Tri-branched ligands

In an early study, the author s group synthesised the lipophilic, tri-branched ligand 15 for use in two-phase solvent extraction as well as three phase membrane transport studies [33] the parent ring system in this case has been well documented to interact with a range of first-row transition and post transition ions [34],... 

Competitive (seven-metal) solvent extraction experiments (water/chloroform) and related bulk membrane transport (water/chloroform/water) experiments have been performed in which each of the four tri-branched ligands as well as their single ring analogues were employed as the extractant/ionophore in the respective chloroform phases [37], In both sets of experiments the aqueous source phases contained an equimolar mixture of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Ag(I) and Pb(II) nitrates and were buffered at pH 4.9. For membrane transport the aqueous receiving phase was buffered at pH 3 under these conditions any transport will be driven by the back transfer of protons. Under the conditions employed, the results from the solvent extraction and the bulk membrane transport experiments clearly paralleled each other -for each ligand system high extraction/transport selectivity for Ag(I) was observed over the other six metal ions present in the respective source phases. 

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