Synthon robust

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. 

It is well-known, that in most carboxylic acid crystal structures, the conformation of the carboxyl group is synplanar and that the most frequent and dominant interlink is the syn-syn centrosymmetric dimer synthon, II. This synthon is found in nearly a third of all crystalline carboxylic acids, with or without any other functionality being present in the molecule, signifying robustness.1211 Against such a background, the crystal structures of 1,4-cubane-... 

That the dimer synthon is found in as many as a third of all carboxylic acids is quite impressive, considering the very large variety of other functional groups that are present in the acids contained in the CSD. If, however, one were to consider only simple carboxylic adds - that is, with no other functionality present other than carboxyl and hydrocarbon residues - then the proportion of acids that contain dimer synthon II rises to around 85 %. Hence, the qualifier robust is justified in this case. 

Further investigations of the robustness of synthon XX have recently been reported by Batchelor et al. [59]. Co-crystallization of phenazine with the /raw.s-olefinic acids, fumaric 32 and mesaconic 33, produces 1 1 supramolecular tapes incorporating only synthon XX (Figs. 12.16a, b). With the dv-olefinic acids, maleic 34 and citraconic 35, however, 2 1 tapes are produced in which the... 

L. Rajput, K. Biradha, Design of cocrystals via new and robust supramolecular synthon between carboxylic acid and secondary amide honeycomb network with jailed aromatics, Cryst. Growth Des. 9 (2009) 40-42. 

One can also use the motifs as conceptual tools to understand the structure of aggregates and crystals. This is done by substituting the concept of bond by the concept of motif as the central concept in our analysis. This is the idea behind the concept of supramolecular synthons [51], defined as energetically robust motifs that serve as the basis for the crystal structure by propagation of their structure. A... 

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