Supramolecular compounds interactions

So far we have focused on Lehn s definition of a supramolecular compound as one involving non covalent interactions (Section 1.1). Such a definition is entirely appropriate to host-guest chemistry,... 

Supramolecular chemistry may be defined as "chemistry beyond the molecule." bearing on the organized entities of higher complexity that result from the association of two or more chemical species held together by intermo-lecular noncovalent forces, such as metal ion coordination, electrostatic forces, hydrogen bonding, van der Waals interactions, and others.These supramolecular entities derived from supramolecular association are generally called supermolecules or supramolecular compounds. Thus, one may say that "supramolecules are to... 

Supramolecular Compounds Designed for Host-Guest/Receptor-Substrate interactions... 

T0 summarize, it can be said that basic classification of supramolecular compounds has been developed using several criteria, of which the type of interaction and topological considerations are most important. On the other hand, a strict systematic nomenclature for any type of supramolecular compounds is lacking. Instead, a number of trivial names, notations, and semi-systematic names are presently in use. 

Carbohydrates, Recognition of, p. 169 Carbonic Anhydrase Models, p. 178 Carcerands and Hernicarcerands. p. 189 Cation-n Interactions, p. 214 Cavitands, p. 219 Chiral Guest Recognition, p. 236 Classical Descriptions of Inclusion Compounds, p. 253 Classification and Nomenclature of Supramolecular Compounds, p. 261 Clathrate Hydrates, p. 274 Conzplexation of Fullerenes, p. 302 Concepts in Ciystal Engineering, p. 319 Crown Ethers, p. 326 Cryptands, p. 334 Cryptophanes, p. 340 Cyclodextrins, p. 398... 

Vibrational spectroscopy is an important complementary tool to x-ray diffraction for stmctural characterization of materials, including supramolecular compounds. Unlike x-ray diffraction, where all the data must be collected to give the stmcture of the molecule, vibrational spectroscopy can be used to zero-in on part of the structure of interest. Furthermore, information on guest—host interactions of inclusion compounds can be readily determined from infrared (IR) and Raman spectra, whereas this information is not readily accessible from x-ray diffraction. Therefore, IR spectroscopy and more recently Raman spectroscopy are used to study the stmcture and dynamics of inclusion compounds. IR spectroscopy is also widely and routinely used to characterize supramolecular compounds containing macrocyclic molecules. The stmc-tures and dynamics of these compounds can also be studied using resonance Raman spectroscopy. 

Supramolecular compounds are formed by additive and cooperative noncovalent interactions. The noncovalent interactions include a wide range of attractive and repulsive forces. The most common noncovalent interactions, along with approximate energies, are listed in Table 1. A detailed understanding of the origins and scopes, as well... 

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. 

However, in most cases, where multiple spin systems are present and the number of spins and/or their geometrical arrangement is completely unknown is highly unlikely that reliable distances can be directly obtained from REDOR measurements. Furthermore the technique is complicated by rapid motion of the molecular structure. This is the case, for example, of the distance evaluation of the intermolecular distance between host and guest molecular components in supramolecular compounds such as p-tert-butylcalix(4)arene fluorobenzene where the NMR signal is modulated by heteronuclear dipolar interaction with the F containing guest in redox experiments. ... 

Supramolecular Compounds that are created through the interaction of multiple molecular units with bonding that can range from electrostatic to coordinate covalent. 

---