Synthesis and metal binding properties of salicylate-, catecholate-, and hydroxypyridinonate-functionalized dendrimers

The synthesis, characterization, and metal-binding studies of chelate-funct ionalized dendrimers is reported. Salicylate, catecholate, and hydroxy pyri dinonate bidentate chelators have been coupled to the surface of both poly( propyleneimine) (Astramol) and poly(amidoamine) (Starburst, PA-MAM) dendrim ers up to the fifth generation (64 endgroups). A general method has been de veloped for the facile and high quality chromatographic purification of pol y(propyleneimine) and poly(amidoamine) dendrimer derivatives. One- and two- dimensional (TOCSY) H-1 NMR experiments and electrospray ionization mass sp ectrometry (ESI-MS) have confirmed the exhaustive coupling of these chelato rs to the primary amine functionalities of the dendrimers. Spectrophotometr ic titrations were used to investigate the metal binding ability of these m acrochelates. Spectral analysis shows that ferric iron binding to these lig ands is localized to the chelating endgroups, The ability of these dendriti c polymers to bind large numbers of metal ions may lead to applications as metal sequestering agents for waste remediation technologies.