Activity, guest binding

As Figure 3 illustrates, redox active guests introduce PET processes almost by definition and luminescent on-off switching is the norm. However, the inhibitions outlined in Section 5 have not prevented the designers of switchable luminescent devices from exploring systems which bind redox active guests. The combined forces of inorganic coordination chemistry and supramolecular science have proved to be too attractive in many of these instances. It is to be hoped that some of this effort will filter across to the examination of more on-off systems like 17 and 18. 

Juxtaposition of hydroxyl groups, which may take an active part in catalysis, and a hydrophobic cavity for guest-binding. 

As is well known, enzymes also show high substrate specificity. Each of them exclusively chooses a certain substrate (specific substrate) and transforms it into a predetermined product. All other compounds in the system (even if they resemble the specific substrate) are kept intact. Another enzyme takes another specific substrate and executes a different mission. This substrate specificity primarily comes from selective guest binding by substrate-binding sites of enzymes. Furthermore, only the specific substrate is efficiently transformed into the desired products, since the catalytically active amino acid residues of enzymes, located near the substrate-binding sites, are arranged suitably only for this transformation. 

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