PHOTOCONTROLLED CHIRAL RECOGNITION BY [4-(PHENYLAZO)PHENYL] CARBAMOYLATED CELLULOSE AND AMYLOSE MEMBRANES

Cellulose and amylose derivatives bearing a photoresponsive [4-(phenylazo)phenyl]carbamate residue incorporated at the 2,3,6-, 6-, or a,3-positions of the glucose units were prepared. Enantioselective adsorption of several neutral racemates on the solid derivative membranes was investigated during the course of trans-cis isomerization of the pendant azobenzene residues. The chiral recognition ability was influenced by the trans or cis content, and the trans isomers of the polysaccharide derivatives showed higher enantioselectivity than the cis isomers. The difference in chiral recognition of these polymers was discussed on the basis of CD and H-1 NMR spectroscopic data and a molecular modeling study. In addition to the enantioselectivity, the solubility of the polysaccharide derivatives was also controlled reversibly by photoisomerization of the pendant azobenzene moieties.