1. Complexation-Induced Shifts (Δδ = δfree –δcomplexed) for the Interactions between R a‑e H2·4TFA and 4 in Aqueous Media, Association Constant Values, and Stoichiometry Derived from the Corresponding NMR Titration Experiments .
| Δδ 1H macrocycle (ppm) |
Δδ 1H 4 (ppm) |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| macrocycle | Hg | Hf | Ha/j | Ha′/j′ | Ha″/j″ | H2 | H3 | H4 | K a | G⊂H stoichiometry |
| R a H2·4Cl | –0.70 | –0.91 | 0.16/0.17 | –1.26 | –1.99 | –1.24 | (1.61 ± 0.14) × 104 M–1 | 1:1 | ||
| R b H2·4TFA | –0.56 | –0.94 | 0.20/0.25 | 0.14/0.15 | 0.65/0.64 | –0.75 | –1.61 | –1.61 | (1.54 ± 0.11) × 104 M–1 | 1:1 |
| R c H2·4TFA | na | |||||||||
| R d H2·4TFA | –0.61 | –0.78 | 0.23/0.27 | 0.27/0.32 | 0.18/0.23 | –1.14 | –1.17 | –0.98 | (1.63 ± 0.22) × 103 M–1 | 2:1 |
| (4.93 ± 0.87) × 103 M–1 | ||||||||||
| R e H2·4TFA | –0.69 | –0.61 | 0.21/0.23 | 0.24/0.27 | –1.73 | –1.71 | –1.30 | (6.52 ± 0.80) × 103 M–1 | 2:1 | |
| (6.50 ± 1.50) × 103 M–1 | ||||||||||
a
Bold values for 4 indicate the hydrogens that establish C–H···π interactions.
b
Previously reported (ref ).
c
No association observed.
d
Value of the stepwise association constant K 1.
e
K 2.