Organomagnesium Crown Ethers and Their Binding Affinities with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ Ions – A Theoretical Study

Abstract

AbstractNovel organomagnesium crown ether molecules have been computationally characterized using density functional theory (DFT). Monomer units of MgC6 are used as building blocks. Isomers of MgC6H2 have been extensively explored using both DFT and coupled‐cluster methods in the past by some of us. It had been concluded that the seven‐membered ring isomer, 1‐magnesacyclohept‐4‐en‐2,6‐diyne, was the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for designing new organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline‐earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Theoretical binding energies (▵E at 0 K) and thermally corrected Gibbs free energies (▵G at 298.15 K) have been computed for these molecules with MgC6‐6‐crown‐2, MgC6‐9‐crown‐3, and MgC6‐12‐crown‐4 hosts. Higher binding affinity values obtained for Be2+ indicate that these new crown ether molecules could effectively be used for Be2+ encapsulation.