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

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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

Fingerprint

Ruthenium
Paramagnetic resonance
Tuning
Ligands
Discrete Fourier transforms
Oxidation
Electrons
Cyclic voltammetry
Electronic structure
Spectroscopy
bis(bipyridyl)ruthenium(II)

Keywords

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

ASJC Scopus subject areas

  • Inorganic Chemistry

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

Tuning oxyquinolate non-innocence at the ruthenium polypyridyl core. / Zhao, Helen C.; Fu, Bi Li; Schweinfurth, David; Harney, Joseph P.; Sarkar, Biprajit; Tsai, Ming-Kang; Rochford, Jonathan.

In: European Journal of Inorganic Chemistry, No. 25, 01.09.2013, p. 4410-4420.

Research output: Contribution to journalArticle

Zhao, HC, Fu, BL, Schweinfurth, D, Harney, JP, Sarkar, B, Tsai, M-K & Rochford, J 2013, 'Tuning oxyquinolate non-innocence at the ruthenium polypyridyl core', European Journal of Inorganic Chemistry, no. 25, pp. 4410-4420. https://doi.org/10.1002/ejic.201300373
Zhao, Helen C. ; Fu, Bi Li ; Schweinfurth, David ; Harney, Joseph P. ; Sarkar, Biprajit ; Tsai, Ming-Kang ; Rochford, Jonathan. / Tuning oxyquinolate non-innocence at the ruthenium polypyridyl core. In: European Journal of Inorganic Chemistry. 2013 ; No. 25. pp. 4410-4420.
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AB - 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.

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