XAS Diagnostic of the Photoactive State in Co(II) Azobenzene Complex in Organic Solvents

Abstract

X-ray absorption spectroscopy (XAS) was used to characterize the structure of the photoactive Co(II) azobenzene complex. Optical absorption spectra show that photoinduced changes occur only in dimethylformamide (DMF) solvent, while in acetonitrile, this complex is photochemically inactive. Co Kedge XAS spectra indicate 6-coordinated species in acetonitrile with a structure similar to one in the crystalline form of the complex. However, in DMF, an activation process occurs related to the decrease of coordination number, bond shortening and absorption edge shift to the higher energies. Quantitative analysis indicates that observed spectral changes are related to the high spin -low spin transition in the Co complex accompanied by the bond dissociation and solvent coordination.