Fig. 2. (a) Partial ¹H-NMR spectra of 1 titrated with Cl⁻ salt. The top spectrum of 1 is assigned (see inset figure for labels) and the red lines are added as a guide to the eye. For larger scale graphic see Fig. S1 (ESI†); (b) partial ¹H-NMR spectra of 1 titrated with NO₃⁻ salt. The top spectrum of 1 is assigned (see inset figure for labels and Fig. S6, ESI† for larger scale graphic); (c) HypNMR fit of peak shifting involving the indicated signals of 1 during the titration with nitrate salt. Speciation is also giving as coloured lines. Fitting to all 168 data point gave r² = 0.9976 and K_a^2 : 1 = 36 M⁻¹; K_a^1 : 2 = 91.960 M⁻¹ and K_a^1 : 2 = 2.484 M⁻¹. Solvent = in CD₂Cl₂ with 5% DMSO-d₆ (^v/_v).