Mechanism of supramolecular chemistry

The basis of supramolecular chemistry is the binding or complexation event, which is the action of the host molecule binding with a guest molecule to form a host-guest complex or supramolecule. The host is an enzyme or synthetic cycle compound processing a central hole or cavity. The guest is monoatomic cation or simple inorganic anion. In more complex biological interactions, the guest is called a substrate and can be a food particle, hormone, pheromone or neurotransmitter.

Supramolecular chemistry is characterized by the specificity and selectivity of its reactions. The term used to describe this is molecular recognition, as if the reactions will only happen if the molecule recognizes each other. Therefore, a supramolecular interaction can only happen when the host and guest complement each other. (e.g. hydrogen bond donor/acceptor, Lewis acids/base, hardness or softness etc.) An analogy to the mechanism is the lock and key scenario coined by Emil Fischer in 1894. The host molecule serves as the lock and the guest molecule serves as the key. Only when the key matches the lock will the lock open.

Figure 3 Example if a lock key scenario in biological systems