The Nature of the Long-Lived Excited State in a NiII Phthalocyanine Complex Investigated by X-Ray Transient Absorption Spectroscopy

Jiyun Hong, Matthew S. Kelley, Megan L. Shelby, Dugan K. Hayes, Ryan G. Hadt, Dolev Rimmerman, Xiaoyi Zhang, Lin X. Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The nature of the photoexcited state of octabutoxy nickel(II) phthalocyanine (NiPcOBu8) with a 500 ps lifetime was investigated by X-ray transient absorption (XTA) spectroscopy. Previous optical, vibrational, and computational studies have suggested that this photoexcited state has a ligand-to-metal charge transfer (LMCT) nature. By using XTA, which provides unambiguous information on the local electronic and nuclear configuration around the Ni center, the nature of the excited state of NiPcOBu8 was reassessed. Using X-ray probe pulses from a synchrotron source, the ground- and excited-state X-ray absorption spectra of NiPcOBu8 were measured. Based on the results, we identified that the excited state exhibits spectral features that are characteristic of a Ni1, 3(3dz2, 3dz2-yz2) state rather than a LMCT state with a transiently reduced Ni center. This state resembles the (d,d) state of nickel(II) tetramesitylphorphyrin. The XTA features are rationalized based on the inherent cavity sizes of the macrocycles. These results may provide useful guidance for the design of photocatalysts in the future.

Original languageEnglish (US)
Pages (from-to)2421-2428
Number of pages8
Issue number14
StatePublished - Jul 20 2018


  • charge transfer
  • electronic structure
  • photochemistry
  • phthalocyanines
  • x-ray absorption spectroscopy

ASJC Scopus subject areas

  • Environmental Chemistry
  • Chemical Engineering(all)
  • Materials Science(all)
  • Energy(all)


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