Fig. 4. (a) Experimental ¹⁹F NMR chemical shift plotted as a function of temperature for 1 : 1 mixtures (2 mM) of A·D (blue), AA·DD (red), and AAA·DDD (green) in 1,1,2,2-tetrachloroethane-d₂. The fitting equation is reported in the ESI (eqn (S6.1)†) and the dashed lines are the best fit of the data (total rmsd < 0.01 ppm) the values of T_m,N, and are 289 K and −23 kJ mol⁻¹ for A·D, 354 K and −33 kJ mol⁻¹ for AA·DD, and 422 K and −34 kJ mol⁻¹ for AAA·DDD. (b) Structure of the AAA·DDD duplex.