Adsorption of amino acid derivatives on calixarene carboxylic acid impregnated resins

Macrocyclic host molecules calixarene carboxylic acid derivatives are found to act as powerful extractants for biologically important amino compounds. A series of adsorbents were prepared from a methacrylate-based polymer Amberlite XAD-7 by impregnation with various calixarene derivatives, for adsorptive recovery of amino acid derivatives. The larger macrocycles calix6]arene and calix8]arene carboxylic acid derivatives were more effective for adsorption of amino acid derivatives on the impregnated resin than the calix4]arene derivative. Since adsorption proceeds mainly via electrostatic interaction, the carboxylic acid groups introduced into the calixarene platform were important for adsorption of cationic amino acid derivatives. The adsorption selectivity for amino compounds using adsorbent impregnated with the calix6]arene carboxylic acid derivative depends simply on the hydrophobicity of the adsorbates.