N-methylene phosphonic chitosan: A novel soluble derivative

A novel water-soluble chitosan derivative carrying phosphonic groups was synthesized using a one-step reaction that allowed homogeneous modifications without any sharp decrease in its properties, such as filmogenic capacity (this compound and its synthesis have been protected with a patent). The H-1 NMR, C-13 NMR assignments and H-1-C-13 NMR correlation permitted the identification of the structure by the subtituent distribution of the product, which is partly N-monophosphonomethylated (0.24) and N,N-diphosphonomethylated (0.14) and N-acetylated (0.16) without modification of the initial degree of acetylation. The identity of the N-methylene phosphonic chitosan was confirmed by FT-IR spectrometry, X-ray diffraction and elemental analysis. Taking advantage of the known chelating ability of the phosphonic groups, especially for calcium, this new derivative opens new perspectives as biomedical material. (C) 2000 Elsevier Science Ltd. All rights reserved.