Metal ion shuttling mechanism through thiacalix[4]crown: a computational study

The first computational study on the alkali metal ion shuttling mechanism through thiacalix[4]biscrown-5 has been performed using density functional theory (MPWB1K/6-31G(d)//B3LYP/6-31G(d)). The activation free energy for K+ ion shuttling through the calix tube of thiacalix[4]biscrown-5 is computed to be 12.7 kcal/mol which is in good agreement with the experimental value. Throughout the shuttling process, K+ ion maintains the maximum electrostatic interactions with ether oxygens of crown rings, which contributes to lower the activation barrier of the shuttling process.