Metal Assembly in Novel Dendrimers with Porphyrin Cores

Abstract

A series of phenylazozmethine (DPA) dendrimers with a porphyrin core (PnH₂) were synthesized by dehydration using TiCl₄ from meso-tetrakis(4-aminophenyl)porphyrin and the DPA dendrons. The addition of SnCl₂ to a dichloromethane/acetonitrile solution of dendritic cobalt porphyrin resulted in a stepwise spectral change. By using UV−vis spectroscopy to monitor the complexation of the P4Co^IIICl until an equimolar amount of SnCl₂ has been added, four changes in the position of the isosbestic point were observed during the addition of SnCl₂. Titration results suggest that four different complexes are successively formed upon the SnCl₂ addition and that the complexation proceeds in, not a random, but a stepwise fashion from the core imines to the terminal imines of P4Co^IIICl. The electrochemical study reveals that their dendrimers with Tb ion act as a multielectron mediator in CO₂ reduction at high applied potential on the electrode.