Supramolecular forces

One of the fascinations of scientists has long been the ability of nature to use supramolecular forces to create molecular assemblies for carrying out particular functions. As a result, one of the ultimate aims of supramolecular chemistry is to create molecular devices. 

A combination of two different supramolecular forces, namely metal-metal bonds and the ureidopyrimidones were investigated by Schubert et al. [136,137] (Fig. 35). A poly(g-caprolactame) was prepared—with a ter-pyridine moiety at one end and an ureidopyrimidone unit at the other end—via tin-octanoate catalyzed polymerization. Together with iron(ll) ions, double supramolecular polymers formed from chloroform solution. Again, solid-like behavior was observed, similar to results for the purely hydrogen-bonded polymers. 

The ability of a-CD cavity to recognize a metal—chloride bond rather than organic groups in non-aqueous media is likely a consequence of the absence of stronger competing supramolecular forces such as the hydrophobic effect which usually plays a prevailing role in the formation of CD inclusion complexes. 

Heibst, F., Dbhler, D., Michael, P., and Binder, W.H. (2013) Self-healing polymers via supramolecular forces. Macromolecule Rapid Communications, 34, 203-220. 

H-bonding, the prevalent supramolecular force The donor-acceptor FMO interactions are also involved... 

Supramolecular interactions are susceptible to being deformed and destroyed in the liquid phase and gas phase, while structural consequences are frozen and accentuated in the solid state. Both the flexibility and repetition of supramolecular forces are favored by biological and crystallization processes to accomplish self-correction. A main challenge for supramolecular chemists is to understand how to employ weak noncovalent interactions to construct supramolecular compounds. The construction and properties of a supramolecular ensemble will involve molecular recognition and self-assembly of constituent components. In line with the enzyme-substrate lock-and-key mechanism, the interacting partners can comprise host and guest species. 

Nonetheless, many such systems utilize supramolecular forces to achieve the separation of a mixture of compounds injected into a chromatographic or electrophoretic separation system, see, for example. Affinity Capillary Electrophoresis as a Tool to Characterize Intermolecular Interactions or Ion Chromatography and Membrane Separations Using Macrocyclic Ligands, Techniques. 

In order to incorporate these attributes in the design and rational manufacture of supramolecular entities, it is necessary to understand the supramolecular forces and energies for inorganic compounds of interest. The understanding of these systems comes from the observation of structures and patterns, coupled with the theory and... 

Relatively new types of forces, due to supramolecular structuring of amphiphilic molecules and polymers, within foam films have been recently measured. Moreover, several works dating from the turn of the 20th century have demonstrated film-thinning phenomena (commonly referred to as film stratification) which arise from supramolecular forces. The general form of the force curves obtained for these systems is summarized in Figure 21.11. 

Bauza A, Mooibroek TJ, Frontera A (2013) Tetrel-bonding interaction rediscovered supramolecular force Angew Chem Int Ed Engl 52 12317-12321... 

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