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a b s t r a c tLight is a non-invasive stimulus or probe, which retains more and more attention in science and technology. In the present review the reader is informed about the important issue of the interactions of polysaccharides and light. Considering some aspects of polysaccharide structure and properties, topics such as absorption and fluorescence of polysaccharides, the structural analysis using light as a probe, and creation of new materials by combining chromophores and polysaccharides are discussed. Attention is also be given to polysaccharide derivatives, where absorption of light induces structural changes, including photocrosslinking and photochromism.

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Photoactive derivatives of cellulose were prepared by a mild esterification of the biopolymer with 2-[(4-methyl-2-oxo-2H-chromen-7-yl)oxy]acetic acid via the activation of the carboxylic acid with N,N 0 -carbonyldiimidazole. Subsequently, modification with the cationic carboxylic acid (3-carboxypropyl)trimethylammonium chloride was carried out. Thus, water soluble polyelectrolytes decorated with high amounts of photochemically active chromene moieties were obtained. The structures of the novel polysaccharide esters and the polyelectrolytes were evaluated by means of NMR and IR spectroscopy. Moreover, the light triggered photodimerization of the chromene moieties of the photoactive polyelectrolytes was studied by means of UV-Vis spectroscopy in the dissolved state. The photochemistry observed may be used to control the properties of the new polysaccharide derivatives and are thus of interest in the design of smart materials.

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