Water‐Soluble Dendritic Iron Porphyrins: Synthetic Models of Globular Heme Proteins

Abstract

Elsebier. f i~/ r i d i r ( / r o n [8] The nickel-catalyzed bromine--zinc exchange reaction has been studied extensively i n our Liboratories: a) A. Vaupel, P. Knochel. [lo] F Langer. A. Devasagayaraj. P: Y. Chavant, P. Knochel, S.rnlr/r 1994. 410-412. [I I ] The oxidative addition of nickel or palladium(o) complexes to alkyl iodides may proceed hq. ii radical mechanism: a) A. V. Kramer. J. A. Labinger. J. S . Bradley. J A Oiborn. . l A m Clrrrn. Soc. 1974, 96. 7145-7147 b) A. V. Krainer. J. A. Osborn. rhirl. 1974. 96. 7832-7833; c) M . Chanon. Bull. Soc.

Dendrimer Complexes Based on Fine-Controlled Metal Assembling

“…This type also has one limited hybrid structure and conformation similar to that of the ''type A'' dendrimers. 77,78 The dendritic backbones, which can be compared to branches in a tree, are important for characterization of the dendrimer properties such as electrochemical response [79][80][81][82][83][84][85][86] or photo-reactivity, [87][88][89][90][91][92][93][94][95][96][97] although the backbones do not usually play a central role as the functional center. Modification of the backbones by metal ions should result in drastic changes in the entire conformation, in the environment around the core and in the electronic properties of the dendrimers.…”

Dendrimers: synthetic strategies, properties and applications

“…This kind of site isolation was used to mimic different natural systems by introduction of the functional groups (i.e., porphyrins) at the core. For example, Diederich et al prepared zinc porphyrin dendrimers ( Figure 3) as a model to mimic the electron-transfer proteins (e.g., cytochrome C) 34,35,[48][49][50] .…”

Supramolecular chemistry of dendrimers with functional cores

“…Examples are hemoglobin-and myoglobin-like gas binding ability (34)(35)(36), heme monooxygenase activity (14,37), electron acceptor capacity in light-harvesting antenna systems (38), and shell-modulated redox potentials as found in cytochromes (39)(40)(41). We discuss here the model character of dendritic iron porphyrins with tethered axial ligands for cytochromes (42,43).…”

“…The heme microenvironment, created by the surrounding protein shell, has been identified as a major factor influencing the redox potentials that are substantially anodically shifted (by 300-400 mV) compared with simple heme model systems lacking the peptide coverage. We had prepared a series of dendritic iron porphyrins as model compounds for cytochromes (39)(40)(41), in which the protein shell around the buried electroactive core was mimicked by the dendritic superstructure. However, the nature of the axial ligation to the iron center, which is known to have a very strong influence on the redox properties (45), was not controlled in these earlier systems.…”