Syntheses and adsorption properties of novel calixarene polymers: Calix[6]-1,4-crown-4-based netty polymers

By condensation of calix[6]arene hexaesters or calix[6]-1,4-crown-4 tetraesters with poly(ethyleneimine), a series of novel calix[6]amides-based polymers 3a-c and calix[6]-1,4- crown-4-based polymers 6a-c were prepared. The polymers 6a-c were the first examples of calix[6]arene-based polymers with stable cone conformations and regular porous netty architectures. The adsorption experiment of them showed that polymers 3a-c possessed excellent adsorption capabilities, however, little selectivities. Calix[6]-1,4-crown-4-based polymers 6a-c, on the other hand, possessed not only excellent adsorption capabilities but also good adsorption selectivities towards soft cations with small radius (Cu2+, Co2+ and Ni2+). It was concluded that the adsorption capabilities were mainly determined by the functional groups of polymers, and the adsorption selectivities were produced by the stable cone conformation in calix[6]-1,4-crown-4 units and the regular porous netty structures of polymers 6a-c.