Shuhei Koike et al. “Single-shot NMR determination of multiple binding constants in diastereomer-resolved host–guest systems.” ChemRxiv (). https://doi.org/10.26434/chemrxiv.15002238/v2

rac-1/rac-2a–c host–guest systems
¹H NMR, rac-1/rac-2a (500 MHz, CDCl₃/CD₃CN = 9/1 (v/v), 24.3 °C, 4 mM each) All host species δ = 0.82 ppm; complex 1 (C1) δ = −1.47 ppm; complex 2 (C2) δ = −1.40 ppm
¹H NMR integrated peak areas, rac-1/rac-2a C1 1.26; C2 2.22; all-host-species peak area set to 24
¹H NMR signal assignments, rac-1/rac-2a The signal at δ = −1.47 ppm was tentatively assigned to C1 and the signal at δ = −1.40 ppm to C2; these assignments were not experimentally confirmed
¹H NMR internal-standard signal, rac-1/rac-2a The resonance at δ = 0.82 ppm was assigned to the terminal alkyl methyl group of the host capsule; its chemical shift remained unchanged upon complex formation
Concentration-based binding constants from integrated ¹H NMR peak areas and mass-balance relations, rac-1/rac-2a C1 binding constant = 5.96 × 10² M⁻¹; C2 binding constant = 1.05 × 10³ M⁻¹
Concentration-dependence series, rac-1/rac-2a (rac-1 4 mM; rac-2a 1, 2, 4, 6, and 8 mM) Average C1 binding constant = (5.88 ± 0.10) × 10² M⁻¹; average C2 binding constant = (1.06 ± 0.02) × 10³ M⁻¹; no systematic concentration dependence was observed over the range examined
Variable-temperature ¹H NMR, rac-1/rac-2a (−10, 0, 10, 20, 24.3, 30, and 40 °C) Integration of both the C1 and C2 signals at approximately δ = −1.5 ppm and δ = −1.4 ppm, respectively, decreased as the temperature rose
Van’t Hoff linear-regression R², rac-1/rac-2a C1 R² = 0.998; C2 R² = 0.996
Apparent thermodynamic parameters, rac-1/rac-2a ΔH C1 −8.71 ± 0.16 kJ mol⁻¹; ΔH C2 −10.17 ± 0.30 kJ mol⁻¹; ΔS C1 23.92 ± 0.57 J mol⁻¹ K⁻¹; ΔS C2 23.75 ± 1.03 J mol⁻¹ K⁻¹; ΔΔH −1.5 ± 0.3 kJ mol⁻¹; ΔΔS −0.2 ± 1.2 J mol⁻¹ K⁻¹
Van’t Hoff linear-regression R², rac-1/rac-2b C1 R² = 0.991; C2 R² = 0.995
Apparent thermodynamic parameters, rac-1/rac-2b ΔH C1 −11.33 ± 0.49 kJ mol⁻¹; ΔH C2 −14.75 ± 0.49 kJ mol⁻¹; ΔS C1 13.38 ± 1.68 J mol⁻¹ K⁻¹; ΔS C2 13.26 ± 1.70 J mol⁻¹ K⁻¹; ΔΔH −3.4 ± 0.7 kJ mol⁻¹; ΔΔS −0.1 ± 2.3 J mol⁻¹ K⁻¹
Van’t Hoff linear-regression R², rac-1/rac-2c C1 R² = 0.992; C2 R² = 0.990
Apparent thermodynamic parameters, rac-1/rac-2c ΔH C1 −6.00 ± 0.24 kJ mol⁻¹; ΔH C2 −7.25 ± 0.33 kJ mol⁻¹; ΔS C1 30.35 ± 0.84 J mol⁻¹ K⁻¹; ΔS C2 30.31 ± 1.13 J mol⁻¹ K⁻¹; ΔΔH −1.3 ± 0.4 kJ mol⁻¹; ΔΔS 0.0 ± 1.4 J mol⁻¹ K⁻¹
Binding-constant and thermodynamic-parameter reporting qualifier The reported binding constants are concentration-based values obtained under the specified solvent, temperature, and concentration conditions rather than activity-based thermodynamic equilibrium constants; the apparent thermodynamic parameters are best used to compare related complexes measured under identical conditions rather than as activity-corrected absolute thermodynamic quantities