Correlated Reaction Coordinate Motion Produces Nonadditive Rate Enhancement for Electron and Energy Transfer in...

Area of Science:

• Physical Chemistry
• Quantum Chemistry
• Molecular Biophysics

Background:

• Molecular structures with multiple donor, bridge, or acceptor units can exhibit quantum interference.
• Electron and energy transfer (ET and EnT) rates are influenced by these quantum effects.
• Experimental studies show a 4-5 fold increase in ET rates for systems with two acceptors versus one.

Purpose of the Study:

• To analyze the coupling interactions in multi-acceptor molecular systems.
• To explain the observed rate enhancements in electron and energy transfer beyond simple additive models.
• To identify strategies for tailoring ET and EnT kinetics in complex molecular architectures.

Main Methods:

• Analysis of coupling interactions in multi-acceptor systems.
• Theoretical investigation of quantum interference effects on ET and EnT rates.
• Examination of factors influencing reaction free energy, donor-acceptor couplings, and reaction-coordinate motion.

Main Results:

• Rate enhancements in multi-acceptor systems exceed simple additive predictions.
• Acceptor-acceptor interactions are identified as the source of these enhanced rates.
• These interactions modify reaction free energy, donor-acceptor couplings, and reaction-coordinate dynamics.

Conclusions:

• The surprising rate enhancements in multi-acceptor systems are explained by inter-acceptor interactions.
• Understanding these interactions allows for prediction and control of ET and EnT rates.
• This work provides a framework for designing molecular systems with tailored electron and energy transfer properties.