Biological processes coordination complexes

Many hydroxycarboxylic acids are naturally occurring, and their coordination chemistry is of importance in biological processes. These complexes also have uses in many other areas such as analytical chemistry, electroplating processes, and pharmacology. The most widely studied ahphatic hydroxy acids are the lower members of the 2-hydroxyalkanoic acids, while studies of aromatic hydroxy acids have often centered on salicylic acid. A number of these acids contain one or more chiral carbon centers, and hence complexes of these acids have been useful in studying chiroptical properties such as the Cotton Effect see Cotton Effect). 

If the plasma membrane is relatively impermeable, how do most molecules enter a cell How is selectivity of this movement established Answers to such questions are important in understanding how cells adjust to a constantly changing extracellular environment. Metazoan organisms also must have means of communicating between adjacent and distant cells, so that complex biologic processes can be coordinated. These signals must arrive at and be transmitted by the membrane, or they must be generated as a consequence of some interaction with the membrane. Some of the major mechanisms used to accomplish these different objectives are listed in Table 41-3. 

Because of the interest in the potential biological applications of complexes containing coordinated dioxygen, and the importance of superoxides as a by-product of aerobic metabolic processes, aqueous stud-... 

Among the metals which have achieved prominence only recently, molybdenum must certainly occupy first place. It has attracted interest chiefly because of its role in biological processes and also because it shows a great variety of oxidation states and coordination numbers. Steifel s extensive review of molybdenum complexes covers their chemistry up to 1977.3 Because of their use in nuclear medicine, the complexes of technetium have received recent interest.4... 

The nse of polysnlfide complexes in catalysis has been discnssed. Two major classes of reactions are apparent (1) hydrogen activation and (2) electron transfers. For example, [CpMo(S)(SH)]2 catalyzes the conversion of nitrobenzene to aniline at room temperature, while (CpMo(S))2S2CH2 catalyzes a number of reactions snch as the conversion of bromoethylbenzene to ethylbenzene and the rednction of acetyl chloride, as well as the rednction of alkynes to the corresponding cw-alkenes. Electron transfer reactions see Electron Transfer in Coordination Compounds) have been studied because of their relevance to biological processes (in, for example, ferrodoxins), and these cluster compounds are dealt with in Iron-Sulfur Proteins. Other studies include the use of metal polysulfide complexes as catalysts for the photolytic reduction of water by THF and copper compounds for the hydration of acetylene to acetaldehyde. ... 

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