title: Probing the selective separation of potassium ion from sodium ion with cyclopentadienyl anion as receptor: a computational study.
abstract: A systematic computational study has been carried out using post-Hartree-Fock and density functional theory methods on half sandwich (M-Cp), sandwich (Cp-M-Cp), inversed sandwich (M-Cp-M), and multi-decker chain complexes of alkali metal ions (Na(+), and K(+)). The binding affinity of cyclopentadienyl anion (Cp) with K(+) and Na(+) ions has been studied in half sandwich, sandwich, inversed sandwich, and multi-decker chain complexes. These complexes have been examined in the aqueous phase. The calculated results show that Cp anion can preferentially bind with Na(+) ion over K(+) ion in aqueous phase. The results obtained from DFT calculations have been compared with the crystal structures of Cp-Na and Cp-K complexes. The Bader's atoms in molecule (AIM) analysis were performed to characterize the non-covalent cation-π interactions in the Cp-M complexes. The calculated electron density at cage critical point indicates the strength of the Cp-M complexes. Energy decomposition analysis (EDA) has also been performed to investigate the origins of these interactions. The electrostatic interaction contributes significantly to the total interaction energy in Cp-M complexes. The relative stability difference of cyclopentadienyl anion (Cp) with K(+) and Na(+) ions in aqueous phase can be exploited for the separations from mixture such as sea bittern. The lower stability of K-Cp complex can induce to precipitate the K(+) ions more easily than the corresponding Na(+) ions. Graphical Abstract Potassium ion from sodium ion with cyclopentadienyl anion as receptor.
authors.affiliation: Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility), CSIR-Central Salt & Marine Chemicals Research Institute, Bhavnagar, Gujarat, India, 364 002.
authors.forename: Mittal L
authors.initials: ML
authors.lastname: Desai
authors.forename: Mrinal Kanti
authors.initials: MK
authors.lastname: Si
authors.forename: Rabindranath
authors.initials: R
authors.lastname: Lo
authors.forename: Bishwajit
authors.initials: B
authors.lastname: Ganguly
mesh_terms: D000838:Anions; D003198:Computer Simulation; D003517:Cyclopentanes / Q000737:chemistry*; D008958:Models, Molecular; D011188:Potassium / Q000737:chemistry*; D012964:Sodium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000838:Anions; D003517:Cyclopentanes; D014867:Water; D012964:Sodium; D011188:Potassium