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Some water-soluble porphyrins aggregate in aqueous media to form fibrous assemblies. When polynucleotides are used as matrices, porphyrin monomers are aligned at the periphery or intercalated. Porphyrin-porphyrin interactions hardly occur. Metal-metal or metal-ligand-metal interactions have been observed in 0x0-oligomers, pyrazine-bridged dimers and radical dimers. 13-Substituted metalloporphyrins, however, form no polymers. The only linear polymerization, which has so far been observed in molecular asemblies, occurs with amphiphilic porphyrin amides, amines and carboxylates and their metal complexes in water and of bacteriochlorophyll in DMF/water. These compounds form long-lived high molecular weight micellar, inverse micellar and vesicular fibers spontaneously in aqueous media. The porphyrin fibers in water are about 4 -6 nm thick and up to several of bm long. The fibrous porphyrin assemblies show a rich photochemistry. The monomers adsorbed to nucleic acids can be used as catalysts for photochemical cleavage reactions. The non-fluorescent fibers produce anion radicals upon laser flashing.

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