Enhancing molecular recognition in electron donor-acceptor hybrids via cooperativity

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photochemistry

Background:

• Development of artificial systems mimicking natural photosynthetic processes is crucial.
• Electron donor-acceptor hybrids are key components in artificial photosynthesis and organic electronics.
• Precise control over molecular assembly and electronic interactions is essential for optimizing function.

Purpose of the Study:

• To synthesize and characterize a novel supramolecular electron donor-acceptor hybrid.
• To investigate the binding interactions and cooperativity within the hybrid.
• To explore the photoinduced electron transfer dynamics and charge-separated state lifetimes.

Main Methods:

• Synthesis of guanidinium bis-porphyrin tweezers (1) and fullerene carboxylate (3).
• Spectroscopic characterization (NMR, absorption, fluorescence) to confirm assembly and binding.
• Transient absorption spectroscopy to study photoinduced electron transfer.

Main Results:

• Successful assembly of a supramolecular hybrid (1@3) with exceptionally high binding constant.
• Demonstration of cooperative binding through hydrogen bonding and π-π/charge-transfer interactions.
• Observation of efficient photoinduced electron transfer from porphyrin to fullerene, yielding nanosecond-lived charge-separated states.

Conclusions:

• The novel supramolecular hybrid 1@3 exhibits strong self-assembly driven by multiple non-covalent interactions.
• Positive cooperativity between binding motifs enhances the stability and efficiency of the donor-acceptor system.
• The observed photoinduced electron transfer and long charge-separated state lifetimes show potential for applications in artificial photosynthesis and optoelectronics.