Supramolecular assembly mechanisms

This contribution is restricted to supramolecular chiral phenomena on solid surfaces. Neither interaction of molecules with chiral inorganic surfaces [4], nor chiral amphiphilic molecules at the air-water interface are considered [5-8]. It is the intent of this review to present principle aspects of surface chirality. That is, examples are used to highlight typical chiral assembly mechanisms and structures. Most of these examples, however, belong to more than one aspect presented within this review. Hopefully, this set-up will be accessible to the reader who is not working with surfaces as well as informative to those who are familiar with the subject. 

Alternatively, the use of reversible, thermodynamically-controlled synthetic methods - similar to those used to make the supramolecular polymers discussed in Figure 1 - can be used to assemble mechanically interlocked molecules in near quantitative yields (Figure 7)." However, imlike the supramolecular systems, once formed (after removal of the catalyst) the mechanically interlocked structures are robust and cannot be destroyed without breaking a (strong) covalent bond ... 

Fig. 24 Structure of a mechanoresptmsive metallo-supramolecular polymer network and schematic representation of (dis)assembly mechanisms, (a) Formation of (5)i j-[Eu(CI04)3] netwraks by assembly of 5 and Eu(C104)3-6H20 (C104 counterions are omitted for clarity), (b)...

One area that is surely set to benefit from research aimed at developing the self-assembly of mechanical systems is molecular electronics. Initially, one can look with considerable interest towards the development of chemical sensors and molecular switches of a quite novel design. Furthermore, the ability to store and manipulate information at a molecular level and on the nanometer-scale is clearly on the horizon. It will open the way for the development of molecular electronics and, ultimately perhaps, the molecular-scale computer. The objective at present is to be able to control die assembly, the form, and the function of synthetic nanometer-scale structures with the same degree of precision that is displayed by nature, so as to make it possible to achieve these ambitious goals. Only now are chemists beginning to learn how to construct molecular assemblies and supramolecular arrays such that information might ultimately be written into them, processed by them, stored in them, and eventually read back out of them. 

The complex balance of localized interactions is the main component of binding constants and contact forces that promote supramolecular polymerization. Accordingly, the two main assembly mechanisms based on localized interactions will be presented below. Assembly mechanisms prevalently based on nonspecific (smoothed-out) interactions will instead be presented in Section II.C within the context of the latter type of interaction. 

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