TY - JOUR
T1 - A general formulation for magnetic exchange coupling within long-distance radical ion pairs
AU - Weiss, Emily A.
AU - Wasielewski, Michael R.
AU - Ratner, Mark A.
PY - 2005/8/8
Y1 - 2005/8/8
N2 - A Hubbard model-based expression for the magnetic exchange interaction, 2J, between the spins of a radical ion pair is derived for a generic donor-bridge-acceptor (D- Bn -A) system in terms of the superexchange coupling, t, between molecular orbitals of the donor, bridge, and acceptor and the energies, ε, and same-site Coulomb repulsions, U, of these orbitals. The formulation is used to predict 2J for the photophysically well-characterized series phenothiazine- p- (phenylene)n -perylene diimide, n=2,3,4,5, where the superexchange coupling is calculated with multipathway, second- and third-order perturbation theory coupled with the extended Huckel formalism. U and ε are estimated through experimentally determined electrochemical potentials. Due to multiple interactions arising from the large distance between magnetic centers in these donor-bridge-acceptor systems, agreement with experiment was substantially improved when third-order corrections were included in the calculation of t and 2J.
AB - A Hubbard model-based expression for the magnetic exchange interaction, 2J, between the spins of a radical ion pair is derived for a generic donor-bridge-acceptor (D- Bn -A) system in terms of the superexchange coupling, t, between molecular orbitals of the donor, bridge, and acceptor and the energies, ε, and same-site Coulomb repulsions, U, of these orbitals. The formulation is used to predict 2J for the photophysically well-characterized series phenothiazine- p- (phenylene)n -perylene diimide, n=2,3,4,5, where the superexchange coupling is calculated with multipathway, second- and third-order perturbation theory coupled with the extended Huckel formalism. U and ε are estimated through experimentally determined electrochemical potentials. Due to multiple interactions arising from the large distance between magnetic centers in these donor-bridge-acceptor systems, agreement with experiment was substantially improved when third-order corrections were included in the calculation of t and 2J.
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U2 - 10.1063/1.1995691
DO - 10.1063/1.1995691
M3 - Article
C2 - 16122323
AN - SCOPUS:24144466582
VL - 123
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 6
M1 - 064504
ER -