Latest ArticlesRemote ether groups could be used as directing groups to prepare fully substituted 5-ether-1,2,3-triazoles with exclusive 1,5-regioselectivities and excellent chemoselectivities. Ether group could coordinate with iridium catalyst by lone-pair electron at a distance (up to four σ bonds) away from alkyne to control the regioselectivity by weak coordination effect. The cycloaddition reaction chemoselectively occurred at the propargyl ether moiety of diyne to give unique fully substituted 4-alkynyl-triazole.
Several simple, fast and practical protocols have been developed to synthesize internal or terminal propargylamines and chalcones via A3-coupling reaction of aldehydes, amines, and alkynes catalyzed by an easily available catalyst Ag2CO3 under solvent-free condition. The reaction proceeded smoothly to deliver various products in good-to-excellent yields with good functional group tolerance. Gram-scale preparation, bioactive molecule synthesis and asymmetric substrates have been demonstrated. Furthermore, plausible mechanisms for the synthesis of different products have been proposed.
By introducing a host molecule cucurbit[8]uril (CB[8]) into a charge transfer system containing an amphiphile 1-[11-(naphthalene-2-ylmethoxy)-11-oxoundecyl]pyridinium (NP) and an electron-deficient molecule methyl viologen (MV), a novel and anisotropic ternary building block was constructed by host-guest interactions, thereby leading to the morphology transformation of the final assemblies from thin-films (NP/MV complexes) into diamond-like structures (NP/MV/CB[8] complexes). These intriguing assemblies were firstly discovered and were similar with the shape of well-known metal organic frameworks (MOFs), but just comprised three small organic molecules without metal ions. This finding can enrich the shape of current supramolecular assemblies and thus contributing to more potential applications in material science.
In situ formation of composite micro-mesoporous dendritic fibrous nano-silica (DFNS) and Al-DFNS was prepared using a cetylpyridinium bromide (CPB) template synthetic system. Dealumination is induced by impregnation of zirconium with flux followed by a sulfuric acid treatment. This procedure results in a series of highly uniform nano-spheres, which exhibit stronger acid property than that of Al-MCM-41. In the selective alkylation of anthracene with tert‑amyl alcohol, SO42− modified Zr-contained dealuminated Al-DFNS (SZ-DeAl-DFNS) shows great catalytic activity and higher conversion (60.8%). The DFNS samples were characterized with XRD, SEM, TEM, NH3-TPD and other techniques. The results reveal that DFNSs consist of center-radial micro-mesopores and that the acid contribution of SZ-DeAl-DFNS is much broader, as compared with amorphous aluminosilicate
Palladium-catalyzed oxidative formal [4 + 1] annulation of pyridine-substituted acrylonitriles toward divergent fused N-heterocycles synthesis is reported. The heterodifunctionalization reaction with Cu(OAc)2 and urea as the nitrogen source accesses to nitrile-substituted pyrazolo[1, 5-a]pyridines in moderate to good yields, while the homodifunctionalization reaction with FeBr3 leads to synthesis of nitrile-substituted indolizines in excellent yields.
Mixed metal sulfides have been widely used as anode material of sodium-ion batteries (SIBs) because of their excellent conductivity and sodium ion storage performance. Herein, ReS2@NiS2 heterostructures have been triumphantly designed and prepared through anchoring ReS2 nanosheet arrays on the surface of NiS2 hollow nanosphere. Specifically, the carbon nanospheres was used as hard template to synthesize NiS2 hollow spheres as the substrate and then the ultrathin two-dimensional ReS2 nanosheet arrays were uniformly grown on the surface of NiS2. The internal hollow property provides sufficient space to relieve the volume expansion, and the outer two-dimensional nanosheet realizes the rapid electron transport and insertion/extraction of Na+. Owing to the great improvement of the transport kinetics of Na+, NiS2@ReS2 heterostructure electrode can achieve a high specific capacity of 400 mAh/g at the high current density of 1 A/g and still maintain a stable cycle stability even after 220 cycles. This hard template method not only paves a new way for the design and construct binary metal sulfide heterostructure electrode materials with outstanding electrochemical performance for Na+ batteries but also open up the potential applications of anode materials of SIBs.
Spatial isolation of different functional sites at the nanoscale in multifunctional catalysts for steering reaction sequence and paths remains a major challenge. Herein, we reported the spatial separation of dual-site Au and RuO2 on the nanosurface of TiO2 (Au/TiO2/RuO2) through the strong metal-support interaction (SMSI) and the lattice matching (LM) for robust photocatalytic hydrogen evolution. The SMSI between Au and TiO2 induced the encapsulation of Au nanoparticles by an impermeable TiOx overlayer, which can function as a physical separation barrier to the permeation of the second precursor. The LM between RuO2 and rutile-TiO2 can increase the stability of RuO2/TiO2 interface and thus prevent the aggregation of dual-site Au and RuO2 in the calcination process of removing TiOx overlayer of Au. The photocatalytic hydrogen production is used as a model reaction to evaluate the performance of spatially separated dual-site Au/TiO2/RuO2 catalysts. The rate of hydrogen production of the Au/TiO2/RuO2 is as high as 84 μmol h−1g−1 under solar light irradiation without sacrificial agents, which is 2.5 times higher than the reference Au/TiO2 and non-separated Au/RuO2/TiO2 samples. Systematic characterizations verify that the spatially separated dual-site Au and RuO2 on the nanosurface of TiO2 can effectively separate the photo-generated carriers and lower the height of the Schottky barrier, respectively, under UV and visible light irradiation. This study provides new inspiration for the precise construction of different sites in multifunctional catalysts.
An efficient and practical methods for the synthesis of carbamoyl quinoline-2, 4-diones via the reaction of ortho-cyanoarylacrylamides with oxamic acids was described. This cyclic reaction could be performed efficiently under metal free conditions. Various products with functional groups could be obtained with moderate to high yields via radical mechanism.
Herein, a rapid alkenylation of quinoxalin-2(1H)-ones enabled by a combination of Mannich-type reaction and solar photocatalysis is demonstrated. A wide range of functional groups are compatible, affording the corresponding products in moderate-to-good yields. Control experiments illustrate that the in situ generated 1O2 plays a central role in this reaction. This green and efficient strategy provides a practical solution for the synthesis of potentially bioactive compounds that containing a 3, 4-dihydroquinoxalin-2(1H)-one structure.
H2O2 has been widely applied in the fields of chemical synthesis, medical sterilization, pollutant removal, etc., due to its strong oxidizing property and the avoidable secondary pollution. Despite of the enhanced performance for H2O2 generation over g-C3N4 semiconductors through promoting the separation of photo-generated charge carriers, the effect of migration orientation of charge carriers is still ambiguous. For this emotion, surface modification of g-C3N4 was employed to adjust the migration orientation of charge carriers, in order to investigate systematically its effect on the performance of H2O2 generation. It was found that ultrathin g-C3N4 (UCN) modified by boron nitride (BN), as an effective hole-attract agent, demonstrated a significantly enhanced performance. Particularly, for the optimum UCN/BN-40% catalyst, 4.0-fold higher yield of H2O2 was obtained in comparison with the pristine UCN. As comparison, UCN modified by carbon dust demonstrated a completely opposite tendency. The remarkably improved performance over UCN/BN was ascribed to the fact that more photo-generated electrons were remained inside of triazine structure of g-C3N4, leading to the formation of larger amount of 1, 4-endoxide. It is anticipated that our work could provide new insights for the design of photocatalyst with significantly improved performance for H2O2 generation.
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