Calorimeteric and NMR binding studies of hydrogen-bonding receptors for carboxylates

Two receptors (1 and 2) were designed and prepared to bind carboxylate anions through donor-donor hydrogen-bonding motifs provided by thiourea (1) and squaramide (2) groups. The binding efficacy of each receptor was studied using NMR and isothermal calorimetric titrations in DMSO and CH(3)CN/CHCl(3) solvent systems. Binding constants and changes in enthalpy and entropy of the binding process were calculated and evaluated. (C) 2010 Elsevier B.V. All rights reserved.