Ln-MOFs with window-shaped channels based on triazine tricarboxylic acid as a linker for the highly efficient capture of cationic dyes and iodine

Exploring the adsorption of small molecules, such as dyes and iodine, by using novel functionalized MOFs has aroused widespread interest. In this work, seven isostructural compounds were synthesized successfully under solvothermal condition, namely [Ln(2)(TATAB)(2)]center dot xDMF center dot yH(2)O (1-7; Ln = Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+ and Y3+), by the reaction of 4,4 ',4 ''-((1,3,5-triazine-2,4,6-triyl)tri(azanediyl))tribenzoic acid (H(3)TATAB) and rare earth metal ions. X-Ray diffraction analysis revealed that a window-shaped 3D structure was formed by paddle wheel-type [Ln(2)(CO2)(6)] secondary structural units connected to eight H(3)TATAB ligands, in which the channel size reached 2.73 nm and the available volumes of all the compounds surpassed 61%. Considering such large porosity and the pi-electron walls of TATAB(3-), the adsorption performance of 1 as a representative for five kinds of dyes in aqueous solution and iodine in cyclohexane solution were studied. Interestingly, 1 displayed a highly sensitive and selective adsorption behaviour to the cationic dye methylene blue (MB). Moreover, the iodine-adsorption experimental results demonstrated that 1 had a reversible adsorption effect on iodine with an adsorption capacity of 758.72 mg center dot g(-1).

Automated summary

Exploring the adsorption of small molecules using novel functionalized MOFs has attracted widespread interest. In this study, seven isostructural compounds with large porosity were successfully synthesized, with one compound showing highly sensitive and reversible adsorption behavior towards cationic dye and iodine.