title: Dendrimers with a copper(I) bis(phenanthroline) core: synthesis, electronic properties, and kinetics.
abstract: The copper(I) bis(chelate) complex Cu(L(0))(2) has been prepared from 2,9-diphenethyl-1,10-phenanthroline and Cu(CH(3)CN)(4)BF(4). Derivative Cu(L(0))(2) has been characterized by NMR, UV-vis spectroscopy, and X-ray crystallography. Interestingly, owing to the presence of the ethylene linker, the interligand pi-pi stacking interactions between the phenyl rings and the phenanthroline subunits in Cu(L(0))(2) do not induce significant distortions of the pseudotetrahedral symmetry around the Cu(I) center in the solid state or in solution. Following the synthesis of Cu(L(0))(2), dendrimers Cu(L(1)(-)(4))(2) with a Cu(I) bis(2,9-diphenethyl-1,10-phenanthroline) core surrounded by Fréchet type dendritic branches have been prepared and the kinetics of their cyanide-assisted demetalation studied. Importantly, the surrounding dendritic wedges have no significant influence on the coordination geometry of the Cu(I) center, as deduced from their absorption spectra. Therefore, the variations of the rate constants only reflect changes resulting from the presence of the dendritic branches. The kinetics of the cyanide-mediated demetalation reaction indeed revealed that cyanide diffusion through the dendritic shell is slightly influenced by the size of the branches. Significant effects were observed in the kinetics when going from the third to the fourth generation and have been ascribed to changes in the lipophilicity around the metallic core as a result of dendritic encapsulation.
authors.affiliation: Laboratoire de Physico-Chimie Bioinorganique, Université Louis Pasteur et CNRS (UMR 7509), Ecole Européenne de Chimie, Polymères et Matériaux (ECPM), 25 rue Becquerel, 67087 Strasbourg Cedex 2, France.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Gumienna-Kontecka
authors.forename: Yannick
authors.initials: Y
authors.lastname: Rio
authors.forename: Cyril
authors.initials: C
authors.lastname: Bourgogne
authors.forename: Mourad
authors.initials: M
authors.lastname: Elhabiri
authors.forename: Rémy
authors.initials: R
authors.lastname: Louis
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Albrecht-Gary
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Nierengarten