Inorganic-Organic Framework Constructed by the Intercalation of a Double-Decker Porphyrin Metal Complex into Clay Nanosheets and Its Efficient Dye Adsorption Ability

An inorganic-organic framework composed of layered clay nanosheets bridged by pillar-shaped metal complexes was synthesized via the insertion of a heptacationic pillar-shaped double-decker-type gadolinium porphyrin complex with long alkyl side chains into montmorillonite through a cation exchange reaction. The double-decker-type gadolinium porphyrin complex was distributed homogeneously in the montmorillonite, and the interlayer distance of the montmorillonite was significantly expanded after the interaction. The obtained inorganic-organic framework efficiently adsorbed anionic organic dyes in an aqueous solution, whereas pristine montmorillonite hardly adsorbed these dyes. We found that the dye absorption rate of the obtained inorganic-organic framework was much faster than that of montmorillonites modified with long-chain alkylammonium or pyridinium ions. Therefore, this inorganic-organic framework possesses unique internanosheet gaps that can be utilized for molecular recognition.