Latest ArticlesEfficient selective adsorption and separation using porous frameworks are critical in many industrial processes, where adsorption energy and dynamic diffusion rate are predominant factors governing selectivity. They are highly susceptible to framework charge, which plays a significant role in selective adsorption. Currently, ionic porous frameworks can be divided into two types. One of them is composed of a charged backbone and counter ions. The framework with zwitterionic channels is another type. It is composed of regular and alternating arrangements of cationic and anionic building units. Herein, we report a hydrogen-bonded ionic framework (HIF) of {(CN3H6)2[Ti(μ2O)(SO4)2]}n with 1D channel exhibits unique adsorption selectivity for Ar against N2 and CO2. Density functional theory (DFT) results suggest that CO2 cannot be adsorbed by HIF at the experimental temperature due to a positive adsorption free energy. In addition, due to a relatively large diffusion barrier at 77 K, N2 molecules hardly diffuse in HIF channels, while Ar has a negligible diffusion barrier. The unique net positively-charged space in the channel is the key to the unusual phenomena, based on DFT simulations and structural analysis. The findings in this work proposes the new adsorption mechanism and provides unique perspective for special separation applications, such as isotope and noble gasses separations.
Synergy strategy of photocatalysts and polymer resins are promising technology for marine antifouling. However, it is still a main challenge to obtain a green, safe, and efficient antifouling coatings. Herein, carbon (graphene or CNT) modified TiO2 photocatalyst was synthesized via hydrothermal and annealing process and has successfully applied in acrylate fluoroboron polymer (ABFP) composite coating. Morphology and chemical composition were detailed characterized. The graphene or CNT acted as a bridge with supplemental spatial structures (petal gaps, entanglement) and new functional groups (CO, CTiO, etc.) on TiO2 particle. Carbon nanotube (CNT) modified TiO2-ABFP coatings (BTCP) achieved excellent antibacterial and anti-diatom adhesion rate of 89.3%–96.70% and 99.00%–99.50%, which was 1.84–4.94-fold more than that of the single ABFP. CNT or graphene served as electronic bridges was considered as the crucial mechanism, which significantly improved the light absorption range and capacity, conductivity, and photoelectric response of TiO2, and further accelerated the generation and transfer of free radicals to the surface of BTCP or FTGP. Moreover, the improvement of catalyst activity synergizes with the smooth surface, hydrophilicity, and slow hydrolysis of composite coatings, achieved long-term and efficient antifouling performance. This work provides a new insight into the modification of TiO2 and antifouling mechanism of polymer coating.
Photocatalytic H2 production from water splitting is a promising candidate for solving the increasing energy crisis and environmental issues. Herein we report a novel g-C3N4/AgInS S-scheme heterojunction photocatalyst for water splitting into stoichiometric H2 and H2O2 under visible light. The catalyst was prepared by depositing 3D bimetallic sulfide (AgInS) nanotubes onto 2D g-C3N4 nanosheets. Owing to the special 3D-on-2D configuration, the photogenerated carriers could be rapidly transferred and effectively separated through the abundant interfacial heterostructures to avoid recombination, and therefore excellent performance for visible light-driven water splitting could be obtained, with a 24-h H2 evolution rate up to 237 µmol g−1 h−1. Furthermore, suitable band alignment enables simultaneous H2 and H2O2 production in a 1:1 stoichiometric ratio. H2 and H2O2 were evolved on the conduction band of g-C3N4 and on the valance band of AgInS, respectively. The novel 3D-on-2D configuration for heterojunction construction proposed in this work provided alternative research ideas toward photocatalytic reaction.
A visible light-promoted fast photochemical Wolff rearrangement was developed toward synthesis of α-substituted amides in continuous flow with the use of a photochemical oscillatory flow reactor (POFR). The control experiment indicates that a fast process of the Wolff rearrangement (<40 s) is involved. Notably, this protocol does not require excess use of any reactants, and the resulting α-substituted amides could be isolated by recrystallization in good to excellent yields.
The quest for efficient and durable catalysts using abundant resources has garnered significant interest in the field of bifunctional oxygen electrocatalysis. In this contribution, we have designed a FeN4 or CoN4 embedded graphene-based bilayer as active layer and TMC3 or TMN3 doped graphene as supporting layer, named as FeN4/TMC3 or FeN4/TMN3 and CoN4/TMC3 or CoN4/TMN3, wherein TM strands for transition metal. Based on density functional theory calculations, our results demonstrate that the interaction formed between dual metal atoms in the bilayer interspace leads to the coordination environment altered from flat four-coordination to spatial five-coordination, further stabilizing the bilayer structure and impairing its affinity toward the O-containing intermediates. According to thermodynamic analysis, the bilayers of CoN4/CoN3, FeN4/FeC3, FeN4/CoC3, FeN4/NiC3, FeN4/ZnC3, FeN4/FeN3, FeN4/CrN3 and FeN4/ZnN3 are attractively promising for bifunctional oxygen electrocatalysis due to the small overpotential difference Δη between oxygen reduction and oxygen evolution that are less than 1 V. Density functional theory calculations combined with machine learning analysis directly identify the key role played by the inter-binding formed between bilayers, that boosts catalytic activity, which establishes a predictable framework for a fast screen for graphene-based bilayer vertical heterojunction. This work opens up a new path for designing the efficient electrocatalysts via modification of coordination environment.
The nano-MOF-303 synthesized by microwave method exhibited efficient adsorption capacity (232 mg/g) toward Ag+, in which the adsorption behaviors were fitted by the pseudo-second-order kinetic and the Freundlich isotherm model. The outstanding Ag+ sorption ability of nano-MOF-303 could be contributed to electrostatic interactions, weak coordination interaction of Ag-N, and AgCl precipitates originating from the stored Cl− in nano-MOF-303. Besides the adsorbent regeneration, the formed Ag/AgCl onto nano-MOF-303 could produce Ag/AgCl/MOF-303 as a photocatalyst for sulfamethoxazole degradation under visible light. In this work, both the adsorption and photocatalysis mechanisms were clarified, which might provide insight to develop more effective adsorbents for mining the critical resource from the wastewater.
Accurate determination of lung cancer margins at the molecular level is of great significance to determine the optimal extent of resection during surgical operation and reduce the risk of postoperative recurrence. In this study, internal extractive electrospray ionization mass spectrometry (iEESI-MS) was used to trace potential molecular tumor margins in lung cancer tissue. Molecular differential model for the determination of lung cancer tumor margin was established via partial least-squares discriminant analysis (PLS-DA) of iEESI-MS data collected from lung tissue pieces within cancer tumor area and iEESI-MS data collected from lung tissue pieces outside cancer tumor area. Proof-of-concept data demonstrate that the developed molecular differential model yields ca. 1–2 mm wider potential molecular tumor margin of a lung cancer compared to the conventional histological analysis, showing promising potential of iEESI-MS to increase the accuracy of tumor margins determination and lower risk of lung cancer postoperative recurrence. Furthermore, our results revealed that creatine and taurine showed positive correlations with lung cancer.
It is well known that cationic polymers have excellent antimicrobial capacity accompanied with high biotoxicity, to reduce biotoxicity needs to decrease the number of cationic groups on polymers, which will influence antimicrobial activity. It is necessary to design a cationic polymer mimic natural antimicrobial peptide with excellent antibacterial activity and low toxicity to solve the above dilemma. Here, we designed and prepared a series of cationic poly(β-amino ester)s (PBAEs) with different cationic contents, and introducing hydrophobic alkyl chain to adjust the balance between antimicrobial activity and biotoxicity to obtain an ideal antimicrobial polymer. The optimum one of synthesized PBAE (hydrophilic cationic monomer: hydrophobic monomer = 5:5) was screened by testing cytotoxicity and minimum inhibitory concentration (MIC), which can effectively kill S. aureus and E. coli with PBAE concentration of 15 µg/mL by a spread plate bacteriostatic method and dead and alive staining test. The way of PBAE killing bacterial was destroying the membrane like natural antimicrobial peptide observed by scanning electron microscopy (SEM). In addition, PBAE did not exhibit hemolysis and cytotoxicity. In particular, from the result of animal tests, the PBAE was able to promote healing of infected wounds from removing mature S. aureus and E. coli on the surface of infected wound. As a result, our work offers a viable approach for designing antimicrobial materials, highlighting the significant potential of PBAE polymers in the field of biomedical materials.
This work develops a protein imprinted nanosphere with varied recognition specificity for bovine serum albumin (BSA) and lysozyme (Lyz) under different UV light through a gradient dual crosslinked imprinting strategy (i.e., covalent crosslinking and dynamic reversible crosslinking). The imprinting cavities are initially constructed using irreversible covalent crosslinking to specifically recognize BSA, and then the coumarin residues in the imprinting cavities are crosslinked under 365 nm UV light to further imprint Lyz, because Lyz has smaller size than BSA. Since the photo-crosslinking of coumarin is a reversible reaction, the imprinting cavities of Lyz can be de-crosslinked under 254 nm UV light and restore the imprinting cavities of BSA. Moreover, the N-isopropyl acrylamide (NIPAM) and pyrrolidine residues copolymerized in the polymeric surface of the nanospheres are temperature- and pH-responsive respectively. Therefore, the protein rebinding and release behaviors of the nanospheres are controlled by external temperature and pH. As a result, the materials can selectively separate BSA from real bovine whole blood and Lyz from egg white under different UV light. This study may provide a new strategy for construction of protein imprinted materials with tunable specificity for different proteins.
Pyridyl-based ketones and 1, 6-diketones are both attractive and invaluable scaffolds which play pivotal roles in the construction and structural modification of a plethora of synthetically paramount natural products, pharmaceuticals, organic materials and fine chemicals. In this context, we herein demonstrate an unprecedented, robust and generally applicable synthetically strategy to deliver these two crucial ketone frameworks via visible-light-induced ring-opening coupling reactions of cycloalcohols with vinylazaarenes and enones, respectively. A plausible mechanism involves the selective β-C-C bond cleavage of cycloalcohols enabled by proton-coupled electron transfer and ensuing Giese-type addition followed by single electron reduction and protonation. The synthetic methodology exhibits broad substrate scope, excellent functional group compatibility as well as operational simplicity and environmental friendliness.
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