Assembly of polyoxometalate-templated metal-organic framework with effective peroxidase-like catalytic activity

A new polyoxometalate (POM)-templated 3-D copper(II)-triazole framework [Cu₁₀(trz)₁₀(OH)₆(Cl)₄][H₃PW₁₂O₄₀]·2H₂O (trz = 1,2,3-triazole) has been synthesized and characterized by single crystal X-ray diffraction and other routine methods. The 3-D POM/copper(II)-triazole hybrid framework with a 1-D channel possesses a pcu topology under the template of bulk Keggin-type phosphotungstate. As a new kind of peroxidase mimetic, the new compound effectively catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H₂O₂. The electrostatic interactions and hydrogen bonds/π-π stacking interactions among TMB, trz, and phosphotungstate are responsible for the enhancement of peroxidase-like activity. In addition, application for colorimetric sensing of H₂O₂ is also explored; the new compound exhibits a wide linear range (1–80?μM), low detection limit (0.21?μM), and fast response (2?min).

     

A composite metal-organic framework material with high selective adsorption for dibenzothiophene

A composite metal-organic framework material Ag⁺/MOF-101 was synthesized and applied to adsorb dibenzothiophene (DBT) from model oils. The loading of Ag⁺ enhanced the deep adsorptive desulfurization capacity for DBT and significantly weaken the adsorption competitiveness of toluene.     

High-performance,synergistically catalytic luminescent nanozyme for the degradation and detection of endocrine-disrupting chemical diethylstilbestrol

A synergistically catalytic luminescent nanozyme was designed and synthesized for the degradation and enzymatic fluorescence detection of diethylstilbestrol, an endocrine-disrupting environmental pollutant. Because of the integration of cocatalytic Cu²⁺ ion and CeO₂ particle, luminescent Tb³⁺ ion, and functional ligand dipicolinic acid through flexible metal-organic framework structure, this nanozyme has not only the dual functions of luminescence and multienzyme such as laccase and horseradish peroxidase but also synergistically catalytic effect via a regeneration of Cu²⁺ oxidized by CeO₂. The synergistically catalytic effect of nanozyme greatly enhances the degradation of diethylstilbestrol. The resultants sensitized the luminescence of Tb³⁺ ions, which was used to sense the pM level of diethylstilbestrol in environmental samples. Such a high-performance catalytic luminescent nanozyme can be used to replace natural enzymes for the enzyme-based degradations and ultrasensitive assays. The strategy of constructing artificial enzymes directly from functional units provides a new way for developing fit-for-purpose multifunctional artificial enzymes.     

Recent developments in the adsorptive removal of heavy metal ions using metal-organic frameworks and graphene-based adsorbents

Clean and potable water is a growing concern around the globe. Among the different water pollutants, heavy metal ions pose a serious health concern to all living beings. The quest for new adsorbents to remove heavy metal ions received a boost with the development in the field of metal-organic framework (MOF). The advancement in synthetic strategies and designing of MOF enabled the researchers to tune the adsorption characteristics and tailor the material specific to a heavy metal ion. Similar to MOF, graphene-based two-dimensional and three-dimensional materials are also promising due to the diverse functionalization possibilities and cost-effectiveness. There had been growing interest in applying MOF and graphene-based materials for the removal of heavy metal ions in the past decade. This review summarizes these developments in detail.     

A stable Co(II)-based metal-organic framework with dual-functional pyrazolate-carboxylate ligand: Construction and CO2 selective adsorption and fixation

By taking the functional advantages of both pyrazolate and carboxylate ligands, a unique dual-functional pyrazolate-carboxylate ligand acid, 4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid (H₃PCBA) was designed and synthesized. Using it, a new Co(II)-based metal-organic framework (MOF), Co₃(PCBA)₂(H₂O)₂ (BUT-75) has been constructed. It revealed a (3,6)-connected net based on the 6-connected linear trinuclear metal node, and showed good chemical stability in a wide pH range from 3 to 12 at room temperature, as well as in boiling water. Due to the presence of rich exposed Co(II) sites in pores, BUT-75 presented high selective CO₂ adsorption capacity over N₂ at 298 K. Simultaneously, it demonstrated fine catalytic performance for the cycloaddition of CO₂ with epoxides into cyclic carbonates under ambient conditions. This work has not only enriched the MOF community through integrating diverse functionalities into one ligand but also contributed a versatile platform for CO₂ fixation, thereby pushing MOF chemistry forward by stability enhancement and application expansion.     

A heterobimetallic metal-organic framework with tunable reactive metal sites: synthesis, characterization, and reactivity

A technique for preparing heterobimetallic frameworks with tunable metal sites is demonstrated by the synthesis of a new two-dimensional metal-organic framework that is constructed from tetra(4-carboxyphenyl)porphyrin and Cd(II) species. The solid can be prepared in the presence of other divalent transition metals to yield the same framework with the smaller metal ions occupying the porphyrin ligands.     

Anisotropic Electrical,Magnetic, and Thermal Properties of In3Ni2 Intermetallic Catalyst

We present the anisotropic electrical and thermal transport coefficients (electrical resistivity, magnetoresistance, thermoelectric power, thermal conductivity), the magnetic properties, the specific heat and the electronic density of states of a monocrystalline In₃Ni₂ intermetallic compound, representing a precious-metal-free (and noble-metal-free) intermetallic catalyst for the selective hydrogenation of α,β-unsaturated aldehydes. The investigated physical parameters were determined along three orthogonal crystal-symmetry directions of the trigonal structure, the twofold axis, the 3 axis and within the mirror plane. All the investigated tensorial and vectorial quantities show the same anisotropy, with the quantities being isotropic for the twofold direction and in the mirror plane, whereas there is small, though still significant anisotropy to the 3 direction. The In₃Ni₂ crystal conducts the electricity and heat somewhat less efficiently along the 3 direction than along the twofold direction and in the mirror plane, but the differences are not large, of about 20 %. In₃Ni₂ is a diamagnetic intermetallic compound, with a presumably simple Fermi surface and electrons as the majority charge carriers.     

Iron tetrasulfophthalocyanine immobilized on metal organic framework MIL-101: synthesis, characterization and catalytic properties

Iron tetrasulfophthalocyanine (FePcS) has been irreversibly inserted into nanocages of the metal organic framework MIL-101 to give a hybrid material FePcS/MIL-101 which demonstrated a superior catalytic performance in the selective oxidation of aromatic substrates with (t)BuOOH than homogeneous FePcS.     

Zn-based metal organic framework derivative with uniform metal sites and hierarchical pores for efficient adsorption of formaldehyde

A Zn-containing graphite carbon (Zn-GC) with uniform Zn metal sites and hierarchical pore structure was obtained by pyrolysis of Zn-based metal organic framework (MOF). Zn-GC exhibited excellent adsorption capacity and reproducibility for formaldehyde. The adsorption capacity of Zn-GC was 736 times that of commercial activated carbon and 5.6 times that of ZSM-5 adsorbents. The characterization and experimental results showed that the surface chemical characteristics of the adsorption material play an important role in the adsorption performance. The superior performance was attributed to Zn metal sites and oxygen-containing functional groups on the MOF derivative as well as hierarchical pore structure. The material showed a great potential in the field of organic pollutant removal.     

Structure and morphology controllable synthesis of Ag/carbon hybrid with ionic liquid as soft-template and their catalytic properties

Ag/carbon hybrids were fabricated by the redox of glucose and silver nitrate (AgNO₃) in the presence of imidazolium ionic liquid ([C₁₄mim]BF₄) under hydrothermal condition. Monodisperse carbon hollow sub-microspheres encapsulating Ag nanoparticles and Ag/carbon cables were selectively prepared by varying the concentration of ionic liquid. Other reaction parameters, such as reaction temperature, reaction time and the mole ratio of silver nitrate to glucose, play important roles in controlling the structures of the products. The products were characterized by XRD, TEM (HRTEM), SEM, energy-dispersive X-ray spectroscopy (EDX), FTIR spectroscopy and a Raman spectrometer. The possible formation mechanism was proposed. The catalytic property of the hybrid in the oxidation of 1-butanol by H₂O₂ was also investigated.     

一种新型三维配位聚合物的合成以及表征和磁性测定(英文)

通过水热法合成了三维(3D)网状金属有机框架物[Pr(NTA)(H2O)]n(NTA=nitrilotriacetic acid);利用元素分析、红外光谱分析、X射线单晶衍射等表征了产物的结构,利用热重分析和示差热重分析评价了其热稳定性,并测定了其磁性能.结果表明,目标配合物的Pr(Ⅲ)采取九配位模式(N1O8)形成三帽三角棱柱几何构型,配位聚合物通过O-C-O链组装成高度有序的3D结构.此外,合成的配合物具有较高的热稳定性,并因(O2C-C-C-CO2)2桥联而显示反铁磁性.     

Enhancing of asphaltene adsorption onto Fe3O4 nanoparticles coated with metal-organic framework Mil-101 (Cr) for the inhibition of asphaltene precipitation

In this study, the potential of MOF (Mil-101-Cr)-coated Fe₃O₄ magnetic nanoparticles (Fe₃O₄-MOF MNPs) for asphaltene adsorption was investigated for the first time and the results were compared with magnetic Fe₃O₄ nanoparticles (Fe₃O₄ MNPs). The coprecipitation method was used for the synthesis of both nanoparticles and were verified using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM). The initial asphaltene concentration, nanoparticles concentration, and temperature were the investigated parameters that influenced the adsorption capacity. Increasing the asphaltene concentration, decreasing the mass of nanoparticles, and reducing the temperature could enhance the maximum asphaltene adsorption capacities of 0.79 for Fe₃O₄ MNPs and 0.98?mg?m^?2 for Fe₃O₄-MOF MNPs. Adsorption isotherms tests showed that the Langmuir model was in agreement with the experimental data. In addition, the evaluation of adsorption kinetics demonstrated that the pseudo-second-order Lagergren model predicted the results more precisely. The amount of asphaltene adsorption for Fe₃O₄-MOF MNPs was higher than that for Fe₃O₄ MNPs. These results recommend the application of MOF as an appropriate and effective coating for enhancing asphaltene adsorption.     

A 4-fold interpenetrated metal-organic diamondoid framework: synthesis,crystal structure,and properties

The coordination polymer, [Cu₂(bpp)₄Cl₂]Cl₂, was prepared by self-assembly of benzo[f] [1,10]phenanthroline-6,7-dicarboxylic acid and bpp [bpp = 1,3-bis(4-pyridyl)propane] with CuCl₂·2H₂O, and determined by X-ray crystallographic diffraction, IR spectrum, and thermal analysis. The complex features a 3-D 4-fold interpenetrated metal–organic framework with diamondoid topology. There are two sets of diamondoid frameworks independently constructed by bpp bridging the same copper centers, and the two sets of diamondoid frameworks interpenetrate one another to form an interesting 4-fold interpenetrating 3-D architecture.     

聚乙烯亚胺功能化磁性纳米颗粒制备及其吸附分离蒽醌类阴离子染料性能研究

在室温下,采用戊二醛化学交联法制备聚乙烯亚胺功能化的磁性纳米吸附剂(Fe3O4-PEI).利用TEM、XRD、FT-IR、VSM和TGA等手段对其进行结构表征,并以茜素红、核固红及茜素绿3种蒽醌类染料为目标吸附质,通过静态吸附实验考察了pH值、吸附时间、染料初始浓度、操作温度等因素对吸附的影响,同时进行了吸附动力学和吸附等温线模拟研究.结果表明,在pH=3和温度303 K的条件下,茜素红、核固红和茜素绿的最大吸附量分别为256.1,138.8和134.6 mg/g;初始浓度和吸附时间对染料吸附效率有明显的影响,吸附可在60 min内达到平衡,且吸附过程符合准二级动力学模型;Langmuir等温线模型能更好地描述染料的吸附;蒽醌类染料在Fe3O4-PEI上的吸附是一个自发的吸热过程.另外,Fe3 O4-PEI良好的稳定性和重复使用性,使其可作为一种潜在的水处理吸附剂.     

Hybrid compounds of Keggin polyoxotungstate with transition metal ion as the central atom. Synthesis,structure and properties

The compounds (Hbipy)₂[Co(bipy)₂(H₂O)₄]₂(CoW₁₂O₄₀)·2bipy·7H₂O (1) and [Ni₂(Hbipy)₂(bipy)(H₂O)₄(H₂W₁₂O₄₀)]·5H₂O (2) (bipy = 4,4-bipyridine) were synthesized hydrothermally and characterized by elemental analysis, IR spectroscopy, TG analyses, solid ultraviolet diffuse spectroscopy and single crystal X-ray diffraction method. In 1 the complex ions, [Co(bipy)₂(H₂O)₄]²⁺, construct a supramolecular layer through π-π stacking interaction. The heteropolyanions with central Co atom and supramolecular layers are linked by hydrogen bonds. In 2 a 2D structure is formed from metatungstate anions and binuclear Ni-bipy complexes through the coordination of metatungstate anions and bipy to Ni ions. Between the layers and bipyridine molecules are the hydrogen bond interactions. The formation of 1 and 2 shows that the solution acidity and metal ions influence greatly the structure of the compounds. Solid ultraviolet diffusion results indicate that the compounds 1 and 2 are potential semiconductor materials. In 1 and 2 there exists a weak antiferromagnetic interaction.     

Three new 2-D metal-organic frameworks containing 1-D metal chains bridged by N-benzesulfonyl-glutamic acid: Syntheses, crystal structures and properties

To explore the possibility of obtaining the metal-organic frameworks (MOFs) bearing the bsgluH₂ ligand, two new Cd(II) and one Cu(II) coordination polymers, [Cd(bsglu)(bipy)]_n (1), [Cd(bsglu)·(H₂O)]_n (2) and {[Cu₂(bsglu)₂(bipy)₂]·4H₂O}_n (3) (bsglu=N-benzesulfonyl-glutamic acid bianion, bipy=2,2′-bipyridine) were synthesized and characterized by IR, elemental analysis and X-ray diffraction analysis. Compounds 1 and 3 exhibit one-dimensional coordination chains, which are further connected to form two-dimensional supramolecular networks through π-π aromatic stacking interactions in a novel zipper-like way. Compound 2 presents a two-dimensional layer structure. To the best of our knowledge, 2 is the first two-dimensional complex formed from transition metal and bsgluH₂ ligand. Interestingly, the bsglu anion exhibits remarkable versatile coordination modes in these complexes. Fluorescent analyses show that 1 exhibits photoluminescence in the solid state. Magnetic measurements for 3 revealed that the Cu(II) chain exhibit a weak antiferromagnetic behavior with a J value of −0.606 cm⁻¹.     

A microporous lanthanide metal-organic framework containing channels:Synthesis,structure,gas adsorption and magnetic properties

Under solvothermal condition,the reaction of furan-2,5-dicaboxylate(H2FDA) and glycol with Gd(NO3)3.6H2O gave microporous lanthanide metal-organic framework(MOF),{[Gd(FDA)1.5(glycol)].1.5H2O}}n(1).This compound was characterized by single crystal X-ray diffraction,infrared spectroscopy,elemental analysis,thermogravimetry analysis,and powder X-ray diffraction.The Gd(III) ions were connected by carboxylic group of FDA2-to give 1D chains,which were further linked by FDA2-,forming a 3D porous framework with 3D ...     

Mn3O4 nanoplates and nanoparticles: Synthesis, characterization, electrochemical and catalytic properties

Mn₃O₄ hexagonal nanoplates and nanoparticles were synthesized via a solvent-assisted hydrothermal oxidation process at low temperature and a solvothermal oxidation method, respectively. The synthesized product was characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), electron diffraction (ED), Fourier transform infrared (FT-IR) spectroscopy. Their capability of catalytic oxidation of formaldehyde to formic acid at room temperature and atmospheric pressure and electrochemical properties by cyclic voltammogram (CV) were compared. The results showed that Mn₃O₄ hexagonal nanoplate is a better catalyst, and the hexagonal nanoplates and nanoparticles modified electrodes blended with carbon black have a higher specific capacitance.