Synthesis And Characterization Of Azo-Dye (Congo Red) Intercalated Layered Doubled Hydroxides

The ranges and effects of use of many azo-dyes are greatly limited because of their low photo and thermal stabilities. Based on host-guest supramolecular intercalated structures of layered double hydroxides (LDHs), azo-dyes have been intercalated into LDHs with different host layers by the anionic exchange under hydrothermal conditions in autoclave, and the intercalated compounds perform good photo and thermal stabilities. Combining of characterization of XRD, FT-IR, TG/DTA and ICP, crystal structures and photo and thermal stabilities of intercalation precursors, guest molecules and intercalated products have been investigated respectively. We also studied the properties of the intercalated products in complex materials.LDHs precursors like ZnAl-NO₃-LDHs and MgAl-NO₃-LDHs have been synthesized by separate nucleation and aging steps, and the structures have been studied. In addition, the synthesizing conditions influencing the structure of LDHs such as aging temperature and time, have also been investigated.LDHs intercalated with Congo Red (CR) has been synthesized by the anionic exchange under hydrothermal conditions in autoclave, and the best synthesis condition is aging at 120℃and for 12h. Based on characterizations, CR-LDHs with supramolecular structures have been confirmed, and host-guest and guest-guest interactions exist in such systems. In CR-LDHs, interlayer guest anions are accommodated in a monolayer arrangements with their long axis tilted to the layers and effect with host through electrostatic force and hydrogen bond.The characterization of photo and thermal stabilities show that CR-LDHs have more thermal stability than that of CR with decomposition temperature increasing from 500℃to 521℃, and their photostability also improved. There results indicate that LDHs functioned as molecular container for CR have restricted geometry effect on interlayer guests. In addition, photo stability of inorganic-organic hybrid materials (CR-LDHs and organic materials) have been improved, indicative of their specific applications.