Iron-oxide based clusters for the preparation of hybrid materials

Alan J Rodriguez-Santiago; Raphael G Raptis, PhD

Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States

The field of hybrid materials lies at the interface of organic and inorganic chemistry. In recent years this field has yielded novel and exciting materials that bridge the gap between the properties of the organic polymer hosts and the inorganic guests providing new alternatives to current challenges.

Our research group has synthesized a pyrazolato based octanuclear iron cluster (Fe₈) with the chemical formula: [Fe^III₈(μ₄-O)₄(μ-4-R-pz)₁₂X₄]. This cluster can be modified by functionalizing the pyrazole and the terminal ligand. In our project Fe₈ and a phenolic organic polymer are combined to yield a new hybrid material by substitution of the terminal ligand by phenolate.

To probe the versatility of this type of hybrids, two different polymers and two different Fe₈ derivatives were used. Specifically, poly-4-vinylphenol (PVPOH) and poly-4-vinylphenol-co-methylmethacrylate (PVPOH-co-MMA) for the organic polymer and [Fe^III₈(μ₄-O)₄(μ-4-H-pz)₁₂X₄] and [Fe^III₈(μ₄-O)₄(μ-4-Me-pz)₁₂X₄] as the inorganic motifs. This work presents the preparation and characterization of these hybrid materials by means of UV-vis, IR, and ⁵⁷Fe-Mössbauer spectroscopy as well as electrochemistry. Furthermore, casting and gas adsorption properties are also explored.

The resulting materials fall into the class-II hybrid materials.