Influence of axial and peripheral ligands on the electronic structure of titanium phthalocyanines

David F. Pickup, Juan Maria García Lastra, Celia Rogero, Angel Rubio, J. Enrique Ortega, Ioannis Zegkinoglou, Phillip S. Johnson, F.J. Himpsel, Beatriz Ballesteros, Carolina R. Ganivet, Gema De La Torre, Peter L. Cook, Frank De Groot

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To discover how molecular changes affect the electronic structure of dye molecules for solar cells, we have investigated four titanium phthalocyanines customized by axial and peripheral ligands (monodentate oxo versus bidentate catechol and tert-butyl versus tert-butylphenoxy, respectively). X-ray absorption spectroscopy and photoelectron spectroscopy were combined with density functional theory (DFT) and crystal-field multiplet calculations to characterize the Ti 3d and N 2p valence electrons that form the frontier orbitals. When a monodentate oxo axial ligand was replaced by a bidentate catechol ligand, the multiplet structure of the Ti 2p-to-3d transitions was found to change systematically. The most noticeable change was an additional transition into the low-lying 3dxy level, which is attributed to a reduction in local symmetry from 4-fold to 2-fold at the Ti center. An increase of the Ti 2p core-level binding energy was observed in the bidentate complex and compared to a calculated core-level stabilization. DFT predicts a change of the LUMO from the inner phthalocyanine ring to the Ti dxy orbital and a reversal of the high-lying dx2-y2 and d z2 orbitals. The N 1s edge was calculated using time-dependent density functional theory (TDDFT) and compared to experiment. © 2013 American Chemical Society.
Original languageEnglish
JournalThe Journal of Physical Chemistry Part C
Issue number9
Pages (from-to)4410-4420
Publication statusPublished - 2013


  • Binding energy
  • Density functional theory
  • Electronic structure
  • Nitrogen compounds
  • Phenols
  • Photoelectron spectroscopy
  • Three dimensional computer graphics
  • Titanium
  • X ray absorption spectroscopy
  • Ligands

Cite this

Pickup, D. F., García Lastra, J. M., Rogero, C., Rubio, A., Ortega, J. E., Zegkinoglou, I., Johnson, P. S., Himpsel, F. J., Ballesteros, B., Ganivet, C. R., De La Torre, G., Cook, P. L., & De Groot, F. (2013). Influence of axial and peripheral ligands on the electronic structure of titanium phthalocyanines. The Journal of Physical Chemistry Part C, 117(9), 4410-4420.