Photo- and redox-active dendritic molecules with soft, layered nanostructures

Molecules with one photoactive group (porphyrin) and multiple redox-active groups (ferrocenes) are described. The molecules are based on dendritic frameworks, with the ferrocenyl groups attached at the "internal" positions and the porphyrin attached at the focal point, leading to a characteristic layer architecture. Molecules of up to the third generation were synthesized and examined. The results of 1H NMR spectroscopy and fluorescence quenching indicated that the ferrocenyl groups at the second layer approach the core porphyrin most closely, which is consistent with the results of molecular-dynamics simulations. The electrochemistry of the molecules was also examined in detail, and a new formula is proposed for the analysis of multiple-electron transfer in these "redox-pool" molecules.