Synthesis and characterization of azocalix[4]arene ester and ketone derivatives incorporated in a polymeric backbone with bisphenol-A and their cation-binding properties

This study comprises synthesis and characterization of azocalix[4]arene compounds having copolymeric structures. The novel bisazocalixphenol-A and copolymer containing pendant azocalix[4]arene units with ester (5) and ketone (6) functionalities at their lower rim have been synthesized via diazo-coupling reaction. The phase transfer study is performed by liquid–liquid extraction method. It has been deduced from the observations that their precursors 25,26,27-tribenzoyloxy-28-hydroxy-5-(4-aminophenylazo)calix[4] arene (3), 25,27-diacetoniloxy-26,28-dihydroxy-5,17-(4-aminophenylazo)calix[4]arene (4) and bisazocalixphenol-A (5) show a good phase transfer affinity towards selected transition metal cations, unlike copolymer (6). These compounds are studied by the selective extraction of Fe3+ cation from the aqueous phase into the organic phase and it is carried out using compounds 1–6. It is observed that the reduced azocalix[4]arene 4 is the most efficient (82.93 %) carrier of all compounds (3–6) in the extraction of Fe3+ at pH 5.4.