Kang Liu

Multifunctional Luminescent Porous Organic Polymer for Selectively Detecting Iron Ions and 1,4-Dioxane via Luminescent Turn-off and Turn-on Sensing

The first case of selective Fe(3+) ions and 1,4-dioxane luminescent sensor based on a porous organic polymer, POP-HT, was synthesized by reaction of tetra(p-aminophenyl)methane and chromophoric 2,5,8-trichloro-s-heptazine. POP-HT displayed prominent fluorescence quenching or enhancement in the presence of Fe(3+) ion or 1,4-dioxane. Moreover, an excellent linear relationship was established between luminescent intensity and the corresponding Fe(3+) ion or 1,4-dioxane concentration. The mechanisms of luminescence quenching and enhancement were also studied by both experiment and theoretical calculation. The results of this study suggest that POP-HT can work as an effective luminescent indicator for qualitative and quantitative detection of Fe(3+) ions and 1,4-dioxane in aqueous solution over other metal ions and organic solvents.

In-Situ Ligand Formation-Driven Preparation of a Heterometallic Metal–Organic Framework for Highly Selective Separation of Light Hydrocarbons and Efficient Mercury Adsorption

By means of the in situ ligand formation strategy and hard-soft acid-base (HSAB) theory, two types of independent In(COO)4 and Cu6S6 clusters were rationally embedded into the heterometallic metal-organic framework (HMOF) {[(CH3)2NH2]InCu4L4·xS}n (BUT-52). BUT-52 exhibits a three-dimensional (3D) anionic framework structure and has sulfur decorating the dumbbell-shaped cages with the external edges of 24 and 14 Å by the internal edges. Remarkably, because of the stronger charge-induced interactions between the charged MOF skeleton and the easily polarized C2 hydrocarbons (C2s), BUT-52 was used for C2s over CH4 and shows both high adsorption heats of C2s and selective separation abilities for C2s/CH4. Furthermore, BUT-52 also displays efficient mercury adsorption resulting from the stronger-binding ability beween the sulfur and the mercury and can remove 92% mercury from methanol solution even with the initial concentration as low as 100 mg/L. The results in this work indicate the feasibility of BUT-52 for the separation of light hydrocarbons and efficient adsorption/removal of mercury.

A microporous yttrium metal–organic framework of an unusual nia topology for high adsorption selectivity of C2H2 and CO2 over CH4 at room temperature

A new microporous yttrium metal–organic framework Y-H3TDPAT [H6TDPAT = 2,4,6-tris(3,5-dicarboxylphenyl-amino)-1,3,5-triazine] with Lewis basic sites on the pore surface was solvothermally synthesized and structurally determined as an unusual (6,6)-connected nia topology. The small pores and the Lewis basic sites within the desolvated Y-H3TDPAT have improved the affinity for C2H2 and CO2 which has been revealed in their large isosteric heats of adsorption (38.2 and 30.9 kJ mol−1). In addition, highly selective separation of C2H2/CH4 and CO2/CH4 at room temperature makes Y-H3TDPAT possess a potential application in natural gas purification.

Di-ionic multifunctional porous organic frameworks for efficient CO2 fixation under mild and co-catalyst free conditions

Conversion of CO2 into value-added chemicals is currently considered to be a significant field in the energy industry mainly due to its environmental and economic benefits. Porous organic frameworks (POFs), as a new class of advanced porous materials, have demonstrated great potential in catalysis, because the functionality and spatial arrangement of their active sites can be precisely managed. We report herein a new strategy for the construction of di-ionic multifunctional POF materials using multiple building blocks with different ion exchange functional sites to construct di-ionic POFs. Based on this strategy, a new di-ionic POF material, POF-DI, was prepared for the first time, which could serve as a substrate material for the preparation of a series of di-ionic multifunctional POF heterogeneous catalysts, POF-Zn2+-Cl−, POF-Zn2+-Br− and POF-Zn2+-I− by a feasible post-synthesis ion exchange method. Because of the synergetic role of dual functional ionic sites including Zn2+ cations as the Lewis acid site and halogen anions (Cl−, Br− or I−) as the nucleophile, POF-Zn2+-Cl−, POF-Zn2+-Br− and POF-Zn2+-I− demonstrate excellent catalytic performance in the cycloaddition of CO2 and epoxides under mild and co-catalyst free conditions. Moreover, such di-ionic multifunctional POF heterogeneous catalysts can be easily recovered and recycled several times without leaching or loss of activity. Overall, our work could not only open a new route for the development of novel POF catalysts for CO2 conversion, but also advance di-ionic POFs as a new kind of platform for multifunctional material design.

Integration of Open Metal Sites and Lewis Basic Sites for Construction of a Cu MOF with a Rare Chiral O h-type cage for high performance in methane purification

A Cu metal-organic framework (MOF), [Cu4 (PMTD)2 (H2 O)3 ]⋅20 H2 O, 1, (where PMTD is 1,4-phenylenebis(5-methyl-4H-1,2,4-triazole-3,4-diyl)bis(5-carboxylato-3,1-phenylene)bis(hydroperoxymethanide)), with a rare chiral Oh -type cage, and dual functionalities of open metal sites and Lewis basic sites, based on a designed U-shaped ligand, was synthesized by hydrothermal methods. It exhibits high CO2 , C2 , and C3 hydrocarbon storage capacity under atmospheric pressure, as well as high H2 (1.96 wt.%) adsorption capacity at 77 K. Methane purification capacity was tested and verified step by step. Isosteric heats (Qst ) studies reveal that CH4 has the weakest van der Waals host-guest interactions among the seven gases at 298 K. Ideal adsorbed solution theory (IAST) calculation reveals that compound 1 is more selective toward CO2 , C2 H6 , and C3 H8 over CH4 in further calculating its separation capacity, as exemplified for CO2 /CH4 (50:50, 5:95), C2 H6 /CH4 (50:50, 5:95), or C3 H8 /CH4 (50:50, 5:95) binary gas mixtures. Breakthrough experiments show that 1 has a significantly higher adsorption capacity for CO2 , C2 H6 , and C3 H8 than CH4 . The selective adsorption properties of 1 make it a promising candidate for methane purification.