Arylene-bridged bis(benzoaza-15-crown-5) synthesis and selective binding to alkali/heavy metal ions

Three new bis(benzoaza-15-crown-5) derivatives, i.e., N,N'-m-phenylene-dimethyl-bis(benzoaza-5-crown-5) (1), N,N'-isophthaloyl-bis(benzoaza-15-crown-5) (2) and N,N'-terephthaloyl-bis(benzoaza-15-crown-5) (3), have been synthesized by reaction of 11,12-benzo-1,7,10,13-tetraoxa-4-aza-cyclopentadec-11-ene (benzoaza-15-crown-5) with alpha,alpha'-dibromo-m-xylene, isophthaloyl chloride and terephthaloyl chloride, respectively, and an X-ray crystallographic structure was obtained for 3. Their cation binding behavior to alkali and heavy metal ions was evaluated by solvent extraction of aqueous metal picrates. The result obtained indicates that 2 displays high selectivity to Na+ and Ti+, while 1 shows high extractability and selectivity to Ag+.