Spectroscopy on Copper Enzyme Model Complexes

Abstract

In this work a variety of inelastic light scattering experiments are conducted to investigate the structure, the function and the structure-function relationship of a multitude of bio-inorganic model complexes. The spectroscopic range spans from from X-ray over deep UV to optical and mid-infrared wavelengths. The experimental setups are custom-designed to the samples and contain different cryo-setups and condensed matter or liquid sample environments. Different complexes were measured and the respective ligands themselves were tested in modified versions to shine light on what affects the properties of the entire complex. While Raman investigations showed characteristic vibrations, the X-ray absorption data was used to fully identify bond lengths and angles that are necessary to relate the structural formation of the complex to its function as a model complex in catalysis. The catalysis itself was monitored with operando Raman spectroscopy and the dynamics of a reaction with substrates was revealed. Investigating modified versions of a complex, suited as a model for entatic state chemistry, lead to a better understanding of the leading factors of the geometric and electronic structure that drive the electron self-exchange rate of entatic state model complexes. It was found that not only minimizing the structure difference Δτ4 is important to raise the electron self-exchange rate, but also optimizing the geometry to not favor either one of the binary options tetrahedral or square-planar. A difference frequency generation setup was successfully installed using many different nonlinear crystals to produce femtosecond mid-infrared laser light to be used as a tool to influence and manipulate the transient structure of the sample. It was successfully tested on experimentally less-challenging condensed matter systems such as a reflectivity probe on a trichalcogenide system and in its destined use in a mid-infrared pump and Raman probe setup on multilayer graphene systems. As such, the road is now paved for selective mid-infrared pump distortion of the low-energy vibrations in the ligand sphere in entatic state complexes and to investigate the influence that these transient modifications of the geometric structure will have on the function of the charge-transfer systems and the interplay of the ligand-metal relationship.