Self-assembled fibers made of lipidporphyrinato-zinc(II) and iron(II) complexes with an intramolecular coordinated axial imidazole

Amphiphilic tetraphenylporphyrinato−metal (Zn(II), Fe(II)) derivatives with four alkylphosphocholine chains and an intramolecular coordinated axial imidazole (lipidporphyrins) produced stable colloidal solutions in water. Electron microscopy showed rodlike fibers with a uniform thickness of 10 nm, which corresponds to a double length of lipidporphyrin. The obtained fibers had some micellar characteristics and were sensitive to neither addition of electrolyte (for example, NaCl) nor change in pH. Scanning force microscopy (SFM) revealed evaporated fibers with a height of 2.8 nm on graphite. In the center of the fiber, there is probably a tetragonal tube constructed by densely packed porphyrin planes. The red shift in the broadened Soret band absorption by exciton interaction and the photophysical properties of the Zn(II) complex fibers suggested the formation of porphyrin J-aggregates. Furthermore, the first SFM images of the porphyrin fibers under liquid conditions are given. A Benesi−Hildebrand analysis ...