Synthesis and properties of calix[4]arene polymers containing amide groups: Exploration of their extraction properties towards dichromate and nitrite anions

The article describes the synthesis and extraction properties of three new diamide substituted calix[4] arene based polymers (3a, 4a, and 5a). The examination of their recognition abilities towards some selected oxyanions shows that the new calix[4]arene polymers are more effective receptors than their amide derivatives for dichromate anions and nitrite. It has been observed that receptor 4a is a better extractant for dichromate and nitrite anions at low pH.