Supramolecular tectons

The foregoing discussion plainly indicates that Sn... r interactions can and do exist in the structures described herein. At a minimum, molecules aggregate to form a dimer and more often than not, these form the supramolecular tecton that associates via other intermolecular interactions, sometimes of the type Sn... ITT, into one-, two- and three-dimensional supramolecular architectures. Without exception, Sn... tt interactions involve tin atoms present in the formal oxidation state -l-II. This leads to the conclusion that one possible explanation for Sn... itt interactions lies in a charge transfer from the tin-bound lone pair of electrons into the LUMO of the aromatic system. 

Supramolecular Tectons The molecular components of a crystal, held together by supramolecular synthons. 

Porphyrins have been extensively studied for their use as supramolecular tectons. This is because the structuring of... 

Selective modification of cydodextrin was motivated by the potential appHcations of these derivatives. Now, the new patterns of functionahTation have to be induded in the synthesis of new molecular architectures, supramolecular tectons, and materials. 

Keywords Halogen bonding Supramolecular chemistry Crystal engineering Tecton Topology... 

Fig. 13 Schematic representation of supramolecular assemblies of phosphorylated cavitand tectons...

We saw in Figure 1.2c that supramolecular chemistry is not just about solid state or solution host-guest chemistry but increasingly emphasises self-assembly and the construction of multi-nanometre scale devices and ultimately materials based on nanometre-scale components (a nanometre is 10 9 of a metre). Strict supramolecular self-assembly (Chapter 10) involves the spontaneous formation of a multi-component aggregate under thermodynamically controlled conditions based on information encoded within the individual building blocks (referred to as tectons ) themselves. The aggregate might comprise only one kind of molecule (as in the multiple copies of the same protein that comprise... 

A supramolecular synthon represents a reproducible, frequently occurring kind of non-covalent interaction found in molecular crystal structures. It has predictive power and may be used in crystal design. Supramolecular synthons are distinct from tectons, the molecules or the building blocks of the crystal. 

Self-assembly is the spontaneous and reversible association of molecules or ions (tectons) to form larger, more complex supramolecular entities according to the intrinsic information contained in the molecules themselves. 

Whereas the direct exploitation of homochiral tectons would seem to be the most obvious approach because the absence of a center of inversion is guaranteed, it in no way implies or affords any control of molecular orientation and therefore optimization of bulk polarity. Furthermore, reliance upon the use of pure enantiomers raises the substantial problem of needing to control the stereochemistry at the molecular level without yet solving the problem of controlling the supramolecular... 

Wuest has demonstrated that the pyridone moiety also generates a hydrogen-bonded supramolecular synthon that is suitable for building extended arrays.67 Remarkably, methanetetra(6-phenylethynyl-2-pyridone) exhibits a diamondoid network, sevenfold interpenetration and cavities large enough to enclathrate butyric or valeric acid.27 Wuest introduced the concept of tectons to describe molecules that inherently possess the molecular structure and intermolecular recognition features to predictably self-assemble into crystalline networks. He followed this study with several other examples of diamondoid networks sustained by the pyridone moiety 27c d... 

In recent years, the development of new concepts for the rational design of larger, more complex molecules has led to considerable progress in supramolecular chemistry to afford structures of a variety of symmetries, sizes, and stoichiometries. nF complexes have provided versatile molecular tectons in a plethora of such structures. 

The term synthon is more familiar to organic chemists and describes fragments from which varions molecnles can be bnilt by synthetic procedures. Sometimes the term was also used to describe structural units within supermolecules which can be formed and/or assembled by known or conceivable synthetic operations involving intermolecular interactions To avoid confusion, the term tecton was introduced to describe the molecular units of supramolecular structures assembled through noncovalent forces. Thus, the tecton has been defined as any molecule whose interactions are dominated by particular associative forces that induce self-assembly of an organized network Here, we will use the term synthon for... 

Treatment of 2,9-dibromophenanthrene with Pt (Et3P)4 followed by bromine-nitrate exchange gave the desired 60° tecton, 2,9-6/i [/ra 5 -Pt(PEt3)2(N03)]phenanthrene, which with different linear connectors afforded a series of self-assembled supramolecular triangles <03JA5193>. A series of related binuclear metallomacrocycles [Cd(N03)2L]2, where L is an angular exo-bidentate, such as 4-(4 -pyridinyl)(2-pyridinylethynyl) benzene, have been reported... 

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