beta -Cyclodextrin (beta -CD) was coupled to chitosan by the intermediate of its monochlorotriazinyl derivative, called beta W7MCT, so that a chitosan derivative bearing cyclodextrin was obtained. Because the average degree of substitution of the cyclodextrin derivative was 2.8, the reaction yielded crosslinked insoluble products. The structure of these materials has been investigated by high-resolution magic-angle spinning (HRMAS) with gradients. For the first time, HRMAS spectra of chitosan polymers containing beta -CD were obtained. This NMR technique produced one- and two-dimensional well-resolved solid-state spectra. These data confirm the proposed structure. Decontamination of waters containing textile dyes were carried out with the crosslinked derivatives. These tests showed that the new chitosan derivatives are characterized by a rate of sorption and a global efficiency superior to that of the parent chitosan polymer and of the well-known cyclodextrin-epichlorohydrin gels. (C) 2000 John Wiley & Sons, Inc.