Superstructures macrocycles

An original pathway for producing reversible iron(II) clathrochelated structures has been discovered [131]. In particular, the clathrochelate systems [Fe(L 245)] +, [Fe(L 1010)] +, [Fe(L 244)] " and [Fe(L lOll)] were produced by treating complexes of superstructural macrocyclic ligands [Fe(L245)] +, [Fe(L1010)] +, [Fe(L244)] + and [Fe(LlOll)] with base in methanol in an inert atmosphere (Scheme 4-14). 

Barboiu, M., Vaughan, G. and van der Lee, A. (2003) Self-organized heteroditopic macrocyclic superstructures. Organic Letters, 5, 3073-3076. 

Approaches to artificial ion channels have, for instance, made use of macrocyclic units [6.72,6.74] (see also below), of peptide [8.183-8.185] and cyclic peptide [8.186] components, of non-peptidic polymers [8.187] and of various amphiphilic molecules [6.11, 8.188, 8.189]. The properties of such molecules incorporated in bilayer membranes may be studied by techniques such as ion conductance [6.69], patch-clamp [8.190] or NMR [8.191, 8.192] measurements. However, the nature of the superstructure formed and the mechanism of ion passage (carrier, channel, pore, defect) are difficult to determine and often remain a matter of conjecture. 

The synthesis of interlocked molecules has become commonplace over the past 25 years with the gradual development of a number of highly facile template methods for their construction. What were once laboratory curiosities have now taken a prominent place in the broad field of supramolecular chemistry, especially regarding their uses and further potential as molecular switches and machines [1], We present here an overview of the main synthetic approaches to these molecules, with a focus on methods in which macrocyclization reactions result in interlocked products. The analysis is by no means meant to be comprehensive or exhaustive in detail, but rather to convey the variety and utility of the selected synthetic strategies in generating abiotic rotaxane and catenane superstructures. 

Barboiu M, Vaughan G, van der Lee A Self-organized heteroditopic macrocyclic superstructures. Org. Lett. 2003 5 3073-3076. 

Porphyrin chromophores have received much attention, particularly as photoelectric devices and molecular wires. Efficient re-electronic communication between porphyrin macrocycles is pivotal in various complex functions. K.M. Smith et al. showed that neighboring acetylenic units on porphyrins provide a means for the efficient construction of aromatic superstructures triggered by the Bergman cyclization reaction conditions and give rise to novel [n]phenacenoporphyrins, which belong to a new class of highly re-extended porphyrins." ... 

Figure 11 A macrocyclical molecule and the corresponding superstructure. Atoms in common are marked by black circles.

Fig. 8. Self-assembly of H-bonded superstructures from enantiomeric components 12 A heterochiral strand B homochiral macrocycle C observed homochiral assembly...

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