Latest ArticlesHerein, we report the first RhIII-catalyzed regioselective C8 arylation of quinoline N-oxides with commercially available arylboronic acids as coupling partners. This procedure is simple, and the reaction shows perfect regioselectivity, a broad substrate scope, and isolated yields of up to 92%. We demonstrate the utility of the reaction by using it for late-stage functionalization of a fungicide.
As one of the most environmentally friendly photovoltaic (PV) conversion equipments, aqueousprocessed CdTe nanocrystal solar cells (NC SCs) have attracted great interest in recent years because of their excellent properties such as high charge-carrier mobility and broad absorption. However, two issues including interfacial recombination and leakage current seriously restrict their performance. In this paper, insulating polymer poly(vinyl pyrrolidone) (PVP) is introduced into CdTe NC SCs to solve the problems. The experimental results of transmission electron microscopy (TEM), atomic force microscopy (AFM) and dark current measurements, etc., demonstrate the leakage current is effectively suppressed by introducing PVP. Through further designing device structure, the reduction of interfacial recombination after introducing PVP is confirmed. By strategically taking the advantages of PVP properties (e.g., water solubility and thermostability), the power conversion efficiency of the devices with PVP is enhanced by almost 37% compared to pure CdTe devices. This work demonstrates an effective and low-cost method to fabricate NC SCs via aqueous route. Moreover, it also proves that appropriate content of insulating polymer is of beneficial in promoting the PV performance.
Recently, ZnO-based gas sensors have been successfully fabricated and widely studied for their excellent sensitivity and selectivity, especially in CO detection. However, detailed explorations of their mechanisms are rather limited. Herein, aiming at clarifying the sensing mechanism, we carried out density functional theory (DFT) calculations to track down the CO adsorption and oxidation on the ZnO (1010) and (1120) surfaces. The calculated results show that the lattice O of ZnO(1010) is more reactive than that of ZnO(1120) for CO oxidation. From the calculated energetics and structures, the main reaction product on both surfaces can be determined to be CO2 rather than carbonate. Moreover, the surface conductivity changes during the adsorption and reaction processes of CO were also studied. For both ZnO (1010) and (1120), the conductivity would increase upon CO adsorption and decrease following CO oxidation, in consistence with the reported experimental results. This work can help understand the origins of ZnO-based sensors' performances and the development of novel gas sensors with higher sensitivity and selectivity.
H2S can cause multiple diseases and poses a great threat to human health. However, the precise detection of extremely toxic H2S at room temperature is still a great challenge. Here, a facile solvent evaporation induced aggregating assembly (EIAA) method has been applied for the production of ordered mesoporous carbon (OMCs) in an acidic THF/H2O solution with high-molecular-weight poly(ethylene oxide)-b-polystyrene (PEO-b-PS) copolymers as the structure-directing agent, formaldehyde and resorcinol as carbon precursors. Along with the continuous evaporation of THF from the mixed solution, cylindrical micelles are formed in the solution and further assemble into highly ordered mesostructure. The obtained OMCs possesses a two-dimensional (2D) hexagonal mesostructure with uniform and large pore diameter (~19.2 nm), high surface area (599 m2/g), and large pore volume (0.92 cm3/g). When being used as the resonant cantilever gas sensor for room-temperature H2S detection, the OMCs has delivered not only a superior gas sensing performance with ultrafast response (14 s) and recovery (21 s) even at low concentration (2 ppm) but also an excellent selectivity toward H2S among various common interfering gases. Moreover, the limit of detection is better than 0.2 ppm, indicating its potential application in environmental monitoring and health protection.
Poly(N, N-dimethyl acrylamide)-block-poly(styrene)-block-poly(N, N-dimethyl acrylamide) (PDMAc-b-PSt-b-PDMAc) amphiphilic triblock copolymer micro/nano-objects were synthesized through reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of St mediated with poly(N, N-dimethyl acrylamide) trithiocarbonate (PDMAc-TTC-PDMAc) bi-functional macromolecular RAFT agent. It is found that the morphology of the PDMAc-b-PSt-b-PDMAc copolymer micro/nano-objects like spheres, vesicles and vesicle with hexagonally packed hollow hoops (HHHs) wall can be tuned by changing the solvent composition. In addition, vesicles with two sizes (600 nm, 264 nm) and vesicles with HHHs features were also synthesized in high solid content systems (30 wt% and 40 wt%, respectively). Besides, as compared with typical AB diblock copolymers (A is the solvophilic, stabilizer block, and B is the solvophobic block), ABA triblock copolymers tend to form higher order morphologies, such as vesicles, under similar conditions. The finding of this study provides a new and robust approach to prepare block copolymer vesicles and other higher order micelles with special structure via PISA.
In this study, flower-like MoS2 constructed by nanosheets was synthesized by a simple hydrothermal method. The hydrothermal process was optimized and the effects of hydrothermal condition, including reaction temperature, reaction time and the ratio of Mo source to S source (Mo:S) in precursor, on microwave absorption performances and dielectric properties were investigated. Our results showed that when the reaction temperature was 180℃, the reaction time was 18 h, and the Mo:S was 1:3.5, the synthesized MoS2 had the best performance:Its minimum reflection loss could reach -55.78 dB, and the corresponding matching thickness was 2.30 mm with a wide effective bandwidth of 5.17 GHz. Further researches on the microwave absorption mechanism revealed that in addition to the destructive interference of electromagnetic waves, various polarization phenomena such as defect dipole polarization were the main reasons for microwave loss. We believe that MoS2 is a candidate for a practical microwave absorbent.
(±)-Magoilgomer A[(±)-1] and magoilgomer B (2) were identified from the bark of Magnolia officinalis var. biloba. (+)-1 and (-)-1 were a pair of novel biphenyl derivatives featuring three C6-C3 subunits. 2 was an unprecedented adduct containing magnolol and honokiol. These three oligomers possessed new parallel mode which should be biosynthesized from the coupling of three or four C6-C3 subunits. The structures of (±)-1 and 2 were elucidated based on the spectroscopic data analyses and electronic circular dichroism (ECD) calculations. 2 exhibited neuroprotective effects of oxygen glucose deprivation-induced SK-N-SH cell injury.
Herein we wish to propose the concept of "element-transfer reaction", which may afford the access to elemental compounds by transferring certain elements from easily available resources efficiently, concisely and precisely. A good element-transfer reaction with industrial application potential shall not generate waste and is performed under energy-saving and environment-friendly conditions. During the past decade, we have developed a series of methods for the synthesis of fluorine-and seleniumcontaining compounds via the fluorine-and selenium-transfer reactions, while the redox reactions were considered to be the oxygen-and hydrogen-transfer reactions as well and were also widely studied by our group for producing the high-value-added fine chemicals. Some of these technologies have been successfully industrialized. This review summarizes our staged research results on fluorine-, oxygen-, hydrogen-and selenium-transfer reactions and makes a prospect on the developing trend in the field.
A friendly biomimetic process was adopted for the mild preparation of "all-inclusive" organic-inorganic nanospheres, which effectively integrate biorecognition function and signal amplification function. The resulted Ca3(PO4)2-Ab2-BSA nanospheres were employed as signal labels for enhancing detection of nuclear matrix protein 22 (NMP 22). The fabricated electrochemical immunosensor exhibited a linear range (0.08-77.00 U/mL) and an ultralow limit of detection (0.01 U/mL) towards NMP 22, which can be taken as a promising tool for clinical diagnosis of bladder cancer.
Peptide amphiphiles with well-organized secondary structure are an important family of molecules that are known to assemble into a variety of nanostructures. In this work, we present three guanidiniocarbonylpyrrole (GCP) containing peptide amphiphiles, which show versatile morphology and secondary structure changes as a result of different chain lengths and in different concentration regimes. The random coil conformation, α-helix, and β-sheet are obtained for peptide 1, peptide 2, and peptide 3, respectively under neutral aqueous conditions. Furthermore, all peptide amphiphiles can aggregate to form nanoparticles at low concentrations. However, at high concentrations, peptide 1 selfassembles into left-handed twisted helical fibers, while longer bamboo-like morphology can be observed exclusively for peptide 2. For peptide 3, freshly prepared samples show uniform spherical morphology, whereas an obvious morphological transition from original nanoparticles to disordered fibers was realized after incubating for one week. These fascinating morphology changes were determined by the combination of circular dichroism, dynamic light scattering, transmission electron microscopy, atomic force microscopy, and theoretical calculations.
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