Infrared vibrational spectroscopy of [Ru(bpy)2(bpm)] 2+ and [Ru(bpy)3]2+ in the excited triplet state

Tatsuhiko Mukuta, Naoto Fukazawa, Kei Murata, Akiko Inagaki, Munetaka Akita, Sei'Ichi Tanaka, Shin Ya Koshihara, Ken Onda

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Abstract

This work involved a detailed investigation into the infrared vibrational spectra of ruthenium polypyridyl complexes, specifically heteroleptic [Ru(bpy)2(bpm)]2+ (bpy = 2,2′-bipyridine and bpm = 2,2′-bipyrimidine) and homoleptic [Ru(bpy)3]2+, in the excited triplet state. Transient spectra were acquired 500 ps after photoexcitation, corresponding to the vibrational ground state of the excited triplet state, using time-resolved infrared spectroscopy. We assigned the observed bands to specific ligands in [Ru(bpy)2(bpm)]2+ based on the results of deuterium substitution and identified the corresponding normal vibrational modes using quantum-chemical calculations. Through this process, the more complex vibrational bands of [Ru(bpy)3] 2+ were assigned to normal vibrational modes. The results are in good agreement with the model in which excited electrons are localized on a single ligand. We also found that the vibrational bands of both complexes associated with the ligands on which electrons are little localized appear at approximately 1317 and 1608 cm-1. These assignments should allow the study of the reaction dynamics of various photofunctional systems including ruthenium polypyridyl complexes.

Original languageEnglish
Pages (from-to)2481-2490
Number of pages10
JournalInorganic chemistry
Volume53
Issue number5
DOIs
Publication statusPublished - Mar 3 2014
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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