Association constants (K, [M−1]) expressed as log K, effective molarities (EM), limiting NMR chemical shifts (δfree and δbound) and limiting complexation-induced changes in chemical shift (Δδ) measured by NMR titrations in chloroform-d at 298 Ka.
| Complex | log K (M−1) | K fold | EMf (mM) | X fold | 19F NMRb (ppm) | 1H NMRb (ppm) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 19F (1) | 19F (2) | 1H (1) | |||||||||||
| δ free | δ bound | Δδ | δ free | δ bound | Δδ | δ free | δ bound | Δδ | |||||
| DA·DA | 3.3 ± 0.1 | 0.0 | 0.0 | 0.0 | −60.6 | −62.0 | −1.4 | — | — | — | 5.0 | 10.3 | 5.3 |
| DAA·DAAc | 3.8 ± 0.1 | 0.0 | 0.0 | 0.0 | −60.7 | −62.1 | −1.4 | — | — | — | — | — | — |
| DDA·DDAc | 3.4 ± 0.1 | 1.1 | 0.2 | 0.5 | −60.7 | −61.9 | −1.2 | −60.9 | −61.5 | −0.6 | — | — | — |
| ADD·ADDc | 2.6 ± 0.1 | 3.9 | 0.6 | 0.9 | −60.7 | −61.9 | −1.2 | −62.0 | −61.9 | 0.1 | — | — | — |
a
Each titration was repeated twice, and the average value is reported with errors at the 95% confidence limit.
b
Data for the signals due to the OH and CF3 groups on the phenol recognition units.
c
Signals due to the OH protons were too broad to be detected.