Macrocycles supramolecular assemblies

We have already reported that synthetic peptide lipids, having ot-amino acid residuefs) interposed between a polar head moiety and a hydrophobic doublechain segment, can be used as models for functional simulation of biomembranes [23]. On this ground, we are to clarify molecular recognition specificity by supramolecular assemblies formed in combination of the macrocyclic receptors with the peptide lipid as artificial cell-surface receptors. 

A biomembrane is an excellent example of supramolecular assemblies, in which various functional molecules are structurally organized for molecular recognition. In order to develop artificial supramolecular systems capable of mimicking biomembrane functions, it seems important to investigate molecular recognition by macrocyclic hosts embedded in synthetic bilayer membranes. 

Jerry L. Atwood St. Andrews, United Kingdom Macrocycles as Building Blocks for Large Supramolecular Assemblies... 

A bimetallic Os(II) complex of the macrocyclic ligand MAC1 (Scheme 2) was prepared and characterized by Venturi et al. Each Os(II) center of the complex has a [(bpy)20s(II)] fragment attached to one of the bipyridyl units of MAC1. The complex has absorption and luminescence behavior reasonably similar to that of [Os(bpy)3]2+ with an absorption maximum of 488 nm and emission with a maximum of 740 nm (trt = 59 ns, 0rt = 0.003). The complex may be used in the development of supramolecular assemblies [23]. 

Figure 2.5.3 Frequent tin-containing secondary building units (SBUs) that can be used for the generation of macrocyclic or extended supramolecular assemblies (a) Sn202 dimers (b) Sn402X2Y2-distannoxanes (c) Sn Oe drums...

Abstract This review presents an overview of the area of anion-templated synthesis of molecules and supramolecular assemblies. The review is divided into two main sections the first part deals with anion-templated systems where the final products are linked by bonds that are not reversible under the conditions of the experiment Several recent examples of macrocycles, cages and interlocked species are presented in this section. The second part of the chapter, presents a discussion of anion-templation in systems containing reversible bonds that give rise to dynamic combinatorial libraries (either by formation of coordination metal-ligand bonds or by reversible covalent bonds). 

In 1990, using the suitably hindered square-planer metal center [(en)Pd(N03)2] (en=ethylene- 1,2-diamine) and 4,4 -bipyridine, Fujita and coworkers reported the self-assembly of macrocyclic supramolecular squares.Later work revealed that the replacement of 4,4 -bipyridine with more flexible dipyridyl ligands such as trans l,2-bis 4-pyridyl)ethylene resulted in an equilibrating mixture of molecular squares and triangles (Fig. 3). 

Figure 73. Representation of the self-assembly reaction of two tetracationic porphyrins 135 with four macrocycles 136 to generate the supramolecular assembly 137.

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