Characterization of Free Base and Metal Complex Thioalkyl Porphyrazines by Magnetic Circular Dichroism and TDDFT Calculations

Year: 2021

Authors: Ghidinelli S., Abbate S., Santoro E., Belviso S., Longhi G.

Autors Affiliation: Univ Brescia, Dipartimento Med Mol & Traslaz, I-25123 Brescia, Italy; Ist Nazl Ottica INO, Res Unit Brescia, CNR, I-25123 Brecia, Italy; Univ Basilicata, Dipartimento Sci, I-85100 Potenza, Italy.

Abstract: UV-vis absorption and magnetic circular dichroism (MCD) spectra of octakis thioethyl free baseporphyrazine 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.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY B

Volume: 125 (1)      Pages from: 264  to: 280

More Information: Research was carried out with the support of resources of Big & Open Data Innovation Laboratory (BODaI-Lab), University of Brescia, granted by Fondazione Cariplo and Regione Lombardia and of the Computing Center CINECA (Bologna), Italy. Financial support from the Cariplo Foundation, through Agrofood Lab, University of Brescia for E.S. is acknowledged. The research team in Brescia acknowledges funding from the Italian Ministry of Education, University and Research (MIUR) through the PRIN 2017 program (Project 2017A4XRCA_003 Physico-chemical Heuristic Approaches: Nanoscale Theory of Molecular Spectroscopy [PHANTOMS]). S.B. acknowledges financial support from Universita della Basilicata (R.I.L. 2016 grant) and from MIUR, Project PON RI 2014-2020 BIOFEEDSTOCK.
KeyWords: Nonlinear-optical Properties; Density-functional Theory; Pi-electron Systems; B-terms; Td-dft; Spectroscopic Properties; Hydrosulfide Complexes; Discotic Mesomorphism; Algebraic-solution; Mcd Spectroscopy
DOI: 10.1021/acs.jpcb.0c09277

Citations: 5
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