Latest ArticlesPotassium-ion batteries (PIBs) have attracted enormous attention due to the abundance of potassium resources, low cost, fast ionic conductivity of electrolyte and relatively high operating voltage. Despite great efforts and progress, researches on PIBs are still at the initial stage, especially in the emerging field of flexible and wearable PIBs. The inevitable challenges for PIBs include low reversible capacity, unsatisfactory cycling stability and insufficient energy density, the solution to which mostly relies on designing advanced electrodes. Binder-free electrodes have emerged as promising electrode architecture for PIBs. Such electrodes avoid the use of insulating binders, which can be designed with various synergistic functional materials to address the aforementioned PIB issues and be endowed with flexibility/wearability. In this review, we mainly summarize the recent progress on binder-free electrodes for PIBs, with the focus on the methodologies, detailed strategies and functional materials for electrode construction. One strategy for binder-free electrodes is to assemble free-standing architecture with the help of carbon nanotubes (CNTs), graphitic fibers, and other carbon or mechanically robust materials, either alone or in combination. The other effective strategy is current collector substrate-assisted direct growth, including the use of carbon cloth, metal, MXenes and other conductive substrates. Additionally, challenges and research opportunities are put forward at the end as the guidance for future development of binder-free PIB devices.
Pillar[n]arene-based amphiphiles, mainly including amphiphilic pillar[n]arenes and supra-amphiphilic pillar[n]arenes, have obtained considerable interests in recent years due to their fascinating chemical structures, various self-assembly behaviors, and widely applications. Thanks to the pillar-like frameworks and the rich host-guest recognitions of the cavities, these amphiphiles can be easily controlled to form dimensional and morphologic assemblies for multiple applications. Compared with traditional linear covalent amphiphiles, the introduction of host-guest recognitions facilitated the preparation and controllability of these supramolecular amphiphilic systems. Moreover, the host-guest recognitions endow the assemblies from pillar[n]arene-based amphiphiles with stimuli-responsive functions. In this mini-review, we summarized the chemical structures, self-assembly features, and the applications of pillar[n]arene-based amphiphiles. However, several research topics of pillar[n]arene-based amphiphiles can be further developed in the future, such as larger cavity amphiphilic pillar[n]arenes, co-assembly with 2D materials and utilization of the host-guest interactions.
Luminescent conjugated network polymer is one of the most promising chemo-sensors owing to their good chemical/optical stability and multiple functionalization. Herein, three conjugated network polymers were prepared by using aggregation-induced emission active 1, 1, 2, 2-tetrakis(4-formyl-(1, 1'-biphenyl))-ethane (TFBE) unit as monomer and hydrazine as linker. Through regulating the synthetical condition, the polymeric network can form either uniform two-dimensional azine-linked nanosheets (A-NS), conjugated microporous polymers (A-CMP) or covalent organic frameworks (A-COF). All of these polymers exhibited good stability and high fluorescence quantum efficiency with the quantum yield of 6.31% for A-NS, 5.26% for A-CMP, and 5.80% for A-COF, as well as fast and selective fluorescence quenching response to 2, 4, 6-trinitrophenol (TNP). And the best TNP sensing performance with the Stern-Volmer constants (Ksv) values up to 8×105 L/mol and a detection limit of 0.09 μmol/L was obtained for A-NS. The study explores various strategies to construct conjugated polymers with different nanoarchitectures based on the same building block for sensitive detection of explosives.
Using particle swarm optimization (PSO) methodology for crystal structure prediction, we predicted a novel two-dimensional (2D) monolayer of silicide diphosphorus compound: SiP2, which exhibits good stability as examined via cohesive energy, mechanical criteria, molecular dynamics simulation and all positive phonon spectrum, respectively. The SiP2 monolayer is an indirect semiconductor with the band gap as 1.8484 eV (PBE) or 2.681 eV (HSE06), which makes it more advantageous for high-frequency-response optoelectronic materials. Moreover, the monolayer is a relatively hard auxetic material with negative Possion's ratios, and also possesses a ultrahigh carrier mobility (1.069×105 cm2 V-1 s-1) which is approximately four times the maximum value in phosphorene and comparable to the value of graphene and CP monolayers. Furthermore, the effects of strains on band structures and optical properties of SiP2 monolayer have been studied, as well as CO2 molecules can be strongly chemically adsorbed on the SiP2 monolayer. A semiconductor-to-metal transition for -9.5% strain ratio case and a huge optical absorption capacity on the order of 106 cm-1 in visible region present. These theoretical findings endow SiP2 Monolayer to be a novel 2D material holding great promises for applications in high-performance electronics, optoelectronics, mechanics and CO2 capturing material.
Multishelled hollow structures have drawn increasing interest because of their peculiar compartmentation environments and physicochemical properties. In this work, deformable double-shelled hollow mesoporous organosilica nanocapsules (DDHMONs) were successfully synthesized by a multi-interfacial etching strategy. The obtained DDHMONs have a double-shelled structure with aninorganic-organic hybrid framework, a uniform outer layer (~320 nm) and inner layer (~180 nm), ordered mesochannels (~2.21 nm), and a large specific surface area (~1233 m2/g). In vitro toxicity tests show that the DDHMONs have excellent biocompatibility when coincubated with human breast cancer cells. In addition, the anticancer substance doxorubicin (DOX) can be highly loaded in DDHMONs (~335 μg/mg). The results from flow cytometry together with confocal laser scanning microscopy show that DOX can be efficiently delivered into MCF-7 cells by DDHMONs, thus improving chemotherapeutic efficiency and demonstrating that DDHMONs have potential nanomedicine applications as anticancer agents.
Structure-efficacy effect of small molecular drug attracts wide attentions, but it has always been ignored in nanomedicine research. To reveal the efficacy modulation of nanomedicine, we developed a new type of paclitaxel (PTX)-conjugated gold nanoparticles (PTX-conjugated GNPs) to investigate the influence of drug position in controlling their in vitro properties and in vivo performance. Two therapeutic ligands (TA-PEG-NH-N=PTX and TA-PTX=N-NH-PEG) were synthesized to conjugate PTX on the surface of GNPs at different positions, locating on the surface of gold conjugate and inserting between GNPs and polyethylene glycol (PEG, molecular weight 1000 Da), respectively. It was found that PEG-PTX@GNPs with PTX located between GNP and PEG exhibited higher aqueous solubility, biocompatibility, and stability. In addition, an acid sensitive hydrazone bond has been inserted between PTX and PEG in both ligands for drug release of PTX and PTX-PEG segment, respectively, at the tumor site. Further release of PTX from PTX-PEG segment is based on the esterase hydrolysis of an ester bond between PTX and PEG. This two-step drug release mechanism offers PEG-PTX@GNPs effective and sustained release behavior for desirable anticancer activity, enhanced therapeutic efficacy, and lower systematic toxicity in Heps-bearing animal models.
In continuation of our efforts toward the discovery of potent HIV-1 NNRTIs with diverse structures, a series of novel S-DACO analogues of 6-(2-cyclohexyl-1-alkyl)-2-(2-oxo-2-phenyl-ethylsulfanyl)pyrimidin-4(3H)-ones were designed, synthesized and evaluated for their antiviral activities in MT-4 cells. Most of these new compounds showed moderate to good activities against wild type HIV-1 with IC50 values ranging from 7.55 μmol/L to 0.018 μmol/L. Among them, compound 5c was identified as the most promising inhibitor against HIV-1 replication with an IC50 = 0.018 μmol/L, CC50 = 194 μmol/L, and SI = 12791, which was much more potent than the reference drugs NVP and DLV and comparable to AZT and EFV. In addition, 5c also exhibited improved activity against double mutant HIV-1 strain RES056 compared to that of the reference drugs NVP/DLV and DB02. The preliminary structure-activity relationship (SAR) and molecular modeling studies were also discussed, which provides some useful indications for guiding the further rational design of new S-DACO analogues.
Using the global particle-swarm optimization method and density functional theory, we predict a new stable two-dimensional layered material: MgSiP2 with a low-buckled honeycomb lattice. Our HSE06 calculation shows that MgSiP2 is an indirect-gap semiconductor with a band-gap of 1.20 eV, closed to that of bulk silicon. More remarkably, MgSiP2 exhibits worthwhile anisotropy along with electron and hole carrier mobility. A ultrahigh electron mobility is even up to 1.29×104 cm2 V-1 s-1, while the hole mobility is nearly zero along the a direction. The large difference of the mobility between electron and hole together with the suitable band-gap suggest that MgSiP2 may be a good candidate for solar cell or photochemical catalysis material. Furthermore, we explore MgSiP2 as an anode for sodium-ion batteries. Upon Na adsorption, the semiconducting MgSiP2 transforms to a metallic state, ensuring good electrical conductivity. A maximum theoretical capacity of 1406 mAh/g, a small volume change (within 9.5%), a small diffusion barrier (~0.16 eV) and low average open-circuit voltages (~0.15 V) were found for MgSiP2 as an anode for sodium-ion batteries. These results are helpful to deepen the understanding of MgSiP2 as a nanoelectronic device and a potential anode for Na-ion batteries.
A nickel(Ⅱ)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions generated in situ from corresponding acetals with carboxylic acid derivatives to prepare β-alkoxyl carbonyl moieties with diverse α-substituents has been disclosed. The method exhibited broad scope of acetals and carboxylic acid derivatives with excellent enantioselectivity and good functional group compatibility, and can be conducted in a gram-scale without obvious loss of efficiency.
Charge transfer via electron hopping from an electron donor (D) to an acceptor (A) in nanoscale, plays a crucial role in optoelectronic materials, such as organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs). Here, we propose a strategy for binding D/A units in space, where intramolecular charge-transfer can take place. The resulted material DM-Me-B is able to give bright emission in this molecular architecture because of the good control of D/A interaction and conformational rigidity. Moreover, DM-Me-B presents small singlet-triplet splitting energy, enabling thermally activated delayed fluorescence. Therefore, the DM-Me-B exhibits ~20% maximum external quantum efficiency and low efficiency roll-off at 1000cd/m2, certifying an effective strategy in controlling D/A blocks through space.
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