Dimethylaluminium aldiminophenolates: synthesis, characterization and ring-opening polymerization behavior towards...

Area of Science:

• Organometallic Chemistry
• Polymer Science
• Catalysis

Background:

• Salicylaldimine derivatives are versatile ligands in coordination chemistry.
• Aluminum complexes are known catalysts for polymerization reactions.
• Ring-opening polymerization (ROP) is a key method for synthesizing polyesters like polylactide.

Purpose of the Study:

• To synthesize novel dimethylaluminum aldiminophenolate complexes.
• To investigate the catalytic activity of these complexes in the ring-opening polymerization of lactides.
• To understand the influence of ligand structure on catalytic performance and polymer properties.

Main Methods:

• Stoichiometric reaction of salicylaldimine derivatives (L1-L12) with trimethylaluminum.
• Characterization of resulting complexes (C1-C12) using NMR spectroscopy and elemental analysis.
• Single-crystal X-ray diffraction for structural determination of representative complexes (C1, C6, C8).
• Ring-opening polymerization (ROP) of L-lactide, D-lactide, and rac-lactide activated by BnOH.

Main Results:

• Successfully synthesized and characterized twelve dimethylaluminum aldiminophenolate complexes (C1-C12).
• X-ray diffraction revealed distorted tetrahedral geometry around the aluminum center in representative complexes.
• Catalytic ROP studies showed higher efficiency for D-lactide polymerization.
• Ligand structure significantly impacted catalytic activity and the properties of the resulting polylactides.

Conclusions:

• Dimethylaluminum aldiminophenolates are effective catalysts for lactide ROP.
• The choice of salicylaldimine ligand is crucial for tuning catalytic efficiency and polymer characteristics.
• These findings contribute to the development of tailored catalysts for controlled polyester synthesis.