Fabrication of carbon-based materials derived from a cobalt-based organic framework for enhancing photocatalytic degradation of dyes

The pyrolysis of metal-organic frameworks (MOFs) has emerged as a promising route to synthesize carbon/metal oxide-based materials with diverse phase compositions, morphologies, sizes and surface areas. In this paper, 1,3,5-benzoic acid (BTC) and 2,4,6-tri(4-pyridinyl)-1-pyridine (TPP) were used as ligands to prepare a novel cobalt-based MOF (Co-MOF) which was used as a precursor to obtain five carbon-based materials at different temperatures (Co-C200/400/600/800/1000). Furthermore, five dyes were used as degradation targets to investigate the photocatalytic degradation performance of the title materials under UV light irradiation. Co-C1000 exhibited the best photocatalytic degradation performance for methyl orange (MO), and the degradation rate could reach 99.21%. The enhanced photocatalytic activity was attributed to narrower band-gaps and a synergistic effect originating from the well-aligned straddling band structures between Co/CoO/Co3O4 and C, also resulting in a faster interfacial charge transfer during the photocatalytic reaction. This study will aid in the development of photocatalysts generated from carbon-based materials via the pyrolysis transformation of MOFs, therefore greatly enhancing the photocatalytic performance.

UiO-66 framework with an encapsulated spin probe: synthesis and exceptional sensitivity to mechanical pressure

Probes sensitive to mechanical stress are in demand for the analysis of pressure distribution in materials, and the design of pressure sensors based on metal-organic frameworks (MOFs) is highly promising due to their structural tunability. We report a new pressure-sensing material, which is based on the UiO-66 framework with trace amounts of a spin probe (0.03 wt%) encapsulated in cavities. To obtain this material, we developed an approach for encapsulation of stable nitroxide radical TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl) into the micropores of UiO-66 during its solvothermal synthesis. Pressure read-out using electron paramagnetic resonance (EPR) spectroscopy allows monitoring the degradation of the defected MOF structure upon pressurization, where full collapse of pores occurs at as low a pressure as 0.13 GPa. The developed methodology can be used in and ex situ and provides sensitive tools for non-destructive mapping of pressure effects in various materials.

Construction of a New 3D Cu(II) Compound with Photocatalytic Activity and Therapeutic Effect on Ventriculitis

A new Cu(II) compound, that is {[Cu(L)(ClO4)(H2O)(CH3CN)](ClO4)}n (1, L is 4-(furan-2-yl)-2,6-bis(pyridin-2-yl)pyridine), was solvothermally synthesized and structurally characterized. It features a 0D isolated unit, and these 0D isolated units are further hydrogen-bonded into a 3D supramolecular framework. The framework of 1 can be stable up to 284°C, and the optical band gap of 1 is 3.71 eV. Under the irradiation of ultraviolet light, complex 1 as a photocatalyst exhibits high activity for methylene blue (MB) degradation in the water solution. The above compound’s inhibitory activity on the inflammatory cytokines releasing was tested through exploiting ELISA detection. The real time RT-PCR was conducted to assess the compound’s suppression on the expression of bacterial survival gene.

Two new photoactive metal-organic compounds for degradation of methylene blue and treatment in ophthalmic local anesthesia

Two new metal-organic compounds, namely [Cu(CrO₄)(4,4'-bipy)(H₂O)]·n(H₂O) (1) together with [Mn(Cr₂O₇)(bpp)₂]_n (2) (4,4'-bipy is 4,4'-bipyridine and bpp is 1,3-bis(4-pyridyl)propane), were hydrothermally generated, which were characterized structurally through a series of characterization techniques. Moreover, compounds 1 and 2 have 2.95 eV and 3.02 eV of narrow optical band gap values, and possess outstanding photocatalytic effects for the methylene blue degradation under irradiation of visible light. The application of above compounds in the ophthalmic local anesthesia was examined and the specific mechanism was tested. First of all, the acetylcholine content in the synaptic cleft was measured with enzyme linked immunosorbent assay (ELISA) assay after treated with the CPs. The acetylcholine receptor relative expression on nerve cells was subsequently measured via real time reverse transcription-polymerase chain reaction (RT-PCR) under the treatment of compounds. In the end, the complexes' toxicity was evaluated by Cell Counting Kit-8 (CCK-8) detection.

Crystal structure of catena-poly[(μ2-1,1′-(biphenyl-4,4′-diyl)bis(1H-imidazol)-κ2 N:N′)-bis(4-bromobenzoate-κ1 O)cobalt(II)], C32H22Br2CoN4O4

C32H22Br2CoN4O4, monoclinic, P21/c (no. 4), a = 6.5529(11) Å, b = 24.375(4) Å, c = 18.379(3) Å, β = 97.491(3)°, V = 2910.6(8) Å3, Z = 4, R gt (F) = 0.0404, wR ref (F 2) = 0.1268, T = 296(2) K.

Ligand-induced synthesis of two Cu-based coordination polymers and derivation of carbon-coated metal oxide heterojunctions for enhanced photocatalytic degradation

In this study two new Cu-CPs have been constructed as precursors for the preparation of carbon-coated metal oxide heterojunctions. Moreover, we have used Mo metal as a doping agent to boost the photodegradation activity of the CP-derived carbon nanostructures.

Fully unsaturated all-carbon bifluorenylidene-based polymeric frameworks: synthesis and efficient photocatalysis

Conjugated porous polymers with fully unsaturated all-carbon frameworks possess strong visible light-absorbing abilities, enabling efficient photodegradation of dye pollutants.

Synthesis of a 2D Cu@TiO2 composite via the design of a 1D Cu-based coordination polymer precursor for efficient and selective photodegradation of dyes

A 2D Cu@TiO₂ composite with a porous and crystalline structure was successfully synthesized via one-step and low-temperature calcination of a 1D Cu-based coordination polymer (Cu-CP), namely [Cu₂(3-dpha)(1,4-NDC)₂(H₂O)₃]_n (3-dpha = N,N′-bis(3-pyridyl)adipamide and 1,4-H₂NDC = 1,4-naphthalenedicarboxylic acid). Moreover, the Cu@TiO₂ membrane was fabricated by a simple filtration of the as-grown Cu@TiO₂ composite. Compared with the benchmark TiO₂ photocatalyst, the Cu@TiO₂ composite material with high specific surface area and reduced photogenerated electron–hole ratio exhibited good photodegradation activity and durability for gentian violet (GV), which could be attributed to the combined effect of co-doping of Cu and TiO₂ structure. Furthermore, the ˙OH and ˙O₂⁻ radicals were predicted to dominate the photocatalytic process. Therefore, this new efficient photocatalyst is a promising candidate for efficient and selective photodegradation of organic pollutants.

A 2D Cu@TiO₂ composite was synthesized via low-temperature calcination of a 1D Cu-CP. Moreover, the Cu@TiO₂ membrane was fabricated by a simple filtration of the Cu@TiO₂ composite which exhibited selective photodegradation activity for GV.

Construction strategies to modulate the photocatalytic efficiency of Cd(ii) MOFs to photodegrade organic dyes

Two new tuned 3D Cd(ii) MOFs were synthesized and used as photocatalysts for dye degradation.

Cu-Organic framework-derived V-doped carbon nanostructures for organic dye removal

Metal-organic frameworks (MOFs) have recently emerged as a type of uniformly and periodically atom-distributed precursor and efficient self-sacrificial template to fabricate hierarchical porous-carbon-related nanostructured functional materials. In this work, we used Cu(II) ions and aromatic dicarboxylic acid to construct [Cu₃(4,4'-oba)₂(μ₂-OH)₂(H₂O)₂]_n (4,4'-H₂oba = 4,4'-oxybisbenzoic acid) as a precursor for the preparation of carbon nanostructures. Doping foreign elements into intrinsic MOF-based nanomaterials is an effective way to enhance the adsorption property and photocatalytic activity; thus, we designed a facile method to synthesize a vanadium-doped mixture of Cu₂O and Cu nanoparticles encapsulated in a Cu-MOF-derived carbon nanostructure (C-V-1) in this work for the first time. Benefiting from the protection of the carbon shell and regulation of the electronic structure by doping vanadium and phase-mixing Cu₂O and Cu, the adsorption capacities of C-V-1 for MB, RhB, MO, CR and GV at room temperature are 174.13, 147.06, 179.92, 275.90 and 611.81 mg g^-1 in 240 min, respectively, while the photocatalytic degradation rates are 88.14% for MB, 79.80% for RhB, 71.31% for MO, and 71.19% for CR after 4 h. In addition, the degradation rate is larger than 99.01% for GV after only 30 min of UV irradiation. This strategy of using a diverse MOF as a structural and compositional material to create a multifunctional composite/hybrid may expand the opportunities to explore highly efficient, fast and robust adsorbents and photocatalysts for water treatment.

2D MOFs-based Materials for the Application of Water Pollutants Removing: Fundamentals and Prospects

Water quality can have serious impacts on human health. One crucial issue of water pollution seriously affects our safety due to the continually emerging of discovered anthropogenic pollutants. The water treatment technologies are persistent improvement to adapt such new contaminants, which accelerates the evolution of materials science to explore solving the problems. Metal-organic Frameworks (MOFs) as the significant porous and multi-dimensional networks has been concerned for toxic pollutant elimination, especially probed the applications of outstanding layered 2D skeletons MOFs-based materials. The emphases of this review highlight the 2D MOFs-based materials used in water remediation and treatment strategies including adsorption and catalysis methods. Further, the prospects and challenges of 2D MOFs-based materials for water treatments applications would be surveyed meticulously for the future research and development.

New Cd(ii) coordination polymers bearing Y-shaped tricarboxylate ligands as photocatalysts for dye degradation

Two Cd(ii) coordination polymers derived from a Y-shaped tricarboxylate ligand were synthesized and their photocatalytic properties against decomposition of methylene blue were investigated experimentally and computationally.