Supramolecular chemistry/architecture

This is a very new field, but given the current interest in both dendrimer chemistry and supramolecular chemistry, it is one that is likely to receive attention in the future. The prospect of preparing well-defined molecular assemblies, rather than ill-defined clusters, is attractive, and is expected to give access to new properties that can be controlled by the molecular architecture of the assembly. New and useful materials seem likely to emerge as this chemistry grows and is exploited in the years to come. 

In this review, CPOs constructed by covalent bonds are mainly focused on however, stable coordination bonds comparable to the stability of the covalent bonds have potential for future enhanced molecular design of novel CPOs. One representative is the bond between pyridine-type nitrogen and metal, which is widely used in supramolecular chemistry, that is, the cyclic supramolecular formation reaction between pyridine-substituted porphyrin and metal salts (Fig. 6d) [27,28]. Palladium salts are frequently used as the metal salts. From the viewpoint of the hard and soft acid and base theory (HSAB), this N-Pd coordination bond is a well-balanced combination, because the bonds between nitrogen and other group X metals, N-Ni and Ni-Pt coordination bonds, are too weak and too strong to obtain the desired CPOs, respectively. For the former, the supramolecular architectures tend to dissociate into pieces in the solution state, and for the latter. 

Baxter, P. N. W. Metalion directed assembly of complex molecular architectures and nanostructures. In Comprehensive Supramolecular Chemistry Sauvage, J.-P. Hosseini M. W., Eds. Pergamon Oxford, UK, 1996 Vol. 9, pp 165-211. 

Since 1982 there have been enormous developments in metal-based chemistry, particularly the emergence of supramolecular chemistry - chemistry beyond the molecule, molecular architecture, and molecular engineering. Comprehensive Supramolecular Chemistry was published in 1996, a survey which contains much of interest to coordination chemists. Consequently in this volume review material relating to supramolecular systems is mainly restricted to developments since 1990. 

Dendrimers produced in this way will necessarily possess unique cavities, clefts, and void regions thereby facilitating the investigation of novel, dissymmetric architectures [polycelles = poly(micelles)] [214], and thus add the next chapter to this ever expanding field of supramolecular chemistry. 

One point to address concerns the use of the words s pramolecular and supermolecule. The concept of supramolecular chemistry has become a unifying attractor, in which areas that have developed independently have spontaneously found their place. The word supramolecular has been used in particular for large multiprotein architectures and organized molecular assemblies [1.16]. On the other hand, in theoretical chemistry, the computational procedure that treats molecular associations such as the water dimer as a single entity is termed the supermolecule approach [1.34,1.35]. Taking into account the existence and the independent uses of these two words, one may then propose that supramolecular chemistry be the broader term, concerning the chemistry of all types of supramolecular entities from the well-defined supermolecules to extended, more or less organized, polymolecular associations. The term super molecular chemistry would be restricted to the specific chemistry of the supermolecules themselves. 

We have come to the end of our journey through supramolecular chemistry. The bulk of the discussion in this chapter has centred upon the role of the metal ion in controlling the conformation of a co-ordinated ligand. We have seen that a variety of novel molecular architectures may be achieved from the simple principles that we have developed. 

Fritz Vogtle is Professor and Director at the Kekule-Institute for Organic Chemistry and Biochemistry at the University of Bonn, Germany. His research interests are supramolecular chemistry deformed helical molecules and their chiroptical properties and compounds with appealing architectures such as rotaxanes, catenanes, knots, and dendrimers [37-40],... 

Hierarchical self-assembly starts with the integration of individual components into complex structures, which in turn organize themselves to form higher-level architectures. This spontaneous assembly continues in a hierarchical way until the solid is completely built. This phenomenon-common to supramolecular chemistry and many biological systems- [53] produces solids with new properties that are not present in its original components. 

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