Latest ArticlesRecognized as one of the important active species involved in various reactions, singlet oxygen (1O2) shows potential applications in chemical, biological, and environmental related fields. However, the controlled capture and release of 1O2 are still facing huge challenges due to its short lifetime and high reactivity. Herein, a framework-interpenetration tuning strategy was applied on a metal-organic framework (MOF) that aiming to improve the capture and release rate of 1O2. The porosity of the MOF was remarkably enhanced with the structural evolution from seven-fold (termed NKM-181) to six-fold interpenetration (termed NKM-182), and the active anthracene sites became much more accessible. Such drastic process can be achieved as simple as exchanging the primitive MOF in selected solvent and occurred surprisingly as single-crystal to single-crystal transformation. Also, additionally owing to the unblocked regular channels, NKM-182 shown significantly improved 1O2 trapping and releasing rates compared to that of in NKM-181. This work demonstrates an unprecedented regulation of 1O2 capture and release process, along with achieving the highest 1O2 capture and release rate among reported porous materials. Furthermore, the obtained endoperoxides with 1O2 loaded (termed EPO-NKM-181 and EPO-NKM-182) can be used as a high efficiency smart material for anti-fake application
Template-oriented multi-component synthesis method has been proven to be an exceedingly reasonable and excellent method for the synthesis of giant two-dimensional (2D) and three-dimensional (3D) supramolecules, but designing and constructing heteroleptic and controllable self-assembly without unexpected by-products remains a challenge. Here we report two discrete trefoil-shaped metallacycle S1 and metallacage S2 by heteroleptic self-assembly using one hexaphenylbenzene core ligand and two capping ligands. The 2D trefoil-shaped metallacycle S1 could resemble the emblem of the classic 'Mitsubishi' motif. The use of template-oriented ligand and bent spacer ligand promotes the quantitative formation of the desired 3D trefoil-shaped metallacage S2. The formed metallacage S2 possesses a molecular weight up to 36 kDa, diameter 6.6 nm and height 3.0 nm. All supramolecular coordination complexes were fully characterized by NMR spectroscopy (1H NMR, 2D COSY, 2D NOESY, 2D DOSY), high-resolution electrospray ionization mass spectrometry ESI-MS, ESI-TWIM-MS, TEM and AFM.
Epoxidation is an important chemical process for the production of epoxides, key building blocks in chemical industry. Despite great efforts being made to facilitate this process, it remains a significant challenge to develop cost-effective, environmental-friendly, and selective catalysts. Herein, we reported a highly dispersed Mn supported by g-C3N4 (Mn/g-C3N4) with Mn loading up to 2.56 wt%. The Mn/g-C3N4 exhibited satisfied catalytic performance for olefin epoxidation with excellent conversion (91%), high selectivity (93%) as well as outstanding recycling stability. Further analysis revealed the importance of Mn-N structure for the generation of active oxo-containing species and subsequent oxygen atom transfer. Besides, an efficient synthesis of cyclic carbonates from styrene epoxide and CO2 has been achieved (88% conversion, 89% selectivity) based on the polar Mn-N coordinated characteristics of Mn/g-C3N4 catalyst.
Two-dimensional organic-inorganic hybrid ferroelastics with high-temperature reversible phase transitions are very rare and have become one of the research hotspots in the field of ferroelastic materials. Herein, we report three new layered organic-inorganic hybrid perovskites based on halogen-substituted phenethylaminium, (3-XC6H5CH2CH2NH3)2[CdCl4] (X = F (1), Cl (2) and Br (3)). They undergo structural phase transitions at 376/371 K, 436/430 K, and 421/411 K, respectively, between the isomorphic high-temperature phases (space group I4/mmm, Z = 2) and different room-temperature phases with the reduced structural symmetries, i.e., P21/a (Z = 2) in 1, (Z = 4) in 2, and P21/a (Z = 4) in 3, respectively. These ferroelastic transitions arise from the order-disorder transition of organic cations together with the synchronous displacement of inorganic layers, accompanying with ferroelastic spontaneous strains of 0.16, 0.13 and 0.12 for 1−3, respectively. By enriching layered perovskite ferroelastics based on halogen-substituted cations, this work provides important clues for exploring new ferroic materials based on hybrid crystals.
A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes (P1) and 3,9-diazatetracyclododecanes (P2) is reported for the first time. The types of reaction product clearly differ with solvent, regardless of the irradiation wavelength. The difference in P1 and P2 lies in the second step of the intramolecular [2 + 2] photocyclization. In order to further investigate this phenomenon and gain a deeper understanding of the photochemical behavior of 1,4-dihydropyridines, DFT and TDDFT theoretical calculations are performed. The results provide a good explanation for the formation of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes.
Accurate and sensitive detection of cancer cells is of significant importance for early diagnosis and treatment of cancer. Here, we developed an extracellular ATP-activated hybridization chain reaction (HCR) amplification strategy to meet this purpose. This strategy relies on three DNA probes, Apt-trigger, H1-ATP aptamer duplex and hairpin H2. The Apt-trigger probe consists of two components: an aptamer sequence for specific recognition of the target cells, and a trigger sequence for the HCR assembly. The duplex structure of H1-ATP aptamer causes the toehold in hairpin H1 to be hidden, preventing the strand-displacement reaction between hairpin H1 and Apt-trigger. Upon activation with ATP, the ATP aptamer will bind to ATP to dissociate from hairpin H1, thus leading to an Apt-trigger-induced strand-displacement reaction and subsequent HCR with hairpin H2 on the target cell surface. Benefiting from aptamer recognition and ATP-activated HCR amplification, this strategy can not only perform sensitive quantitative analysis with a detection limit of 25 cells in 200 µL of binding buffer, but also show desirable specificity and accuracy for identifying target cells from control cells and mixed cell samples. Importantly, this method retains stable and good performance for target cell detection in 10% fetal bovine serum, demonstrating great potential for clinical diagnosis in complex biological matrices. Furthermore, this strategy can be adapted to detect various types of cancer cells by changing the corresponding aptamer sequence.
Poly(m-phthaloyl-m-phenylenediamine) (PMIA) is promising as the separator in lithium-ion batteries (LIBs) for its excellent thermostability, insulation and self-extinguishing properties. However, its low mechanical strength and poor electrolyte affinity limit its application in LIBs. In this work, a new PMIA@polyacrylonitrile-polyvinylidene fluoride hexafluoropropylene-titanium dioxide (PMIA@PAN/PVDF-HFP/TiO2) composite fibrous separator with a coaxial core-shell structure was developed by combining coaxial electrospinning, hot pressing, and heat treatment techniques. This separator not only inherits the exceptional thermostability of PMIA, showing no evident thermal shrinkage at 220 ℃, but also reveals improved mechanical strength (29.7 MPa) due to the formation of firm connections between fibers with the melted PVDF-HFP. Meanwhile, the massive polar groups in PVDF-HFP play a vital role in improving the electrolyte affinity, which renders the separator a high ionic conductivity of 1.36 × 10−3 S/cm. Therefore, the LIBs with PMIA@PAN/PVDF-HFP/TiO2 separators exhibited excellent cycling and rate performance at 25 ℃, and a high capacity retention rate (76.2%) at 80 ℃ for 200 cycles at 1 C. Besides, the lithium metal symmetric battery assembled by the separator showed a small overpotential, indicating that the separator had a role in inhibiting lithium dendrites. In short, the PMIA@PAN/PVDF-HFP/TiO2 separator possesses a wide application prospect in the domain of LIBs.
Because of abundant redox activity, broad tunability, and specific atomic structure, polyoxometalates (POMs or POM) clusters have attracted burgeoning interests in electrochemical especially energy storage fields. Nevertheless, due to the high solubility and fully oxidized state, they often suffer from electrically insulation as well as chemical and electrochemical instability. Traditional noncovalent loading or covalent grafting of POMs on conductive substrates have been successfully performed to overcome this problem. However, severe shedding or agglomeration of POMs arising from weak interactions with substrates or excessive entrapment or weak destruction in conductive supports cause significantly reduced availability and stability. To this end, precise confinement of POMs into conductive supports has been tried to improve their dispersibility and stability. Herein, recent progress of POMs from surface loading to precise confinement in the electrochemistry energy storage field is reviewed. Firstly, we illustrate the typical non-confinement methods (viz. covalent and non-covalent) for supported POMs in energy storage applications. Secondly, different strategies for precise confinement of POMs in organic and inorganic materials for related applications are also discussed. Finally, future research directions and opportunities for confined POMs, and derived ultrafine nanostructures are also proposed. This review seeks to point out future research directions of supported POMs in the electrochemistry-related fields.
Zinc-air batteries (ZABs) are regarded as promising next-generation energy storage devices but limited by their sluggish oxygen reduction/evolution reactions (ORR/OER). Herein, the bifunctional catalyst consisting of MXene and metal compounds has been constructed via a controllable strategy. For demonstration, a 3D MXene framework with anchored heterostructure CoNi/CoNiP and nitrogen-doped carbon (NC) called H-CNP@M is constructed by metal-ion inducement and phosphorization. The bimetal-semiconductor heterostructure greatly enhances the catalytic performance. The H-CNP@M exhibits superior activities toward ORR (E1/2 = 0.833 V) and OER (η10 = 294 mV). Both aqueous and all-solid-state ZAB assembled with H-CNP@M demonstrate superior performance (peak power density of 166.5 mW/cm2 in aqueous case). This work provides a facile and general strategy to prepare MXene-supported bimetallic heterostructure for high-performance electrochemical energy devices.
Detection of mercury ions (Hg2+) in actual samples is of significant importance due to the toxicity of Hg2+ to human health. In this work, a simple tetraphenylethene (TPE) derived fluorescent probe TPE-Hg based on aggregation-induced emission (AIE) mechanism was synthesized. TPE-Hg can visually recognize Hg2+ in THF/HEPES (1:9, v/v, HEPES 20 mmol/L, pH 7.3) system with rapid response, strong anti-interference ability, large Stokes shift (203 nm), and low detection limit (7.548 × 10−7 mol/L). The results show that Hg2+ triggered elimination of TPE-Hg lead to releasing of an AIE-active compound 2 is responsible to the sensing mechanism. TPE-Hg is applicable to detect Hg2+ in actual water samples and image Hg2+ in living MCF-7 cells. In addition, TPE-Hg is suitable to assay the Hg2+ level in seafood and tea samples, and it is also applicable in test strips.
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