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Metal–organic framework (MOF) materials with aqueous stability have a good potential application in the field of mimetic enzymes.

A series of triarylborane derivatives were prepared by introducing different push–pull electronic groups. Upon incorporation into a PMMA matrix, these triarylborane derivatives with a D–π–A system (BN) had good versatility for photo-induced ultra-long RTP materials.

Triarylphosphine-based pure organic long persistent luminescence materials are rarely investigated because of their poor stability and low photoluminescence quantum yield. Herein, we demonstrate that the introduction of a methoxy group (TPP

Highly-dispersed and small-sized Au (2.2 nm)/ZnO catalyst was prepared using metal ions and 2-methylimidazole by one-pot coordination–calcination method, and showed superior performances for vanillin synthesis via base-free oxidation.

Since the concept of aggregation-induced emission (AIE) was proposed, along with the development of new AIE molecules and broadening of its application field, the exploration of its mechanism has attracted more and more attention.

A series of ultralong RTP materials with photostimulus-responsive behavior were prepared by facile doping processes.

Photochromic materials are constructed with molecules accompanied by structural change after triggering by light, which are of great importance and necessity for various applications. However, because of space-confinement effects, molecule stacking of these photoresponsive chromophores within coordination polymers (CPs) always results in an efficiency decrement and a response delay, and this phenomenon will lead to a poor photochromic property. Herein, a CP (named CIT-E) with a 3-fold-interpenetrating network structure, which was prepared with (Z)-1,2-diphenyl-1,2-bis[4-(pyridin-3-ylmethoxy)phenyl]ethene (1Z) and a CuI cluster, showed fast reversible photochromic behavior. Under UV-light illumination, the color of CIT-Z changed from pale yellow to reddish brown. With the illumination of green light, the polymer could return to its initial color within 10 s. To reveal the mechanism of reversible photochromic behavior of CIT-Z, single-crystal structures of each color state were fully studied, and other scientific study methods were also used, such as time-dependent density functional theory calculation and control experiments. It was found that, with light illumination, this behavior of CIT-Z was the result of a ligand-to-metal charge-transfer process, and this process was triggered by subtle molecular conformation variation of tetraphenylethylene. It should be noted that CIT-Z has high thermal and chemical stability, which are excellent advantages as smart photoresponsive materials. As a proof of concept, a uniform thin film with such a fascinating photochromic property allows applications in invisible anticounterfeiting and dynamic optical data storage. Overall, the present study opens up a new avenue toward reversible photochromic materials.

The morphology of nanomaterials (geometric shape and dimension) play a significant role in its various physical and chemical properties. Thus, it is essential to link morphology with performance in specific applications. For this purpose, the morphology of copper metal-organic polyhedra (Cu-MOP) can be modulated through distinct assembly process, which facilitates the exploration of the relationship between morphology and catalytic performance. In this work, the assemblies of Cu-MOP with three different morphologies (nanorods, nanofibers and nanosheets) were facilely prepared by the variation of solvent mixture of N, N-dimethylformamide (DMF) and methanol, revealed the important role of the interaction between the surface group and the solvent on the morphology of these assemblies. Cu-MOP nanofibers exhibited the highest mimetic peroxidase enzyme activity over the Cu-MOP nanosheets and nanorods, which have been utilized in the detection of glucose. Cu-MOPs assemblies with tunable morphology accompanied with adjustable mimic peroxidase activity, had great potential applications in the field of bioanalytical chemistry and biomedicals.

A novel Pd(II) ion-imprinted polymer (Pd(II)-AAP-IIP@VMWCNTs) was constructed by using 2-(N-allyl)aminopyridine (AAP), vinyl functionalized multi-walled carbon nanotubes (VMWCNTs), ethylene glycol dimethacrylate (EGDMA) and Na2PdCl4 as functional monomer, carrier, cross-linker and template ions, respectively. The structure, morphology, adsorption property and applicability as adsorbent in solid phase extraction were characterized by Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), binding experiment and solid phase extraction (SPE) experiment, respectively. The equilibrium adsorption capacity and imprinting factor of Pd(II)-AAP-IIP@VMWCNTs for Pd(II) were found to be 9.053 mg/g and 3.46, respectively. The SPE column packed with Pd(II)-AAP-IIP@VMWCNTs displayed good adsorption selectivity to Pd(II). The adsorption rate and extraction rate of this column to Pd(II) were more than 90% and 74%, but below 40% and 15% to the other coexisting ions under the optimized SPE conditions. The obtained Pd(II)-AAP- IIP@VMWCNTs-based SPE method could be combined with inductively coupled plasma optical emission spectroscopy (ICP-OES) for determination of Pd(II) in environmental water. The recoveries were in the range of 87.2%–91.6% with the relative standard deviations of 2.5%–6.8%.

In this study, we established a simple colorimetric method for visual detection of chromium (III) ions using aggregated silver nanoprisms induced by monohydrogen phosphate. The detection strategy had two steps, selective aggregation of silver nanoprisms with monohydrogen phosphate at high temperature, and anti aggregation of silver nanoprisms in the presence of chromium (III) ions. In this strategy, significant spectral shift of the localized surface plasmon resonance (LSPR) absorption peak of silver nanoprisms could be visualized with the color changed from yellow to blue. The spectral peak shift of silver nanoprisms in the anti-aggregation process was linear with the concentrations of the added chromium (III) ions in the range of 20.0–800.0 nM. Thus, a colorimetric method for chromium (III) ions detection was established with the detection limit of 3.6 nM. The experimental results of real water samples indicated that the colorimetric sensor was potential in environmental monitoring.

The development of a facile synthesis and controllable layer stacking approach for covalent organic frameworks (COFs) is an important issue for modulating their properties and realizing their application diversity. Herein, three COF isomers with different stacking models (eclipsed AA, staggered AB, and ABC stacking) were obtained by modulating the reaction temperature and solvent medium. Experimental and theoretical calculations show that the ABC stacking isomer obtained at room temperature is the kinetic product, while the AA stacking isomer prepared by the solvothermal method is a thermodynamic product. Owing to the tautomerism involved in the reaction process, these isomers possess different ratios of enol and keto forms. Thus, they exhibit different generation efficiencies of Type I and Type II reactive oxygen species (ROS). The ABC stacking isomers could be employed as metal-free heterogeneous photocatalysts for visible-light-induced oxidation of amines to imines, owing to the highest generation efficiency of Type I ROS.

The base-free aerobic oxidation of 5-hydroxymethylfurfural (HMF) in water to 2,5-furandicarboxylic acid (FDCA) is a sustainable upgrading process for cellulosic carbohydrates. A mesoporous NiO-supp...

Cysteine is widely used as a stabilizer for the preparation of fluorescent gold nanoclusters (Au NCs) with different fluorescence properties. Herein, by using cysteine as a stabilizer and controlling the synthesis conditions, a new non-fluorescent cysteine stabilized gold nanocluster (Cys-Au NCs) probe was prepared and a new strategy for "turning on" the fluorescence of the Cys-Au NCs was studied for rapid and selective detection of silver ions. In this strategy, the addition of silver ions to non-fluorescent Cys-Au NCs solution could quickly induce a visible fluorescence "turn on" phenomenon in 30 s. Further studies indicated that this fluorescence "turn on" phenomenon is specific for silver ions and the "turn on" fluorescence intensity has a linear relationship with the amount of silver ions in the range from 3.0 to 30.0 μM. Therefore, the non-fluorescent Cys-Au NCs were applied to the detection of silver ions in environmental water samples and a limit of detection (LOD) of 0.26 μM was obtained. This research sheds light on new applications of Au NCs and proposes a simple, rapid, sensitive, and visual method for the detection of metal ions.

Direct oxidative coupling of alcohols with amines using a non-precious metal oxide catalyst under mild conditions is highly desirable for imine synthesis. In this work, a mesoporous Mn1ZrxOy solid solution catalyst prepared by a co-precipitation method showed excellent catalytic performance in imine synthesis from primary alcohols and amines without base additives in an air atmosphere. XRD, N2 physisorption, H2-TPR, O2-TPD, EPR and XPS were comprehensively used to unravel its structural, redox and amphoteric properties that closely depended on the interaction between MnOy and ZrO2 with a variable Zr ratio. The Mn1Zr0.5Oy catalyst presented the highest fractions of Mn3+ ions and reactive oxygen species on the surface, and the highest concentrations of acidic–basic sites, which were disclosed to play important roles in activating alcohols and molecular O2 in the rate-determining step. In the model reaction of oxidative coupling of benzyl alcohol with aniline, such enhanced features of the Mn1Zr0.5Oy catalyst can promote the intrinsic catalytic activity (iTOF of 1.87 h−1) and boost benzylideneaniline formation (5.56 mmol gcat.−1 h−1) based on a >99% yield at 80 °C respectively at a fast response. It can also work effectively at a room temperature of 30 °C, as well as for the gram-grade synthesis. This is one of the best results among all the MnOy-based catalysts in the literature. Moreover, this catalyst showed good stability and a wide substrate scope with good to excellent yields of imines.

Oxidative transformations of HMF are key routes toward a wide variety of chemicals and biofuels through an environmental friendly process. Co3O4 NPs decorated Mn-Co-O solid solution, donated as Co3O4/MnXCo, was prepared by co-precipitation method and used as non-precious metal catalyst for base-free oxidation of HMF to FDCA in the presence of O2 and water. Comprehensive characterizations such as XRD, H2-TPR, O2-TPD, XPS, NH3/CO2-TPD and TEM were used to study materials properties especially the oxygen mobility and acidity-basicity. The effect of Mn/Co molar ratio in catalyst and the reaction conditions were investigated and optimized. In addition, the kinetics of the reaction was monitored to reveal the reaction route and rate-determining step. The variation of Mn/Co molar ratio was found to affect not only HMF conversion but also distribution of products. When the Mn/Co ratio was of 0.2, the Co3O4/Mn0.2Co catalyst showed the optimal catalytic performance (i.e., >99% yield of FDCA obtained under 1 bar O2 at 140 °C after 24 h) due to the highest content of both Lewis and Bronsted acid sites on the surface, leading to the strongest ability of HMF adsorption and COOH group formation, as well as the enhanced oxygen mobility. This catalyst was shown stable after a minor deactivation (≤8%) during six recycling uses and its activity can be entirely regenerated by calcination in air.

The effective control of particle size and electron density of metal active sites is challenging yet important for supported nanoparticles, as size effects and promoter effects play vital roles in ...

A highly sensitive enzyme-induced metallization-based electrochemical signal amplification strategy was developed based on the integration of the enzyme-induced metallization reaction, Au nanoparticles (AuNPs)-induced silver deposition, chemically modified electrode and highly sensitive stripping voltammetry detection. The presence of alkaline phosphatase (ALP) catalyzed ascorbic acid 2-phosphate into ascorbic acid, which reduced Ag+ to Ag0 on the surface of the AuNPs/multi-walled carbon nanotubes/polyethyleneimine/glassy carbon electrode (AuNPs/MWNTs/PEI/GCE). As a result, the enzyme-generated product was accumulated on the surface of the AuNPs/MWNTs/PEI/GCE by means of silver deposition via this signal amplification strategy, which enhanced the detection signal dramatically. Amounts as low as 1 × 10–8 U/mL (corresponding to 10 aM) ALP can be detected using this strategy, which is about 4−7 orders of magnitude more sensitive than with other reported methods for ALP determination. In addition, this strategy can be applied to ALP detection in real complex samples, which shows great potential in the early diagnosis of diseases.

A series of silver coordination complexes (CCs) have been synthesized through self-assembly of five pyridine-substituted tetraphenylethylene stereoisomer ligands with silver ions (named Ag-TPE-2by-1-E, Ag-TPE-2by-2-E, Ag-TPE-2by-2-Z, Ag-TPE-2by-3-E, and Ag-TPE-2by-3-Z). These silver CCs show distinct topologies including beaded chain frameworks, linear structures, and discrete metallacycles. The single-crystal analysis results reveal the critical role of the space distribution of the coordination site and stereoisomer ligands in controlling the silver CCs' geometry configuration and modulating the optical properties. Luminescent investigations revealed that Ag-TPE-2by-2-E, Ag-TPE-2by-2-Z, Ag-TPE-2by-3-E, and Ag-TPE-2by-3-Z possess obvious mechanocharomic behaviors, which can be achieved several reversible cycles through repeated grinding and methanol soaking processes. However, the Ag-TPE-2by-1-E showed tenacious stability toward mechanical grinding and temperature. Thus, these silver CCs provide a good platform to investigate the influence of the space distribution of the coordination site of ligands on their geometry and mechanocharomic properties.

The Fe–Ca catalysts in catalytic pyrolysis of brown coals were studied to investigate the catalytic activity of the Fe–Ca in a fixed-bed reactor. Experimental results showed the maximum yields of the light aromatic hydrocarbons (LAHs) were 5.90 wt% (0.88 wt% of benzene, toluene and xylene ‘BTX’, 4.10 wt% of phenol and cresol ‘PC’ and 0.92 wt% of naphthalene) when the 1.5% Ca was added into 5% Fe-loaded brown coal. The yields of water and gas significantly reduced, the tar yield gradually increased with increasing heating rate. The characterization results indicated that when calcium promoter was impregnated with iron, Ca2Fe2O5, CaO, Fe2O3 and α-Fe were formed on the surface of the coal char, Ca2Fe2O5 and α-Fe decomposed polyaromatic tar, CaO and Fe2O3 accelerated water gas shift reaction to enhance the H2 yield, the Fe2O3 and Ca2Fe2O5 could be reduced to α-Fe by volatiles (C, CO and H2) under high temperature catalytic pyrolysis. The synergistic effects between iron and calcium improved brown coal pyrolysis and the volatiles such as free radical fragments were further pyrolyzed, indicating that Fe–Ca catalysts inhibited α-Fe deactivation by tar and carbon deposition, thus promoting brown coal pyrolysis and formation of COx, H2 and LAHs.

The abuse of antibiotics would seriously affect human health and has become of worldwide critical concern, thus it is urgent to develop an environmentally friendly and nontoxic fluorescent probe for antibiotics sensing. In this work, a lead-free Cs

Single-cells coated with functional shells to protect them from external harsh condition have great potential applications in many fields such as tissue engineering, cell-based devices, cell biology, and so on. Herein, copper metal organic polyhedron (Cu-MOP) hydrogel has been applied as a soft shell for cell protection under both physical and chemical stimulations. Compared with a previous strategy, this MOP-Gel shell not only possesses more satisfied protection effect but also could be prepared and removed facilely without any damage to the encapsulated cells.

Nowadays, there are many ways to obtain cesium lead halide perovskite nanocrystals. In addition to the synthesis methods carried out in solution, the solid-phase synthesis was reported involving grinding and milling. In this paper, we synthesized luminescent CsPbBr3/Cs4PbBr6 perovskite nanocrystals (PNCs) by three solid-phase synthesis methods (grinding, knocking, stirring) using L-lysine as a ligand. This is the first attempt to use an amino acid for assisting the solid phase synthesis of perovskite and to study the difference in the products obtained by the three solid phase synthesis methods. The results show that the productivity of the solid-phase synthesis methods can be greatly improved by adding L-lysine and the perovskites obtained by the methods are more resistant to water due to the addition of L-lysine. The simplicity of the synthesis process expanded the use of solid-phase synthesis to obtain more perovskites and provided potential applications of perovskite in analytical detection and sensing in aqueous solution.

A one-pot synthesized CoRu–CoOX nanocomposite was shown to be a magnetically recoverable hydrogenation catalyst for the quantitative conversion of furfural to furfuryl alcohol in water at ambient H2 pressure.

The thickness of washcoat loading on high-performance monolithic catalysts is normally determined by vernier caliper procedure, which gives rough result of washcoat thickness but does not address such parameters as morphology and homogeneity, accurate thickness of the layer and chemical composition of the coated layers in honeycomb-shaped monolithic catalysts. In this work, we proposed a methodology of washcoat analysis including the thickness and chemical composition of the coated layers in honeycomb-shaped monolithic catalysts. The method can realize accurate determination of washcoat thickness and the direct analysis of chemical composition in washcoat of single-layered or double-layered monolith catalyst, which is applicable for research and development of e coating technology and detection of product.

Direct oxidative coupling of alcohols and amines is regarded as an effective and green approach for imine synthesis under mild conditions. In this work, Zn-doped γ-Al2O3 supported Au nanoparticles was demonstrated as highly active and selective heterogeneous catalyst for a series of imine productions with good to excellent yields, from alcohols and amines via direct oxidative coupling under air atmosphere without extra base additives. Various physicochemical techniques, including ICP-MS, XRD, N2 physisorption, TEM, XPS and CO2-/NH3-TPD, were used to study the properties of the catalysts. Well-dispersed Au0 nanoparticles with a mean size of ca. 2.9 nm were found highly effective in activating alcohols in the presence of reactive amines. The amount of Zn2+ dopant and the calcination temperature of support during catalyst preparation showed crucial impact on tuning the intrinsic activity for oxidation of benzyl alcohol to benzaldehyde (i.e., the rate-determining step for the model reaction), which was disclosed to be related with the active surface oxygen species and the acidic-basic property of support. The 0.4% Au/Zn0.02Al2O3 catalyst calcined at 400 °C exhibited the highest TOF (39.1 h−1) at 60 °C based on a >99% yield to benzylideneaniline among all the ever-reported Au-based catalysts. Moreover, this catalyst could afford 98% yield to benzylideneaniline at only 30 °C and work effectively for the gram-scale synthesis. It also showed considerable stability after five consecutive recycling.

Over the last decade, the controllable reversible phase transition of functional materials has received growing interest as it shows unique suitability for various technological applications. Although many metal-organic frameworks (MOFs) possess a lamellar structure, the reversible structural transformation of MOFs between their three-dimensional (3D) phase and two-dimensional (2D) phase remains a largely unexplored area. Herein, we report for the first time a europium MOF with unprecedented reversible morphology in different solvents at room temperature. This europium MOF displayed a 3D nanorod morphology in organic solvent and a 2D nanobelt architecture in water. As a proof of concept for potential applications of this reversible-phase-transition MOF, we were able to use a delamination recovery method to load dye molecules that previously could not be loaded into europium MOFs.