Chemical CO₂ fixation by a heterogenised Zn(ii)-hydrazone complex.

Area of Science:

• Coordination Chemistry
• Heterogeneous Catalysis
• Green Chemistry

Background:

• Development of efficient catalysts for CO2 utilization is crucial for sustainable chemistry.
• Immobilization of metal complexes onto solid supports can enhance catalyst stability and recyclability.
• Hydrazone ligands offer versatile coordination environments for metal ions.

Purpose of the Study:

• To synthesize and characterize a new zinc(II) coordination compound with a hydrazone ligand.
• To immobilize the zinc(II) complex onto silica gel to create a heterogeneous catalyst.
• To evaluate the catalytic performance of the supported catalyst in CO2 fixation reactions.

Main Methods:

• Synthesis and structural characterization of the zinc(II) complex using spectroscopic techniques and X-ray analysis.
• Immobilization of the complex onto functionalized silica gel via amidification.
• Characterization of the heterogeneous catalyst using various analytical methods.
• Testing the catalytic activity in the cycloaddition of CO2 to styrene epoxide.

Main Results:

• A five-coordinated zinc(II) complex, [Zn(HL)(OAc)2] (1), featuring a free amine group was successfully synthesized.
• The complex was effectively immobilized onto silica gel, forming the heterogeneous catalyst Si-[Zn(HL)(OAc)2].
• The supported catalyst demonstrated efficient catalytic activity in the formation of cyclic carbonate from styrene epoxide and CO2.

Conclusions:

• The synthesized heterogeneous zinc(II) catalyst is effective for the cycloaddition of CO2 to epoxides.
• Immobilization of the coordination compound onto silica gel provides a recyclable and efficient catalytic system.
• This approach offers a promising route for CO2 utilization in the synthesis of valuable cyclic carbonates.