Aryl isocyanides bearing free-base and metallo-porphyrins were prepared and polymerized with a Pd-Pt mu-ethynediyl complex as the initiator to give polymers with narrow polydispersity indices. The molecular weights of the resulting polymers were precisely controlled by the initial feed ratio of the porphyrin monomer to the initiator. The UV-VIS spectra suggested that the porphyrin pendants are regularly arranged to form stacked columns. Metallo-porphyrin polymers were also prepared by reacting free-base porphyrin polymers with metal salts. The successive reactions of free-base and zinc-porphyrin monomers resulted in the formation of diblock polymers. (c) 2005 Wiley Periodicals, Inc.