Orthogonal Lumophore-Receptor Systems

Lumophore-receptor systems where the two components are sterically held orthogonal can be considered to have a virtual Co spacer between the lumophore and receptor. Thus these systems can be approximately considered as a PET system. A deeper analysis would take twisted intramolecular charge transfer (TICT) states [116] into account whose thermodynamics is, unsurprisingly, very similar to that of PET systems. 

On examining structure 1, we notice the steric crowding at the link between the tetracarboxylate receptor and the linearly fused tricyclic system. Thus, orthogonalization occurs at this link, making it a virtual spacer. The spatial isolation of the two ji-electron systems allows us to describe the tricyclic unit as the lumophore. The tetracarboxylate receptor also coexists as a clearly distinguishable module. 

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