X-ray Emission Spectroscopy of Biomimetic Mn Coordination Complexes.
Scott C JensenKatherine M DavisBrendan SullivanDaniel A HartzlerGerald T SeidlerDiego M CasaElina KasmanHannah E ColmerAllyssa A MassieTimothy A JacksonYulia PushkarPublished in: The journal of physical chemistry letters (2017)
Understanding the function of Mn ions in biological and chemical redox catalysis requires precise knowledge of their electronic structure. X-ray emission spectroscopy (XES) is an emerging technique with a growing application to biological and biomimetic systems. Here, we report an improved, cost-effective spectrometer used to analyze two biomimetic coordination compounds, [MnIV(OH)2(Me2EBC)]2+ and [MnIV(O)(OH)(Me2EBC)]+, the second of which contains a key MnIV═O structural fragment. Despite having the same formal oxidation state (MnIV) and tetradentate ligands, XES spectra from these two compounds demonstrate different electronic structures. Experimental measurements and DFT calculations yield different localized spin densities for the two complexes resulting from MnIV-OH conversion to MnIV═O. The relevance of the observed spectroscopic changes is discussed for applications in analyzing complex biological systems such as photosystem II. A model of the S3 intermediate state of photosystem II containing a MnIV═O fragment is compared to recent time-resolved X-ray diffraction data of the same state.
Keyphrases
- high resolution
- density functional theory
- single molecule
- molecular docking
- room temperature
- dual energy
- electron transfer
- solid state
- healthcare
- mass spectrometry
- computed tomography
- molecular dynamics simulations
- transition metal
- magnetic resonance imaging
- big data
- magnetic resonance
- nitric oxide
- electronic health record