Supramolecular interactions hydrogen bonding

The directed manipulation of intermolecular interactions (hydrogen bonding, van der Waals forces, metal coordination) gives access to a supramolecular engineering of molecular assemblies and of polymers (see, for instance, [7.10-7.13, 7.44, 9.142, 9.157, 9.161-9.163]) through the design of instructed monomeric and polymeric species. It leads to the development of a supramolecular materials chemistry (see Section 9.8). 

Based on the fundamental charge-dipole interaction, hydrogen bonding need not necessarily mandate the presence of lone electron pairs in the guest anion. If present, this electronic feature dominates the supramolecular behaviour of anions. As a corollary, it is the most prominent aspect to be removed in the construction of so-called non-coordinative anions (BPhj, BHj, closo-CBnHf2 etc.) that are required in the isolation and study of reactive cationic... 

Fullerenes C60 and C70 form supramolecular adducts with a variety of molecules, such as crown ethers, ferrocene, calixarene, and hydroquinone. In the solid state, the intermolecular interactions may involve ionic interaction, hydrogen bonding, and van der Waals forces. Figure 14.2.9 shows a part of the structure of [K(18C6)]3-C6o-(C6H5CH3)3, in which Cgg is surrounded by a pair of [K+(18C6)] complexed cations. 

Taking into account the basic considerations outlined in the previous section, we reasoned that a chiral complexing agent, which needs to be applicable in photochemistry, requires a general binding motif. In addition, it appeared necessary to employ directed interactions in such a template rather than an unspecific complexation as encountered in chiral solvents or larger supramolecular entities. Hydrogen bonds appealed... 

A relatively new field called supramolecular chemistry has been developed over the last three decades. Supramolecular assemblies and supramolecular polymers differ from macromolecules, where the monomeric units are covalently linked. In a supramolecular polymer, the monomeric units self-assemble via reversible, highly directional, noncova-lent interactions. These types of bonding forces are sometimes called secondary interactions. Hydrogen bonding is the secondary force most utilized in supramolecular chemistry, but metal coordination and aromatic tt-tt electronic interactions have also been used. From a materials standpoint, supramolecular assemblies are promising because of the reversibility stemming from the secondary interactions. The goal is to build materials whose architectural and dynamical properties can respond reversibly to external stimuli. Solid phases are prepared by self-assembly from solution. In the solid-state, supramolecular polymers can be either crystalline or amorphous. 

Results obtained by Brillouin scattering range from the determination of the elastic and photoelastic constants of materials to the analysis of material transformations phase transitions, polymerization, glass transitions, pho-toinduced transformations, etc. (It is out of the scope of this presentation to present all.) We will limit our discussion to some examples selected in the field of supramolecular products defined as complexes consisting of two or more chemical entities associated through van der Waals interactions, hydrogen bonds, or charge-transfer mechanisms. " ... 

Supramolecular Chemistry The study of systems involving aggregates of molecules or ions held together by non-covalent interactions, such as electrostatic interactions, hydrogen bonding, dispersion interactions and solvophobic effects. 

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... 

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