Intercalation of azo compounds into layered aluminium dihydrogentriphosphate and a layered double hydroxide

The inner surfaces of inorganic layered compounds such as aluminium dihydrogentriphosphate (ADHP) and layered double hydroxide (LDH) were modified by azo compounds. Upon intercalation of 4-phenylazoaniline and 4,4'-azodianiline into ADHP, the interlayer spacing increased from 6.4 to 21.5 Angstrom and 20.6 Angstrom, respectively. The intensity of IR peaks due to P-OH of ADHP and amino groups of guests decreased by the thermal treatment of the intercalates. The interlayer spacings also decreased to 16.9 Angstrom and 16.7 Angstrom, respectively, indicating a dehydration reaction between P-OH and amino groups. The LDH inner surface was modified by the reaction with trans- p-phenylazobenzoylchloride (PAB-Cl). Upon surface modification, the interlayer spacing increased from 7.6 Angstrom to about 27 E. The absorption of this surface-modified LDH near 410 nm increased upon irradiation with UV light and decreased upon irradation with visible light, indicating the occurrence of trans-cis isomerization of PAB-Cl between the layers.