Formulation of Long-Range Transport Rates through Molecular Bridges: From Unfurling to Hopping

Area of Science:

• Physical Chemistry
• Molecular Biophysics
• Quantum Mechanics

Background:

• Charge transfer in molecular systems is crucial for biological and synthetic processes.
• Understanding charge transport mechanisms in donor-bridge-acceptor systems is key to designing efficient molecular devices.
• Existing models often describe charge transfer as hopping or ballistic, but other mechanisms may exist.

Purpose of the Study:

• To investigate the role of molecular bridge fluctuations in charge transfer mechanisms.
• To differentiate between quantum unfurling and hopping transport in molecular bridges.
• To explain the observed length independence of charge transfer rates.

Main Methods:

• Theoretical modeling of charge transfer in donor-bridge-acceptor systems.
• Analysis of the effects of static disorder and local fluctuations on transport mechanisms.
• Development of a unified formulation to explain observed phenomena.

Main Results:

• Weak fluctuations drive charge transfer via quantum unfurling, a novel mechanism.
• Static disorder can induce a transition from unfurling to hopping transport.
• Both mechanisms yield similar charge transfer rates, nearly independent of molecular bridge length.

Conclusions:

• Quantum unfurling is a distinct charge transfer mechanism in molecular bridges.
• A unified theoretical framework explains the length-independent charge transfer rates.
• Proposed experimental tests can distinguish unfurling from hopping in DNA models.