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.
N1 - Funding Information:
One of the authors (E.A.W.) would like to thank Michael Ahrens and Jovan Giaimo for electrochemical measurements and the Link Foundation and Northwestern University for fellowships. Another author (M.A.R.) thanks DARPA and the NSF and ONR chemistry divisions for support of this work. One of the authors (M.R.W.) acknowledges support of the National Science Foundation under Grant No. 0415730.
Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
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 -