Extraction and complexing abilities of a series of p-tert-butylcalix[4]arenes substituted by N-carbonylmonoaza-12-crown-4

The present study is a continuation of our work on the complexing properties of supramolecular architectures based on calixarenes and crown ethers. This work discloses the complexing and extraction abilities of calix[4]arene derivatives depending upon the size of the intramolecular cavity formed by different numbers of identical crown ether substituents. The extraction and complexing properties of a series of p-tert-butylcalix[4]arene derivatives containing N-methoxycarbonylmonoaza-12-crown-4 as substituents were evaluated through liquid-liquid extraction and spectrophotometric titration methods. It has been demonstrated that monosubstituted calixarene is an effective and highly selective extractant towards sodium cations. Calixarene´s derivative comprising two crown ether substituents tend to interact with alkali metal cations with formation of 1:1 complexes. On the contrary, cesium cation forms with the disubstituted calixarene a biligand mononuclear complex. The tetrasubstituted analog is an effective but not selective extractant for both s-element cations and cadmium and iron cations in the d-element series. Both tri- and tetrasubstituted calixarenes form mononuclear complexes with sodium cations in the alkali metal series and calcium ions in the alkaline earth metal series with lgK>5. At the same time, these macrocycles form the complexes of 1:1 and 1:2 compositions (ligand-cation) with barium and strontium cations. The ability of calix[4]arene with four crown ether substituents to form binuclear complexes with cations of transition metals - copper, nickel, cobalt and cadmium - has also been demonstrated.