Formation of charge-transfer complexes from neutral bis(porphyrin) sandwiches

Lanthanide(III) bis(porphyrin) sandwich complexes of octaethyltetraazaporph yrin (OETAP) were synthesized and characterized by UV-vis, IR, and NMR spec troscopies. Cyclic voltammetry results indicate that these neutral sandwich complexes are very easily reduced. Charge-transfer reactions were performe d in solution with Ln-(OETAP)(2) sandwiches and zirconium(IV) bis(porphyrin ) sandwiches. The lanthanide sandwiches partially oxidize the zirconium san dwiches in solution, and a solvent dependence of the charge-transfer reacti on was observed. The solid-state properties of these charge-transfer materi als were also studied. Magnetic susceptibility results suggest weak intermo lecular interactions between the sandwiches. The conductivities of the char ge-transfer species are greatly improved relative to those of the insulatin g undoped sandwiches, but the conductivities are in the fewer semiconductin g region. The low conductivity values are thought to be due to poor intermo lecular overlap.