3/27/2023 0 Comments Spacechem double bonds![]() In addition to the two-electron interaction identified by Dexter, one-electron interactions (applied to second or higher order) also couple D to A. However, most Dexter systems of interest today involve chemically bridged species. The two-particle pathway framework developed here shows how Dexter energy-transfer rates depend on donor, bridge, and acceptor energetics, as well as on orbital symmetry and quantum interference among pathways.ĭexter’s 1953 analysis of spin-forbidden excitation energy transfer between donor (D) and acceptor (A) moieties in contact invoked coupling via the electron–electron Coulomb operator ( 5). ![]() The effects of virtual bridge excitons were neglected in earlier treatments. ![]() Virtual donor–acceptor charge-transfer exciton intermediates dominate at shorter distances or higher tunneling energy gaps, whereas virtual intermediates with an electron and a hole both on the bridge (virtual bridge excitons) dominate for longer distances or lower energy gaps. We dissect the bridge-mediated Dexter coupling mechanisms and formulate a theory for triplet energy transfer coupling pathways. However, Dexter coupling pathways must convey both an electron and a hole from donor to acceptor, and this adds considerable richness to the mediation process. Dexter transfer between chemically linked donors and acceptors is bridge mediated, presenting an enticing analogy with bridge-mediated electron and hole transfer. Energy transfer with an associated spin change of the donor and acceptor, Dexter energy transfer, is critically important in solar energy harvesting assemblies, damage protection schemes of photobiology, and organometallic opto-electronic materials. ![]()
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