Synthesis of multidentate functional monomer for ion imprinting.

In this work, N,N,N-tri(2-carboxyethyl)-3-(2-aminoethylamino)propyl-trimethoxysilane was prepared as a multidentate functional monomer. The 3D model of the monomer coordinating with Cu2+ indicated that the monomer is able to provide five ligating atoms like ethylenediaminetetraacetic acid-Cu2+ to complex with Cu2+. When Cu2+ was used as a template ion, the synthesis conditions of Cu2+-imprinted polymers were optimized upon orthogonal design. It is interesting to find that Cu2+-imprinted polymer offers a selectivity coefficient of 192.2 when the molar ratio of Cu2+ to monomer was exactly 1:1. That means there is no excess ligating atom in the ion-imprinted polymer and therefore, the nonspecific adsorption could be avoided. Benefiting from the excellent selectivity of Cu2+-imprinted polymer, even if the concentration of Zn2+ was 25 times that of Cu2+, Cu2+-imprinted polymer still affords a high selectivity coefficient. Finally, the optimal synthesis conditions for Cu2+-imprinted polymer, except the pH, were adopted to prepare Ni2+-imprinted polymer, and Ni2+-imprinted polymer also offered satisfying selectivity to Ni2+. That implies this multidentate monomer is adaptable in ion imprinting and, the optimal synthesis conditions of Cu2+-imprinted polymer except pH are likely suitable for the imprinting of other ions besides Cu2+.