Three Anionic Indium–Organic Frameworks for Highly Efficient and Selective Dye Adsorption, Lanthanide Adsorption, and Luminescence Regulation

Through solvothermal reaction of InCl3 and tetracarboxylate ligands with different substituent groups on diphenyl ethers, three new anionic indium–organic frameworks have been successfully prepared. They are {[(CH3)2NH2]­In­(G-1)­(H2O)}·9DMF (1), {[(CH3)2NH2]­In­(G-2)}·15DMF (2), and {[(CH3)2NH2]2In2(G-3)2}·16DMF (3) {DMF = N,N′-dimethylformamide; H4(G-1) = 5′,5″″-oxybis­(2′-methoxy­[1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic acid); H4(G-2) = 5′,5″″-oxybis­(2′-amino­[1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic acid); H4(G-3) = 5′,5″″-oxybis­([1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic acid)}. Compounds 1–3 can be simplified as unimodal 4-connected frameworks with different topological types: lon, cag, and dia, respectively. Compounds 1 and 3 display 2-fold interpenetrating nets, while compound 2 is non-interpenetrating. Compounds 1 and 3 can adsorb cationic methylene blue (MB) with good capacity and a high adsorption rate due to their anionic frameworks and channel-type voids. In particular, compound 1 exhibits great selectivity for cationic MB in the mixtures of MB and methyl orange. In addition, the adsorption behavior of rare earth ions (Eu3+ and Tb3+) on compounds 1 and 3 has also been studied. Due to the different structural features and channel sizes of compounds 1 and 3 caused by different substituents on the ligands, the adsorption properties of rare earth ions on the two compounds are different.