Zhenyu Xiao

A multi-aromatic hydrocarbon unit induced hydrophobic metal–organic framework for efficient C2/C1 hydrocarbon and oil/water separation

Oil spills have led to more and more energy waste and economic losses all over the world. Developing highly hydrophobic materials for efficient oil/water separation has become key in solving this global issue. Here we report a highly hydrophobic porous metal–organic framework, named UPC-21, constructed from a pentiptycene-based organic ligand, for efficient oil/water separation. Large and pure crystals of UPC-21 could be obtained with high yield through a developed “diauxic growth” strategy. Due to the existence of multi-aromatic hydrocarbon units in the central pentiptycene core of the ligand, UPC-21 exhibits high hydrophobicity with a water contact angle of 145 ± 1° and superoleophilicity with an oil contact angle of 0°. Strikingly, oil/water separation measurements reveal that UPC-21 can efficiently separate toluene/water, hexane/water, gasoline/water, naphtha/water, and crude oil/water with a separation efficiency being above 99.0% except for crude oil/water due to its high viscosity and complex composition. Our work presented here may open a new avenue for the application of porous MOF materials.

Pentiptycene-Based Luminescent Cu (II) MOF Exhibiting Selective Gas Adsorption and Unprecedentedly High-Sensitivity Detection of Nitroaromatic Compounds (NACs)

The assembly of a fluorescent pentiptycene-based ligand with copper ion resulted in the formation of a 3D porous metal-organic framework (UPC-21) based on well-known paddlewheel SBUs. UPC-21 exhibits selective adsorption of CO2 over CH4 and N2 at 273 K and 295 K, C2H2 over CH4 at 273 K. The most significant performance of UPC-21 is its highly efficient detection of NACs such as 4-NP, 1,4-DNB, NB, and 1,3-DNB with the calculated quenching constants, Ksv, being 3.097 × 106, 1.406 × 106, 4.420 × 105, and 1.498 × 105 M−1 for 4-NP, 1,4-DNB, NB, 1,3-DNB, respectively, which keeps a record on the fluorescence detection of NACs. This is the first porous Cu(II) MOF that exhibits fluorescent detection of NACs with high sensitivities.

Crystal structures, topological analysis and luminescence properties of three coordination polymers based on a semi-rigid ligand and N-donor ligand linkers

Three new mixed-ligand coordination networks, [Cd2(ADDA)(bipy)(H2O)2]·2H2O (1), [Zn(ADDA)(bipy)0.5]·NMP·2H2O (2), and [Co(ADDA)(bip)(H2O)2]·H2O (3) (bipy = 4,4′-bipyridine, bip = 1,4-di(1H-imidazol-1-yl)benzene, H2ADDA = 3,3′-(anthracene-9,10-diyl)diacrylic acid), have been synthesized based on 3,3′-(anthracene-9,10-diyl)diacrylate acid and different N-donor ligands under solvothermal conditions, and structurally characterized by single-crystal X-ray diffraction analyses, infrared spectroscopy (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Topological analysis reveals that 1 features a rare 8-connected 3D ilc network with the point symbol of {4∧24.5.6∧3}; complex 2 possesses a 3D open framework based on the infinite Zn–(CO2) chain with the point symbol of {6∧2.8∧4}; while complex 3 shows a normal 2D 3-connected coordination network with hcb topology and the point symbol of {6∧3}. Besides, the luminescence properties of complexes 1 and 2 were also investigated. The results show that complex 2 bears rapid and selective sensing of Fe3+ in methanol suspension at room temperature.

Fluorescence turn-on detection of uric acid by a water-stable metal–organic nanotube with high selectivity and sensitivity

Herein we provide a new strategy for fluorescence detection of uric acid (UA) using a metal–organic nanotube of CD-MONT-2 for the first time. This novel fluorescent probe exhibits high selectivity and sensitivity for UA with a very good detection limit of 4.3 μM. The results of density functional theory calculations and 1H NMR spectra show that the turn-on sensing mechanism arises from the host–guest interactions of capsule-like CD-MONT-2 with UA to result in electron transfer between UA and CD-MONT-2′. Furthermore, CD-MONT-2′ exhibits very fast adsorption of UA molecules in aqueous solution as confirmed by UV-Vis spectra and HPLC analysis, making it a potential candidate for application in the removal of UA from the human blood.

Synthesis, structure, and properties of a 3D porous Zn(II) MOF constructed from a terpyridine-based ligand

A new 3D porous metal–organic framework [Zn2L2]·5H2O (H2L = 4′-(furan-2-yl)-[2,2′:6′,2′′-terpyridine]-4,4′′-dicarboxylic acid) has been solvothermally synthesized and structurally characterized by TGA, PXRD, elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 possesses a 3D porous framework with a sra topology. Gas adsorption measurements with N2, H2 and CO2 confirm its permanent porosity. Importantly, complex 1 exhibits excellent fluorescence properties that have been exploited to sense organic nitro compounds and metal ions, and the results show that complex 1 bears rapid and selective sensing capabilities for 4-NPH and 4-NP through fluorescence quenching.

Green Fabrication of Ultrathin Co3O4 Nanosheets from Metal–Organic Framework for Robust High-Rate Supercapacitors

Two-dimensional cobalt oxide (Co3O4) is a promising candidate for robust electrochemical capacitors with high performance. Herein, we use 2,3,5,6-tetramethyl-1,4-diisophthalate as a recyclable ligand to construct a Co-based metal-organic framework of UPC-9, and subsequently, we obtain ultrathin hierarchical Co3O4 hexagonal nanosheets with a thickness of 3.5 nm through a hydrolysis and calcination process. A remarkable and excellent specific capacitance of 1121 F·g-1 at a current density of 1 A·g-1 and 873 F·g-1 at a current density of 25 A·g-1 were achieved for the as-prepared asymmetric supercapacitor, which can be attributed to the ultrathin 2D morphology and the rich macroporous and mesoporous structures of the ultrathin Co3O4 nanosheets. This synthesis strategy is environmentally benign and economically viable due to the fact that the costly organic ligand molecules are recycled, reducing the materials cost as well as the environmental cost for the synthesis process.

A yolk–shelled Co9S8/MoS2–CN nanocomposite derived from a metal–organic framework as a high performance anode for sodium ion batteries

Sodium-ion batteries (SIBs) are considered as a promising energy storage device, and anode materials are proved to essentially affect their electrochemical performance. In this work, a yolk–shell structured Co9S8/MoS2 polyhedron with N-doped carbon composite (Co9S8/MoS2–CN) was designed and synthesized through a step by step process using ZIF-67 as the precursor. And this composite is demonstrated to be an excellent electrode candidate material for SIBs due to the magnificent yolk–shelled structures, in situ CN coating and the synergistic effect of the binary sulfides. The Co9S8/MoS2–CN composite electrode shows highly stable cycling performance and delivers a reversible discharge capacity of 438 mA h g−1 within 150 cycles at a current density of 1.0 A g−1, which is much higher than that of Co9S8–CN or MoS2 electrodes. Even at a high current density of 2.0 A g−1, it can also deliver an impressively stable capacity of 421 mA h g−1 within 250 cycles.

Optimizing crystallinity and porosity of hierarchical Ni(OH)2 through conformal transformation of metal–organic framework template for supercapacitor applications

MOFs (metal–organic frameworks) are widely utilized as both the templates and precursors to prepare nanomaterials as supercapacitor electrodes. However, traditional thermolysis routes are difficult to control and usually lead to collapse of the MOF skeletons, which hinders wider applications. Herein, we describe a simple and facile strategy for fabricating the Ni(OH)2 hierarchical structure by the “conformal transformation” of one particular Ni-MOF through hydrolysis in the KOH aqueous solution. By controlling the concentration of KOH solution and the soaking time, the obtained Ni(OH)2 nanomaterial possesses both optimized crystallinity and porosity, extremely beneficial for electron transportation and ion migration within the electrodes. Taking these advantages, the Ni(OH)2 electrode presents a remarkable specific capacity of 830.6 C g−1, and the fabricated all-solid state asymmetric supercapacitor presents a remarkable energy density of 37.8 W h kg−1 at a power density of 252.67 W kg−1, which surpasses most Ni(OH)2 based supercapacitor devices. After 15 000 cycles, the capacitance remains at over 93% of the initial value.