Fundamental studies regarding synergism between calix[4]arene-bis(tert-octylbenzo-crown-6) and alcohol modifiers in the solvent extraction of cesium nitrate

This work emphasizes the crucial role of polar solvating molecules known as phase modifiers in solvent-extraction systems. The focus of these studies was the extraction of cesium by calix[4]arene-bis(tert-octylbenzo-crown-6) in dodecane modified with various lipophilic alcohols. Results of equilibrium modeling are consistent with aggregation of the alcohol molecules with each other and with the calixarene-cesium nitrate complexes. These modeling results are supported by electrospray mass spectrometry experiments, clearly showing the alcohol:anion adducts containing several alcohol molecules. They are also supported by crystallographic evidence showing the existence of a hexameric aggregate in the solid state for a derivative of one of the alcohol modifiers used for solvent extraction, in agreement with the species giving the best modeling results.