Synthesis and electrochemical properties of slipped-cofacial porphyrin dimers of ferrocene-functionalized Zn-imidazolyl-porphyrins as potential terminal electron donors in photosynthetic models

A systematic series of ferrocene-functionalized Zn-imidazolyl-porphyrins were synthesized to assemble into the slipped-cofacial porphyrin dimers through imidazolyl-to-zinc complementary coordination as artificial photosynthetic models. Direct substitution at the meso position of the porphyrin ring with ferrocence and octamethylferrocene leads to the characteristic electronic structures, while the ferrocene substituents through phenylene-ethenylene and phenylene-ethylene spacers mitigate the electronic communications. Bathochromic shift of Q band, fluorescence quenching, and redox potentials of porphyrin ring are rationalized by the degree of electron-donating ability of the terminal ferrocenes.