Long-range electron transfer in zinc-phthalocyanine-oligo(phenylene-ethynylene)-based donor-bridge-acceptor dyads

Area of Science:

• Materials Science
• Photochemistry
• Supramolecular Chemistry

Background:

• Efficient long-range electron transfer is key for solar energy conversion.
• Donor-bridge-acceptor dyads are crucial for studying electron transfer dynamics.
• Understanding electronic coupling and charge recombination is vital for optimizing energy conversion.

Purpose of the Study:

• To synthesize and characterize new zinc(II) phthalocyanine oligophenylene-ethynylene based donor-bridge-acceptor dyads.
• To investigate the photophysical properties and electronic coupling in these dyads.
• To compare the performance of gold(III) porphyrin and fullerene acceptors with a tin(IV) porphyrin acceptor.

Main Methods:

• Synthesis of ZnPc-OPE-AuP(+) and ZnPc-OPE-C(60) dyads.
• Photophysical characterization including absorption spectroscopy.
• Computational characterization using TD-DFT calculations.

Main Results:

• ZnPc-OPE-AuP(+) exhibits strong electronic coupling (>3 nm) with ultrafast photoinduced electron transfer (1.0 × 10^12 s^-1) and slow charge recombination (1.0 × 10^9 s^-1).
• ZnPc-OPE-C(60) shows slower electron transfer (1.1 × 10^9 s^-1) and faster recombination (≈5 × 10^10 s^-1).
• TD-DFT calculations suggest gold-centered reduction in ZnPc-OPE-AuP(+) contributes to its long-lived charge-shifted state.

Conclusions:

• The ZnPc-OPE-AuP(+) dyad demonstrates highly efficient and long-lived charge separation, promising for solar energy applications.
• The nature of the electron acceptor significantly influences charge transfer and recombination dynamics.
• Understanding electron relaxation pathways is critical for designing advanced photovoltaic materials.