Reverse biomimetics

At the present time, "interest in reversed micelles is intense for several reasons. The rates of several types of reactions in apolar solvents are strongly enhanced by certain amphiphiles, and this "micellar catalysis" has been regarded as a model for enzyme activity (. Aside from such "biomimetic" features, rate enhancement by these surfactants may be important for applications in synthetic chemistry. Lastly, the aqueous "pools" solubilized within reversed micelles may be spectrally probed to provide structural information on the otherwise elusive state of water in small clusters. 

The second group of hydroxamate-based chelators consists of biomimetic ferrichrome analogs modified by introducing hydrophobic amino acids between the template and the hydroxamic acid binding sites 59, 60, 66, 68, 70, 199 and 200. Since they function to withhold iron from cells in contrast to their original function of iron delivery, they were named reversed siderophores (RSF) . ... 

D Network Polymers Containing Biomimetic Reversibly Unfolding Crosslinkers for Advanced Mechanicai Properties... 

Kushner AM, Gabuchian V, Johnson EG, Guan Z. Biomimetic design of reversibly unfolding modular cross-linker to enhance mechanical properties of 3D network polymers. J Am Chem Soc 2007 129 14110. 

In natural processes, metal ions are often in high oxidation states (2 or 3), whereas in chemical systems the metals are in low oxidation states (0 or 1). This fact inverts the role of the metal center, such that it acts as a one-electron sink in a natural system, but as a nucleophile in an artificial ones (see other chapters of this book and the review by Aresta et al. [109]). Nevertheless, important biochemical processes such as the reversible enzymatic hydration of C02, or the formation of metal carbamates, may serve as natural models for many synthetic purposes. Starting from the properties of carbonic anhydrase (a zinc metalloenzyme that performs the activation of C02), Schenk et al. proposed a review [110] of perspectives to build biomimetic chemical catalysts by means of high-level DFT or ah initio calculations for both the gas phase and in the condensed state. The fixation of C02 by Zn(II) complexes to undergo the hydration of C02 (Figure 4.17) the use of Cr, Co, or Zn complexes as catalysts for the coordination-insertion reaction of C02 with epoxides and the theoretical aspects of carbamate synthesis, especially for the formation of Mg2+ and Li+ carbamates, are discussed in the review of Schenk... 

However, the reverse reaction of alcohol oxidation in this system can be performed with flavin co-factor added (FMNH2 —> FMN), where molecular oxygen is reduced to H202. The entire biomimetic process under consideration is well illustrated by the following diagram [128] ... 

When new and academic-looking reactions are discovered in the laboratory, it often seems only a short time before they are found in nature as well. However, the development of polyolefin cycliza-tion reactions in synthesis occurred by the reverse philosophy—it was inspiration from Nature that led W. S. Johnson to use the reactions in synthesis, including steroid synthesis. This is biomimetic synthesis, a strategy that is bound to work provided we can just master the practical details. 

The reversible FeTe1 FeTe11 couple of an N-heterocyclic carbene dinuclear FeTe1 complex, (p-pdt) [FeI(CO)2(PMe3)][FeI(CO)2(IMes)] (IMes= l,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene), complex D, has led to the isolation of the mixed-valent cationic complex D as a biomimetic of the 2Fe2S subsite of the oxidized H cluster in... 

Non-biomimetic interfaces which are constructed as they are from supramolecular associations or reversible covalent linkages. An approach to such an interface can be envisaged through the application of supramolecular chemistry and dynamic constitutional chemistry which are both conducive to adaptive structures. 

---