Planarity-recognition enhancement of N-(2-pyridylmethyl)chitosan by imprinting planar metal ions

Chitosan was successfully converted into more reactive N-(2-pyridylmethyl)chitosan (PMC) via Schiff's base formation followed by its reduction. The PMC was then complexed with Ni(II) and Cu(II) to imprint their own planar geometry onto it, followed by crosslinking with 2-(chloromethyl)oxirane. The corresponding metal ions were finally stripped out by HCl and EDTA/HCl, respectively. The both imprinted PMC adsorbed to the corresponding metal ions at much lower pH than its native counterpart, the crosslinked PMC, does. In addition, it has also enhanced the planarity recognition properties of the imprinted materials as suggested by selective adsorption of Pd(II), Au(III), Cu(II) and Ni(II) away from other metal ions compared to non-imprinted PMC.