Table 2. Association constant values (M–1), free energies of complexation (ΔG, kcal mol–1) and values for the enthalpic (ΔH, kcal mol–1) and entropic components (TΔS, kcal mol–1, 298 K) for the complexes formed between [2]rotaxane 5 and the different ammonium salts 3a–d determined in chloroform solution using ITC experiments.
| K a × 10–5 | ΔG | ΔH | TΔS | |
| 3a | 7.9 ± 0.2 | –8.0 ± 0.02 | –11.7 ± 1.7 | –3.7 ± 1.7 |
| 3b | 0.4 ± 0.1 | –6.3 ± 0.1 | –10.7 ± 2.1 | –4.4 ± 2.1 |
| 3c | 0.5 ± 0.2 | –6.4 ± 0.2 | –6.3 ± 0.4 | 0.1 ± 0.4 |
| 3d | 158 ± 16 | –9.8 ± 0.06 | –9.6 ± 0.3 | 0.2 ± 0.3 |