Binding in Supramolecular Chemistry

The complexation event is determined by how the host and guest bind to each other. All sorts of non-covalent binding is used in supramolecular chemistry that sometimes, it is been called the study of every type of bonding besides the covalent bond. The host will possess convergent binding site (e.g. hydrogen bond acceptor) while the guest possesses divergent binding site (e.g. hydrogen bond acceptor).

Intermolecular forces that come into play are: 

1. Electrostatic energy-interaction energy of the unperturbed charge distributions of the molecules.

2. Induction energy-energy resulting from the distortion of one molecule by the mean electric field due to other molecules.

3. Dispersion energy-they result from intermolecular correlations in the fluctuations of the electronic coordinates of the molecules and are a consequent of the quantum mechanical nature of the electron

4. Resonance energy-additional interaction energy that results from the lifting of degeneracy by the interaction.

5. Magnetic interactions.

6. Short range interactions-overlap of electron clouds

I will not go into detail how the molecules interact with each other due to its complexity and tediousness, but I will give a list of interactions that are used, sometimes in combination during a binding event.

ion-ion, ion-dipole, dipole-dipole, p stacking, hydrogen bonding, close packing in solid state and hydrophobic effects.

In supramolecular chemistry, not only must the electronic character match, the coordinates of the binding sites must match too. Therefore, we are looking at very selective reactions.