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The Nature of the Long‐Lived Excited State in a Ni II Phthalocyanine Complex Investigated by X‐Ray Transient Absorption Spectroscopy
Author(s) -
Hong Jiyun,
Kelley Matthew S.,
Shelby Megan L.,
Hayes Dugan K.,
Hadt Ryan G.,
Rimmerman Dolev,
Zhang Xiaoyi,
Chen Lin X.
Publication year - 2018
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201800777
Subject(s) - excited state , ultrafast laser spectroscopy , phthalocyanine , absorption spectroscopy , spectroscopy , nickel , ground state , absorption (acoustics) , synchrotron , x ray absorption spectroscopy , chemistry , atomic physics , spectral line , photochemistry , materials science , nanotechnology , physics , optics , organic chemistry , quantum mechanics , astronomy , composite material
The nature of the photoexcited state of octabutoxy nickel(II) phthalocyanine (NiPcOBu 8 ) 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 NiPcOBu 8 was reassessed. Using X‐ray probe pulses from a synchrotron source, the ground‐ and excited‐state X‐ray absorption spectra of NiPcOBu 8 were measured. Based on the results, we identified that the excited state exhibits spectral features that are characteristic of a Ni 1, 3 (3dz2,3dx2 - y2) 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.