Supramolecular macrocycles

Figure 1.4 (a) Molecular structure of the supramolecular macrocyclic heterodimer catalyst used by Warnmark et al. (b) CAChe minimized 3D representation of a substrate bound inside the hydrogen bonded macrocycle. Long alkyl chains are reduced to a methyl groupfor clarity. The substrate and the Mn atom (purple) are shown in CPK representation. 

Fig. 37. Self-assembly of either a supramolecular ribbon (top) or a supramolecular macrocycle (bottom) from barbituric acid and 2,4,6-triaminopyrimidine units [9.122].

With the above simple examples we wish to emphasize that the synthetic use of hydrogen bonding assemblies in the effective formation of supramolecular macrocycles relies on high EM values and on the establishment of stable intermolecular arrays of hydrogen bonds capable of affording a high enthalpic gain to compensate for the entropic cost of the assembly. 

Strategies to Build up Supramolecular Macrocycles Based on Hydrogen Bonds... 

Figure 3.5 Proposed self-assembly of the self-complementary molecule 16 (R = C8Hn7) into a supramolecular macrocycle schematic (left, A = acceptor, D = donor) and structural (right) representation.

Finally, supramolecular macrocycles involving porphyrins can be made.115... 

Marsh, A. Silvestri, M. Lehn. J.-M. Self-complementary hydrogen bonding heterocycles designed for the enforced assembly into supramolecular macrocycles. Chem. Commun. 1996. 1527. 

BaHester P, de Mendoza J. Supramolecular macrocycle synthesis by H-bonding assembly. In Diederich F, Stang PJ, Tykwinski RR, eds. Modern Supramolecular Chemistry Strategies for Macrocycle Synthesis. Weinheim Wdey-VCH 2008 69—111. 

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