Ring-Opening Polymerization of ε-Caprolactone by Using Aluminum Complexes Bearing Aryl Thioether Phenolates: Labile...

Area of Science:

• Organometallic Chemistry
• Polymer Science
• Catalysis

Background:

• Aluminum complexes are versatile catalysts.
• Ferrocene-based ligands offer unique electronic properties.
• ε-caprolactone polymerization is crucial for biodegradable polymers.

Purpose of the Study:

• Synthesize and characterize aluminum complexes with ferrocene-based and arylthiomethylphenolate ligands.
• Investigate their catalytic activity in ε-caprolactone polymerization.
• Elucidate the role of ligand structure and redox state on catalytic performance.

Main Methods:

• Synthesis of novel aluminum complexes.
• ε-caprolactone polymerization experiments.
• Density Functional Theory (DFT) calculations.

Main Results:

• Reduced aluminum complexes exhibited higher catalytic activity than oxidized forms.
• Specific complexes like fc(OAlMe)2 showed rapid polymerization (40 min, 100% conversion).
• Electron-deficient substituents on phenolate ligands decreased catalytic activity.

Conclusions:

• Thioether coordination is vital for stabilizing transition states in aluminum-catalyzed ε-caprolactone polymerization.
• The labile nature of the thioether group makes it a suitable chelating moiety for these catalysts.
• Redox state of the ferrocene ligand significantly impacts catalytic efficiency.