Use of tertiary solvent mixtures to study solvent effects

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The physical properties of the solvent influence the rate constant of Photoinduced electron transfer (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 ET reactions [1]. Electron-transfer kinetics is also influenced by diffusion and therefore by the solvent viscosity η. Unfortunately, most measurements published use different solvents in a not consequent way [2].
We present here the results of experiments made in a series of solvent mixtures comprising propyl acetate (PA), butyronitrile (BN), and diethyl phthalate (DEP), spanning a wide range of dielectric constants, keeping the n and η constant [3]. We used the PET reaction of singlet excited pyrene and indole whose solvent dependence is already described in the literature [2]. Quenching rate constants were obtained from Stern-Volmer plots based on both static and dynamic (TCSPC) measurements. The ΔG-dependence of ln kq are reported for the solvent mixtures and compared with results reported in pure organic solvents [2].

[1] M. Berghold, J. Bächle, S. Landgraf, G. Grampp, ChemPhysChem, 18,128 (2017).
[2] H. A. Montejano, J.J. Cosa, H.A. Garrera, C.M. Previtali, J. Photochem. Photobiol. A Chem. 86,115 (1995).
[3] A. Wankmüller, M. Berghold, S. Landgraf, J. Mol. Liquids, 333, 115880 (2021).
Period18 Jul 202219 Jul 2022
Event title28th PhotoIUPAC Amsterdam 2022 Symposium
Event typeConference
LocationAmsterdam, NetherlandsShow on map
Degree of RecognitionInternational

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy

Fields of Expertise

  • Advanced Materials Science