade for our existing 400 MHz solid-state NMR spectrometer we will be able to pursue several directions of research: In project line A we will develop new polarizing agents based on paramagnetic metal ion complexes and investigate fundamental aspects of DNP. New polarizing agents can be attached to (macro-)molecules or surfaces of interest via spin labeling or can be directly incorporate into analyte phases via doping. Furthermore, we will investigate the distance dependence of the direct DNP transfer as well as of the relayed transfer via spin diffusion in the immediate vicinity of the electron spin. These topics play a critical role in achieving site-specific DNP enhancement which is the main aim of project line B. Here, we want to achieve the specific polarization enhancement of nuclear spins within a certain distance to the electron spin of the polarizing agent or of a specific component of interest within a complex mixture. For this we will investigate three scenarios: (i) a DNP-active metal ion is specifically or endogenously bound within a macromolecule; (ii) a DNP-active spin label is bound to a target molecule; (iii) a (diamagnetic) spy function is introduced which specifically creates hyperpolarization on nuclear spins via dynamics-induced cross relaxation (SCREAM-DNP). In project line C we will finally apply DNP-enhanced NMR spectroscopy on interesting questions of biomolecular as well as of materials science. We aim at topics including the structure or folding of polymers in solution, the specific NMR spectroscopy of ligands bound in complexes or on surfaces, the time-resolved molecular switching in compounds with natural isotope abundance, as well as the investigation of hitherto unknown mechanisms in heterogeneous catalysis.