Photoinduced electron transfer in a ferrocene-distyryl BODIPY dyad and a ferrocene-distyryl BODIPY-C₆₀ triad

A ferrocene-distyryl BODIPY dyad and a ferrocene-distyryl BODIPY-C ₆₀ triad are synthesized and characterized. Upon photoexcitation at the distyryl BODIPY unit, these arrays undergo photoinduced electron transfer to form the corresponding charge-separated species. Based on their redox potentials, determined by cyclic voltammetry, the direction of the charge separation and the energies of these states are revealed. Femtosecond transient spectroscopic studies reveal that a fast charge separation (k _CS=1.0×10¹⁰ s^-1) occurs for both the ferrocene-distyryl BODIPY dyad and the ferrocene-distyryl BODIPY-C₆₀ triad, but that a relatively slow charge recombination is observed only for the triad. The lifetime of the charge-separated state is 500 ps. Charge recombination of the dyad and triad leads to population of the triplet excited sate of ferrocene and the ground state, respectively.