The synthesis and properties of three representatives of a new class of chemically modified silicas containing aminophosphonic acids, namely, (N-methyl-Npropylamino)methylenephosphonic, N-propylaminodi(methylenephosphonic), and N-[2-, covalently grafted on the silica surface are reported. The modified silicas were obtained by the two-step Kabachnik--Fields reaction in high yields. The concentrations of the grafted groups were determined by elemental analysis and pH-titration. The new materials were characterized by IR and 31p and J3C high resolution solid state NMR spectroscopy. The hydration of the modified silicas was found to result in a significant change in the structure of the grafted layer and to increase the mobility of the grafted groups.
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