Self-Assembled Fibers Made of Lipidporphyrinato−Zinc(II) and −Iron(II) Complexes with an Intramolecular Coordinated Axial Imidazole

Abstract

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 revealed that the unit aggregate number for the Zn(II) complex was four, supporting a tetramer repeating structure. Fe(II) complex fibers, on the other hand, produced a kinetically stable O2 adduct reversibly at 25 °C. The coordination structures of the axial imidazole and O2 molecule in the Fe(II) complex have been clarified by resonance Raman spectroscopy. The O2-binding equilibrium and kinetic parameters were also evaluated.

Micellar Cobaltporphyrin Nanorods in Alcohols

“…Porphyrins are major building blocks for self-assembled supramolecular systems based on π−π stacking interactions. − In water, a variety of porphyrin amphiphiles are known to self-organize into micellar fibers, − while in organic solutions, examples are not as frequent as those involving zinc(II) porphyrins. − By analogy to reverse micelles, which provide a stable dispersion of water in nonpolar solvents, we have anticipated that porphyrins bearing polar amido groups with which peripheral long alkyl chains are linked would self-organize even in nonaqueous media, leading to long-lived micelles stabilized through hydrogen bonding and hydrophobic interactions. We present here the properties of a reverse micelle made up of CoTAPP that exhibits a remarkable nanorod behavior.…”

Aggregation of a Zn(II) Complex of a Long-Chain Triester of meso-Tetrakis[p-carboxy]phenyl Porphyrin in Hydrocarbons: Structure of Tetrameric Rodlike Assemblies

“…A porphyrin−porphyrin distance of 7.3 Å has even been evoked in a tetrapyridyl porphyrin . The variety of molecular arrangements provided by the class of porphyrins , is such that an example of a zinc(II) porphyrin complex is known in which tetramer repeating units are involved in J-aggregates . A somewhat similar tetrameric association by hydrogen bonding has also been reported for mono-pyrazolylporphyrins in chloroform solutions.…”

Morphology and Photophysical Properties of One-Dimensional Arrayed Porphyrin Aggregates Assisted by Cyclodextrin Inclusion Complexation

“…Especially, a one-dimensional higher-ordered aggregate is expected to have a wide range of applications. Some researchers had found that amphiphilic molecule such as detergents, phospholipids and ionic liquid can promote the aggregate formation [3][4][5]. The formation of water-soluble tetrakis(4-sulfonatophenyly)porphyrins aggregates was reportedly controlled by changing the pH [6].…”