Intercalation of nucleotides into layered double hydroxides by ion-exchange reaction

We have investigated the intercalation behavior of nucleotides (AMP, ADP, ATP, CMP, GMP and UMP) for the NO3/Zn–Al and Mg–Al LDHs by ion-exchange reaction as well as the thermal stability of the AMP and CMP/LDHs. According to XRD and FT-IR, the solid products were found to have the layered double hydroxide (LDH) structure. The basal spacing (003) of the nucleotides/LDH was expanded to 1.38–1.67 nm, and the absorption peak of NO3− at 1385 cm−1 was decreased with increasing the amount of nucleotides intercalated, indicating that nucleotides were intercalated for the LDH. The expanding interlayer space of the nucleotide/LDH supported that nucleotides were vertically oriented to the LDH layer. The basal spacing of the AMP, ADP and ATP/LDHs was reduced with increasing number of phosphate groups, because the electrostatic force of attraction was increased between the negative nucleotides and the positive LDH layer. In the experiments for thermal stability of the AMP and CMP/LDHs, 80–90% of the intercalated nucleotide were stable at 100 °C, whereas 80–90% of the pure nucleotides were decomposed. The thermal stability of nucleotide, therefore, was improved by the intercalation for the LDH interlayer space. Furthermore, the disintegration of the LDH structure and the formation of the metal oxide and phosphate were also observed at 500 and 800 °C.