Charge transfer complexes, biological

As the preceding section correctly suggests, aromatic rings a-hound in compounds that show biologic activity. The reasons for this are many the role of the pi electrons in some form of charge transfer complex ranks among the more Important. There ire few monocyclic alicyclic compounds known that are used as medicinal agents. 

Gorski T. 1969. Biological role of charge-transfer complexes of aromatic hydrocarbon oxy derivatives in chemical carcinogenesis. Neoplasma 16 403-408. 

This review will be concerned with recent progress made towards an understanding of conduction phenomena in typical homomolecular crystals, e.g. anthracene and the phthalocyanines, with certain charge-transfer complexes, selected biological systems, certain novel one-dimensional systems and other materials which serve to illustrate a particular theoretical approach or the value of an experimental technique. Little attention will be given to experimental procedures other than when these are not in common use and have not been adequately described in the earlier reviews. 

R. Boyer, Concepts in Biochemistry, Brooks/ Cole, Monterey, CA, 1999. See also F. Gutmann, C. Johnson, H. Keyzer, J. Molnar, Charge-Transfer Complexes in Biological Systems, Dekker, New York, 1977. 

Finally, the field of organic conductors has interesting implications in biological and pharmacological sciences, providing useful concepts and models to any problem concerned with electrochemistry and charge-transfer complex formation [10,11] (see also Chapter 14). 

Related Topics I Charge-Transfer Complexes in Biological Systems... 

III. EXAMPLES OF CHARGE-TRANSFER COMPLEXES IN BIOLOGICAL SYSTEMS... 

DNA and RNA, containing purines and pyrimidines, have been studied in terms of charge-transfer complexes, no doubt because of their importance in genetics and biological phenomena, such as cancer. Some of the earlier studies were sketchy in this regard. For instance, DNA mixed with acridines are yellow in DMSO [163]. However, the color change mentioned above cannot constitute a priori evidence of electron charge transfer, especially in an active solvent such as DMSO, which can affect the steric properties of DNA normally found in aqueous environments. 

The electron affinities of organic halides and environmental pollutants are evaluated in Chapter 11 and those of biological molecules in Chapter 12. Many of the Ea measured in the gas phase are tabulated in the NIST tables [1], These are listed in the appendices according to molecules containing CHX, CHNX, CHOX, and CHONX with references. The ECD values for some of the aromatic hydrocarbons in NIST have not been updated. L. G. Christophorou s compilation includes Ea from half-wave reduction potentials and charge transfer complexes [2]. Some of these Ea will be revised and evaluated in this chapter based on gas phase measurements. 

Before 1990 there were no accurate experimental or theoretical values for the Ea of AGCUT. It was recognized that ionization potentials and electron affinities were important to charge transfer in biological processes, but there were three potential measures of the Ea. These were donor acceptor complex data, reduction potentials, and theoretical calculations, each of which resulted in different measures of the Ea. Much of our work during the past decade has attempted to reconcile these differences. 

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