title: Anionic sulfonated and carboxylated PPI dendrimers with the EDA core: synthesis and characterization of selective metal complexing agents.
abstract: Herein we describe the synthesis and characterization of new sulfonated and carboxylated poly(propyleneimino) (PPI) dendrimers with the ethylenediamino (EDA) core, at generations 1, 2 and 3. By means of UV-Vis and EPR spectroscopy, using Cu(2+) as a probe, we concluded that these dendrimers show a specific pattern in the coordination of metal ions. In agreement with the UV-Vis studies, EPR spectra of carboxylated compounds are constituted by 3 different signals which appear and then disappear with increasing copper concentration, corresponding to the saturation of different copper complexation sites. At the lowest copper concentration up to a 1:1 molar ratio between Cu(II) and the dendrimer, the spectrum is characteristic of a CuN2O2 coordination at the core of the dendrimer. The spectrum appearing at higher Cu(II) concentrations indicates a peripheral location of the ions coordinating one nitrogen and 3 oxygen atoms in a square planar geometry in restricted mobility conditions. For the highest concentrations tested, copper ions are confined at the external dendrimer surface with CuO4 coordination. For sulfonate systems, the EPR results are in line with a weaker interaction of Cu(II) with the nitrogen sites and a stronger interaction with the oxygen (SO3(-)) groups with respect to the interactions measured by EPR for carboxylate systems.
authors: Departamento de Química Inorgánica, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares, Spain.
authors: Sandra
authors: S
authors: García-Gallego
authors: Michela
authors: M
authors: Cangiotti
authors: Luigi
authors: L
authors: Fiorani
authors: Alberto
authors: A
authors: Fattori
authors: Ma Ángeles
authors: MÁ
authors: Muñoz-Fernández
authors: Rafael
authors: R
authors: Gomez
authors: M Francesca
authors: MF
authors: Ottaviani
authors: F Javier
authors: FJ
authors: de la Mata
mesh_terms: D000838:Anions / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D050091:Dendrimers / Q000138:chemical synthesis* / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D011126:Polypropylenes / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013451:Sulfonic Acids / Q000737:chemistry
chemical_list: D000838:Anions; D002264:Carboxylic Acids; D056831:Coordination Complexes; D050091:Dendrimers; D011126:Polypropylenes; D013451:Sulfonic Acids; C443641:poly(propyleneimine); D003300:Copper