Xianfa Zhang,Shuaibing Yu,Xuliang Pang,Xiaochen Ren,Bo Zhang,Jinming Kong,Lianzhi Li
A solvent-directed, new Schiff base multiple correspondence fluorescent probe, (E)-2-(2-hydroxybenzylidene) hydrazine-1-carboxamid (L), was synthesized for selective sensing of Cu 2+ and Mg 2+ ions. L showed excellent selectivity and high sensitivity toward Cu 2+ in “turn off” mode with a detection limit of 40.5 nM in 10 mM, pH = 7.0 PBS buffer. Contrary to that, when acetonitrile was used as the solvent, L exhibited highly selective and sensitive fluorescence sensing ability for Mg 2+ in “turn on” mode with a detection limit of 9.5 nM. L can coordinate to Cu 2+ and Mg 2+ in a 1:1 molar ratio, respectively, evidenced by Job’s plot analysis. Their binding modes were investigated by NMR, IR and XPS spectroscopies. Moreover, the satisfied results were obtained when L was used to detect Cu 2+ and Mg 2+ in real water samples.
La-based materials have garnered considerable attention as potential adsorbents for phosphate removal because they capture phosphate with high affinity, producing an ultralow phosphorous-concentration output. Herein, La-based metal–organic frameworks (La–MOFs, La-1,3,5-benzentricarboxylate) with tunable structures were fabricated by regulating the coordination solvent environment, which largely determines both the pore structure and chemical components of their corresponding La 2 O 2 CO 3 derivatives and the phosphate adsorption performance. A porous La 2 O 2 CO 3 derivative (W–D T500) derived from the water/N,N-dimethylformamide (DMF) guided La–MOF showed abundant mesopores and a high surface area, because the pore-opening degree under high-temperature pyrolysis is higher in W–D T500 than in the La 2 O 2 CO 3 derivative obtained from the water/ethanol solvent–guided La–MOF. W–D T500 also had higher La (78.3%) and carbonate contents of the crystal structure owing to the higher efficiency of carbon conversion to carbonate-oxides in W–D T500. Consequently, the porous La 2 O 2 CO 3 derivative W–D T500 exhibited superior phosphate adsorption capacity (91.6 mg P/g), high adsorption selectivity, and excellent recycling performance. Phosphate was attached to the La 2 O 2 CO 3 adsorbents via a ligand-exchange mechanism between phosphate and CO 3 2− /–OH. This study provides a solvent guidance strategy to construct functional La–MOFs and La 2 O 2 CO 3 derivatives for excellent phosphate removal.
Dan Lai,Fuqiang Chen,Lidong Guo,Lihang Chen,Jie Chen,Qiwei Yang,Zhiguo Zhang,Yiwen Yang,Qilong Ren,Zongbi Bao
The adsorptive separation of CH 4 from CO 2 is a promising process for upgrading natural gas. However, thermodynamically selective adsorbents exhibit a strong affinity for CO 2 and thus require a high energy compensation for regeneration. Instead, kinetic separation is preferred for a pressure swing adsorption process, although precise control of the aperture size to achieve a tremendous discrepancy in diffusion rates remains challenging. Here, we report a guest solvent-directed strategy for fine-tuning the pore size at a sub-angstrom precision to realize highly efficient kinetic separation. A series of metal–organic frameworks (MOFs) with isomeric pore surface chemistry were constructed from 4,4′-(hexafluoroisopropyli-dene)-bis(benzoic acid) and dicopper paddlewheel notes. The resultant CuFMOF·CH 3 OH (CuFMOF-c) exhibits an excellent kinetic separation performance thanks to a periodically expanding and contracting aperture with the ideal bottleneck size, which enables the effective trapping of CO 2 and impedes the diffusion of CH 4 , offering an ultrahigh kinetic selectivity (273.5) and equilibrium-kinetic combined selectivity (64.2). Molecular dynamics calculations elucidate the separation mechanism, and breakthrough experiments validate the separation performance.
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