Macrocycles host-guest systems based

A useful approach for the synthesis of highly ordered host-guest systems is based on the use of macrocycles. One of these systems makes use of the couple cyclo[12]thiophene 9 and Ceo fullerene, which are a ring-shaped p-type and a spherical n-type organic semiconductor, respectively [41, 55], Compound 9 and Ceo self-assemble on HOPG as demonstrated by STM imaging (Figure 13.3). The deposition was realized... 

Cucurbit [6] uril and increasingly its higher homologues have been used extensively in a variety of host-guest chemistry and nanostructure assemblies. Of particular appeal are rotaxanes and molecular necklaces, mechanically interlocked assemblies of molecules based on CB [6]. Efficient synthesis of ID, 2D and 3D polyrotaxanes and molecular necklaces (cucurbituril beads linked by a macrocyclic molecule string ) has been achieved by a combination of self-assembly and coordination chemistry. We discuss rotaxanes and molecular necklaces in Section 10.7, and cucurbil-based systems are summarised in a recent review.23... 

The effect of macrocyclic receptors as components of catalytic systems based on metal complex on catalytic processes depends on the composition and structure of the resulting host-guest complexes. The macrocycle can interact either with the substrate or with the metal complex, which subsequently determines the characteristics of the catalyzed reaction. 

There are two directions in the development of supramolecular catalytic compositions, that is, (1) creation of systans based on macrocyclic compounds as host molecules that bind substrates with their hydrophobic cavity and (2) development of the systems that bind substrates using aggregates formed by am-phiphihc compounds. Compounds that form host-guest complexes like modified cahxarenes are able to aid transport of substrates into the aqueous phase. This approach has been implemented in the Wacker oxidation [40,41], oxidation of alkylaromatic compounds [42], hydroxylation of aromatic compounds [43], hydrogenation [44,45], hydroformylation [45-48], and carbonylation [49]. In this case, the substrate is transported into the aqueous phase in the form of the corresponding inclusion complex. This not only affects the activity of the catalyst, but also provides selectivity of the process. Thus, in the Wacker oxidation of 1-alkenes the maximum yield of methyl ketone was achieved when 1-hexene is used, and for systems based on calix[6]arene with 1-octene among catalytic systems with modified calix[4]arenes [50]. 

Thus, macrocyclic amphiphiles are reviewed by Huang et al. with respect to cyclodextrins, calixarenes, cucurbiturils and pillararenes [1]. Similarly, Ma and Zhao present biomedical applications of supramolecular systems based on host-guest interactions, with a focus on cyclodextrins, calixarenes and cucurbiturils [2]. Sansone et al. published a review on calixarenes as multivalent ligands for biomolecular recognition [3]. 

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