Latest ArticlesA new kind of emissive small-molecular organic cage has been developed via the combination of coupling and condensation reactions, which shows outstanding solubility, structural stability and potential spatial isomeric chirality. Interestingly, through the introduction of proper donor and acceptor units, this emissive organic cage is the first among organic cages to exhibit red aggregation-induced delayed fluorescence with photoluminescence emission at 603 nm. The finding not only expands the types of emissive small-molecular organic cages, but also represents an important step for further development of red delayed fluorescence materials with good solubility and aggregation-induced emission feature.
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.
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.
Nanoparticle surface property is crucial for circulation stability, cellullar uptake and other biological characteristics. Zwitterionic pillar[n]arenes (ZPns) were used to coat gold nanoparticles (GNPs) via host-guest interaction. The resulting GNPs demonstrated higher stability in blood serum compared to polyethylene glycol (PEG)-coated GNPs. ZPn-coated GNPs were responsive to UV-irradiation, competitive displacement and acidic pH. UV-irradiation or competitive displacement could lead to the removal of ZPn coating to expose GNPs, which enhanced cell uptake efficiency by 5.9- and 7.4-fold, respectively.
Irradiated by visible light, the recyclable (PhTe)2-catalyzed oxidative deoximation reaction could occur under mild conditions. In comparison with the thermo reaction, the method employed reduced catalyst loading (1 mol% vs. 2.5 mol%), but afforded elevated product yields with expanded substrate scope. This work demonstrated that for the organotellurium-catalyzed reactions, visible light might be an even more precise driving energy than heating because it could break the Te-Te bond accurately to generate the active free radical catalytic intermediates without damaging the fragile substituents (e.g., heterocycles) of substrates. The use of O2 instead of explosive H2O2 as oxidant affords safer reaction conditions from the large-scale application viewpoint.
Radiotherapy is commonly used to treat advanced pancreatic cancers and can improve survival by 2 months in combination with gemcitabine. However, prognosis and survival improvement remain unsatisfactory, and effective therapies are urgently needed. Piperlongumine has been demonstrated to have therapeutic potentials against various cancers. In this study, we synthesized a series of piperlongumine derivatives and provided evidence that piperlongumine derivatives could be used as effective radiosensitizers in pancreatic cancer. Two compounds enhanced the radiosensitivity of Panc-1 and SW1990 cells. In a pancreatic bi-flank xenograft tumor model, they significantly inhibited tumor growth. Piperlongumine derivatives could induce reactive oxygen species (ROS) expression and regulate the Keap1-Nrf2 protective pathway with enhancement of radiation-induced DNA damage, G2/M-phase cell cycle arrest, and apoptosis. Collectively, our data offer a proof of concept for the use of piperlongumine derivatives as a novel class of radiosensitizers for the treatment of pancreatic cancer.
Azithromycin loaded fumaryl diketopiperazine (FDKP) dry powder inhalationwas designed and prepared for the treatment of community-acquired pneumonia. The solubility of FDKP and stability of azithromycin solution was investigated. Formulation of azithromycin loaded FDKP microparticle was investigated and optimized by the single factor experiment. High-pressure homogenization and spray drying conditions were also optimized to prepare the particles by spray drying azithromycin dissolved FDKP microparticle suspension at pH 4.5. The in vitro antibacterial efficiency and in vitro dispersion performance was also investigated to confirm the antibacterial efficiency, dispersion and deposition behavers. FDKP/azithromycin mass ratio (3:2) was the optimized formulation of azithromycin loaded FDKP microparticle with the maximal drug loading efficiency. High-pressure homogenization and spray drying conditions were also optimized. The in vitro antibacterial results indicated that only with the antibiotic concentration higher than mutant prevention concentration could totally inhibit the reproduction of bacteria. In vitro dispersion performance of azithromycin loaded FDKP microparticles (AZM@FDKP-MPs) also shows remarkable improvement of dispersion and deposition behavers of AZM. AZM@FDKP-MPs dry powder inhalation as a targeting delivery route has better potential for lung infection treatment.
Functional groups in the molecule play an important role in the molecular organization process. To reveal the influence of functional groups on the self-assembly at interface, herein, the self-assembly structures of three liquid crystal molecules, which only differ in the functional groups, are explicitly characterized by using scanning tunneling microscopy (STM). The high-resolution STM images demonstrate the difference between the supramolecular assembly structures of three liquid crystal molecules, which attribute to the hydrogen bonding interaction and π-π stacking interaction between different functional groups. The density functional theory (DFT) results also confirm the influence of these functional groups on the self-assemblies. The effort on the self-assembly of liquid crystal molecules at interface could enhance the understanding of the supramolecular assembly mechanism and benefit the further application of liquid crystals.
CO oxidation at ceria surfaces has been studied for decades, and many efforts have been devoted to understanding the effect of surface reduction on the catalytic activity. In this work, we theoretically studied the CO oxidation on the clean and reduced CeO2(111) surfaces using different surface cells to determine the relationships between the reduction degrees and calculated reaction energetics. It is found that the calculated barrier for the direct reaction between CO and surface lattice O drastically decreases with the increase of surface reduction degree. From electronic analysis, we found that the surface reduction can lead to the occurrence of localized electrons at the surface Ce, which affects the charge distribution at surface O. As the result, the surface O becomes more negatively charged and therefore more active in reacting with CO. This work then suggests that the localized 4f electron reservoir of Ce can act as the "pseudo-anion" at reduced CeO2 surfaces to activate surface lattice O for catalytic oxidative reactions.
Here, the selective adsorption behaviors of guest molecule COR in two hexamer host grids were investigated by means of scanning tunnelling microscope (STM). The assembled structures of small functional organic molecules TTBTA and TATBA were thermodynamically stable. Interestingly, the introduction of the guest molecule COR destroyed the original hexamer structure of TTBTA and combined with it to form a new triangular host-guest system. Different from TTBTA, the introduction of the guest molecule COR did not affect the six-membered ring structure of TATBA. Furthermore, the co-assembly structure of TTBTA/TATBA/COR was established and the guest molecule COR showed preferential adsorption to the TATBA host grid. Density functional theory (DFT) calculations had been performed to disclose the mechanism of the involved assemblies.
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