Search

Ag NPs were generated by reducing silver ions with sodium borohydride and then loaded into a zirconium-based MOF, PCN-222, resulting in a deep purple powder, PCN-222@AgNPs, which exhibited photocatalytic activity. The material was characterized and found to have Ag NPs uniformly dispersed in the pores of PCN-222, with a content of 6.0306%. PCN-222@AgNPs had rod-shaped structures of micrometer sizes with irregular spherical Ag NPs on their surfaces, as revealed by scanning electron microscopy and transmission electron microscopy. In experiments on Ag NPs release and reactive oxygen species (ROS) detection, PCN-222@AgNPs effectively released Ag NPs into an aqueous solution and promote ROS generation. Finally, the antibacterial activities of PCN-222@AgNPs against Escherichia coli and Staphylococcus aureus were assessed by in vitro experiments. Results indicated that PCN-222@AgNPs had lower minimum bactericidal concentration (MBC) compared to PCN-222 in both light and dark environments. The MBC further decreased under light conditions due to the enhanced photocatalytic performance of the composite material and the promotion of Ag NPs release by ROS. These findings demonstrate that PCN-222@AgNPs have synergistic antibacterial effects under visible light irradiation. [ABSTRACT FROM AUTHOR]

A novel acylamide MOF, Zn2(L)(oba)2·2DMF·2H2O [1, H2oba = 4,4′-oxybis(benzoic acid), L = N1,N4-di(pyridin-4-yl)terephthalamide], has been synthesized by a solvothermal method. The adsorption study indicates that 1 shows higher selective adsorption behaviors of CO2 rather than CH4, CO, N2 and significant isosteric heat (Qst) of CO2 (39.3 kJ mol−1), which are attributed to the nature of the acylamide groups holding unique affinity towards CO2. Vapor adsorption studies indicate that 1 has higher selective adsorption of water vapor over ethanol and methanol vapor. In addition, tunable luminescence properties dependent on the excitation wavelengths were observed. [ABSTRACT FROM AUTHOR]

The restriction of sulfur content in fuels has become increasingly stringent as a result of the growing environmental concerns. Although several MOF-derived materials like POM@MOF composites have shown the ability to catalyze oxidative desulfurization (ODS), their catalytic activities inevitably obstructed by the encapsulated catalytic sites like POM due to the blockage of cavities. Therefore, MOFs with intrinsic and accessible catalytic sites are highly desirable for their applications in ultradeep ODS. Herein, four representative Zr-based MOFs (Zr-MOFs), namely, UiO-66, UiO-67, NU-1000, and MOF-808, were assessed for catalytic ODS. These MOFs were confirmed that they have peroxidase-like activity and can catalyze ODS with H 2 O 2 as oxidant. Among them, MOF-808 showed the highest catalytic activity and it can fully desulfurize dibenzothiophene (DBT) in a model gasoline with a S concentration of 1000 ppm under 40 °C within 5 min. An extremely low apparent Arrhenius activation energy (22.0 KJ·mol -1 ) and an extraordinarily high TOF value (42.7 h -1 ) were obtained, ranking MOF-808 among the best catalysts for the catalytic DBT oxidation. Further studies confirmed that the excellent catalytic activity is mainly responsible for the high concentration of the accessible Zr-OH(H 2 O) catalytic sites decorated in MOF-808. The superoxide radicals ( • O 2 - ) and hydroxyl radicals ( • OH) were identified and were proved to involve in the DBT oxidation. Besides, the effects of Brönsted and lewis acidity to the catalytic efficiency were also discussed. Based on the experimental results, a plausible mechanism concerning on Zr-OH(H 2 O) groups promoting the H 2 O 2 decomposion in to both • O 2 - and • OH was first proposed. Moreover, MOF-808 can be facilely reused for at least eight runs without significant loss of its catalytic activity. By the integration of facile synthesis, high catalytic efficiency, and good stability, MOF-808 thus represents a new benchmark catalyst for catalytic oxidative desulfurization.

The model compound [Zn(HCOO)2(4,4'-bipy)] (1; 4,4'-bipy = 4,4'-bipyridine) is selected in this work to demonstrate the effectiveness of our previously proposed design strategy for electron-transfer photochromic metal-organic complexes. The electron-transfer photochromic behavior of 1 has been discovered for the first time. Experimental and theoretical data illustrate that the photochromism of 1 can be attributed to the electron transfer from formato to 4,4'-bipy and the formation of a radical photoproduct. The electron transfer prefers to occur between formato and 4,4'-bipy, which are combined directly by the Zn(II) atoms. A high-contrast (up to 8.3 times) photoluminescence switch occurs during the photochromic process. The similarity of photochromic behaviors among 1 and its analogues as well as viologen compounds has also been found. Photochromic studies of this model compound indicate that new electron-transfer photochromic metal-organic complexes can be largely designed and synthesized by the rational assembly of nonphotochromic electron-donating and electron-accepting ligands.