CMP(O) tripodands: synthesis, potentiometric studies and extractions

Abstract

Ligand systems containing three carbamoylmethylphosphonate (CMP) or -phosphine oxide (CMPO) moieties attached to a tripodal platform have been synthesized for metal complexation and subsequent extraction from HNO₃ solutions. The incorporation into ion selective electrodes (ISE) and picrate extractions with Na⁺, K⁺, Ag⁺, Ca²⁺, Cd²⁺, Hg²⁺, Pb²⁺, Cu²⁺, Eu³⁺ and Fe³⁺ shows that CMPO tripodand 3 is very selective for Eu³⁺ and forms a very stable complex (log β_ML = 28.3). Liquid–liquid extractions performed with Eu³⁺ and Am³⁺ show reasonable extraction properties of the CMP(O) tripodands 3, 11 and 13 in 1,1,2,2-tetrachloroethane, while in 1-octanol for all tripodands studied the distribution coefficients are low. Upon addition of the synergistic agent hexabrominated cobalt bis(dicarbollide) anion (bromo-COSAN) the distribution coefficients for Am³⁺ and Eu³⁺ extraction increase considerably for CMP(O) tripodands 3 and 4. Covalently linked COSAN only enhances the extraction of Am³⁺ and Eu³⁺ at 0.001–0.01 M HNO₃. The functionalization of dendrimer coated magnetic silica particles with CMP(O) tripodands led to very effective particles (31 and 32) for Am³⁺ and Eu³⁺ removal from 0.01 M HNO₃ solutions.