Tuning oxyquinolate non-innocence at the ruthenium polypyridyl core

Helen C. Zhao, Bi Li Fu, David Schweinfurth, Joseph P. Harney, Biprajit Sarkar, Ming-Kang Tsai, Jonathan Rochford

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The electronic structure of [Ru(bpy)2(OQN)]+ (where bpy = 2,2′-bipyridine and OQN = 8-oxyquinolate) has been revisited using a complimentary suite of theoretical (DFT/TD-DFT), electrochemical (cyclic voltammetry) and spectroscopic techniques (UV/Vis/NIR absorption, EPR spectroscopy). Through functionalization of the R-OQN ligand (R = 2-Me; 5,7-Me2; 5-F; 5-Cl; 5,7-Cl2; 5-NO2) charge delocalization across the non-innocent ruthenium-oxyquinolate framework has been investigated and correlated with substituent Hammett parameters. Combined spectroscopic and computational studies indicate substantial mixing at the HOMO-3, HOMO and LUMO+2 levels between the Ru and R-OQN π-systems allowing controlled tuning of complex redox potentials while maintaining panchromatic absorption characteristics. UV/Vis/NIR and EPR spectroelectrochemical data is reported which shows strong evidence for substituent dependence of hole delocalization onto the R-OQN ligand following one-electron oxidation of the hybrid Ru(R-OQN) based HOMO level. EPR data correlates very well with Mulliken spin-density calculations confirming non-innocence of the R-OQN ligand which allows control of spin-distribution across the Ru(R-OQN) π-system Several [Ru(bpy)2(R-OQN)]+ complexes show enhanced charge delocalization across the non-innocent ruthenium-oxyquinolate framework that correlates well with substituent Hammett parameters (R = 2-Me; 5,7-Me 2; 5-F; 5-Cl; 5,7-Cl2; 5-NO2). Control of hole delocalization onto R-OQN ligands is demonstrated following one-electron oxidation as probed by UV/Vis/NIR, EPR and spin-density investigations.

Original languageEnglish
Pages (from-to)4410-4420
Number of pages11
JournalEuropean Journal of Inorganic Chemistry
Issue number25
DOIs
Publication statusPublished - 2013 Sep 1

Keywords

  • EPR spectroscopy
  • Electrochemistry
  • Non-innocent ligands
  • Polypyridyl ligands
  • Ruthenium

ASJC Scopus subject areas

  • Inorganic Chemistry

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  • Cite this

    Zhao, H. C., Fu, B. L., Schweinfurth, D., Harney, J. P., Sarkar, B., Tsai, M-K., & Rochford, J. (2013). Tuning oxyquinolate non-innocence at the ruthenium polypyridyl core. European Journal of Inorganic Chemistry, (25), 4410-4420. https://doi.org/10.1002/ejic.201300373