Open AccessCharacterization of “Free Base” and Metal Complex Thioalkyl Porphyrazines by Magnetic Circular Dichroism and TDDFT Calculations
Author(s) -
Simone Ghidinelli,
Sergio Abbate,
Ernesto Santoro,
Sandra Belviso,
Giovanna Longhi
Publication year - 2020
Publication title -
the journal of physical chemistry. b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 392
eISSN - 1520-6106
pISSN - 1520-5207
DOI - 10.1021/acs.jpcb.0c09277
Subject(s) - time dependent density functional theory , chemistry , magnetic circular dichroism , porphyrazine , density functional theory , circular dichroism , metal , crystallography , spectral line , photochemistry , computational chemistry , physics , organic chemistry , astronomy
UV-vis absorption and magnetic circular dichroism (MCD) spectra of octakis thioethyl "free base" porphyrazine H 2 OESPz and its metal complexes MOESPz (M = Mg, Zn, Ni, Pd, Cu), as well as of [MnOESPz(SH)] were recorded. In the last case, MCD proved to have quite good sensitivity to the coordination of this complex with 1-methylimidazole (1-mim) in benzene. Time-dependent density functional theory (TDDFT) calculations were carried out for the considered porphyrazine complexes and showed good performance on comparing with MCD and UV-vis experimental spectra, even in the open-shell Cu and Mn cases. Calculations accounted for the red shift observed in the thioalkyl compounds and allowed us to reveal the role of sulfur atoms in spectroscopically relevant molecular orbitals and to highlight the importance of the conformations of the thioethyl external groups. Calculated MCD spectra of [MnOESPz(SH)] confirm the Mn(III) → Mn(II) redox process, which leads to the [Mn(OESPz)(1-mim) 2 ] species, and the relevance of the spin state for MCD is revealed.