Calorimetric investigation of nano-basket's binding

Abstract

Eleven scaffolds of di-ionizable calix[4]arene conformers bearing two pendant groups of N-phenyl-sulfonyl carboxamides were synthesized and examined using isothermal titration calorimetry. The binding mechanisms of those conformers towards alkali metal cations were evaluated and two main interactions were assessed including cation-p interaction between alkali metal cation and the aromatic unit of conformer as well as the strong binding ion-dipole interaction between nitrogen atoms in the pendant groups and alkali cation. The isothermal titration calorimetry data revealed that the bindings of cone and partial-cone conformers towards alkali metal cations exhibited one-step mechanism, while both 1,2-alternate and 1,3-alternate conformers bound the alkali metal cations in a two-steps mechanism.