The ion selectivity of the Goedken-Peng cryptand: prediction of ion selectivity by quantum chemical calculations XVII

Abstract

The cryptand developed by Virgil L. Goedken and Shie-Ming Peng, along with its interactions with alkaline and alkaline earth metal ions, was investigated using computational chemistry (B3LYP/LANL2DZp) to gain insight into the influence of the flexibility of the chelating N-C-C-N group on overall selectivity towards metal ions. According to DFT calculations, the most suitable cation for the cryptand is Li+, as Na+ is too large and would prefer a longer bond between Na+ and the N-donor. Additionally, the Be2+-N bond in the Goedken-Peng cryptand is excessively long compared to the Mg2+-N-cryptate bond, which is too short. The most effective method for hosting the guest cations is for the cryptand to twist itself, and the flexibility of the chelating N-C-C-N group serves as the most effective structural motive for the Goedken-Peng cryptand to interact with the guest cation.