Synthons supramolecular

Decomposition of the crystal structure into supramolecular synthons allows for a certain degree of predictability of a crystal structure A given functional group can participate in certain supramolecular synthons. Furthermore, the 

An obvious prerequisite for the formation of a supramolecular synthon between two functionalities is complementarity - one must act as a donor and the other as an acceptor of a bond. However, polyatomic functional groups can act both as donors and acceptors (e.g., carboxyl group, primary amide group, 2-aminopyridine, or 2-pyridone). In this case, groups which are most likely to 

1) As the hydrogen bond in the most common strong and directional interaction in (oi anic) crystals, the principle is commonly expressed for hydrogen bond donors and acceptors. However, it holds for other interactions as well, for erample, halogen bond. 

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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Paraphrasing Corey s historic definition of synthon [203], Desiraju defined a supramolecular synthon as a structural unit within a supermolecule that can be formed or assembled by known or conceivable synthetic operations involving intermolecular interactions [204], The robustness of the XB has allowed several supramolecular synthons based on this interaction to be identified and some examples have been presented in this chapter. 

Keywords Synthesis m Crystal engineering m Supramolecular synthon... 

It has been noted above that synthon VIII incorporates within it synthon VII. Which of these is the more useful representation The efficacy of a supramolecular synthon as an indicator of crystal pack-... 

F. H. Allen, J. P. M. Lommerse, V. J. Hoy J. A. K. Howard, G. R, Desiraju, The halogen—O(nitro) supramolecular synthon in crystal engineering a combined crystallographic database and ab initio molecular orbital study , Acta CrystaUogr, Section B, 1997, 53,1006-1016. 

The identification of the set of interactions that constitute a synthon is, in the end, subjective. In the limit, any possible combination of interactions may be defined as a supramolecular synthon but then there is the risk that the term will be degraded or fall into disuse much like its molecular sibling. Interactions or groups of interactions that are needlessly identified as supramolecular synthons, but are unable subsequently to sustain a predictive role in crystal engineering, will... 

Supramolecular structuring, 12 5-6 Supramolecular synthons, synthesis and structures of, 24 39-40 Supramolecules, formation of, 24 34 Supraventricular arrhythmias, 5 88, 104 Supraventricular tachycardia, 5 88, 101, 105, 108 Suprilent... 

Supramolecular architectures in which transition metal cationic centres are linked via hydrogen-bonded supramolecular synthons [1,2] comprise an increasingly important class of inorganic co-ordination polymers [3], owing to their multi-dimensional, multi-functional network structures. 

The network structures to be discussed will all involved hydrogen bonding as the supramolecular synthon. It should be noted however that other interactions such as coordinate bonds and host-guest interactions may also organise host molecules into network structures. Coordination polymers constructed from molecular hosts may involve functionalised calixarenes [8-11], cyclotriveratrylene [12], or cucurbituril [13]. Calixarenes have also been used to build up network structures via host-guest interactions [14,15]. It is also notable that volatile species may be trapped within the solid state lattice of calix[4] arene with a structure entirely composed of van der Waals interactions [16]. 

Scheme 9 Strategy for the 1,6-polymerization of triacetylene, a Polymerization principles for triacetylene, b Supramolecular synthon as the host to arrange triacetylene molecules as the guest with a stacking distance of 7.4 A. c Successful and unsuccessful examples for the combination of host and guest molecules with carboxylic acid or pyridine moieties [63]...

Halogen-halogen interaction as the supramolecular synthon has a significant potential in the presence of other weak interactions (for example, CH/n inter-... 

Interactions can be combined by a designed placement of functional groups in the molecular skeleton to generate supramolecular synthons, which are defined as structural units within supermolecules that can be formed and/or assembled by known or conceivable synthetic operations involving intermolecular interactions (Desiraju, 1995). In other words supramolecular synthons are spatial arrangements of intermolecular interactions. 

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