A new bisglycolamide substituted calix[4]arene-benzo-crown-6 for the selective removal of cesium ion: combined experimental and density functional theoretical investigation

Abstract

A new bisglycolamide substituted calix-benzo-crown-6 (CBCBGA) ionophore has been synthesized and characterized by using 1 H, 13 C NMR, ESI-MS and elemental analysis. Detailed investigations on the effect of various parameters such as the aqueous phase acidity, ionophore concentration and nitrate ion concentration on extraction of cesium have been carried out. The new ionophore is found to be highly selective for Cs over other metal ions present in the simulated high level liquid waste solution. The complexing ability of this novel ionophore towards Cs + and Na + metal ions was further complimented by predicting the structure, extraction free energy and fraction of charge transfer using the B3LYP density functional employing a split-valence plus polarization (SVP) basis set in conjunction with the conductor like screening model. The unusually high selectivity of CBCBGA for Cs + ion over Na + ion was established by the calculated value of difference in the free energy, DDG (DG ext,Cs + À DG ext,Na +), À9.46 kcal mol À1 , which is in good agreement with the experimentally determined value of À5.59 kcal mol À1 . The calculated values of r and V2r at the bond critical point for the hydrated Na + ion are found to be reduced during complexation with the CBCBGA, whereas for the hydrated Cs + ion, though r remains same, the value of V2r is increased which seems to play a decisive role in the higher selectivity to Cs + ion over Na + ion of CBCBGA. The new CBCBGA ionophore shows promise for the selective removal of Cs + ion over other metal ions present in the simulated high level liquid waste solution.

Alkali Metal Ion Partitioning with Calix[4]arene-benzo-crown-6 Ionophore in Acidic Medium: Insights from Experiments, Statistical Mechanical Framework, and Molecular Dynamics Simulations

“…The results imply that CBCBGA is highly efficient for Cs + over the other metal ions. These results also indicate that the selectivity of the metal ions for CBCBGA decreases with the decreasing size of the metal ions in the following order: Cs + > Rb + > K + > Na + . , …”

“…The partitioning of cesium ion from simulated high level liquid waste solution using 1,3-dioctyloxy calix[4]­arene-benzo-crown-6 has been earlier investigated by Kumar et al The high selectivity of Cs + ion over Na + ion with bis­(2-propyloxy)­calix[4]­crown-6 has been investigated by Ali et al The use of nitrobenzene as an organic diluent for the extraction of alkali metal ions using dibenzo-18-crown-6 has been reported by Makrlík et al Michael et al reported a theoretical study on the neat water–nitrobenzene liquid–liquid interface at 300 K. Chevrot et al studied the effect of dicarbollide anions on the separation of the highly hydrophilic Eu 3+ /Cs + cations by nitrogen-based bis-triazine-pyridine ligands to an octanol solution. The selectivity of Cs + and Na + ions in chloroform–water system was also performed by Muzet et al Kumar et al reported a new calix-benzo-crown-6 (CBCBGA) ionophore, which was found to be highly selective for the removal of Cs + ion over other metal ions from the acidic waste solution.…”

Achieving highly efficient and selective cesium extraction using 1,3-di-octyloxycalix[4]arene-crown-6 in n-octanol based solvent system: experimental and DFT investigation

“…In this respect, the density functional theory (DFT) method is currently widely used 40,41 which is an appropriate level of calculation can comprehensively provide molecular level insights of the experimentally obtained results on the selective extraction processes by different ligand systems. For instance, Ali and coworkers 42 have reported an unusually high selectivity of Cs + in a calix-crown based ligand using DFT calculations. Similarly, Boda et al studied the selective binding of Cs + over Na + with a macrocyclic calix-bis-crown ether using DFT studies, whereby the calculated results correlate well with the experimental ndings.…”

Extraction Equilibrium of Typical Alkali Metals with a Macrocyclic Calixbiscrown Derivative in Two-Phase System HNO3/o-Nitroanisole and HNO3/HCCl3

“…Some separation techniques, such as ion exchange, solid-phase adsorption, solvent extraction, metal–organic frameworks, ionic liquids, and others, have been investigated. − A few technical processes, cesium separation by calix-crown extraction, fission product extraction, universal extraction, caustic side solvent extraction, and so forth, were proposed to remove cesium from acidic or alkaline medium. − Some macrocyclic derivatives of crown ethers and calix[4]­crowns were studied. They showed better supramolecular recognition for cesium through non-covalent bond interactions based on size-matching principle. − The authors developed two technical processes, SPEC and GPSC, for cesium and/or strontium removal using macroporous/mesoporous silica-based molecular materials containing two kinds of different derivatives, calix[4]­arene-R14 and 4,4′,(5′)-di­( tert -butylcyclohexano)-18-crown-6. , The removal of Cs and/or Sr was achieved by extraction chromatography. − The mechanism is different from conventional complexing agents or chelating ligands through coordination bond interactions. This provides a valuable pathway for Cs removal by application of calix[4]­crown-6 derivatives or relevant functional materials via host–guest supramolecular recognition.…”