Electronic structure of catalysts and bioorganic molecules

People

Project coordinator: Sergey Bokarev
Co-workers: Olga Bokareva
Collaborations: Emad F. Aziz (HMZ Berlin), Saadullah G. Aziz (King Abdulaziz University Jeddah), Christian Bressler (European XFEL Hamburg)

Project description

Transition metal ion–coordinated ligand interactions govern a large fraction of processes in everyday life and their understanding on a microscopic level is of key importance for chemistry, biochemistry, catalysis, and material science. Soft L-edge X-ray spectroscopic techniques (photon energies 0.1-1.0 keV) enjoy popularity as a local atom-specific electronic probe of atomic interactions with their chemical environment due to the dipole allowed nature of the underlying 2p-3d transitions. The popular variants include X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) techniques. The former focuses on the electronic transitions, where the core electron is excited to the manifold of the unoccupied molecular orbitals, whereas the latter detects the emission signal resulting from the refill of the core-hole by electrons occupying valence and deeper lying shallow core molecular orbitals. However, the L-edge spectra usually posses quite complex structures which stem from strong electron correlation and spin-orbit coupling, triggered upon core-hole formation. Thus, their interpretation and quantitative analysis requires aid from the first principles structure theory. Within this project we develop a flexible approach based on the restricted active space self-consistent field theory for the description of XAS and RIXS spectra. The list of problems in focus includes study of specific ion-ligand interactions, nature and strength of chemical bonds, redox reactions and aggregation effects in catalytically and biologically active transition metal complexes.

Publications

  1. S. I. Bokarev, M. Khan, M. Abdel-Latif, J. Xiao, R. H. Hilal, S. G. Aziz, E. Aziz, O. Kühn
    Unraveling Electronic Structure of Photocatalytic Manganese Complexes by L-edge X-ray Spectroscopy
    J. Phys. Chem. C 119, 19192 (2015)
  2. N. Engel, S. I. Bokarev, E. Suljoti, R. Garcia-Diez, K. M. Lange, K. Atak, R. Golnak, A. Kothe, M. Dantz, O. Kühn, E. F. Aziz
    Chemical Bonding in Aqueous Ferrocyanide: Experimental and Theoretical X-ray Spectroscopic Study
    J. Phys. Chem. B 118, 1555 (2014)
  3. S. I. Bokarev, M. Dantz, E. Suljoti, O. Kühn, E. F. Aziz
    State-Dependent Electron Delocalization Dynamics at the Solute-Solvent Interface: Soft-X-Ray Absorption Spectroscopy and Ab Initio Calculations
    Phys. Rev. Lett. 111, 083002 (2013)
  4. E. Suljoti, R. Garcia-Diez, S. I. Bokarev, K. M. Lange, R. Schoch, B. Dierker, M. Dantz, K. Yamamoto, N. Engel, K. Atak, O. Kühn, M. Bauer, J.-E. Rubensson, E. F. Aziz
    Direct observation of molecular orbital mixing in a solvated organometallic complex
    Angew. Chem. Int. Ed. 52, 9841 (2013)
  5. K. Atak, S. I. Bokarev, M. Gotz, R. Golnak, K. M. Lange, N. Engel, M. Dantz, E. Suljoti, O. Kühn, E. F. Aziz
    Nature of the chemical bond of aqueous Fe2+ probed by Soft X-ray spectroscopies and ab initio calculations
    J. Phys. Chem. B 117, 12613 (2013)

Financing

DFG Grant KU 952/10-1
Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah, (Grant No. D-003-435)