Synthesis and Dichromate Anion Extraction Ability of Calix[4]arene Schiff Base Derivatives.

This study reports the synthesis and complexation properties of five new Schiff base derivatives of calix[4]arene (4-8), which have been synthesized from the condensation of bis(3-aminopropoxy)calix[4]arene with respective aldehyde (2-pyrrolecarbaldehyde, 2-thiophenecarboxaldehyde, furfural, l-methylpyrrol-2-carboxaldehyde, or biphenyl-4-carboxaldehyde). In this synthesis, the role of a different binding site of calix[4]arene in the extraction of dichromate anions has been observed. The complexation properties of the new Schiff base derivatives of calix[4]arene toward HCr2O7-/Cr2(>7- ions were studied by liquid-liquid extraction experiment. The results showed that the receptor 8 is more effective than other compound (4-7) for the removal of dichromate anion. The protonated Schiff base forms of the receptors were effective for transferring the HCnOy- anion from aqueous phase to a dichloromethane phase. [ABSTRACT FROM AUTHOR]