en
Scientific article
English

On the role of ligand-field states for the photophysical properties of ruthenium(II) polypyridyl complexes

Published inCoordination chemistry reviews, vol. 282-283, p. 87-99
Publication date2015
Abstract

The role of ligand-field states for the photophysical properties of d6 systems has been discussed in a large number of publications over the past decades. Since the seminal paper by Houten and Watts, for instance, the quenching of the 3MLCT luminescence in ruthenium(II) polypyridyl complexes is attributed to the presence of the first excited ligand-field state, namely a component of the 3T1(t2g5eg1) state, at similar energies. If this state lies above the 3MLCT state, the luminescence is quenched via thermal population at elevated temperatures only. If it lies well below, then the luminescence is quenched down to cryogenic temperatures. In this contribution we present transient absorption spectra on non-luminescent ruthenium polypyridyl complexes such as [Ru(m-bpy)3]2+, m-bpy = 6-methyl-2,2'-bipyridine, in acetonitrile at room temperature, which reveal an ultra-rapid depopulation of the 3MLCT state but a much slower ground state recovery. We propose that in this and related complexes the methyl groups force longer metal-ligand bond lengths, thus resulting in a lowering of the ligand-field strength such that the 3dd state drops to below the 3MLCT state, and that furthermore the population of this state from the 3MLCT state occurs faster than its decay to the ground state. In addition we demonstrate that in this complex the luminescence can be switched on by external pressure, which we attribute to a destabilisation of the ligand-field state by the pressure due to its larger molecular volume compared to the ground state as well as the 3MLCT state.

Keywords
  • Ruthenium(II) polypyridyl complexes
  • Ligand-field states
  • Luminescence quenching
  • Photophysical properties
  • High-pressure
Citation (ISO format)
SUN, Qinchao et al. On the role of ligand-field states for the photophysical properties of ruthenium(II) polypyridyl complexes. In: Coordination chemistry reviews, 2015, vol. 282-283, p. 87–99. doi: 10.1016/j.ccr.2014.07.004
Main files (1)
Article (Published version)
accessLevelRestricted
Identifiers
ISSN of the journal0010-8545
705views
0downloads

Technical informations

Creation11/24/2014 8:43:00 AM
First validation11/24/2014 8:43:00 AM
Update time03/14/2023 10:17:29 PM
Status update03/14/2023 10:17:29 PM
Last indexation01/16/2024 2:32:32 PM
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack