A DFT study on the metal binding selectivity of 12-crown-4 and its heterocyclic analogs

In this paper, the complexes of 12-Crown-4 with Be2+ and its heterocyclic derivatives containing N, P, and S atoms were studied by the density functional theory without strict for their geometries. The metal binding selectivity of these crown ethers was evaluated using the binding energy. The effects of different heteroatoms on the binding capability were also investigated through explicit NBO and AIM analysis. To the system under consideration, the calculation results indicated that aza-12-crown-4 exhibited the highest metal binding selectivity, and phospha- or thia- analog of 12-crown-4 ether offered a weaker ligand toward the metal cations. The heterosubstitution of crown ether appeared to be crucial in the metal binding selectivity.