Four highly porous covalent organic frameworks (COFs) containing pyrene units were prepared and explored for photocatalytic H2O2 production. The experimental studies are complemented by density ...functional theory calculations, proving that the pyrene unit is more active for H2O2 production than the bipyridine and (diarylamino)benzene units reported previously. H2O2 decomposition experiments verified that the distribution of pyrene units over a large surface area of COFs plays an important role in catalytic performance. The Py‐Py‐COF though contains more pyrene units than other COFs which induces a high H2O2 decomposition due to a dense concentration of pyrene in close proximity over a limited surface area. Therefore, a two‐phase reaction system (water‐benzyl alcohol) was employed to inhibit H2O2 decomposition. This is the first report on applying pyrene‐based COFs in a two‐phase system for photocatalytic H2O2 generation.
Four highly porous pyrene‐based covalent organic frameworks (COFs) were prepared for photocatalytic H2O2 generation. The reported findings highlight that the presence of pyrene active sites in very close proximity leads to unwanted H2O2 decomposition. Accordingly, a biphasic system (benzyl alcohol and water) was employed to inhibit H2O2 decomposition.
Covalent Organic Frameworks (COFs), an emerging class of crystalline porous materials, are proposed as a new type of support for grafting lanthanide ions (Ln3+) and employing these hybrid materials ...as ratiometric luminescent thermometers. A TpBpy‐COF—prepared from 1,3,5‐triformylphloroglucinol (Tp) and 2,2′‐bipyridine‐5,5′‐diamine (Bpy) grafted with Eu/Tb and Dy acetylacetone (acac) complexes can be successfully used as a luminescent thermometer in the 10–360 K (Eu) and 280–440 K (Tb) ranges with good sensing properties (thermal sensitivity up to 1.403 % K−1, temperature uncertainty δT<1 K above 110 K). For the Eu/Tb systems, we observe an unusual and rarely reported behavior, that is, no thermal quenching of the Tb3+ emission, a result of the absence of ion‐to‐ligand/host energy back‐transfer. The LnCOF materials proposed here could be a new class of materials employed for temperature‐sensing applications following up on the well‐known luminescent metal–organic framework thermometers.
A hot candidate: Covalent organic frameworks (COFs) are reported to be an excellent support for the grafting of lanthanide ions/complexes and allow the development of novel types of luminescent thermometers. A unique behavior, that is, no thermal quenching of the Tb3+ emission, is observed in these LnCOF materials.
Hybrid materials displaying multistage security behavior, where a single material shows both wavelength‐ and temperature‐dependent luminescence properties, are reported. The materials consist of ...mixed‐lanthanide β‐diketonate complexes grafted into the pores of a nanosized 2,2′‐bipyridine‐5,5′‐dicarboxylate‐acid MOF. A very specific choice of lanthanides and their ratios, as well as β‐diketonate ligand, is crucial for obtaining the desired properties. The wavelength‐dependent luminescence properties of the materials are very well matched with the excitation wavelengths of a standard UV lamp, and a clearly visible change in luminescence is observed in a narrow temperature range (slightly below and above room temperature), proving them to be excellent materials for use in anti‐counterfeit technologies, which would be almost impossible to mimic.
Hybrid lanthanide/metal–organic‐framework materials for application in multistage security technologies are proposed. These materials show both wavelength‐ and temperature‐dependent luminescence properties. They exhibit “chameleon” behavior by changing their emission color in response to changes in the environment. For this application, the combination of Tb3+/Sm3+ is superior to that of Tb3+/Eu3+, which is most often investigated for temperature‐dependent luminescence.
Single‐cell and in situ cell‐based operation with nanopipette approach offers a possibility to elucidate the intracellular processes and may aid the improvement of therapy efficiency and precision. ...We present here a photo‐responsive hydrogel‐nanopipette hybrid system that can achieve single‐cell operation with high spatial/temporal resolution and negligible cell damage. This strategy overcomes long‐time obstacles in nanopipette single‐cell studies as high electric potential (ca. 1000 mV) or organic solvent is always used during operations, which would inevitably impose disturbance and damage to targeted cells. The light‐triggered system promotes a potential‐free, non‐invasive single‐cell injection, resulting in a well‐retained cell viability (90 % survival rate). Moreover, the photo‐driven injection enables a precisely dose‐controllable single‐cell drug delivery. Significantly reduced lethal doses of doxorubicin (163–217 fg cell−1) are demonstrated in corresponding cell lines.
The fabrication of photo‐responsive hydrogel‐nanopipette system ensures both precision single‐cell operation and high cell preservation. Upon light‐controlled, non‐invasive operation, a high cell viability over 90 % as well as precise quantification of injection are obtained. Hence, a single‐cell precise‐dosing is achieved with a minimum lethal dose of 163–217 fg cell−1.
A Pd/UiO-66 catalyst was synthesized with well-dispersed Pd nanoparticles. The obtained catalyst was tested in the hydrogenation of furfural to tetrahydrofurfuryl alcohol in various solvents, Water ...was found to be the most suitable solvent. Pd/UiO-66 exhibited much higher activity than Pd/SiO2 and Pd/γ-Al2O3, completely converting furfural to tetrahydrofurfuryl alcohol with 100% selectivity under mild conditions. The hydrogenation of CO moiety in tetrahydrofurfural was rate-determining step. Static adsorption measurement indicated that the adsorption of furfural on UiO-66 was significantly stronger than that on SiO2 or γ-Al2O3, suggesting that the adsorption play an important role in the gas-liquid-solid furfural hydrogenation reaction.
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•A Pd/UiO-66 catalyst was prepared with average Pd particle size of 2–3 nm.•100% selectivity to tetrahydrofurfuryl alcohol was achieved by Pd/UiO-66.•Hydrogenation of CO moiety in tetrahydrofurfural was the rate-determining step.
The hybrid materials that are created by supporting or incorporating polyoxometalates (POMs) into/onto metal–organic frameworks (MOFs) have a unique set of properties. They combine the strong ...acidity, oxygen-rich surface, and redox capability of POMs, while overcoming their drawbacks, such as difficult handling, a low surface area, and a high solubility. MOFs are ideal hosts because of their high surface area, long-range ordered structure, and high tunability in terms of the pore size and channels. In some cases, MOFs add an extra dimension to the functionality of hybrids. This review summarizes the recent developments in the field of POM@MOF hybrids. The most common applied synthesis strategies are discussed, together with major applications, such as their use in catalysis (organocatalysis, electrocatalysis, and photocatalysis). The more than 100 papers on this topic have been systematically summarized in a handy table, which covers almost all of the work conducted in this field up to now.
Determination of hydrogen peroxide (H2O2) with high sensitivity and selectivity in living cells is a challenge for evaluating the diverse roles of H2O2 in the physiological and pathological ...processes. In this work, we present novel surface enhanced Raman scattering (SERS) nanosensors, 4-carboxyphenylboronic acid (4-CA) modified gold nanoparticles (Au NPs/4-CA), for sensing H2O2 in living cells. The nanosensors are based on that the H2O2-triggered oxidation reaction with the arylboronate on Au NPs would liberate the phenol, thus causing changes of the SERS spectra of the nanosensors. The results show the nanosensors feature higher selectivity for H2O2 over other reactive oxygen species, abundant competing cellular thiols and biologically relevant species, as well as excellent sensitivity with a low detection limit of 80nM, which fulfills the requirements for detection of H2O2 in a biological system. In addition, the SERS nanosensors exhibit long term stability against time and pH, and high biocompatibility. More importantly, the presented nanosensors can be successfully used for monitoring changes of H2O2 levels within living biological samples upon oxidative stress, which opens up new opportunities to study its cellular biochemistry.
•We present novel surface enhanced Raman scattering nanosensors for detection of H2O2 in living cells.•The nanosensors feature higher selectivity for H2O2 and show excellent sensitivity with a low detection limit of 80nM.•The nanosensors can be successfully used for monitoring changes of H2O2 levels within biological samples under oxidative stress.
Upgrading furfural (FAL) to cyclopentanone (CPO) is of great importance for the synthesis of high-value chemicals and biomass utilization. The hydrogenative ring-rearrangement of FAL is catalyzed by ...metal-acid bifunctional catalysts. The Lewis acidity is a key factor in promoting the rearrangement of furan rings and achieving a high selectivity to CPO. In this work, highly dispersed Pd nanoparticles were successfully encapsulated into the cavities of a Zr based MOF, UiO-66-NO2, by impregnation using a double-solvent method (DSM) followed by H2 reduction. The obtained Pd/UiO-66-NO2 catalyst showed a significantly better catalytic performance in the aforementioned reaction than the Pd/UiO-66 catalyst due to the higher Lewis acidity of the support. Moreover, by using a thermal treatment. The Lewis acidity can be further increased through the creating of missing-linker defects. The resulting defective Pd/UiO-66-NO2 exhibited the highest CPO selectivity and FAL conversion of 96.6% and 98.9%, respectively. In addition, the catalyst was able to maintain a high activity and stability after four consecutive runs. The current study not only provides an efficient catalytic reaction system for the hydrogenative ring-rearrangement of furfural to cyclopentanone but also emphasizes the importance of defect sites.
A vanadium 2,6‐naphthalenedicarboxylate, VIII(OH)(O2C–C10H6–CO2)·H2O, denoted as COMOC‐3as (COMOC = Center for Ordered Materials, Organometallics and Catalysis, Ghent University), has been ...synthesized under hydrothermal conditions by means of both a solvothermal and a microwave synthesis procedure. The structure shows the topology of an aluminium 2,6‐naphthalenedicarboxylate, the so‐called MIL‐69 (MIL = Materials of the Institute Lavoisier). After calcination at 250 °C in air, the VIII center was oxidized to VIV with the structure of VIVO(O2C–C10H6–CO2) (COMOC‐3). The oxidation process was verified by cyclic voltammetry and EPR spectroscopy. The crystallinity was investigated by variable‐temperature XRD. The title compound is stable against air and moisture. The catalytic performance of COMOC‐3 was examined in the liquid‐phase oxidation of cyclohexene. COMOC‐3 exhibited similar catalytic performance to MIL‐47 VO(O2C–C6H4–CO2). The compound is reusable and maintains its catalytic activity through several runs.
A vanadium‐based metal–organic framework (COMOC‐3) has been synthesized and fully characterized. It crystallizes in the monoclinic system with the space group C2/c (no. 15). This closed MIL‐69 analogue shows excellent thermal stability and good catalytic performance in the liquid‐phase oxidation of cyclohexene. The catalyst can be regenerated and reused without significant loss of activity.
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