Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands

Maria Abrahamsson, Maria J. Lundqvist, Henriette Wolpher, Olof Johansson, Lars Eriksson, Jonas Bergquist, Torben Rasmussen, Hans Christian Becker, Leif Hammarström, Per Ola Norrby, Björn Åkermark, Petter Persson

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Abstract

The structural effect on the metal-to-ligand charge transfer (MLCT) excited-state lifetime has been investigated in bis-tridentate Ru(II)-polypyridyl complexes based on the terpyridine-like ligands [6-(2,2′-bipyridyl)](2-pyridyl)methane (1) and 2-[6-(2,2′-bipyridyl) ]-2-(2-pyridyl)propane (2). A homoleptic ([Ru(2)2]2+) and a heteroleptic complex ([Ru(ttpy)(2)]2+) based on the new ligand 2 have been prepared and their photophysical and structural properties studied experimentally and theoretically and compared to the results for the previously reported [Ru(1)2]2+. The excited-state lifetime of the homoleptic RuII complex with the isopropylene-bridged ligand 2 was found to be 50 times shorter than that of the corresponding homoleptic Ru II complex of ligand 1, containing a methylene bridge. A comparison of the ground-state geometries of the two homoleptic complexes shows that steric interactions involving the isopropylene bridges make the coordination to the central RuII ion less octahedral in [Ru(2)2]2+ than in [Ru(1)2]2+. Calculations indicate that the structural differences in these complexes influence their ligand field splittings as well as the relative stabilities of the triplet metal-to-ligand charge transfer (3MLCT) and metal-centered (3MC) excited states. The large difference in measured excited-state lifetimes for the two homoleptic RuII complexes is attributed to a strong influence of steric interactions on the ligand field strength, which in turn affects the activation barriers for thermal conversion from 3MLCT states to short-lived 3MC states.

Original languageEnglish
Pages (from-to)3540-3548
Number of pages9
JournalInorganic Chemistry
Volume47
Issue number9
DOIs
Publication statusPublished - May 5 2008

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2,2'-Dipyridyl
Ruthenium
Excited states
ruthenium
Ligands
life (durability)
ligands
excitation
Metals
metals
Charge transfer
charge transfer
Propane
Methane
methylene
propane
Ground state
Structural properties
field strength
methane

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Abrahamsson, M., Lundqvist, M. J., Wolpher, H., Johansson, O., Eriksson, L., Bergquist, J., ... Persson, P. (2008). Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands. Inorganic Chemistry, 47(9), 3540-3548. https://doi.org/10.1021/ic7019457

Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands. / Abrahamsson, Maria; Lundqvist, Maria J.; Wolpher, Henriette; Johansson, Olof; Eriksson, Lars; Bergquist, Jonas; Rasmussen, Torben; Becker, Hans Christian; Hammarström, Leif; Norrby, Per Ola; Åkermark, Björn; Persson, Petter.

In: Inorganic Chemistry, Vol. 47, No. 9, 05.05.2008, p. 3540-3548.

Research output: Contribution to journalArticle

Abrahamsson, M, Lundqvist, MJ, Wolpher, H, Johansson, O, Eriksson, L, Bergquist, J, Rasmussen, T, Becker, HC, Hammarström, L, Norrby, PO, Åkermark, B & Persson, P 2008, 'Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands', Inorganic Chemistry, vol. 47, no. 9, pp. 3540-3548. https://doi.org/10.1021/ic7019457
Abrahamsson M, Lundqvist MJ, Wolpher H, Johansson O, Eriksson L, Bergquist J et al. Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands. Inorganic Chemistry. 2008 May 5;47(9):3540-3548. https://doi.org/10.1021/ic7019457
Abrahamsson, Maria ; Lundqvist, Maria J. ; Wolpher, Henriette ; Johansson, Olof ; Eriksson, Lars ; Bergquist, Jonas ; Rasmussen, Torben ; Becker, Hans Christian ; Hammarström, Leif ; Norrby, Per Ola ; Åkermark, Björn ; Persson, Petter. / Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands. In: Inorganic Chemistry. 2008 ; Vol. 47, No. 9. pp. 3540-3548.
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AU - Johansson, Olof

AU - Eriksson, Lars

AU - Bergquist, Jonas

AU - Rasmussen, Torben

AU - Becker, Hans Christian

AU - Hammarström, Leif

AU - Norrby, Per Ola

AU - Åkermark, Björn

AU - Persson, Petter

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