In-situ X-ray Absorption Spectroelectrochemistry for Determination of the Oxidation States and the Local Structure of Metalloprotein Model Compounds.

Abstract

X-ray absorption spectroscopy combined with an in-situ electrochemical cell has been developed for characterization of unstable, but electrochemically stable metalloprotein model compounds with various oxidation states in solution. The technique has been applied to some dimanganese Sehiff base complexes as a model of Photosystem II and [Ru2(t-O)(}-CH3COO)2(bpy)2L] 2(L=pyridine and l. -methylimidazole) as a model off hemerythrin. It has been found that X-ray absorption near-edge structure (XANES) patterns correlate well with the formal oxidation states of the metal ions and aggregation. The analysis of extended X-ray absorption fine structure (EXAFS) data has revealed characteristic metal-ligand and metal-metal distances within the model compounds with different oxidation states.

The applications of X-ray absorption spectroscopy in the study of solid state ionics

“…Combining XAFS and small-angle Xray scattering (SAXS)/wide-angle scattering (WAXS) allows the monitoring of local structure and texture, which is particularly useful in alloys and amorphous systems [13,14]. Other examples of combined studies include XAFS with differential scanning calorimetry (DSC) [15], Fourier transform infra-red (FTIR), [16] and electrochemical measurements [ 17].…”