Latest ArticlesA ferrocene-initiated radical reaction of benzoquinone with amines has been successfully developed for the direct access to diaminobenzoquinone imines in high yields, in which the commercially available and cheap ferrocene was employed as a radical initiator and TBHP was used as an oxidant. Moreover, this reaction could be achieved with low loading of ferrocene (0.5 mol%). This protocol is highly efficient with good substrate tolerance and provides a new approach for the construction of benzoquinone imines with potential pharmaceutical interest.
Based on block copolymer assisted topochemical polymerization, a new strategy for facilely producing robust nanoporous membranes with controlled incorporation of functional groups onto nanopores is developed. As exemplified by preparing nanoporous polypyrrole decorated with amino acids, this strategy exhibits a high degree of freedom for tailoring the surface functionality in the created pores.
Cu@Ag/Bi2Te3 nanocomposites were prepared for the first time by ultrasonic dispersion-rapid freezedrying method combined with spark plasma sintering (SPS). By changing the content of Cu@Ag nanoparticle, we could modulate the temperature dependent thermoelectric properties. The highest ZT value can be obtained at 450 K for 1 vol% Cu@Ag/Bi2Te3, which is benefited from the decoupling of electrical and thermal properties. With the increase of electrical conductivity, the absolute value of Seebeck coefficient lifts while the thermal conductivity declines. Meanwhile, the average ZT value between 300 K and 475 K was 0.61 for 1 vol% Cu@Ag/Bi2Te3, which is much higher than that of pristine Bi2Te3. Therefore, the decoupling effect of Cu@Ag nanoparticles incorporation could be a promising method to broaden the application of Bi2Te3 based thermoelectric materials.
Several novel pyridine-oxadiazole iridium complexes were synthesized and characterized through X-ray crystallography. The designed iridium complexes revealed surprisingly high catalytic activity in C-N bondformation of amides and benzyl alcohols with the assistance of non-coordinating anions. In an attempt to achieve borrowing hydrogen reactions of amides with benzyl alcohols, N, N'-(phenylmethylene)dibenzamide products were unexpectedly isolated under non-coordinating anion conditions, whereas N-benzylbenzamide products were achieved in the absence of non-coordinating anions. The mechanism explorations excluded the possibility of "silver effect" (silver-assisted or bimetallic catalysis) and revealed that the reactivity of iridium catalyst was varied by non-coordinating anions. This work provided a convenient and useful methodology that allowed the iridium complex to be a chemoselective catalyst and demonstrated the first example of non-coordinating-anion-tuned selective C-N bond formation.
The energy density of non-aqueous carbon-based electrochemical capacitors (cEC) is mainly determined by the specific capacitance and operational voltage range. In this study, we propose to construct an unbalanced structure to make full use of stable voltage range for improving energy density. The stable voltage range is firstly carefully explored using cyclic voltammetry. Then an unbalanced carbon-based electrochemical capacitor (ucEC) is constructed with an optimized positive electrode to negative electrode weight ratio and voltage range. Its electrochemical performance is comprehensively investigated, including energy density, power density as well as cycle life. The ucEC is capable to deliver an improved energy density up to 64.9 Wh/kg (1.4 times as high as a general cEC) without sacrificing the power density and cycle life. The electrode properties after cycling are also analyzed, illustrating the change of electrode potential caused by unbalanced structure. The proposed structure demonstrates a great potential for improving the energy density at little cost of electrode design and cell configuration.
It has been demonstrated that the conductivity and electrochemical properties of TiO2 nanomaterials can be significantly improved by an incorporation of carbon additives. In the study, we develop a novel Ndoped TiO2 mesoporous nanostructure via the addition of carbon quantum dots (CQDs) solution following a scalable hydrothermal process. The as-made TiO2 product shows well-defined morphology, high conductivity, large surface area, and abundant mesopores. When evaluated as anodes for sodiumion batteries, the CQDs@TiO2 product annealed at 500℃ exhibits a superior sodium storage capability. It delivers a high reversible capacity of 168.8 mAh/g at 100 mA/g over 500 cycles and long cycling stability. The remarkable performance of CQDs@TiO2 mainly arises from the large surface area and mesoporous architecture constructed by ultrathin TiO2 nanosheets, as well as the full cooperation between CQDs and TiO2.
Antimony-based materials have become promising anodes within lithium-ion batteries (LIBs) due to their low cost and the high theoretical capacity. However, there is a potential to further enhance the electrochemical performance of such antimony-based materials. Herein, Sb2Se3@C nanofibers (Sb2Se3@CNFs) are designed and obtained via a novel electrospinning method. Upon electrochemically testing as an anode within LIBs, the Sb2Se3@CNFs (annealed at 600 ℃) delivers a remarkably good cycling performance of 625 mAh/g at 100 mA/g after 100 cycles. Moreover, it still remains at 490 mAh/g after 500 cycles with an applied current density of 1.0 A/g. The excellent performance of the Sb2Se3@CNFs can be attributed to the fact that the N-doped C matrices not only remit the volume expansion of materials, but also enhance the electrical and ionic conductivity thusly increasing the lithium-ion diffusion. The obtained Sb2Se3@CNFs are promising anode for LIBs in the future.
Existing grasping technologies have persistent challenges with unstructured objects and environments, highlighting an increasing demand for methods that conform to various application scenarios. Inspired by the chameleon tongue, a soft-contact grasping manipulator empowered by a class of adhesive gels has been demonstrated. The adhesives enable the manipulator to rapidly and strongly adhere to diverse substrates with varied surfaces, shapes and sizes, also to release objects under mild conditions. The robustness of such adhesive gels was highlighted with the remarkable recyclability, broad temperature tolerance and long-term stability. Furthermore, a general approach was developed to reconcile the contradiction of simultaneously enhancing their interfacial adhesion and cohesion strength that exists in conventional glues. We anticipate that this work will offer a strategy of developing adhesive materials and pave the way towards new applications of soft materials in the emerging fields of soft robotic devices and smart manufacturing.
The chiral phosphoric acid catalyzed asymmetric[3 + 2] annulation of substituted 2-vinylindoles with azlactones has been established. This reaction represented a practical approach for the synthesis of structurally diverse pyrrolo[1, 2-a]indoles with two vicinal stereocenters including one tetrasubstituted stereocenter in good yields and good stereoselectivities under mild conditions.
We report on the synthesis of two acentric and one centrosymmetric Zn metal-organic complexes with 3-tetrazolemethyl pyridine spacers obtained in situ by hydrothermal routes. X-ray diffraction structural analysis reveals that they have the same equivalent nodes but with dissimilar topologies. The two acentric frameworks[Zn(Tzmp)Cl]n (1) and ([Zn(Tzmp)Br]n (2), HTzmp=3-tetrazolemethyl pyridine) are isomorphism which exhibit an acentric 3D framework with (10, 3)-b net called "ths", while the centrosymmetric complex ([Zn(Tzmp)N3]n (3)) features a distinctive 2D sheet with Shubnikov hexagonal plane net. Photo-luminescent studies suggest the ligand-field strength of coordinated negative ions (Cl- > Br- > N3-) has ordered adjusting effects on the emission redshift. The second harmonic generation (SHG) measurement shows that compounds 1 and 2 are nonlinear optically active, with SHG responses being 2/3 and half of the standard potassium dihydrogen phosphate (KDP), respectively.
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