Search

We have developed a (4 + 2) radical annulation approach for the synthesis of diverse chromans. This method is complementary to the traditional Diels–Alder [4 + 2] annulation of ortho-quinone methides and electron-rich dienophiles.

Herein, we have developed an electrochemical oxidative multicomponent reaction for the synthesis of α-amino amides via C(sp3)–H bond activation.

Cyclopentenes are common cores in many natural products, and in bioactive and functional molecules. However, their synthesis remains challenging in terms of harsh conditions, poor selectivity, prefunctionalization of the substrates, over-reliance on volatile activating reagents and the use of noble metals. Herein, we develop an electrochemical mediator-induced intermolecular selective (3+2) annulation of readily available alkenes and alkynes/alkenes, which provides a simple and efficient method for the synthesis of a library of decorated cyclopentenes and cyclopentanes. This protocol features high efficiency, mild reaction conditions, broad substrate scope, good functional group tolerance, and high regioselectivity. Potential applications are demonstrated by gram-scale synthesis as well as the construction of structural diversity and complexity. A preliminary mechanistic investigation was performed, which indicated that an iodine radical and carbon radicals are involved in this transformation.

C–P bonds are widely found in a great many bioactive compounds and functional molecules. Transition-metal-catalyzed dehydrogenative C–H/P–H cross-coupling plays a crucial part in C–P bond formation...

A highly selective, environmentally friendly, and scalable electrochemical protocol for the construction of α-acyloxy sulfides, through the synergistic effect of self-assembly-induced C(sp3)-H/O-H cross-coupling, is reported. It features exceptionally broad substrate scope, high regioselectivity, gram-scale synthesis, construction of complex molecules, and applicability to a variety of nucleophiles. Moreover, the soft X-ray absorption technique and a series of control experiments have been utilized to demonstrate the pivotal role of the self-assembly of the substrates, which indeed is responsible for the excellent compatibility and precise control of high regioselectivity in our electrochemical protocol.

The construction of C(sp2)-X (X = B, N, O, Si, P, S, Se, etc.) bonds has drawn growing attention since heteroatomic compounds play a prominent role from biological to pharmaceutical sciences. The current study demonstrates the C(sp2)-S/Se and C(sp2)-N bond formation of one carbon of isocyanides with thiophenols or disulfides or diselenides and azazoles simultaneously. The reported findings could provide access to novel multiple isothioureas, especially hitherto rarely reported selenoureas. The protocol showed good atom-economy and step-economy with only hydrogen evolution and theoretical calculations accounted for the stereoselectivity of the products. Importantly, the electrochemical reaction could exclusively occur at the isocyano part regardless of the presence of susceptible radical acceptors, such as a broad range of arenes and alkynyl moieties, even alkenyl moieties.

In this study, intense red and extremely weak green up-conversion (UC) luminescence was obtained in BaGd

Semiconductor photocatalysis is considered to be a promising technique to completely eliminate the organic pollutants in wastewater. Recently, S-scheme heterojunction photocatalysts have received much attention due to their high solar efficiency, superior transfer efficiency of charge carriers, and strong redox ability. Herein, we fabricated an S-scheme heterostructure BiOCl/MoSe

The construction of C(sp2)–X (X = B, N, O, Si, P, S, Se, etc.) bonds has drawn growing attention since heteroatomic compounds play a prominent role from biological to pharmaceutical sciences. The current study demonstrates the C(sp2)–S/Se and C(sp2)–N bond formation of one carbon of isocyanides with thiophenols or disulfides or diselenides and azazoles simultaneously. The reported findings could provide access to novel multiple isothioureas, especially hitherto rarely reported selenoureas. The protocol showed good atom-economy and step-economy with only hydrogen evolution and theoretical calculations accounted for the stereoselectivity of the products. Importantly, the electrochemical reaction could exclusively occur at the isocyano part regardless of the presence of susceptible radical acceptors, such as a broad range of arenes and alkynyl moieties, even alkenyl moieties., We have developed an efficient and sustainable electrochemical strategy for the double C(sp2)–X (S/Se, N) bond formation of isocyanides simultaneously. A series of novel isothio/selenoureas were obtained via a three-component cross-coupling.

The magnetic resonant wireless power transfer (WPT) system with a class E inverter has wide application in mid-range power transmission, especially for several megahertz scenario. However, it is cumbersome for the existing modeling and analysis methods to obtain the analytical solution to the system variables, which limits the evaluation of system characteristic. This paper proposes a nonlinear mathematical model for the WPT system with a class E inverter. The equivalent small parameter method (ESPM) is first adopted to solve the proposed six-order nonlinear model, and symbolic-form steady-state periodic solutions are yielded. During the whole solving process, only three iteration steps are needed for the proposed method. Compared with other existing modeling and analysis methods, the symbolic periodic results acquired by the ESPM exhibit sufficient accuracy by virtue of the combination of more higher harmonics. Meanwhile, the calculation complexity is simplified remarkably. Simulation and available experiments validate the effectiveness and accuracy of the proposed method.

The tandem cyclization of olefinic carbonyls with easily accessible diselenides facilitated by electrochemical oxidation has been successfully developed, which provides an environmentally friendly method for the construction of C–Se and C–O bonds simultaneously. A series of seleno dihydrofurans and seleno oxazolines, bearing fragile heterocycles, subtle C–I bonds and supernumerary vinyl groups, were forged using this elegant chelation strategy. Neither metal catalysts nor external chemical oxidants are required to promote this transformation.

A highly selective, environmentally friendly, and scalable electrochemical protocol for the construction of α-acyloxy sulfides, through the synergistic effect of self-assembly-induced C(sp

GdNbTiO

LaNbO4: Nd3+/Yb3+/Ho3+ phosphors with various concentrations of Nd3+, Yb3+ and Ho3+ were prepared by a traditional high temperature solid-state reaction method. The crystal structure of the as-prepared samples was characterized by X-ray diffraction (XRD) and the results showed that monoclinic LaNbO4 samples were obtained. Green and red up-conversion (UC) emissions of Ho3+ were observed under the excitations of 808 nm and 980 nm. Concentration dependent studies indicated that Nd3+ and Yb3+ played different roles in the UC emissions of Ho3+ under different wavelength excitations. The same optimal concentrations of Yb3+ and Ho3+ ions were obtained when excited by 808 nm and 980 nm lasers. The UC luminescence mechanisms under different excitation sources were discussed by detecting the UC luminescence intensity related to the laser pumped power density. The energy transfer efficiencies from Nd3+ to Yb3+ and Yb3+ to Ho3+ were confirmed via lifetime measurement. By comparing with the commercial green NaYF4: Er3+/Yb3+ UC luminescence phosphor, the UC luminescence performance of Ho3+ doped sample was evaluated. The results showed that LaNbO4: Nd3+/Yb3+/Ho3+ phosphors had excellent green UC luminescence properties under both 808 nm and 980 nm excitations.

GdNbTiO6: Sm3+ phosphors with various Sm3+ concentrations were prepared via a high temperature solid-state reaction method. The crystal structure of the samples was characterized by means of X-ray diffraction (XRD) and the as-prepared samples were confirmed to be orthorhombic phase GdNbTiO6. Photoluminescence properties were investigated by measuring the concentration- and temperature-dependent photoluminescence spectra. Concentration-dependent luminescence quenching and luminescent thermal quenching behaviors were observed and they were respectively ascribed to the electric dipole-dipole interaction between Sm3+ ions and the cooperation of energy transfer and crossover process. The chromatic characteristics were found to be dependent on the excitation wavelength and Sm3+ concentration. In addition, temperature-induced redshift of charge transfer band of GdNbTiO6 host was found in temperature-dependent excitation spectra and the opposite variations of different excitation peaks were utilized for optical thermometry. Finally, the optical transition property was studied on the basis of the diffuse reflectance spectra and Judd-Ofelt (J-O) theory, meanwhile, its accuracy was evaluated by the result of emission spectra.

An efficient synthesis of 3-halo-3-arylacrylonitrile is described from the direct addition between cyanoalkynes and inorganic alkaline metal halides such as LiCl, LiBr and KI in good to satisfactory yields. No transition metal is needed for the synthesis of iodo- and bromo-products, although Pd catalyst is used to accelerate the chloro-product.

Direct halogenation, including chlorination, bromination and iodination of terminal alkynes, are of great importance in organic synthesis. Here an efficient and recyclable nano-Ag/g-C3N4 catalyst system was developed and proved to be remarkably active with 39 examples varied from chlorination, bromination to iodination, of which 14 runs have yielded more than 95% of the product. Recycling of the catalyst was also achieved without obvious activity loss after several runs: 99% yield was observed even after 5 runs in the bromination of phenylacetylene. The catalysts system is of low cost and easy to be prepared, making this procedure versatile, convenient and economic.

Although semiconductor photocatalysis has made great progresses as a promising solution to solve the problem of environmental pollution, the highly efficient decomposition of organic pollutants driven by sunlight is still a challenge. Herein, we successfully constructed a Z-scheme photocatalyst BiOCl-Au-CdS for the first time by stepwise deposition of Au and CdS. It was found that the Au nanoparticles (NPs) were selectively anchored on the {001} facets of BiOCl nanosheets in the process of photoreduction while CdS NPs were further in situ deposited on Au NPs via the strong S–Au interaction. Compared to BiOCl, BiOCl-Au, and BiOCl-CdS, the Z-scheme BiOCl-Au-CdS exhibited evidently higher sunlight-driven photocatalytic activity toward the degradations of anionic dye Methyl Orange, cationic dye Rhodamine B, colorless pollutant phenol, and antibiotic sulfadiazine. The radical trapping experiments indicated that ·OH, h+, and ·O2– are the main reactive species responsible for the degradations of organic pollutan...

An electrochemical oxidative difunctionalization of allyl alcohols for the synthesis of β-trifluoromethyl ketones is achieved through a 1,2-migration process. A series of β-trifluoromethyl ketones can be facilely obtained utilizing CF3SO2Na as a radical source, eliminating the use of metals and sacrificial chemical oxidants. Importantly, this protocol not only realizes aryl migration but also offers alkyl-migration products. Additionally, an electrochemically catalyzed ring expansion and gram-scale reaction demonstrated the synthetic usefulness of this protocol.

Localized surface plasmon resonances (LSPRs) are usually achieved by some small grains of noble metal (Au, Ag et al.) to enhances the light absorption and charge carrier’s concentration of photocatalysts, but the wide application of noble metals is limited by their high cost. Here, we report the preparation of 0D/2D plasmonic Cu2-xS/g-C3N4 nanosheets (CSCNNs) and the utilization of LSPRs generated from Cu2-xS nanodots instead of noble metals to improve the photocatalytic activity for degradation of typical antibiotic levofloxacin (LVX). One-step hydrothermal method was employed to grow the highly dispersed Cu2-xS nanodots on the g-C3N4 nanosheets. Various characterization techniques verify the strong light absorption capacity and longer carriers’ lifetime for CSCNNs. The analysis of band structure reveals the efficient separation and transmission mechanism of photogenerated electrons and holes. More importantly, LSPRs has been proved to be effective in increasing the light absorption in near infrared (NIR) region and the theoretical finite difference time domain (FDTD) simulations demonstrated that Cu2-xS LSPR-induced electromagnetic field in g-C3N4 nanosheets was far stronger than that of Ag and Au in NIR region. Consequently, efficient photocatalytic degradation of LVX under full solar spectrum (UV–vis-NIR) can be achieved for CSCNNs. This work will lead to a cheap and efficient LSPR photocatalysis system for treatment of antibiotic wastewater or other photocatalytic applications.

For the first time, we fabricated Au-BiOBr-Co3O4 hierarchical flower-like microspheres by hydrothermal and photo-deposition methods. Au and Co3O4 nanoparticles (NPs) were selectively deposited on the {0 0 1} and {1 1 0} facets of BiOBr nanopetals, respectively. The light absorption, photoluminescence (PL), and electrochemical analyses revealed that the selectively deposited Au and Co3O4 can effectively enhance both the visible-light absorption and charge carrier separation in space. The photocatalytic degradation of sulfadiazine (SD) indicated that the degradation of SD follows the pseudo-first-order reaction and the reaction rate constant was increased 17 times from BiOBr flower-like microspheres (0.00014 min−1) to Au and Co3O4 co-modified Au-BiOBr-Co3O4 flower-like microspheres (0.00254 min−1). From the high performance liquid chromatography-mass spectrometry (HPLC-MS) measurement, it was disclosed that the desulfonated and bromized products are the main intermediates during SD degradation over Au-BiOBr-Co3O4. Meanwhile, the reactive species trapping experiments confirmed that Au-BiOBr-Co3O4 can produce h+, O2−, and Br0 reactive species responsible for antibiotic degradation. On the basis of these experiment results and discussion, the degradation mechanism of SD over Au-BiOBr-Co3O4 was tentatively discussed. We think this work provides a reference to fabricate novel photocatalytic materials for the effective degradation of antibiotics.

A simple and efficient Pd-catalyzed tandem procedure for the synthesis of β-cyanoindoles was achieved. Unactivated anilines and cyanoalkynes were employed as the starting materials to go through nucleophilic additions to form the N-aryl enamine intermediate, and then followed by Pd-catalyzed double C−H activation to yield the product in one pot. Moderate to good yields were achieved for 19 examples. LiBr was used as the additive to promote the process. Oxygen was used as the sole oxidant, thus high atom efficiency could be achieved.

Nowadays, it is a trend to update electronic products by replacing the traditional wire charging with emerging wireless charging. However, other features of the products must generally be left unchanged, which limits the options in receiving coil design. As a result, asymmetric coil designs should be adopted in wireless charging systems. In this paper, a wireless power transfer system with asymmetric transmitting and receiving coils is modelled using circuit theory. The output power of the asymmetric system is analyzed, and the conditions of the maximum power splitting phenomenon are addressed in detail. Cases for different resonant frequency conditions are elaborated. The splitting frequencies and critical coupling coefficient are obtained, which are different and more complicated compared with the symmetric counterparts. Asymmetric coil designs can be adopted based on the proposed method, so that adequate and efficient output power transfer can be realized. Finally, the asymmetric coils design is utilized in an experimental prototype in order to contactlessly charge a portable power tool lithium-ion battery pack with 18 V DC and 56 W output through 220 V AC input, without altering its original configuration, and the correctness of proposed analysis can thus be verified.

One-pot synthesis of substituted indoles from cyanoalkynes and anilines through Palladium catalyzed double C—H activation is successfully developed.