Micellar fibers of octopus porphyrin, photoinduced electron transfer reactions in aqueous media
- ISSN: 07437463
Symmetrical tetraresorcinolporphyrin with eight alkylphosphocholine side chains (octopus porphyrin) and its zinc(II) complex were dispersed in aqueous media to give a stable colloidal solution. Electron microscopy showed either planar monolayers or micellar fibers with a uniform thickness of 7 nm. A unique spherical arrangement of eight methyl groups on each side of the porphyrin center provides fat droplet like centers which align in a string of pearls in an extremely open fiber structure. Exciton calculations on the basis of a long wavelength shift of the Soret bands (7-8 nm), line broadening, and electron micrographs indicated a tilt stacking arrangement with a porphyrin separation of 11 Angstrom. The octopus porphyrin fibers fluoresced strongly, and laser flash photolysis lead to electron transfer from the porphyrin to hydrophobic phenyl-p-benzoquinone as well as to hydrophilic 1,2-naphtoquinone-4-sulfonate and dimethylviologen acceptors. The fibers were also active as photocatalysts in the reduction of dimethylviologen to the corresponding radical by amines.