Redox chemistry overview

A relatively large number of oxyacids of the halogens exist. Because of the extensive redox chemistry of these compounds, there is an enormous number of reactions involving them. We will give only an overview in keeping with the spirit and space requirements of this survey. 

The present report deals with an overview on the very recent metal-assisted redox chemistry of /w o-octaalkylporphyrinogen. This investigation has led to the discovery of oxidized forms of porphyrinogen other than porphyrins, the so-called artificial porphyrins . 

Riboflavin, commonly known as vitamin B2, is metabolized inside cells to flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), two very important enzyme cofactors. These molecules possess rather unique and versatile chemical properties, which confer on them the ability to be among the most important redox cofactors found in a broad range of enzymes. In this chapter we provide a brief description of riboflavin metabolism and chemistry, overview the different flavoenzymes engaged in fatty acid p-oxidation and their respective roles. We also highlight recent studies shedding light on the cellular processes and biological effects of riboflavin supplementation in the context of metabolic disease. 

A brief introduetion to the spectroscopic properties of vanadium(IV) is provided, along with identification of key concepts crucial to the successful application of EPR methods to research questions in the field. Specific discussions of EPR spectroscopies, sueh as continuous wave and pulsed methods, have been recently reviewed [19,20]. The discussion of the use of VO " ions as spin probes by N.D. Chasteen remains a seminal review paper in the field for its complete overview of the speetroseopie properties of the ion and application to biological systems [21]. Numerous reviews on the biochemmical activity of vanadium compounds are available [22-26], and the rationales for development and synthetic routes to new vanadium compounds are also reported [27,28] A reeent study evaluated the in-vitro activity of 22 compounds currently studied in the literature [29]. In this review, EPR s role in the delineation of structure, chemistry, and in-vivo behavior of vanadium compounds will be discussed. The first seetion of die review foeuses on the use of EPR for the description of solution structures, ternary eomplex formation, and redox chemistry of vanadium(IV) and (V) compounds, wifli the general flieme of highlighting in-vitro studies. This seetion is followed by a diseussion of die application of EPR for in-vivo investigations of vanadium cellular uptake, pharmacokinetics, and in-vivo coordination structure. 

This chapter gives an overview of different types of redox active ligands and the above mentioned four different application strategies. The number of publications on this concept is growing rapidly, especially over the past few years. Some excellent reviews and essays on this subject have appeared recently a Forum issue of Inorganic Chemistry [4], a Special issue of the European Journal of Inorganic Chemistry [5], a tutorial review article in ACS Catalysis [6] and some other reviews [7] have been used in this chapter as a basis for much of the older work on this subject. This chapter also includes relevant new examples in the field of reactive redox active ligands. 

The field of supramolecular chemistry is concerned with a large number of systems ranging from simple host-guest complexes to more complicated solution assemblies, as well as two-dimensional (organized monolayers) and three-dimensional assemblies (crystalline solids). Nonco-valent interactions play an important role in the kinetic assembly and thermodynamic stabilization of all these systems and constitute their most distinctive feature. Electron-transfer reactions can obviously be affected by supramolecular structures, but the reverse is also true. It is possible to alter the structure and the thermodynamic stability of supramolecular assemblies using electrochemical (redox) conversions. In other words, electron-transfer reactions can be utilized to exert some degree of control on supramolecular aggregates. Provided in this article is an overview of the interplay between supramolecular structure and electron-transfer reactions. 

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