عنوان مقاله [English]
Separation of metal ions from nuclear waste is an important issue in nuclear industry. Cyclic chemical compounds including ether groups are called crown ethers. These compounds strongly bind to certain cations, forming complexes. Successive oxygen substitution with nitrogen leads to form new structures called azacrown. In this work, we have used quantum mechanical calculations based on density functional theory (DFT) to investigate the stability of complexes formed between various azacrowns and selective transition metals (M) ( M= Mn2+, Fe2+ and Co2+). The results showed that binding energies (ΔE) for titled transition metals are enhanced by increasing the number of replaced oxygen atoms in modified crowns structure. For example the fully substituted azacrown complexes of Mn2+, Fe2+ and Co2+ transition metals , are about 16.8, 22.4, and 37.2 kcal/mol more stable than corresponded crown ethers complexes, including nitrogen or oxygen atoms respectively. Analogous trends were found for ΔH and ΔG of complexation reactions.