Photocurrent generation through charge-transfer processes in noncovalent perylenediimide/DNA complexes

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Biophysics

Background:

• Noncovalent interactions are crucial for assembling functional molecular systems.
• DNA's unique structure offers potential for organizing chromophores.
• Understanding charge transfer in such complexes is key for molecular electronics.

Purpose of the Study:

• To investigate charge-transfer dynamics in perylenediimide (PDI)/DNA complexes.
• To explore the role of DNA structure in facilitating charge separation.
• To correlate charge separation with photocurrent generation.

Main Methods:

• Nanosecond laser flash photolysis (LFP) to study excited states and charge separation.
• Photocurrent measurements using DNA-modified electrodes.
• Preparation of PDI/DNA complexes by incorporating cationic PDI into DNA.

Main Results:

• Photoexcitation of PDI within DNA efficiently generated long-lived charge-separated states.
• Charge separation efficiency correlated with the number of A-T base pairs between PDIs, indicating electron hopping.
• Photocurrent generation was dependent on PDI arrangement, showing a correlation with charge separation.

Conclusions:

• DNA can precisely arrange organic chromophores like PDI for efficient charge separation.
• Electron hopping between PDIs within DNA is a viable charge transfer mechanism.
• Defined PDI/DNA assembly is critical for optimizing charge transfer and photocurrent in multichromophore systems.