Dendritic polyphenylazomethines: Synthesis, structure, and metal-assembling
function
K. Yamamoto and M. Higuchi
Department of Chemistry, Faculty of Science &
Technology, Keio University,
Yokohama 223-8522, Japan
Abstract: Dendritic polyphenylazomethines (DPAs) were synthesized
as novel topological polymer ligands with pi-conjugated structures by
the convergent method via dehydration of aromatic ketones with aromatic
amines in the presence of TiCl4. DPA G4 molecules are re-
vealed to have a sphere-like structure with a 2.3-nm diameter and are
regularly assembled without deformation of the molecule on a plate as
observed by means of gel permeation chromatography (GPC), molecular
modeling, transmission electron microscopy (TEM),
atomic force microscopy (AFM), and pi-A measurements. The stepwise radial
complexation in DPAs with SnCl2 was observed as a stepwise
shift in the isosbestic point in the UV-vis spectra. The number of added
equivalents of SnCl2 required to induce a shift was in agreement
with the number of imine groups present in the different shells of the
DPAs. These spectral changes suggest that the complexation is proceeding
in a stepwise fashion from the core
imines to the terminal imines of the DPAs, which was further supported
by shell-selective reduction (SSR) of the imines.
*Lecture presented at the symposium "Recent advances
in high performance polymers:A symposium in honour of Allan Hay", as
part of the 39th IUPAC Congress and 86th Conference of the Canadian
Society for Chemistry: Chemistry at the Interfaces, Ottawa, Canada,
10-15 August 2003. Other Congress presentations are published in this
issue, pp. 1295-1603.
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