Supramolecular synthon

In the context of organic synthesis, the term synthon was introduced by Corey in 1967 to refer to structural units within molecules which can be formed and/or assembled by known or conceivable synthetic operations. This general definition was modified by Desiraju for supramolecular chemistry Supramolecular synthons are structural units within supermolcules which can be formed and/or 

The nature of the X X interaction in trimer synthon 44 is illustrated in Fig. 20.1.7. The C-X bond in a halo-substituted phenyl ring is polarized, so that there are regions of positive and negative electrostatic potentials around the X atom. The cyclic interaction of three C-X groups optimizes electrostatic potential overlap in the halogen trimer system. 

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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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