1. Iron Chelation by Polyamidoamine Dendrimers: A Second-Order Kinetic Model for MetalâAmine Complexation.
- Author
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Mankbadi, Michael R., Barakat, Mohamed A., Ramadan, Mohamed H., Woodcock, H. Lee, and Kuhn, John N.
- Subjects
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IRON , *CHELATION , *POLYAMIDOAMINE dendrimers , *CHEMICAL kinetics , *AMINES , *METAL complexes , *NUCLEAR magnetic resonance spectroscopy - Abstract
This study presents a kinetic model of the chelation of iron ions by generation 4 hydroxyl-terminated polyamidoamine (PAMAM) with ethylenediamine core (G4-OH). The coordination processes of iron ions from ferric chloride, FeCl3, and ferrous bromide, FeBr2, to G4-OH dendrimers were analyzed using ultravioletâvisible (UVâvis) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and liquid chromatographyâmass spectrometry (LCâMS). In the visible region, a charge-transfer was observed when the dendrimer was added to a ferric chloride solution. This phenomenon is a ligand-to-metal charge-transfer (LMCT) between the free electron group of the dendrimerâs internal amines and the dehalogenated iron ion that takes 2 h to complete at room temperature. Analysis of potential rate laws and diffusion effects led to a second-order kinetic model for this reaction. By measuring the rate coefficients as a function of temperature (22â37 °C), an apparent activation energy of 41.5 kJ/mol was obtained using the Arrhenius method. The results of this study will fuel research of PAMAM dendrimers for environmental, pharmaceutical, and materials applications. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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