Synthesis of p-sulfonated calix[4]arene-intercalated layered double hydroxides and their adsorption properties for organic molecules

Calixarenes are macrocyclic organo anions, which cavity is capable of molecular recognition, while layered double hydroxides (LDHs) are widely known as hydrotalcite-like compounds, anion exchangers and host–guest materials. In this study, the intercalation of water-soluble p-sulfonated calix[4]arene (CS4) in the interlayer of the Mg–Al and Zn–Al LDHs (M2+/Al ratio = 3) by the coprecipitation method has been investigated as well as the adsorption property of the resulting CS4/LDHs for benzyl alcohol (BA) and p-nitrophenol (NP). It was found that the CS4/LDHs with the molar ratio of CS4/Al = 0.25 (Mg–Al LDH) and 0.12 (Zn–Al LDH) were obtained as a single phase. The arrangement of CS4 in the LDH interlayer was different by the kind of the host metal ions as CS4 cavity axis perpendicular (Mg–Al LDH) and parallel (Zn–Al LDH) to the basal layer, influencing strongly on the BET surface area, N2 adsorbed volume and adsorption property for BA and NP.