RESUMEN
A pair of homochiral coordination polymers, [Cu(DPT)]n (1M and 1P, HDPT = 3,5-di-4-pyridinyl-2H-tetrazole), were assembled from achiral precursors. Crystal structure analysis showed that they are chiral three-dimensional (3D) coordination polymers based on a new double-stranded helical building block that is composed of two different 1D helices. Interestingly, rare symmetry-breaking crystallization was observed, in which the possibility of obtaining enantio-enriched bulk product with excessive M enantiomers (1-A) was obviously higher than that for P enantiomers (1-B) as demonstrated in multiple, repeated experiments with single-crystal diffraction and vibrational circular dichroism (VCD) spectra. Moreover, compound [Cu(DPT)]n shows good chemical stability in water, with pH values ranging from 3 to 13, as well as in many common organic solvents. Photophysical properties, including thermochromic properties and two-photon excited luminescence, were studied, and the potential for applications in temperature sensing was exhibited. In addition, the photocatalytic degradation of methylene blue in water indicated that compound [Cu(DPT)]n can be used as a photocatalyst.
RESUMEN
Cationic framework materials capable of removing anionic pollutants from wastewater are highly desirable but relatively rarely reported. Herein, a cationic MOF (SCNU-Z1-Cl) possessing tubular channels with diameter of 1.5 nm based on Ni(II) and a nitrogen-containing ligand has been synthesized and applied to capture hazardous anionic contaminants from water. The SCNU-Z1-Cl exhibits high BET surface area of 1636 m2/g, and shows high hydrolytically stability in pH range from 4 to 10. Owing to the large tubular channels and the uncoordinated anions in the framework, the aqueous-phase anion-exchange applications of SCNU-Z1-Cl were explored with environmentally toxic oxo-anions including CrO42-, Cr2O72-, MnO4-, and ReO4-, and organic dyes. The adsorption of oxoanions exhibits high uptake kinetics and the adsorption capacities of CrO42-, Cr2O72-, MnO4-, and ReO4- are 126, 241, 292, and 318 mg/g, respectively, which were some of the highest values in the field of MOF/COF. In additional, the selectively is high when other concurrent anions are exist. The anionic dyes with different sizes including methyl orange, acid orange A, congo red, as well as methyl blue can be adsorbed by SCNU-Z1-Cl in few minutes to about 1 h. The adsorption capacities for them are 285, 180, 585, and 262 mg/g, respectively. In contrast, the adsorption kinetics for catinionic dyes with different sizes is obviously lower and exhibit a size-selectively adsorption that only cationic dye with suitable size (rhodamine B) can be adsorbed by SCNU-Z1-Cl. Consequently, SCNU-Z1-Cl can sepearate organic dyes in three different modes: size-dependent, charge-dependent, and kinetics-dependent selective adsorption. The excellent adsorption and separation properties of SCNU-Z1-Cl is attribute to the cationic framework, large tubular channel, as well as the high positive Zeta potential.
RESUMEN
A metal-organic framework (MOF), named SCNU-Z2, based on a new heterotopic tripodal nitrogen-containing ligand, has been constructed. Due to the replacement of one imidazole group in the reported ligand with one tetrazole group, the charge of the framework is changed from cationic to anionic but retains the same framework structure. The framework consists of tubular channels with a diameter of 1.5 nm and exhibits satisfactory stability in water with a pH range of 3-11. The anionic nature of the framework allows the effective adsorption of the cationic dyes MLB, CV, and RhB with capacities of 455.6, 847.4, and 751.8 mg/g, respectively. Among them, the adsorption capacities for SCNU-Z2 on CV and RhB rank as the highest when compared with other reported MOFs. In contrast, SCNU-Z2 exhibits an extremely low capacity for anionic dyes MO and AO, making it useful for the separation of anionic and cationic dyes based on a charge-dependent mode. Interestingly, SCNU-Z2 can be used to degrade an anionic dye, MB, within 30 min under darkness at room temperature. The apparent activation energy of the dye degradation reaction is calculated to be approximately 18.96 kJ·mol-1, implying that the catalytic reaction of MB can be considered as a low-temperature thermocatalytic reaction in the dark/SCNU-Z2 system.
RESUMEN
Developing efficient and durable bifunctional air-cathode catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the key efforts promoting the practical rechargeable zinc-air batteries (ZABs). In this paper, high-performance bifunctional air-cathode catalysts by a two-step strategy: atomically dispersed Ni on N-doped carbon is first derived from MOF to form uniformly dispersed NiNC, which are pyrolyzed together with Fe source at different high-temperatures to form FeNi@NC-T (T = 800, 900, and 1000 °C) catalysts. The as-synthesized non-noble metal FeNi@NC-900 catalyst exhibits a considerably small potential gap (ΔE) of 0.72 V between ORR and OER, which is as the same as commercial noble metal Pt/C + Ir black mixed catalyst. The performance of the ZABs using FeNi@NC-900 as the air-cathode catalyst displays a power density of 119 mW·cm-2 and a specific capacity of 830.1 mAh·g-1, which is superior to that of Pt/C + Ir black mixed catalyst. This work provides a guideline for designing alloy electrocatalysts with uniform size and nanoparticle distribution for metal-air batteries with bifunctional air-cathodes.
RESUMEN
Invited for this month's cover are the collaborating groups of Sheng-Run Zheng and Wei-Guang Zhang from South China Normal University, China. The cover picture shows an amorphous cationic porous metal-organic material that constructed from the covalent linking of large cationic metal-organic cage for the removal of toxic oxo-anions from water with high capacities and rapid kinetics. Read the full text of the article at 10.1002/cplu.202000570.
RESUMEN
A metal-organic framework (MOF), namely SCNU-Z3, based on an imidazole-tetrazole tripodal ligand and Mn(ii), has been constructed. It exhibits a porous 3D framework composed of truncated octahedron cage subunits. Unexpected ligand-induced missing metal-ion defects were observed in the framework. In addition, the application of SCNU-Z3 in a supercapacitor was performed.
RESUMEN
Cationic amorphous metal-organic cage (MOC)-based materials capable of removing anionic pollutants from water are receiving increasing attention but they are still relatively less reported. Herein, for the first time, a cationic porous MOC-based extended framework, namely, CL-aMOC-1, was constructed by covalent linking of a cationic Pd12 L24 (L=3,5-di-pyridin-4-yl-benzaldehyde) cage with a 1,4-bis(4-aminophenyl)benzene (BAPB) linker. Interestingly, the reaction could be completed within 15â min using an amorphous MOC-based solid (aMOC-1) and BAPB as reactant via a low-temperature solid-state reaction. The CL-aMOC-1 showed improved stability, lower solubility and higher oxo-anion uptake in water compared with the original aMOC-1. The adsorption capacities for CrO4 2- , Cr2 O7 2- and ReO4 - on CL-aMOC-1 were 245.1, 311.5 and 452.5â mg/g, respectively, in which the uptake of Cr(VI)-containing oxo-anions was among the highest compared with those of other metal-organic materials. The CL-aMOC-1 can selectively capture oxo-anions in the presence of competitive anions. It exhibits good reusability as over 85 % of the uptake capacity is retained after 5 cycles. Finally, it shows the ability to remove Cr(VI) ions from electroplating wastewater.