The syntheses of phenol-containing diazamacrocycles and liquid membrane transports of alkali cations

Two new bisphenol-containing diazacrown ether derivatives, 7,16-bis(2-hydroxy-5-ethylbenzoatebenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (1) and 7,16-bis(2-hydroxy-3,4-dimethylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (2), have been synthesized via one-pot Mannich reaction. The compound 1 is structurally characterized. The liquid membrane transports of alkali metal cations using these two new diazamacrocycles and the other previously prepared diazamacrocyclic derivative 7,16-bis(3-hydroxy-6-methyl-2-pyridylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (3) as ion-carriers are also studied. The results show that the rates of cation transports are closely related to the number of nitrogen donors and the steric effect of the substituted groups. Compared with other macrocyclic compounds, compound 1 shows a good selectivity for Li⁺, therefore providing a new efficient carrier for Li⁺ extraction.