Latest ArticlesAs a monoatomic bridge, fluoride ion can transmit efficient magnetic interaction between lanthanide ions but its effect on tuning the magnetization dynamics has not been well understood. Herein, two monofluoride-bridged dinuclear dysprosium complexes [Dy2F(bbpen)2(EtOH)2]Br·EtOH (1) and [Dy2F(bbppy)2]Br·2EtOH (2) with Dy-F-Dy angles of ~178° and their diamagnetic-ion diluted analogues 1´ and 2´ were synthesized. Magnetic studies reveal that 1 and 1´ barely show any magnetization dynamics, but 2 and 2´ exhibit strong magnetization dynamics. Systematical experimental analysis combined with ab initio calculations reveals that the different magnetization dynamics between 1 and 2 mainly originate from the effect of magnetic anisotropy by terminal ligand and bridging group of the chelating ligand, and the fluoride bridge can effectively suppress the quantum tunneling of the magnetization and turn on Orbach process in 2.
Defect passivation is one of the important strategies to improve the efficiency and stability of perovskite solar cells. In this work, 2,6-di–tert–butyl–4-methylphenol (BHT) as antioxidant was introduced into the perovskite precursor solution to improve the quality of the prepared perovskite films, so that these films performed a larger and uniform grain size. Moreover, the −OH functional group in BHT interacts with I−, thus reducing the density of defect states and inhibiting the non-radiative recombination. The presence of hydrophobic groups in BHT protects the film from moisture erosion and improves the long-term stability of PSCs devices. The maximum photoelectric conversion efficiency of the constructed ITO/SnO2/BHT-MAPbI3/Carbon device is 16.88%, and the unpackaged cell maintains the initial efficiency of 99.3% after 698 h of storage under the environmental condition of 30% humidity. This work provides an efficient approach to improve the performance of printable hole transport layer-free carbon electrode perovskite solar cells.
The water promotion effects, where water can provide a solution-mediated reaction pathway in various heterogeneous chemical catalysis, have been presented and attracted wide attention recently, yet, the rational design of catalysts with a certain ability of enhancing water-induced reaction process is full of challenges and difficulties. Here, we show that by incorporating alkali (Na, K) cations as an electronic and/or structural promoter into Pd/rGO-ZnCr2O4 (rGO, reduced graphene oxide), the obtained Pd(Na)/rGO-ZnCr2O4 as a representative example demonstrates an outstanding benzyl alcohol oxidation activity in the Pickering emulsion system in comparison to the alkali-free counterpart. The response experiments of water injection confirm the enhanced activity, and the Na-modified catalyst can further enhance the promotion effects of water on the reaction. The effects of alkali cations for Pd nanoparticles are identified and deciphered by a series of experimental characterizations (XPS, in situ CO-DRIFTS, and CO-TPR coupled with MS), showing that there is abundant −OH on the surface of the catalyst, which is stabilized by the formation of Pd−OHx. The alkali-stabilized Pd−OHx is helpful to enhance the water-induced reaction process. According to the results of in situ Raman as well as UV-vis absorption spectra, the Na-modulated Pd(Na)/rGO-ZnCr2O4 enables the beneficial characteristics for distorting the benzyl alcohol structure and enhancing the adsorption of benzyl alcohol. Further, the mechanism for enhanced water promotion effects is rationally proposed. The strategy of alkali cations-modified catalysts can provide a new direction to effectively enhance the chemical reaction involving small molecule water.
The abnormal activation of BRD4 accelerates the progression of acute myeloid leukemia (AML), developing more precise therapeutics to intervene BRD4 promise to be an excellent opportunity to avoid current limitations of chemotherapy in clinic. Herein, a range of small-molecule PROTACs with the privileged 8-methyl-pyrrolo[1,2-a]pyrazin-1(2H)-one scaffold were rationally designed, which harbored different carbon or ethylenedioxy chains to degrade BRD4 mediated by the E3 ubiquitin ligase CRBN. Among them, the most potential B24 exhibited remarkable BRD4 degradation and excellent anti-proliferative activities in MV4-11 cells, with values of DC50 and IC50 for 0.75 nmol/L and 0.4 nmol/L, respectively, which were better than the BRD4 inhibitor (+)-JQ-1. Notably, this compound could time-dependently degrade the target protein in the BRD4-, CRBN-, and proteasome-dependent manner. Besides, B24 dramatically decreased the level of proto-oncogene c-Myc, and induced cell apoptosis by arresting the cell cycle in G0/G1 phase, down-regulating Bcl-2 and up-regulating Bax to amplify apoptotic effectors. This proof-of-concept study also highlighted the feasibility of BRD4-based PROTACs as a more powerful strategy against AML.
As the main target cells of immune regulation, macrophages play an important role in the bone regeneration process. Macrophages can be polarized into the M1 and M2 types under the stimulation of different factors. They have proinflammatory and anti-inflammatory effects, respectively, and play key roles in different stages of bone regeneration. The ratio of M1 to M2 macrophages can be regulated by immunomodulatory biomaterials to promote bone repair and regeneration. In this paper, we review the recent literature on the chemical, physical and biological properties of biomaterials and the regulation of macrophage polarization under the influence of other factors. We also cover new methods for preparing immunomodulatory biomaterials for bone regeneration. This paper will provide new design ideas for the development of biomaterials with immunological properties and will support the clinical translation of bone-related medical biomaterials.
As an attractive C1 synthon, carbon dioxide (CO2) has been extensively used in organic synthesis to produce carboxylic acids. In this research, stereoselective electrochemical carboxylation of α,β-unsaturated sulfones has been developed under transition-metal-free conditions. All the cinnamic acids and the derivatives are obtained selectively in the E-configuration. Besides, arylpropiolates also can be produced from alkynyl sulfones.
Fluoranthenes have attracted tremendous attention due to their unique optoelectronic properties and extensive applications. Although several synthetic methodologies have been developed for the preparation of fluoranthene derivatives, it is still unfavorable to functionalize the fluoranthene framework at different positions due to the relatively low selectivity and reactivity. Herein, a catalyst-free intramolecular [4 + 2] annulation between thiophenes and alkynes is developed towards the synthesis of fluoranthenes. Altogether 20 examples have been demonstrated using this method. Various functional groups can be precisely introduced into the fluoranthene skeleton at different positions by simply tuning the substituents on the thiophenes and alkynes. The conjugation of the fluoranthene can be facilely extended through different directions. Furthermore, the feasibility of this [4 + 2] annulation reaction is also investigated by density functional theory calculations. Therefore, this protocol provides not only a synthetic methodology towards fluoranthenes with substituents functionalized at different positions, but also an effective pathway to construct large polycyclic aromatic hydrocarbons containing fluoranthene moieties.
Aqueous zinc-ion batteries (ZIBs) has been regarded as a promising energy storage system for large-scale application due to the advantages of low cost and high safety. However, the growth of Zn dendrite, hydrogen evolution and passivation issues induce the poor electrochemical performance of ZIBs. Herein, a Na3Zr2Si2PO12 (NZSP) protection layer with high ionic conductivity of 2.94 mS/cm on Zn metal anode was fabricated by drop casting approach. The protection layer prevents Zn dendrites formation, hydrogen evolution as well as passivation, and facilitates a fast Zn2+ transport. As a result, the symmetric cells based on NZSP-coated Zn show a stable cycling over 1360 h at 0.5 mA/cm2 with 0.5 mAh/cm2 and 1000 h even at a high current density of 5 mA/cm2 with 2 mAh/cm2. Moreover, the full cells combined with V2O5-based cathode displays high capacities and high rate capability. This work offers a facile and effective approach to stabilizing Zn metal anode for enhanced ZIBs.
A series of linear poly(ethylene oxide)-b-poly(4-vinylbenzyl chloride)-b-poly(4-tert-butylstyrene) (PEO113-b-PVBC130-b-PtBSx or E113V130Tx) triblock terpolymers with various lengths x (=20, 33, 66, 104, 215) of PtBS block were synthesized via a two-step reversible addition-fragmentation chain transfer (RAFT) polymerization. The E113V130T triblock terpolymers were non-crystalline because the PVBC and PtBS blocks strongly hindered the crystallization of PEO block. The effects of PtBS block length x on the phase structures of E113V130Tx triblock terpolymers were investigated by combined techniques of small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). It was found that with increasing x from 20 to 215, the phase structure of E113V130Tx triblock terpolymers became more ordered and changed from disordered structure, hexagonally-packed cylinder (HEX), hexagonally perforated layer (HPL), to lamellar (LAM) phase structures. Temperature-variable SAXS measurements showed that the HEX, HPL and LAM phase structures obtained for E113V130T66, E113V130T104 and E113V130T215 by thermal annealing, respectively, were thermodynamically stable in the temperature range of 30–170 ℃.
Twenty-four novel neonicotinoid analogues with nitromethylene and five-membered aromatic heterocycles were designed and synthesized. All target molecular structures have been confirmed by analytical and spectral data. Some compounds exhibited notable insecticidal activities against aphid (Aphis medicaginis) and brown planthopper (Nilaparvata lugens). The aqueous stability test confirmed that the stabilities of those compounds were superior to the leading compound, and the photostability was even better than that of imidacloprid.
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