Synthesis and Characterization of Late Transition Metal Complexes of Mono-Acetate Pendant Armed Ethylene Cross-Bridged Tetraazamacrocycles with Promise as Oxidation Catalysts for Dye Bleaching |
| |
Authors: | Tuyet Hoang Somrita Mondal Michael B. Allen Leslie Garcia Jeanette A. Krause Allen G. Oliver Timothy J. Prior Timothy J. Hubin |
| |
Affiliation: | 1.Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA;2.Department of Chemistry, University of Cincinnati, Cincinnati, OH 45220, USA;3.Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA;4.Department of Chemistry, University of Hull, Kingston Upon Hull HU6 7RX, UK |
| |
Abstract: | Ethylene cross-bridged tetraazamacrocycles are known to produce kinetically stable transition metal complexes that can act as robust oxidation catalysts under harsh aqueous conditions. We have synthesized ligand analogs with single acetate pendant arms that act as pentadentate ligands to Mn, Fe, Co, Ni, Cu, and Zn. These complexes have been synthesized and characterized, including the structural characterization of four Co and Cu complexes. Cyclic voltammetry demonstrates that multiple oxidation states are stabilized by these rigid, bicyclic ligands. Yet, redox potentials of the metal complexes are modified compared to the “parent” ligands due to the pendant acetate arm. Similarly, gains in kinetic stability under harsh acidic conditions, compared to parent complexes without the pendant acetate arm, were demonstrated by a half-life seven times longer for the cyclam copper complex. Due to the reversible, high oxidation states available for the Mn and Fe complexes, the Mn and Fe complexes were examined as catalysts for the bleaching of three commonly used pollutant model dyes (methylene blue, methyl orange, and Rhodamine B) in water with hydrogen peroxide as oxidant. The efficient bleaching of these dyes was observed. |
| |
Keywords: | oxidation catalyst dye bleaching cross-bridged tetraazamacrocycle transition metal complex |
|
|