Latest ArticlesSupramolecular interactions such as π-π stacking interaction and charge transfer interaction have drawn much attention in the design and construction of various supramolecular assemblies. Herein, partially oxidized pillar[5]arene (P5A), pillar[4]arene[1]quinone (P4A1Q), pillar[3]arene[2]quinone (P3A2Q), and pillar[2]arene[3]quinone (P2A3Q) were synthesized by one-step reaction. As indicated by experimental characterization data and density function theory modeling results, charge transfer interaction among partially oxidized P5A plays a significant role in host-host self-assembly behavior and corresponding packing morphology. This work provides a unique strategy for the construction of functional macrocyclic assemblies through host-host self-assembly.
High efficiency and low-cost catalyst-driven electrocatalytic CO2 reduction to CO production are of great significance for energy storage and development. The severe competitive hydrogen evolution reaction occurs at large negative potential window limits the achievement of the target product from CO2 at high efficiency. Here, we successfully prepared Cux/CdCO3 composite catalyst rich in interfaces, in which achieved high CO Faraday efficiency exceeded 90% in a wide potential window of 700 mV and highest value up to 97.9% at −0.90 V vs. RHE. The excellent performance can be ascribed to the positive contribution of Cux/CdCO3, which maintains a suitable high local pH value during electrochemical reduction, thus inhibiting the competitive hydrogen evolution reaction. Moreover, the compact structure between Cu and CdCO3 ensures fast electron transfer both inside catalysts and interface, thus speeding up the reaction kinetics of CO2 to CO conversion. Theoretically calculations further prove that the combination of Cu and CdCO3 provides the well-defined electronic structure for intermediates adsorption, significantly reducing the reaction barrier for the formation of CO. This work provides new insights into the design of efficient electrochemical CO2 reduction catalysts for inhibiting hydrogen evolution by adjusting the local pH effect.
Aprotic lithium-air batteries (LABs) have been known as the holy grail of energy storage systems due to their extremely high energy density. However, their real-world application is still hindered by the great challenges from the Li anode side, like dendrite growth and corrosion reactions, thus a pure oxygen atmosphere is usually adopted to prolong the lifetime of LABs, which is a major obstacle to fully liberate the energy density advantages of LABs. Here, a gel polymer electrolyte has been designed through in-situ polymerization of 1,3-dioxolane (DOL) by utilizing the unique semi-open nature of LABs to protect the Li anode to conquer its shortcomings, enabling the high-performance running of LABs in the ambient air. Unlike common liquid electrolytes, the in-situ formed gel polymer electrolyte could facilitate constructing a gradient SEI film with the gradual decrease of organic components from top to bottom, preventing the Li anode from dendrite growth and air-induced corrosion reactions and thus realizing durable Li repeated plating/stripping (2000 h). Benefiting from the anode protection effects of the gradient SEI film, the LABs display a long lifetime of 170 cycles, paving an avenue for practical, long-term, and high-efficiency operation of LABs.
Reactive oxygen species (ROS) are essential for biological processes like cell signaling and chemical processes like organic oxidation. Moreover, the sufficient generation of ROS plays a significant role in targeted tumor treatments or oxidation of organics. Herein, a hydrazone-linked porphyrin covalent organic framework (Por-DETH-COF) is developed for red light-induced generation of ROS like singlet oxygen (1O2) or superoxide (O2•−) to undertake different but targeted oxidations. First, 1O2 is adopted in photodynamic therapy (PDT) for the oxidation of glioma cells. The PDT efficiency of Por-DETH-COF on the apoptosis of glioma cells is explored through flow cytometry and western blot assay. The apoptosis rate of glioma cells significantly increases over Por-DETH-COF under 660 nm red light illumination, suggestive of the potency of 1O2. Second, O2•− is employed for the targeted oxidation of thiols. A series of thiols could be efficiently oxidized to corresponding disulfides over Por-DETH-COF under 660 nm red light illumination, indicative of the significance of O2•−. This work highlights the potential of covalent organic frameworks in generating ROS for precise medical applications of complex chemical environments.
Herein, we describe the selective formation of a barrel-shaped or a ball-shaped fluorescent metallacage by controlling the shape and stoichiometry of the building blocks. Specifically, the tetraphenylethylene-based donor and two acceptors with different numbers of Pt(Ⅱ) centers were combined via coordination-driven self-assembly. Owing to the differences in the shapes of the assemblies, the resultant ball-shaped metallacage displayed stronger and blue-shifted fluorescence compared to the barrel-shaped one in dilute solutions, while a reversal of fluorescence intensities was observed in the aggregation process. Overall, this work demonstrates that the photophysical properties of supramolecular coordination complexes can be affected by subtle geometrical factors, which can be controlled precisely at the molecular level.
Metal-organic frameworks (MOFs) received considerable attention to adsorption and removal of various environmental pollutants because of some inherent advantages. However, it is challenging but meaningful to design and fabricate hierarchical mixed-dimensional MOFs with synergistic effects to enhance the performance for removal and preconcentration of environmental pollutants. Herein, a new hierarchical two-dimensional (2D)-three-dimensional (3D) mixed-dimensional cactus‐like MOF@MOF hybrid material (PCN-134@Zr-BTB) was prepared by in-situ growth of 2D MOF nanosheets (Zr-BTB) on the surface of 3D MOF (PCN-134). The PCN-134@Zr-BTB composites combine the advantages of 2D and 3D MOFs with extensive mesoporous structures and large surface area for effective removal and enrichment of bisphenols (BPs). In comparison with pristine PCN-134 and Zr-BTB materials, the PCN-134@Zr-BTB hybrid material presented excellent adsorption performance for BPs. The adsorption isotherms are consistent with the Langmuir model, and the maximum adsorption capacity of four bisphenols (BPs) ranged from 135.1 mg/g to 628.9 mg/g. The adsorption kinetics are in accordance with the pseudo-second-order model. The recoveries ranged from 72.8% to 108%. The limits of detection were calculated at 0.02–0.03 ng/mL. The enrichment factors were calculated in the range of 310–374. According to FT-IR and XPS analysis, the main adsorption mechanisms are hydrogen bonding and π-π stacking. Nevertheless, this work provides a new and convenient strategy for the preparation of new hierarchical mixed-dimensional MOF@MOF (PCN-134@Zr-BTB) hybrid material for extraction and enrichment of BPs from aqueous matrix.
α-Cyanostilbene (CS) based organic luminescent materials with efficient electrical conductivity, aggregation-induced enhanced emission, and controllable multi-colour emission properties, have been aroused wide attention by scientists over the past few years. Self-assembly of CS-motif in aqueous media refers to an environment-friendly method for preparing luminescent materials. However, it is still challenging to control the intrinsic hydrophobic properties of the organic components in aqueous media. In this study, an amphiphilic dicyanostilbene-functionalized thiophene (ACSTP) derivative was synthesized. Z-ACSTP was identified to dissolve in different organic solvents, accompanied with strong and tunable fluorescence emission. However, when Z-ACSTP was dispersed in water, it was self-assembled into nanofibers, and the fluorescence was red shifted, accompanied with sharp decrease of intensity compared with that in DMSO. Furthermore, Z-form of ACSTP to its E-form under 365 nm irradiation led to the morphology transformation from nanofibers to nanosheets. Notably, upon addition of water-soluble pillar[5]arene (WP5), the nanofibers were transformed into fluorescent hollow particles due to the host–guest interactions between the pyridinium group and WP5 and the obtained fluorescent particles can be further applied in living cell imaging.
Highly enantioselective sulfa-Michael additions (SMA) between 2-alkenyl quinoxalines and aromatic thiols are accomplished using a low loading of chiral phosphoric acid catalyst (1 mol%). It was confirmed by an investigation of a lot of azaarenes that the two C=N units of quinoxalines are indispensable for controlling the reaction enantioselectivities. A series of non-terminal 2-alkenes substituted with aryls or alkyls, even other electro-withdrawing groups such as ketones, esters, or amides, selectively reacted and afforded the desired SMA products (48 examples) in good regioselectivities with high yields (up to 99%) and good ee values (up to 97%).
Herein, we report a semi-synthetic strategy affording a nitrophorin 2 (NP2) variant with a N,N′-bis(2-pyridylmethyl)amine (Dpa) ligand as sidechain selectively installed at position 27, which was assembled from a synthetic peptide thioester bearing the Dpa ligand and an expressed protein segment via native chemical ligation. The semi-synthetic NP2 was able to accept the natural heme b cofactor and the Dpa ligand was able to bind Cu(Ⅱ)/Fe(Ⅲ) ions, leading to heteronuclear active site.
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