Formation of Supramolecular Adducts

This supramolecular approach has been used as a way to facilitate the crystallization of cuboidal aqua ions and to capture single intermediates present in complex solution mixtures. For example, [M3Q4Clx(H20)9.x] (Q = S, Se) supramolecular adducts have been isolated for x =1-5 from aqueous HCl solutions by varying the acid concentrations where the aggregates contain in each case only one of all possible isomers [46]. In addition to the hydrogen bonds, other kinds of interactions, namely C1---H20, C1---C1 and Q---Q contacts, are also involved in the network propagation. This supramolecular approach has also been efficiently employed for the crystallization of a large number of aqua complexes within the [M3M Q4] cubane-type family, where M is a transition or post-transition metal [47]. 

This entry to supramolecular chemistry allows one, at the same time, to develop a host-guest chemistry because the space inside the cucurbituril barrel is sufficient to confine small guesf molecules. This is illustrated with the crystallization of the supramolecular adduct [W3S4(H20)8Cl](pyH ccuc) Cl4a 5.5 H2O with a pyridinium cation inside the cucurbituril cavity [48]. The introduction of guest molecules may vary the net charge on the assembly and consequently the whole packing in the solid state. 

Corbett, Structural and Electronic Paradigms in Cluster Chemistry, 87 (1997), 157. 

Yoshikawa, T. Yamagata, H. Imoto, K. Unoura, Inorg. Chem., 28 (1989), 3588. 

DiSalvo, W. Zhou, D. Tang, P. P. Edwards, /. Alloys Compd., 

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The other critical parameter to consider in the formation of supramolecular adducts is their shape. According to what was stated above, the molecular ellipticity a/b) must be higher than 3 so that /s is relevant. Thus, when spheroid elemental building blocks without particularly directional... 

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