Preparation and properties of snow-flake type porphyrin dendrimers

Abstract

Snowflake-shaped porphyrin dendrimers with and without anthraquinonyl terminals 1 and ,2, respectively, were prepared. When the Zn porphyrin core in dendrimer 1 was excited in degassed THF, the intensity of the Zn porphyrin florescence decreased to 31% compared to dendrimer 1. The fluorescence spectra of dendrimers 1 and 2 were also measured in solvents of various polarities such as 1,4-dioxane, benzonitrile, and DMF. The degree of fluorescence quenching is more remarkable in polar solvent. These results suggest that the fluorescence quenching in dendrimer 1 is attributable to the intramolecular electron transfer. Comparison of the relative fluorescence intensity with reference compound suggested that the remarkable enhancement of the electron transfer rate by dendritic architectures.