Assembly process Electrochemical

Two different types of self-assembling processes are described. The one is a potential-assisted self-assembly of redox enzymes on the surface of an electrode. The potential-assisted self-assembly is followed by electrochemical... 

A similar supramolecular approach, in which both n-n stacking stacking of pyrene on the SWNT surface and alkyl ammonium-crown ether interactions were used in the self-assembly process of a fullerene derivative with SWNTs, was recently reported (Scheme 9.22).72 The nanohybrid integrity was probed with various spectroscopic techniques, , and electrochemical measurements. Nanosecond transient absorption studies confirmed electron transfer as the quenching mechanism of the singlet excited state of C60 in the nanohybrid resulting in the formation of SWNT"1"/ Pyr-NH3 + /crown- charge-separated state. 

The monolayers described so far have all been grown by self-assembly processes, where ligand-stabilized metal nanopartides are deposited on innocent surfaces from solution, followed by a more or less rapid evaporation of the solvent. Depending on the concentration and other experimental conditions, those procedures may occasionally also result in multilayers, or even in small 3-D microcrystals. Self-assembly processes can, however, also be supported by chemical, electrochemical, magnetic, or mechanical effects some examples of these are provided in the following subsections. 

The ubiquinol-cytochrome c oxidoreductase (cytochrome bc complex) of Rhodobacter sphaeroides is an integral component of the intracytoplasmic membrane (ICM) and functions in light-driven cyclic electron flow and the conservation of radiant energy as an electrochemical proton gradient. Previous studies on the assembly of electron transfer constituents in/ , sphaeroides have demonstrated that complete cycles of electron flow do not occur merely upon insertion of newly synthesized reaction centers at sites of initiation of ICM growth, but instead, subsequent synthesis and assembly of redox centers of the be complex are required [1]. To further characterize the assembly process and for detailed structural investigations, the complex was purified and antibodies were raised against the isolated polypeptide constituents. In this report, results on the localization and levels of the feCj complex in various membrane fractions are presented a detailed description of the structurd work will appear elsewhere [2]. 

Morikawa H, Tsuihiji N, Mitsui T, Kanamura K. Preparation of membrane electrode assembly for fuel cell by using electrophoretic deposition process. / Electrochem Soc 2004 151(10) A1733-7. 

H. Zhu and R. J. Kee. Modeling distributed charge-transfer processes in SOFC membrane-electrode assemblies. J. Electrochem. Soc., 155 B715-B729, 2008. 

We continue to be amazed by the extent and efficiency of self-assembly processes in chemical synthesis. There is an enormous potential for the construction of a diverse range of molecular and supramolecular structures. Now that the foundation has been laid, our explorations into just how far structurally (the form) we can take these systems begins. Furthermore, the addition of photoactive or electrochemically active components could very well open the way for control of the function of these systems. One of the messages that has been noted throughout this account is that it is often easier to make the molecular assemblies than to prepare the molecular components by themselves. There could hardly be a stronger recommendation for the utility of self-assembly in chemical synthesis. 

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