Project Details
Projekt
Electron paramagnetic resonance spectrometer for rapid scan, freeze quench and kinetic measurements
Subject Area
Biological Chemistry and Food Chemistry
Term
Funded in 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 500203554
In our interdisciplinary mechanistic-synthetic research that paves the path for the control of redox (electron transfer) processes in living systems, biomimetic catalysis and chemical energy conversion, almost all investigated compounds and their catalytic or stoichiometric reactions are paramagnetic or implicate the formation/decay of paramagnetic species, respectively. Thus, the application of electron paramagnetic resonance (EPR) as a direct and non-invasive technique is an essential tool to characterise compounds of interest (complexes with redox-active metal centres and/or ligands and free radical species such as superoxide, nitric oxide, hydroxyl radical etc.) and clarify the mechanism of their transformation. In particular, it will be crucial for kinetic studies, trapping/characterizing of reactive intermediates and real-time monitoring of fast (catalytic) processes when UV/Vis and NMR methods exhibit their limitations, which is often the case in processes investigated by us that involve multicomponent paramagnetic reaction mixtures (e.g. when reactants, intermediates and products are all paramagnetic) and two or more parallel-running (catalytic) reactions. Thus, the nature or our research requires a rather unconventional EPR device capable of rapid scan (RS), freeze quench (FQ) and stopped-flow (SF) measurements (RS/FQ/SF-EPR). Such a multifunctional, high-performance EPR instrument with unique rapid-mixing and rapid-scan measurement capability does not exist at LMU and to best of our knowledge not even in Germany. For the objectives of our kinetic/mechanistic approaches, the required EPR device, apart from standard EPR measurements (CW, X-band mode), should be able to meet the following requirements: (i) to operate at Q-band microwaves, (ii) to utilise two cooling systems using liquid helium and liquid nitrogen, (iii) to easily handle freeze-quench experiments to catch and characterize short-lived radical intermediates, (iv) to be compatible with the home-built, dielectric ring resonator that is essential to construct the EPR stopped-flow equipment, (v) to operate in rapid-scan mode using the RS-resonator to carry out time-resolved measurements of very short-lived radical/paramagnetic species and (vi) to operate with a mixing (flow) resonator to study short-lived radicals generated in biological medium. Such instrumentation will allow broad application (within our collaborations or service measurements) of the EPR technique for interested groups in different fields and will be indispensable for further scientific achievements of our ongoing and planned projects, contributing to the development of efficient catalysts, redox-modulators, therapeutics or diagnostic tools. It will also allow us to push the boundaries of possible EPR methodology by constructing a rather unique rapid-scan EPR stopped-flow device of improved resolution that would currently be operative in the field of bioinorganic chemistry and chemical energy conversion.
DFG Programme
Major Research Instrumentation
Major Instrumentation
Elektronenspinresonanz-Spektrometer für Rapid-Scan, Freeze-Quench und kinetische Messungen
Instrumentation Group
1770 Elektronenspinresonanz-Spektrometer (EPR, ESR)
Applicant Institution
Ludwig-Maximilians-Universität München
