Novel Resorcinarene Cavitand-Based CMP(O) Cation Ligands: Synthesis and Extraction Properties.
Tetrafunctionalized resorcinarene cavitands (4-6) have been synthesized starting from tetrakis(bromomethyl)cavitand 3. New cavitand-based cation ligands with (carbamoylmethyl)phosphonate (CMP) and -phosphine oxide (CMPO) moieties (8a,b and 9a,b) were prepared via two different routes in good (45-86%) overall yields. The ligands (8a,b and 9b) are very effective europium extractants. Ph(2)CMPON(Pr)-cavitand 8b has the highest extraction constant, determined with radiotracer experiments, for 1:1 complexation with Eu(picrate)(3) (K(ex)(1) = 2.7 x 10(12) M(-)(4)). The steric preorganization of the four CMP(O) moieties on the resorcinarene cavitand improves the efficiency and selectivity [of Eu(III) over UO(2)(II) and Fe(III)] of the metal extraction processes, compared to simple CMP(O) extractants.
Boerrigter
Harold
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Netherlands Energy Research Foundation (ECN), P.O. Box 1, 1755 ZG Petten, The Netherlands, and the Laboratory of Supramolecular Chemistry and Technology (SMCT), University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Verboom
Willem
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Reinhoudt
David N.
DN