What is Supramolecular Chemistry

In many respects, the above question is like asking How long is a piece of string - the answer will depend upon the precise circumstances and who is asked. It is probably true that most workers actively involved in this field have their own private definition. The rapid development of this area over the past decade or so is due to the endeavours of Jean-Marie Lehn more than any other, and it seems appropriate to commence with his own definition. 

7 The Three-Dimensional Template Effect, Supramolecular Chemistry and Molecular Topology  

As no new covalent bonds are formed in the assembly of the supramolecule, the individual molecular components are expected to retain, essentially unchanged, their own molecular character and properties. However, the proximity and the spatial arrangement of the molecular components of the supramolecule may be such that additional interactions between them are optimised, promoted or even initiated. Herein lies one of the real promises of supramolecular chemistry - it allows the precise control of intermolecular processes and reactions by removing the usual requirements for the molecular reactants to form contact pairs with the correct mutual spatial orientation of functionality. In effect, the supramolecule encapsulates that contact pair. 

These descriptions, while helpful, are by their nature noncomprehensive and there are many exceptions if such dehnitions are taken too literally. The problem may be linked to the dehnition of organometallic chemistry as the chemistry of compounds with metal-to-carbon bonds . This immediately rules out Wilkinson s compound, RhCl(PPh3)3, for example, which is one of the most important industrial catalysts for organometallic transformations known in the field. Indeed, it is often the objectives and thought processes of the chemist undertaking the work, as much as the work itself, which determine its field. Work in modern supramolecular chemistry encompasses not just host-guest systems but also molecular devices and machines, molecular recognition, so called self-processes  

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Supramolecular Chemistry, 2nd edition J. W. Steed and J. L. Atwood 2009 John Wiley Sons, Ltd ISBN 978-0-470-51233-3 

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What is supramolecular chemistry In his Nobel lecture, Lehn [1] put it succinctly Supramolecular chemistry is the chemistry of the intermolecular bond, covering the structural and functional entity formed by association of two or more chemical species. The types of interactions may include metal ion coordination, electrostatic interactions, hydrogen bonding, and van der Waals forces, which provide new comprehensive methods for chemical research. The unifying power and... 

But what is "Supramolecular Chemistry" As for any other interdisciplinary field of science, a general definition would necessarily be arbitrary. Different meanings can in fact be attributed to Supramolecular Chemistry and the II NATO Science Forum has shown msmy facets of this interdisciplinary field. The importance of this meeting can be measured, in fact, not only by the number of represented countries (16), but especially by the number of represented disciplines (more than 20). 

Although the classical definition of supramolecular chemistry as the chemistry beyond the molecule is quite useful in general, firom a functional viewpoint the distinction between what is molecular and what is supramolecular can be better based on the degree of intercomponent electronic interactions [1, 5-8]. 

According to these basic concepts, molecular recognition implies complementary lock-and-key type fit between molecules. The lock is the molecular receptor and the key is the substrate that is recognised and selected to give a defined receptor—substrate complex, a coordination compound or a supermolecule. Hence molecular recognition is one of the three main pillars, fixation, coordination, and recognition, that lay foundation of what is now called supramolecular chemistry (8—11). 

Such hybrid molecules and supramolecular solids offer the promise of systems with the flexibility, strength, toughness, and ease of fabrication of polymers, with the high temperature oxidative stability of ceramics, and the electrical or catalytic properties of metals. Polyphosphazene chemistry provides an illustration of what is possible in one representative hybrid system. 

The overwhelming number of dendrimer-related reports flooding the chemical arena, particularly, in the last five years, has made it a difficult task to summarize all important developments in one treatise. The restricted scope of this chapter - supramolecular chemistry within dendritic materials - denotes the utilitarian character to the unique infrastructure of these materials. Surface coatings and attachments to molecular spheres should possess a common theme respective of their frameworks, and thus there should be less differentiation between the mode of construction but rather what is the surface functionality. 

The problem behind all these questions is that perhaps we have automatically and uncritically accepted the artificial distinction between Chemistry and Biochemistry (and even perhaps Biology) as a natural and insuperable barrier. But, what does "Molecular Biology" really mean or "Supramolecular Chemistry" And what about "Bioorganic Chemistry" Has it even nowadays any meaning to differentiate between Organic and Inorganic Chemistry ... 

As in all active areas of research, there are several approaches to the development of nanotechnology. One approach involves techniques similar to sculpting, where one starts with a large piece of material and cuts away what is not needed. The problem is that a lot of the material winds up wasted on the cutting room floor. An alternative approach, described in the following section, starts at the bottom or lower end of the scale and builds up from there. An important feature of this approach is the bonding of molecules to make even larger, more complex molecules—supramolecular chemistry. 

REVIEW This is a strong second volume for what promises to be an important series in the field of supramolecular chemistry. The quality of the graphics is somewhat inconsistent among the chapters, reflecting direct reproduction of the authors variable originals However, this does not detract from an excellent compilation of studies from five laboratories with very diverse approaches to supramolecular chemistry. ... 

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