Predicting Dexter Energy Transfer Interactions from Molecular Orbital Overlaps

Dexter energy transfer (DET), also known as spin forbidden energy transfer (e.g., (3)D(1)A -> (1)D(3)A), is undergoing a resurgence of interest because of its utility in energy science, photocatalysis, and biomedical imaging. The DET reactions enable exciton fission and fusion and have been recently used to facilitate nanoscale imaging of protein assemblies on cell surfaces. While DET and Forster energy transfer rates are often well described using Fermi's golden rule, the donor-acceptor couplings for DET may be bridge-state-mediated and depend on the electronic structure of and interactions among the donor, bridge, and acceptor. We provide a simple approach to approximate DET couplings using a product of molecular orbital overlap factors. This approach may be used to guide the design of DET systems with targeted energy-transfer kinetics.