The deposition of an atomically precise nanocluster, for example, Ag44(SR)30, onto a large‐band‐gap semiconductor such as TiO2 allows a clear interface to be obtained to study charge transfer at the ...interface. Changing the light source from visible light to simulated sunlight led to a three orders of magnitude enhancement in the photocatalytic H2 generation, with the H2 production rate reaching 7.4 mmol h−1 gcatalyst−1. This is five times higher than that of TiO2 modified with Ag nanoparticles and even comparable to that of TiO2 modified with Pt nanoparticles under similar conditions. Energy band alignment and transient absorption spectroscopy reveal that the role of the metal clusters is different from that of both organometallic complexes and plasmonic nanoparticles: A type II heterojunction charge‐transfer route is achieved under UV/Vis irradiation, with the cluster serving as a small‐band‐gap semiconductor. This results in the clusters acting as co‐catalysts rather than merely photosensitizers.
Multitasking: Metal nanoclusters are not merely photosensitizers, they can also act as co‐catalysts under appropriate conditions. Deposition of the atomically precise nanocluster Ag44(thiolate)30 onto a large‐band‐gap semiconductor such as TiO2 led to a type II heterojunction charge‐transfer route being achieved on irradiation with UV/Vis light, with the cluster serving as a small‐band‐gap semiconductor, rather than merely a photosensitizer.
A versatile and general zinc‐mediated intermolecular reductive radical fluoroalkylsulfination of unsaturated C−C bonds has been developed using readily available fluoroalkyl bromides and ...1,4‐diazabicyclo2.2.2octane‐bis(sulfur dioxide) adduct (DABSO) with wide substrate scope and excellent functional group tolerance. Sulfur dioxide anion radical generated in situ from the reduction of sulfur dioxide with zinc may be involved in the reaction mechanism.
A zinc‐mediated intermolecular reductive radical fluoroalkylsulfination of unsaturated C−C bonds has been developed using readily available fluoroalkyl bromides, 1,4‐diazabicyclo2.2.2octane‐bis(sulfur dioxide) adduct (DABSO) and N‐fluorobenzenesulfonimide (NFSI) with wide substrate scope and excellent functional group tolerance. Sulfur dioxide anion radical generated from the reduction of sulfur dioxide with zinc may be involved in the reaction mechanism.
Presented is a novel intermolecular radical trifluoromethylfluorosulfonylation of unactivated alkenes under mild reaction conditions with good functional‐group tolerance in the most atom‐economic ...manner by using readily available Ag(O2CCF2SO2F) and N‐fluorobenzenesulfonimide (NFSI). Both the trifluoromethyl and sulfonyl groups in the products originate from Ag(O2CCF2SO2F).
Making it functional: The title reaction proceeds using the readily available Ag(O2CCF2SO2F) and N‐fluorobenzenesulfonimide (NFSI) under mild reaction conditions, and features good functional‐group tolerance. The CF3 group in the product originates from a AgCF3 species formed from Ag(O2CCF2SO2F), and the in situ generated SO2 is trapped and converted into a sulfonyl group, thus demonstrating the atom economy of the reaction.
A practical and efficient method for the direct trifluoromethylthiolation of unactivated C(sp3)H bonds by AgSCF3/K2S2O8 under mild conditions is described. The reaction has a good functional‐group ...tolerance and good selectivity. Initial mechanistic investigations indicate that the reaction may involve a radical process in which K2S2O8 plays key roles in both the activation of the C(sp3)H bond and the oxidation of AgSCF3.
Direct and mild: A variety of alkyltrifluoromethylthioethers were efficiently synthesized by direct trifluoromethylthiolation of unactivated C(sp3)H bonds under mild reaction conditions. The reagent system comprises AgSCF3 and K2S2O8, the latter of which both activates the C(sp3)H bond and oxidizes AgSCF3. The reaction has a broad substrate scope with good functional‐group tolerance and good selectivity.
Copper is king! A convenient method for the synthesis of trifluoromethylated heteroaromatic compounds under mild conditions has been developed based on the observation that 1 can be reduced by ...certain metals (see scheme). Substrate 1 is assumed to be reduced by copper via a single‐electron transfer mechanism, and CuCF3 is the most probable intermediate in this reaction. DMF=N,N‐dimethylformamide, Tf=triflate.
An efficient method for the iron(III) porphyrin catalyzed olefination of various aldehydes with 2,2,2‐trifluorodiazoethane under neutral conditions is described. This transformation was shown to have ...a broad substrate scope and provide the corresponding CF3‐substituted alkenes in good yields. The number of equivalents of PPh3 that is used in this reaction is crucial to the success of the olefination process. This reaction is a useful supplement to the synthetic applications of CF3CHN2.
An efficient method for the iron(III) porphyrin catalyzed olefination of various aldehydes with 2,2,2‐trifluorodiazoethane (CF3CHN2) under neutral conditions has been developed. This reaction is an important supplement to the synthetic applications of CF3CHN2.
The sulfinatodehalogenation reaction represents one of the most important methodologies to incorporate fluorine into organic molecules. Using inexpensive sulfur-containing reactants such as ...Na(2)S(2)O(4) under mild conditions, per- and polyfluoroalkyl halides (R(F)X, X = Br, I, CCl(3)) can be transformed smoothly into the corresponding sulfinate salts. This method is also used for the perfluoroalkylation of alkenes, dienes, alkynes and aromatics. Notably, after 1998, the sulfinatodehalogenation of perfluoroalkyl chlorides (R(F)Cl) has been realized by using dimethylsulfoxide (DMSO) as a solvent instead of CH(3)CN/H(2)O in the Na(2)S(2)O(4)/NaHCO(3) initiation system. Perfluoroalkyl chlorides, ethyl chlorofluoroacetates and chlorodifluoroacetates, and even nonfluorinated compounds, such as ethyl chloro- or dichloroacetates and chloroform, were either converted into the corresponding sulfinate salts or alkylated alkenes, alkynes and aromatics (including porphyrins). The sulfinatodehalogenation reaction has remarkable advantages. With the increasing demands to utilize the unique properties of fluorine and fluorinated functional groups in medicinal, agricultural and material sciences, we believe that there will continue to be useful developments in sulfinatodehalogenation chemistry and it will be applied more widely in the future.
Aim： To investigate the effects of piperine, a major pungent alkaloid present in Piper nigrum and Piper Iongum, on the tumor growth and metastasis of mouse 4T1 mammary carcinoma in vitro and in vivo, ...and elucidate the underlying mechanisms. Methods： Growth of 4T1 cells was assessed using MTIassay. Apoptosis and cell cycle of 4T1 cells were evaluated with flow cytometry, and the related proteins were examined using Western blotting. Real-time quantitative PCR was applied to detect the expression of matrix metalloproteinases （MMPs）. A highly malignant, spontaneously metastasizing 4T1 mouse mammary carcinoma model was used to evaluate the in vivo antitumor activity. Piperine was injected into tumors every 3 d for 3 times. Results： Piperine （35-280 pmol/L） inhibited the growth of 4T1 cells in time- and dose-dependent manners （the IC5o values were 105±1.08 and 78.52±1.06 pmol/L, respectively, at 48 and 72 h）. Treatment of 4T1 cells with piperine （70-280 pmol/L） dose-dependently induced apoptosis of 4T1 cells, accompanying activation of caspase 3. The cells treated with piperine （140 and 280 pmol/L） significantly increased the percentage of cells in G2/M phase with a reduction in the expression of cyclin BI. Piperine （140 and 280 pmol/L） significantly decreased the expression of MMP-9 and MMP-13, and inhibited 4T1 cell migration in vitro. Injection of piperine （2.5 and 5 mg/kg） dose-dependently suppressed the primary 4T1 tumor growth and injection of piperine （5 mg/kg） significantly inhibited the lung metastasis. Conclusion： These results demonstrated that piperine is an effective antitumor compound in vitro and in vivo, and has the potential to be developed as a new anticancer drug.
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