Metallodendrimers with Chelating Bipyridyl Ligands: Synthesis and Characterization
Abstract
Dendrimers are polymers with chemically well-defined hyper-branched three-dimensional architectures. Metallodendrimers offer attractive advantages over their polymeric counterparts due to their unique properties, which make them suitable for a number of biomedical and industrial applications. Catalysis based on transition metals combine the advantages of both homogeneous and heterogeneous catalytic systems such as selectivity and recyclability. Herein we report a more controlled approach for a covalent attachment of chelating ligands to poly (propylene imine) dendrimer (PPI), followed by complexation with Palladium. PPI dendrimers of three successive generations have been successfully functionalized with covalently attached bipyridyl ligands on the surface of the dendrimer in a single step reaction. A novel series of metal-chelating dendrimers has been synthesized upon complexation of chelating bipyridyl ligands with palladium. Metallodendrimers have also been successfully characterized using NMR, IR and ESI mass spectrometry. It is clear that IR and NMR spectroscopy provides useful signatures for ligand attachment and complexation reactions. However, when the dendrimers become heavier, especially for dendrimers with multiple metal centers, NMR spectra become very complicated and not useful for characterization. We have also shown that ESI mass spectrometry is a very useful characterizational tool when NMR studies are not adequate.
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- OSU Theses [15752]