Binding of cyclic carboxylates to octa-acid deep-cavity cavitand.
As part of the fourth statistical assessment of modeling of proteins and ligands (sampl.eyesopen.com) prediction challenge, the strength of association of nine guests (1-9) binding to octa-acid host was determined by a combination of (1)H NMR and isothermal titration calorimetry. Association constants in sodium tetraborate buffered (pH 9.2) aqueous solution ranged from 5.39 × 10(2) M(-1) in the case of benzoate 1, up to 3.82 × 10(5) M(-1) for trans-4-methylcyclohexanoate 7. Overall, the free energy difference between the free energies of complexation of these weakest and strongest binding guests was ΔΔG° = 3.88 kcal mol(-1). Based on a multitude of previous studies, the anticipated order of strength of binding was close to that which was actually obtained. However, the binding of guest 3 (4-ethylbenzoate) was considerably stronger than initially estimated.
Department of Chemistry, Tulane University, New Orleans, LA, 70118, USA.
Corinne L D
CL
Gibb
Bruce C
BC
Gibb
D001565:Benzoates / Q000737:chemistry; D001665:Binding Sites; D002264:Carboxylic Acids / Q000737:chemistry*; D003500:Cyclization; D004988:Ethers, Cyclic / Q000737:chemistry*; D008958:Models, Molecular; D012118:Resorcinols / Q000737:chemistry*; D013816:Thermodynamics
D001565:Benzoates; D002264:Carboxylic Acids; D004988:Ethers, Cyclic; D012118:Resorcinols; C442939:cavitand; C051230:4-ethylbenzoic acid