title: Photoexcited triplet state properties of brominated and nonbrominated Ga(III)-corroles as studied by time-resolved electron paramagnetic resonance.
abstract: The effect of the corrole macrocycle bromination on its photoexcited triplet state parameters was examined in a comparison study of brominated and nonbrominated Ga(III) 5,10,15-tris(pentafluorophenyl)corroles, employing X-band (9.5 GHz) time-resolved electron paramagnetic resonance (TREPR) spectroscopy. It is demonstrated that the spectrum of the brominated Ga-corrole is characterized by an opposite polarization pattern and a larger zero-field splitting (ZFS) parameter |D|, compared to nonbrominated Ga-corrole. With the assignment of a negative sign for the ZFS parameter D, the dominant intersystem crossing (ISC) pathways are evaluated. Spectral line shape analysis reveals that in the brominated Ga-corrole,the out-of-plane triplet sublevel is overpopulated (A(Z) > A(X), A(Y)), while in nonbrominated Ga-corrole, the in-plane triplet sublevels are preferentially populated (A(X), A(Y) ≫ A(Z)). The differences in the photophysical properties of the corroles are attributed to the heavy atom effect upon corrole skeleton bromination, which enhances the spin-orbit coupling strength in the brominated complex, thus affecting its ISC and ZFS parameters.
authors.affiliation: Department of Physical Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Linn
authors.initials: L
authors.lastname: Wagnert
authors.forename: Roy
authors.initials: R
authors.lastname: Rubin
authors.forename: Alexander
authors.initials: A
authors.lastname: Berg
authors.forename: Atif
authors.initials: A
authors.lastname: Mahammed
authors.forename: Zeev
authors.initials: Z
authors.lastname: Gross
authors.forename: Haim
authors.initials: H
authors.lastname: Levanon