Clean and efficient syntheses of calix[4]arene modified polymer supports

Abstract

The syntheses of two polymer supported calix[4]arenes 8 and 9, using TentaGel S NH₂ and aminomethyl polystyrene, have been significantly improved by the replacement of thionyl chloride and excessive amounts of solvents with carbodiimide coupling reagents. The new, environmentally friendly route reduces the number of synthetic steps from five to three and achieves a high loading of calix[4]arene, as shown by attenuated total reflectance infrared spectroscopy (ATR-IR), NMR and solid-state NMR. Furthermore, the extraction efficiencies of uranium and cadmium by these polymer supported calix[4]arenes demonstrate an additional green aspect to the work.