Synthesis and characterization of novel optically active poly(amide-imide)s and poly(ester-imide)s containing calix[4]arene and amino acid units with binding ability towards alkali metal and toxic heavy metal cations

Abstract

A novel calix[4]arene derivative 2 with amino functional groups at the lower rim was first prepared via introduction of nitro functional groups and amination of the dinitro derivative of calix[4]arene. The optically active monomers were synthesized by dehydration of L-leucine (and L-isoleucine) and 3,3′,4,4′-benzophenonetetracarboxylic-3,3′,4,4′-dianhydride (3) followed by reaction with thionyl chloride to form 5a and 5b. Two methods, polymerization under microwave irradiation and solution polymerization in CH2Cl2/TEA, were then employed to carry out the condensation polymerization of 2 with the optically active monomers 5a and 5b, respectively. The polymerization conditions affected the kind of resulting polymers, poly(amide-imide)s (PAIs) 6a and 6b and poly(ester-imide)s (PEIs) 6a′ and 6b′ were obtained selectively in good yields and moderate inherent viscosities. Sorption-extraction experiments were carried out using cram picrate extraction method and verified good binding ability of the resulting calixarene-based polymers towards silver, alkali metal and toxic heavy metal cations. Also thermogravimetric analysis indicated that the resulting PAIs and PEIs were thermally stable.