The rare earth elements (REE), composed primarily of the fifteen lanthanides, find broad application in many modern devices making these elements indispensable and important to the sustainable, green world approach prevalent these days. Liquid-liquid extraction for the separation of lanthanides using a calix[4]arene scaffold with coordinating ligands on its lower rim has been studied for many years. In the present work, we discuss the synthesis and characterization of new chlorine and amine terminated 2-alkyl-p-tert-butylcalix[4]arenes with phosphine oxide, ketone, ester, and CMPO based coordinating ligands incorporated on the lower rim. These new moieties will act as useful precursors for the synthesis of functionalized stationary phases. Novel heterogeneous materials will be prepared by immobilizing the 2-functionalized amine terminated calix[4]arene derivatives on the surface of a solid support like silica and will find application in chromatographic separation of REE from a wide range of electronic wastes or slurries, subsequently helping to isolate these metals in high purity. Before immobilization onto a solid support, we have investigated the extraction efficiencies of these new calix[4]arenes for rare earth metals in liquid-liquid extraction in order to confirm that functionalization at the 2-position of the calix[4]arenes does not interfere with the extraction properties of the coordinating ligands on the lower rim.

New calix[4]arene based precursors for stationary phases useful in separation of rare earth metals

249th National Meeting (2015)

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