Convergent synthesis of meso-ferrocenyl porphyrins for TiO2 sensitization

Electron-donating ferrocenyl moieties have been incorporated into supramolecular carboxyporphyrin architectures Zn(II)-5-ferrocenyl-10,20-bistolyl-15-(4-methylbenzoate)porphyrin (trans-Fc-ZnP-CO2Me), Zn(II)-5-ferrocenyl-10,15,20-tris(4-methylbenzoate)porphyrin [trans-Fc-ZnP-(CO2Me)3], and Zn(II)-5,15-bisferrocenyl-10,20-bis(4-benzoate)porphyrin [trans-Fc2-ZnP-(CO2Me)2] for self-assembly on metal oxide nanoparticles. Efficient and economic synthesis has required a convergent strategy toward reduced symmetry trans-A2B2 and trans-AB2C substitution patterns about the porphyrin macrocycle minimizing the production of porphyrin side products and increasing yields of the target ferrocenylporphyrins. Preliminary spectroscopic data in solution and in the solid state bound to mesoporous TiO2 films are discussed.