TY - JOUR
T1 - The electronic structure and dynamics of the excited triplet state of octaethylaluminum(III)-porphyrin investigated with advanced EPR methods
AU - Carella, Angelo
AU - Ciuti, Susanna
AU - Wiedemann, Haakon T.A.
AU - Kay, Christopher W.M.
AU - van der Est, Arthur
AU - Carbonera, Donatella
AU - Barbon, Antonio
AU - Poddutoori, Prashanth K.
AU - Di Valentin, Marilena
N1 - Publisher Copyright:
© 2023
PY - 2023/8
Y1 - 2023/8
N2 - The photoexcited triplet state of octaethylaluminum(III)-porphyrin (AlOEP) was investigated by time-resolved Electron Paramagnetic Resonance, Electron Nuclear Double Resonance and Electron Spin Echo Envelope Modulation in an organic glass at 10 and 80 K. This main group element porphyrin is unusual because the metal has a small ionic radius and is six-coordinate with axial covalent and coordination bonds. It is not known whether triplet state dynamics influence its magnetic resonance properties as has been observed for some transition metal porphyrins. Together with density functional theory modelling, the magnetic resonance data of AlOEP allow the temperature dependence of the zero-field splitting (ZFS) parameters, D and E, and the proton AZZ hyperfine coupling (hfc) tensor components of the methine protons, in the zero-field splitting frame to be determined. The results provide evidence that the ZFS, hfc and spin–lattice relaxation are indeed influenced by the presence of a dynamic process that is discussed in terms of Jahn-Teller dynamic effects. Thus, these effects should be taken into account when interpreting EPR data from larger complexes containing AlOEP.
AB - The photoexcited triplet state of octaethylaluminum(III)-porphyrin (AlOEP) was investigated by time-resolved Electron Paramagnetic Resonance, Electron Nuclear Double Resonance and Electron Spin Echo Envelope Modulation in an organic glass at 10 and 80 K. This main group element porphyrin is unusual because the metal has a small ionic radius and is six-coordinate with axial covalent and coordination bonds. It is not known whether triplet state dynamics influence its magnetic resonance properties as has been observed for some transition metal porphyrins. Together with density functional theory modelling, the magnetic resonance data of AlOEP allow the temperature dependence of the zero-field splitting (ZFS) parameters, D and E, and the proton AZZ hyperfine coupling (hfc) tensor components of the methine protons, in the zero-field splitting frame to be determined. The results provide evidence that the ZFS, hfc and spin–lattice relaxation are indeed influenced by the presence of a dynamic process that is discussed in terms of Jahn-Teller dynamic effects. Thus, these effects should be taken into account when interpreting EPR data from larger complexes containing AlOEP.
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U2 - 10.1016/j.jmr.2023.107515
DO - 10.1016/j.jmr.2023.107515
M3 - Article
C2 - 37364432
AN - SCOPUS:85163002050
SN - 1090-7807
VL - 353
JO - Journal of Magnetic Resonance
JF - Journal of Magnetic Resonance
M1 - 107515
ER -