Thiacalix[4]amido-based Netty Polymers: Novel Sorbents for Heavy Metal Cations and Derivatives of Aniline

By reacting p-tert-butylthiacalix[4]arene with ethyl chloroacetate using KI as catalyst in K2CO3/acetone, 5,11,17,23-tert-butyl-25,26,27-tri-ethoxy-2-acetylthiacalix[4]arene and 5,11,17,23-tert-butyl-25,26,27,28-tetra-ethoxy-2-acetylthiacalix[4]arene were prepared in moderate yields. Their further reactions with bi-(ethyleneimine) or tri-(ethyleneimine) produced the first examples of four tri-bridged and tetra-bridged thiacalix[4]amido-based polymers with porous and netty architectures in yields of 81%, 84%, 86%, 89%, respectively. The structures of these polymers were confirmed by FTIR, elemental analysis, H-1 NMR, and SEM, etc. The M-n of these novel polymers were 18000 similar to 22000 which indicated that approximately 17 similar to 20 thiacalix[4] arene units are present in each polymer molecule. The adsorption experiments of these novel polymers showed excellent adsorption abilities for soft metal cations Ag+, Hg2+, Cu2+, Co2+, Ni2+, Cd2+, and Zn2+, but low adsorption towards hard metal cations Na+ and K+. Also, these novel polymers exhibited outstanding adsorption capacity for a series of aniline derivatives. The highest adsorption percentages were 93.4% and 94.2% for Cu2+ and p-nitroaniline, respectively. The saturation adsorption capacities of thiacalix[4]amido-based polymer with tri-(ethyleneimine) for Cu2+ and p-nitroaniline were as high as 1.51 mmol/g and 1.34 mmol/g, respectively. The adsorption percentages of novel polymers reduced sharply in pH < 4, but they can be recycled by desorption in 10% ammonia solution.