Weak effects on electron transfer reactions

Description

The photo-induced electron transfer (PET) plays an important role in many areas of chemistry. With individual changes in the environment, such as an external magnetic field or solvent parameters, one can systematically study the nature of the PET reaction.
Since they proved to be helpful for the clarification of chemical reaction mechanisms, studies of magnetic field effects on chemical reactions are of great interest. The measurements focus on the experimental investigation of magnetic field effects in exciplex forming organic fluorophore-quencher pairs. In these systems quenching occurs via bimolecular PET (or direct exciplex formation) and the recombination fluorescence is magnetosensitive. The magnetic field effect relies on the coherent interconversion between the singlet and the three triplet states as described by the radical pair mechanism.
The physical properties of the solvent influence the rate constant of PET reactions in many ways. Dielectric constant ε and refractive index n influence the solvent dipole reorientations and contribute to the activation energy of the electron transfer reactions [1]. That is why solvent-dependent measurements of ET reactions started quite early. But, electron-transfer kinetics is also influenced by diffusion and, therefore, by the solvent viscosity η. The results of polar and unipolar solvents are compared with high- and low-viscous ones. We will give an overview of possible individual changes in the reaction environment [2] for thermal ET as well as PET reaction. Pure organic solvents and ionic liquids are applicable for these changes depending on the demands of the reaction partners.

[1] M. Berghold, J. Bächle, S. Landgraf, G. Grampp, ChemPhysChem, 18,128 (2017).
[2] A. Wankmüller, M. Berghold, S. Landgraf, J. Mol. Liquids, 333, 115880 (2021).

Period	5 Sept 2023
Event title	GDCh-Wissenschaftforum 2023 : "Rethinking Chemistry"
Event type	Conference
Location	Leipzig, Germany, SaxonyShow on map
Degree of Recognition	International