For clarity, errors are not shown in the table. The error in free energy measurements is in the range ± 0.1-0.2 kcal mol- 1, the error in kf2M is ± 10%, the error in Φ2M < 0.1. Note that Φ-values cannot be considered reliable if the ΔΔGD-N is low27, so Φ-values were not determined where ΔΔGD-N < 0.6 kcal mol- 1 (n.d).