Molecular recognition kinetics

To understand fully processes such as molecular recognition, reactivity and bioactivity, it is therefore imperative to obtain a detailed insight into the thermodynamic and kinetic properties of the metal-based anticancer agent at hand. 

The selective binding of molecules to form productive complexes is of central importance to pharmacology and medicinal chemistry. Although kinetic factors can influence the yields of different molecular complexes in cellular and other non-equilibrium environments,1 the primary factors that one must consider in the analysis of molecular recognition are thermodynamic. In particular, the equilibrium constant for the binding of molecules A and B to form the complex AB depends exponentially on the standard free energy change associated with complexation. 

FIGURE 5.17. Dynamics of molecular recognition. Binding of the target molecule to the receptor. Kinetic zone diagram and characteristic equations. Adapted from Figure 1 of reference 22, with permission from the American Chemical Society. 

So far, the studies of cucurbituril described have been thermodynamic investigations, in which factors contributing to the overall stability of molecular complexes have been explored. While bounteous, these only partly address the question of receptor specificity. For example, in biological systems the kinetics of noncovalent interactions, such as between enzymes and substrates, may be of greater consequence. Clearly, the dynamics of molecular recognition deserve additional attention. Cucurbituril provides diverse opportunities in this area [11]. 

The mechanism of molecular recognition reactions (kinetics and mechanism of substitution and exchange reactions with participation of polycomplexes and free chains) is considered. 

Mechanism of Molecular Recognition and Kinetics of Interpolymer Substitution and Exchange Reactions... 

The last of the important concepts that we will consider is self-assembly. Most chemists have, at some time in their careers, wondered why molecules cannot just make themselves. The process by which molecules build themselves is termed self-assembly and is a feature of many supramolecular systems. If the molecular components possess the correct complementary molecular recognition features and their interaction is thermodynamically favourable then simply mixing them could result in the specific and spontaneous self-assembly of the desired aggregate. This assumes that there is no significant kinetic barrier to the assembly process. The recognition features within the components may be any of the intermolecular bonding processes mentioned above, but we will be concerned with interactions between transition metal ions and polydentate ligands. 

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