An approach to the synthesis of chemically modified bisazocalix[4]arenes and their extraction properties

Abstract

Bisazocalix[4]arenes [ N, N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)benzene ( 1 ), N, N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)biphenyl ( 2 ) and N, N′-bis(5-azo-25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene)-2,2′-dinitro biphenyl ( 3 )] have been synthesized from 25,26,27-tribenzoyloxy-28-hydroxycalix[4]arene by diazocoupling with the corresponding aromatic diamines ( p-phenylenediamine, 4,4′-diamino biphenyl and 4,4′-diamino-2,2′-dinitrobiphenyl). Extraction studies of bisazocalix[4]arenes 1 , 2 , and 3 show no difference in their extraction behavior and selectivity, whereas azocalix[4]arenes are a poor extractant for heavy metal cations. The absorption spectra of the prepared bisazocalix[4]arenes are discussed, both the effect of varying pH and solvent upon the absorption ability of bisazocalix[4]arenes.