Tuning electron donor-acceptor hybrids by alkali metal complexation

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Photochemistry

Background:

• Zinc phthalocyanine (ZnPcTeCr) functionalized with crown ether moieties was synthesized.
• Self-assembly with pyridyl-functionalized perylenebisimides (PDI-Py) or fullerenes (C60-Py) formed novel electron donor-acceptor hybrids.
• Aggregation of ZnPcTeCr was controlled using potassium or rubidium ions, yielding monomers and cofacial dimers.

Purpose of the Study:

• To investigate the self-assembly and photophysical properties of novel electron donor-acceptor hybrids.
• To explore photoinduced electron transfer processes and charge-separated state dynamics.
• To determine association constants between donor and acceptor components.

Main Methods:

• Synthesis of ZnPcTeCr and its subsequent self-assembly with PDI-Py and C60-Py.
• Fluorescence titration experiments to study intermolecular interactions and derive association constants.
• Transient-absorption spectroscopy to confirm photoinduced electron transfer and measure charge-separated state lifetimes.

Main Results:

• Formation of ZnPcTeCr monomers and cofacial dimers in the presence of specific ions.
• Evidence of mutual interactions and photoinduced electron transfer between ZnPcTeCr and PDI-Py/C60-Py in the excited state.
• Observed photoinduced electron transfer within ZnPcTeCr dimers.
• Charge-separated state lifetimes up to 3.4 ns for PDI-Py hybrids and 5.1 ns for C60-Py hybrids.

Conclusions:

• The synthesized donor-acceptor hybrids exhibit efficient photoinduced electron transfer.
• Controlled self-assembly and ion coordination enable tuning of photophysical properties.
• Long charge-separated state lifetimes suggest potential applications in optoelectronics and artificial photosynthesis.