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.
The CO2 photoconversion is sensitive to the local reaction environment, of which activity and selectivity can be regulated by the change of reaction systems. This paper focuses on investigating the photocatalytic CO2 reduction behaviors of MOFs with the involvement of water under different reaction modes, including gas-solid and liquid-solid systems. The CO2 photoreduction in a liquid-solid system shows high performance in generating HCOOH with the selectivity of 100%. In contrast, the gas-solid system referring to the synergistic interaction of MOFs and H2O vapor benefits to the formation of gas-phase products, such as CO and CH4. The possible mechanisms of photocatalytic CO2 reaction in two modes were investigated by in-situ Fourier-transform infrared spectroscopy, which indicates that the distinction in reaction consequence may result from the difference in CO2 chemisorbed modes and the proton provision. The choice of reaction system plays an important role in the achievement of high efficiency and selectivity for photocatalytic CO2 reduction, which is of great practical value in real-world applications.
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.
A double-cable conjugated polymer DCPIC-BO is designed via introducing a long-branched alkyl chains 2-buthyloctyl into the acceptor side unit. Compared with the double-cable polymer (DCPIC-EH) with the 2-ethylhexyl alkyl chains, the solubility of the DCPIC-BO in non-halogen solvents is substantially improved. Therefore, a power conversion efficiency (PCE) of 9.77% can be obtained by the devices processed from o-xylene at 40 ℃, while the DCPIC-EH cannot be processed due to its poor solubility under this condition. Moreover, PCEs of 10.10% for small-area (0.04 cm2) devices and nearly 9% for devices with an area of 1 cm2 are achieved using a non-halogenated solid additive in o-xylene, realizing the "absolutely halogen-free" OSC fabrication.
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.
Wettability transition is a significant responsive mechanism which is widely applied to construct smart materials and systems. The broad-spectrum responsiveness of the wettability transition makes it a promising way to expand innovative applications. Here, we develop a track-guided self-transportation system mediated by sequential wettability transition accompanied with capillary transportation. Alkaline fuel is loaded into polydimethylsiloxane (PDMS) cuboid to trigger the wettability transition of distributed superhydrophobic tracks laid in shallow water. After the wettability transition, the induced capillary force can propel the repetitive track-to-track transportation of PDMS. Importantly, the spacing between adjacent tracks is rationally designed based on multiple factors including threshold of wettability transition, diffusion kinetics and capillary interaction. Furthermore, the track-guided transportation system is applied to realize directed self-assembly of multiple PDMS building blocks for designated configuration, which increases the complexity and intelligence of self-assembly systems.
Emerging organic pollutants (EOPs) in water are of great concern due to their high environmental risk, so urgent technologies are needed for effective removal of those pollutants. Herein, a heterogeneous advanced oxidation process (AOP) of peroxymonosulfate (PMS) activation by functional material was developed for degradation of a typical antibiotic, gatifloxacin (GAT). The reactive species including sulfate radical (SO4•−) and singlet oxygen (1O2) in this AOP were regulated by interlayered ions (Na+/H+) of titanate nanotubes that supported on Co(OH)2 hollow microsphere. Both the Na-type (NaTi-CoHS) and H-type (HTi-CoHS) materials achieved efficient PMS activation for GAT degradation, and HTi-CoHS even exhibited a relatively high degradation efficiency of 96.6% within 5 min. Co(OH)2 was considered the key component for generation of SO4•− after PMS activation, while hydrogen titanate nanotubes (H-TNTs) promoted the transformation of peroxysulfate radical (SO5•−) to 1O2 by hydrogen bond interaction. Therefore, when the interlayer ion of TNTs transformed from Na+ to H+, more 1O2 was produced for organic pollutant degradation. H-TNTs with lower symmetry preferred to adsorb PMS molecules to achieve interlayer electron transport through hydrogen bonding, rather than electrostatic interaction of Na+ for Na-TNTs. In addition, the degradation pathway of GAT mainly proceeded by the cleavage of C–N bond at the 8 N site of the piperazine ring, which was confirmed by condensed Fukui index and mass spectrographic analysis. This work gives new sights into the regulation of reactive species in AOPs by the composition of material and promotes the understanding of pollutant degradation mechanisms in water treatment process.
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.
Graphene and its derivatives have sparked intense research interest in wearable temperature sensing due to their excellent electric properties, mechanical flexibility, and good biocompatibility. Despite these advantages, the weak temperature dependence of charge transport makes them difficult to achieve a highly sensitive temperature response, which is one of the remaining bottlenecks in the progress towards practical applications. Unfortunately, detailed knowledge about the key factors of the charge transport temperature dependence in this material that determines the critical performance of electrical sensors is very limited up to now. Here, we reveal that oxygen absorption on the ultrathin reduced graphene oxide (RGO) films (~3 nm) can significantly increase their conductance activation energy over 200% and thus greatly improve the temperature dependence of thermal-activated charge transport. Further investigations suggest that oxygen introduces the deep acceptor states, distributed at an energy level ~0.175 eV from the valence-band maximum, which allows a highly temperature-dependent impurity ionization process and the resulting vast holes release in a wide temperature range. Remarkably, our temperature sensors based on oxygen-doped ultrathin RGO films show a high sensitivity with temperature conductive coefficient of 14.58% K−1, which is one order of magnitude higher than the reported CNT or graphene-based devices. Moreover, the ultrathin thickness and high thermal conductivity of RGO film allow an ultrafast response time of ~86 ms, which represents the best level of temperature sensors based on soft materials. Profiting from these advantages, our sensors show good capacity to identify the slight temperature difference of human body, monitor respiratory rate, and detect the environmental temperature. This work not only represents substantial performance advances in temperature sensing, but also provides a new approach to modulate the charge transport temperature dependence, which could be benefited to both device design and fundamental research.
Drug-resistant bacteria present a severe threat to public health, emphasizing the importance of developing broad-spectrum antibacterial agents that are free from drug resistance. Among silver-based antibacterial agents, nano-silver has been found to exhibit the most promising and comprehensive performance. The exploration of the antibacterial capacity and morphological changes of silver nanoparticles (AgNPs) could offer a starting point for the development of safe and efficient antibacterial agents. In this study, three types of nano-silver-modified polyphosphazene (PRV) nanoparticles with different morphologies were synthesized using precipitation polymerization. These nanoparticles were characterized using various techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The antibacterial activity of these nanoparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was assessed using minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) tests and inverted fluorescence microscopy. Our results revealed that the antibacterial activity of silver nanoparticles can vary significantly depending on their immobilized form. Ag@PRV Strawberry-like nanoparticles (NPs) exhibited higher antibacterial activity compared to Ag@PRV Yolk-Shell NPs and Ag@PRV Cable-like nanofibers (NFs). Notably, all three types of synthesized nanoparticles demonstrated a stronger bactericidal effect on Gram-positive bacteria than Gram-negative bacteria. Live/dead bacterial staining and scanning electron microscopy demonstrated that silver can kill bacteria by altering the permeability of their cell membranes. These findings offer valuable insights for designing and practically applying new silver-based antibacterial agents in the future.
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