page_title: Dynamic covalent chemistry
section_title: Thermodynamic control
hierarchical_section_title: Dynamic covalent chemistry / Thermodynamic control
caption_attribution_description: English: Reaction Control
context_page_description: Dynamic covalent chemistry is a synthetic strategy employed by chemists to make complex supramolecular assemblies from discrete molecular building blocks. DCvC has allowed access to complex assemblies such as covalent organic frameworks, molecular knots, polymers, and novel macrocycles. Not to be confused with dynamic combinatorial chemistry, DCvC concerns only covalent bonding interactions. As such, it only encompasses a subset of supramolecular chemistries.
  The underlying idea is that rapid equilibration allows the coexistence of a variety of different species among which molecules can be selected with desired chemical, pharmaceutical and biological properties. For instance, the addition of a proper template will shift the equilibrium toward the component that forms the complex of higher stability. After the new equilibrium is established, the reaction conditions are modified to stop equilibration. The optimal binder for the template is then extracted from the reactional mixture by the usual laboratory procedures. The property of self-assembly and error-correcting that allow DCvC to be useful in supramolecular chemistry rely on the dynamic property
context_section_description: In dynamic reaction mixtures, multiple products exist in equilibrium. Reversible assembly of molecular components generates products and semi-stable intermediates. Reactions can proceed along kinetic or thermodynamic pathways. Initial concentrations of kinetic intermediates are greater than thermodynamic products because the lower barrier of activation (ΔG‡), compared to the thermodynamic pathway, gives a faster rate of formation. A kinetic pathway is represented in figure 1 as a purple energy diagram. With time, the intermediates equilibrate towards the global minimum, corresponding to the lowest overall Gibb's free energy (ΔG°), shown in red on the reaction diagram in figure 1. The driving force for products to re-equilibrate towards the most stable products is referred to as thermodynamic control. The ratio of products to at any equilibrium state is determined by the relative magnitudes of free energy of the products. This relationship between population and relative energies is called the Maxwell-Boltzmann distribution.
caption: Figure 1: Thermodynamic versus Kinetic Control[3]
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