Ligand-Field Effects in a Ruthenium(II) Polypyridyl Complex Probed by Femtosecond X-ray Absorption Spectroscopy

Yujin Kim, Rory Ma, Junho Lee, Jessica Harich, Daewoong Nam, Sangsoo Kim, Minseok Kim, Miguel Ochmann, Intae Eom, Nils Huse, Jae Hyuk Lee, Tae Kyu Kim

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4 Citations (Scopus)

Abstract

We employ femtosecond X-ray absorption spectroscopy of [Ru(m-bpy)3]2+ (m-bpy = 6-methyl-2,2′-bipyridine) to elucidate the time evolution of the spin and charge density upon metal-to-ligand charge-transfer (MLCT) excitation. The core-level transitions at the Ru L3-edge reveal a very short MLCT lifetime of 0.9 ps and relaxation to the lowest triplet metal-centered state (3MC) which exhibits a lifetime of about 300 ps. Time-dependent density functional theory relates ligand methylation to a lower ligand field strength that stabilizes the 3MC state. A quarter of the 3MLCT population appears to be trapped which may be attributed to intramolecular vibrational relaxation or further electron transfer to the solvent. Our results demonstrate that small changes in the ligand field allow control of the photophysical properties. Moreover, this study underscores the high information content of femtosecond L-edge spectroscopy as a probe of valence charge density and spin-state in 4d transition metals.

Original languageEnglish
Pages (from-to)12165-12172
Number of pages8
JournalJournal of Physical Chemistry Letters
Volume12
Issue number51
DOIs
Publication statusPublished - 2021 Dec 30

Bibliographical note

Publisher Copyright:
© 2021 The Authors. Published by American Chemical Society

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Physical and Theoretical Chemistry

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