Chemistry

News and events

24 February 2021

Seminar - Photoinduced Symmetry-Breaking Charge Transfer

Presented By Prof. Eric Vauthey (University of Geneva, Switzerland)

About this event

Abstract

A significant number of multichromophoric systems and multipolar conjugated molecules undergo photoinduced charge transfer along one among several energetically equivalent pathways, resulting in a breaking of their symmetry.[1] Understanding and harnessing these processes is crucial for developments and applications in various areas including solar energy conversion and molecular electronics. Several of our efforts towards such a comprehension of the origins and dynamics of these symmetry-breaking phenomena will be presented.

Photoinduced charge separation between two identical sub-units will be illustrated by studies on perylene-based bichromophoric molecules.[2] They reveal the importance of the environment for the direction of the charge separation and of the coupling of the sub-units for the extent of asymmetry in charge distribution.

Excited-state symmetry breaking in quadrupolar and octupolar D-(pi-A)2,3 or A-(pi D)2,3 molecules leads to a dipolar character of their electronic excited state.[3] We will show how this process can be directly visualised using time-resolved spectroscopy.[4] The influence of various parameters, such as solute-solvent interactions and structural disorder, on the symmetry breaking will be discussed.[5,6] Finally, the relevance of this process to the photochemistry of multipolar molecules will be addressed.[7]

  1. [1]  E. Vauthey, ChemPhysChem, 13, 2001-2011 (2012)

  2. [2]  A. Aster, G. Licari, F. Zinna, E. Brun, T. Kumpulainen, E. Tajkhorshid, J. Lacour,

    E. Vauthey, Chem. Sci., 10, 10629-10639 (2019)

  3. [3]  F. Terenziani, A. Painelli, C. Katan, M. Charlot and M. Blanchard-Desce, J. Am.

    Chem. Soc., 128, 15742-15755 (2006)

  4. [4]  B. Dereka, A. Rosspeintner, Z. Li, R. Liska and E. Vauthey, J. Am. Chem. Soc.,

    138, 4643-4649 (2016)

  5. [5]  B. Dereka and E. Vauthey, J. Phys. Chem. Lett., 8, 3927-3932 (2017)

  6. [6]  M. Soederberg, B. Dereka, A. Marrocchi, B. Carlotti and E. Vauthey, J. Phys. Chem. Lett., 10, 2944-2948 (2019)

  7. [7]  B. Dereka, D. Svechkarev, A. Rosspeintner, A. Aster, M. Lunzer, R. Liska, A. M. Mohs, E. Vauthey, Nature Commun., 11, 1925 (2020)