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

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 (logML = 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.