| Abstract
| - The conformational interconversions of four [2]catenanes (1−4) containing a dibenzo-34-crown-10 ether(BPP34C10) interlocked with rings containing two 4,4‘-dipyridiniums tethered by 1,3-bis(ethyloxy)phenyl and bis(p-benzyl)methyl spacers have been studied by VT 1H NMR spectroscopy. Symmetricallyplaced blocking groups on thickened tethers enabled either pathway for circumrotation of the BPP34C10between isoenergetic sites to be blocked. On the basis of chemical shifts of the BPP34C10, its internalp-hydroquinone forms π−π-stacking interactions with only one 4,4‘-dipyridinium ring at a time. Theactivation barrier for migration along either open tether was approximately 11.5 kcal/mol. This studydemonstrates an ability to select the pathway for conformational interconversions in these [2]catenanescontaining the rigid bis(p-benzyl)methyl tether and the lowering the barrier for interconversion throughdestabilization of the ground state structures.
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