Guest hopping

The cavities in dendrimers are not permanent, but can be redistrubuted as the branches, which can possess considerable degrees of flexibility, move about. The inclusion of guest molecules within a dendrimer may occur as a result of movements in the branches, which allow temporary inclusion of the guest molecule within the dendrimer structure. In solution, it is assumed that molecules of solvent are able to move with ease through the branches of dendrimers, hopping between such temporary cavities with little or no hindrance. When the solvent is removed, the dendrimer may collapse to a distinctly reduced volume. 

Coehoom R (2007) Hopping mobility of charge carriers in disordered organic host-guest systems dependence on the charge-carrier concentration. Phys Rev B 75 155203... 

Several studies on CD complexes with aromatic molecules using steady-state and nanosecond spectroscopy have been reported. These studies aimed to understand the photophysical and photochemical behavior of organic guests such as fluorescence and phosphorescence enhancement, excimer/exciplex formation, photocleavage, charge and proton transfer, energy hopping, and cis-trans photo-... 

This and many similar crystalUne systems have been studied quantitatively . Unfortunately, the participation at the overall process of two different elementary processes (host-to-host and host-to-guest) complicates the evaluation of these experiments. Most authors satisfy themselves with a simplified, so called hopping model , by which the excitation is supposed to jump between neighbouring host molecules, until it arrives at a guest molecule. This model neglects the coherence between successive elementary steps and is therefore, not exactly in accord with the weak-coupling properties of the host lattice. 

---