Effect of the species and number of heteroatom on the interaction energy and charge transfer between crown ether and alkali metal ions

Abstract

Crown ether can bind the alkali metal ions, and the binding is related to numerous factors. In present work, we investigated the effect of the species and number of heteroatom on the interaction energy and charge transfer between crown ether and alkali metal ions in the three complexes (12C4O-Li+, 15C5O-Na+ and 18C6O-K+) using density functional method. Our results show that the N- or S-substitution is more favorable to the enhancement of charge transfer between the alkali metal ions and crown ethers than P-substitution; furthermore, the interaction energy of N- or S-substitution is also higher than that of P-substitution. The 12C4O has strongest affinity for Li+ in the three complexes from the perspective of the variation of the species and the number of heteroatom. Thus, take 12C4O for example, it is concluded that the number of N-substitution has slight influence on the interaction energy; however, as the number of P- or S-substitutions increases, the interaction energy values decrease sharply.