Molecular organization using coordination chemistry

The use of anions as templating agents is discussed by Vilar. The chapter starts with a general overview of the area and a discussion of the applications of anion templates in organic and coordination chemistry. The second part of the chapter deals with examples where anions are employed as templates in dynamic combinatorial libraries. This approach promises to provide an efficient route for the synthesis of better and more selective anion receptors. The last chapter by Ewen and Steinke also deals with the use of anions as templates but in this case in the context of molecular imprinted polymers. The first half of the chapter provides an introduction into molecularly imprinted polymers and this is followed by a detailed discussion of examples where anionic species have been used to imprint this class of polymeric materials. 

In conventional organic nomenclature, a polymer is not considered to be an isomer of the repeating molecular unit, because the molecular formulas formally differ. This is a somewhat arbitrary distinction, however, because it is never really an isolated, single molecule of monomer that is compared with the polymer. In an aggregate of monomer molecules, intermolecular forces exist and the constitutional difference from an aggregate of polymer molecules is simply that some intermolecular forces have been converted into true chemical bonds. In any case, the term polymerization isomerism has had a long-standing use in coordination chemistry. It may refer... 

Regarding the liquid/liquid extraction from the metal standpoint is rather different. This is the classical approach of coordination chemistry (most of the publications in this area). Today, it is still difficult to establish a direct link between the two descriptions of the organic extractant phases. To better understand liquid/ liquid extraction, the aggregation number and coordination number must be measured separately for each system and set of initial conditions. This is the only way to determine the role of the aggregates in the extraction efficiency. This important point was emphasized by Yaita et al. (61). In this way, Gannaz et al. has used an approach combining studies on both supramolecular and molecular speciation of extractant systems of the DIAMEX-SANEX process (36). 

The parameterization of a force field can be based on any type of experimental data that is directly related to the results available from molecular mechanics calculations, i. e., structures, nuclear vibrations or strain energies. Most of the force fields available, and this certainly is true for force fields used in coordination chemistry, are, at least partially, based on structural data. The Consistent Force Field (CFF)197,106,1071 is an example of a parameterization scheme where experimentally derived thermodynamic data (e. g., heats of formation) have been used to tune the force field. Such data is not readily available for large organic compounds or for coordination complexes. Also, spectroscopic data have only rarely been used for tuning of inorganic force field parameters113,74,1081. 

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