Molecular recognition - synthons

Desiraju, Crystal Engineering, The Design of Organic Solids , Elsevier, Amsterdam, 1989. 

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The graph set notation of a crystal structure provides precise topological information but inherent in its definition is a drastic reduction in the chemical information underlying molecular recognition. The supramolecular synthon combines chemical and geometrical features and occupies a middle ground between the full crystal structure and its graph set notation. 

In supramolecular chemistry, we operate with synthons (i.e., some special systems of functional groups that fit together perfectly), giving rise to molecular recognition. 

The interaction leads to a molecular complex that facilitates further evolution of the system either by a chemical reaction going on selectively at such a configuration of the molecules, or by further self-organization due to next-step molecular recognition of the newly formed synthons. 

Tectons are the fundamental features that drive the process of self-assembly—they are either the peripheral molecular recognition sites or the scaffolds that orient these sites. Much of crystal engineering is based on the utilization of tectons to influence desirable properties of materials. A supramolecular synthon is the result of the combination of tectons—that is, the synthon is the pattern formed by interacting tectons. 

The supramolecular synthon concept combines the chemical elements of molecular recognition with the geometrical requirements of crystal packing. The seminal 1995 review paper of Desiraju introduced the formal Hterature definition of the supramolecular synthon, based on analogy with Corey s definition of synthons for covalent synthesis. The explicit link between eovalent synthesis and crystal engineering is stressed by this analogy, and co-erystal or... 

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