On the mechanism of vibrational control of light-induced charge transfer in donor-bridge-acceptor assemblies.
Nuclear-electronic (vibronic) coupling is increasingly recognized as a mechanism of major importance in controlling the light-induced function of molecular systems. It was recently shown that infrared light excitation of intramolecular vibrations can radically change the efficiency of electron transfer, a fundamental chemical process. We now extend and generalize the understanding of this phenomenon by probing and perturbing vibronic coupling in several molecules in solution. In the experiments an ultrafast electronic-vibrational pulse sequence is applied to a range of donor-bridge-acceptor Pt(II) trans-acetylide assemblies, for which infrared excitation of selected bridge vibrations during ultraviolet-initiated charge separation alters the yields of light-induced product states. The experiments, augmented by quantum chemical calculations, reveal a complex combination of vibronic mechanisms responsible for the observed changes in electron transfer rates and pathways. The study raises new fundamental questions about the function of vibrational processes immediately following charge transfer photoexcitation, and highlights the molecular features necessary for external vibronic control of excited-state processes.
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Milan
M
Delor
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Theo
T
Keane
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Paul A
PA
Scattergood
Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, STFC, Chilton, Oxfordshire OX11 0QX, UK.
Igor V
IV
Sazanovich
Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, STFC, Chilton, Oxfordshire OX11 0QX, UK.
Gregory M
GM
Greetham
Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, STFC, Chilton, Oxfordshire OX11 0QX, UK.
Michael
M
Towrie
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Anthony J H M
http://orcid.org/0000-0003-4803-3488
AJ
Meijer
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Julia A
JA
Weinstein