Owing to the rapid increase of Hg­(II) ions in water resources, the design and development of new adsorbents for Hg­(II) removal are becoming a significant challenge in environmental protection. Herein, a thiol-functionalized metal–organic framework (SH-MiL-68­(In)) was successfully prepared through a post-synthesis modification procedure, and the framework intactness and porosity were well maintained after this process. SH-MiL-68­(In) exhibited selective adsorption performance for Hg­(II) ions in water. Meanwhile, SH-MiL-68­(In) also shows a high adsorption capacity (450 mg g–1), large adsorption rate (rate constant k 2 = 1.25 g mg–1 min–1), and good recycling of adsorption capacity toward Hg­(II) ions. The excellent adsorption performance resulted from the strong binding interactions between -SH soft basic groups and Hg­(II) soft acidic ions.

A series of isomorphic lanthanide metal–organic frameworks (Ln-MOFs), {[Ln­(L)­(H2O)2]·5H2O} n (1-Ln, where Ln = Eu, Tb, Gd, and Eu x Tb1–x ), have been synthesized by a rigid 1,3-bis­(3,5-dicarboxyphenyl)­imidazolium chloride (H4L+Cl–) ligand and Ln3+ ions via a solvothermal method. Single-crystal X-ray diffraction indicated that 1-Ln exhibited similar three-dimensional porous frameworks with one-dimensional channels decorated by the uncoordinated carboxylate oxygen atoms. The luminescent sensing studies indicated that 1-Eu is an outstanding reusable luminescent probe suitable for the simultaneous detection of Cr2O7 2–, CrO4 2–, and MnO4 – ions in an aqueous solution. Remarkably, the different proportions of Eu3+ and Tb3+ can be combined into the same Ln-MOF to yield a new series of differently doped 1-Eu x Tb 1– x MOFs. At the same excitation wavelength, they generated dual-emission peaks of Eu3+ and Tb3+ to show a gradual change in luminous color between yellow-green, yellow, orange, orange-red, and red. On the basis of the excellent optical properties of 1-Ln complexes, they can be employed as promising luminescent probe and multicolor tunable photoluminescence materials.

A new luminescent metal-organic framework, {[Cd3(HL)2(H2O)3]·3H2O·2CH3CN}n (1) (H4L = 1-(3,5-dicarboxylatobenzyl)-3,5-pyrazole dicarboxylic acid), has been synthesized by solvothermal reaction and characterized by infrared spectroscopy, powder X-ray diffraction, thermogravimetry measurements and so on. 1 shows a new trinodal (4,4,6)-connected topology. Importantly, 1 displays intense luminescence in the solid state and high luminescent sensitivity and selectivity for Fe3+, CrO42- and Cr2O72- ions in aqueous solution, making it a potential probe for detecting these substances. The quenching mechanisms are also further discussed in detail. In addition, further research on the adsorption of dyes shows that 1 can selectively adsorb Congo red dye from other dye molecules.