Figure 4.

(a) Interconversion between two diastereomeric ion pairs composed of a coconformationally MP chiral rotaxane dication, such as 1²⁺, and a chiral monoanion. In the proposed structures, one anion is coordinated to the unencircled triazolium, while another is weakly paired with the encircled site. Simplified potential energy curves for the location of the ring along the axle are also shown. As the two ion pairs can have different stabilities [ΔΔG° ≠ 0], the ring distribution between the two identical stations can become unbalanced. (b) Partial ¹H NMR spectra (500 MHz) of the H_Tr^uresonance in 1²⁺ after the addition of 8 equiv of the tetrabutylammonium salt of (1S)-(+)-10-camphorsulfonate (CD₂Cl₂, 223 K; left) or Δ-TRISPHAT (toluene-d₈, 243 K; right). Black, red, and gray traces show respectively the experimental spectrum, the deconvoluted peaks, and the fitting residuals.