Host pairwise interaction

Within the frame of this approach the interaction energy of two molecules is described as the sum of pairwise interactions. It is assumed that each atom of the host interacts with each atom of the guest independently ... 

Schneider has studied pairwise interactions in supramolecular chemistry in order to correlate the binding energies observed in a large number of host-... 

As we noted previously, an isolated small molecule cannot decay non-radiatively and the relaxation is therefore a sensitive function of the guest-host interaction potential. For this reason it is often instructive to compare the relaxation rates in different hosts. A particularly useful set of solvents for such comparison studies are the four rare-gas solids Ne, Ar, Kr, and Xe. While the pairwise interaction energy increases in this series from 60 cm for two Ne atoms to sa400 cm in the case of Xe, this increase is paralleled by the increase in mass, and the Debye frequency remains for all the rare gases relatively constant near 65 cm . 

Scheme 1 Schematic division of the molecular events producing selectivity from the pairwise interaction of supramolecular binding partners (the host and the various guests). Thermodynamic selectivity (left-hand side) relates to the differential concentrations at equilibrium of the molecular complexes formed whilst kinetic selectivity (right-hand side) refers to their differential rates of breakdown to produce some function.

Type I(chiral), Type II(RRSS racemic), or Type in(RS racemic) is mainly determined by the host-guest pairwise interaction. The interaction energy in a single host-guest pair is probably very small. However, it can be amplified or accumulated, in the crystal phase, to a magnitude large enough to alter the intercolumn interaction. 

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