Recognition and Extraction of Cesium Hydroxide and Carbonate by Using a Neutral Multitopic Ion‐Pair Receptor

Abstract Current approaches to lowering the pH of basic media rely on the addition of a proton source. An alternative approach is described herein that involves the liquid–liquid extraction‐based removal of cesium salts, specifically CsOH and Cs 2 CO 3 , from highly basic media. A multitopic ion‐pair receptor ( 2 ) is used that can recognize and extract the hydroxide and carbonate anions as their cesium salts, as confirmed by 1 H NMR spectroscopic titrations, ICP‐MS, single‐crystal structural analyses, and theoretical calculations. A sharp increase in the pH and cesium concentrations in the receiving phase is observed when receptor 2 is employed as a carrier in U‐tube experiments involving the transport of CsOH through an intervening chloroform layer. The pH of the source phase likewise decreases.