Complexation of Triptycene-Derived Macrotricyclic Polyether with Paraquat Derivatives, Diquat, and a 2,7-Diazapyrenium Salt: Guest-Induced Conformational Changes of the Host

Complexation
between a triptycene-derived macrotricyclic polyether containing two
dibenzo-[30]-crown-10 cavities and different functionalized paraquat
derivatives, diquat, and a 2,7-diazapyrenium salt in both solution
and solid state was investigated in detail. It was found that depending
on the guests with different terminal functional groups and structures,
the macrotricyclic polyether could form 1:1 or 1:2 complexes with
the guests in different complexation modes in solution and also in
the solid state. Especially, the conformation of the macrotricyclic
polyether was efficiently adjusted by the encapsulated guests, which
was to some extent similar to substrate-induced fit of enzymes. Moreover,
the binding and releasing of the guests in the complexes could be
controlled by potassium ions.