The availability of robust, versatile and efficient photocatalysts has been a main bottleneck in practical applications of photocatalytic degradation of organic pollutants. Herein, N-WO 3 /Ce 2 S 3 nanotube bundles (NBs) were synthesized and successfully immobilized on a carbon textile, resulting in a flexible and conducting photocatalyst. Due to the large interfacial area between N-WO 3 and Ce 2 S 3 , the interwoven 3D carbon architecture and, more importantly, the establishment of a heterojunction between N-WO 3 and Ce 2 S 3 , the resultant photocatalyst exhibits excellent light absorption capacity and superior ability to separate photoinduced electron-hole pairs for the photocatalytic degradation of organic compounds in air and water media. Theoretical calculations confirm that the strong electronic interaction between N-WO 3 and Ce 2 S 3 could be beneficial to the enhancement of the charge carrier transfer dynamics of the as-prepared photocatalyst. This work provides a new protocol for constructing efficient flexible photocatalysts for application in environmental remediation.
Manganese dioxide (MnO2), with naturally abundant crystal phases, is one of the most active candidates for toluene degradation. However, it remains ambiguous and controversial of the phase–activity relationship and the origin of the catalytic activity of these multiphase MnO2. In this study, six types of MnO2 with crystal phases corresponding to α‐, β‐, γ‐, ε‐, λ‐, and δ‐MnO2 are prepared, and their catalytic activity toward ozone‐assisted catalytic oxidation of toluene at room temperature are studied, which follow the order of δ‐MnO2 > α‐MnO2 > ε‐MnO2 > γ‐MnO2 > λ‐MnO2 > β‐MnO2. Further investigation of the specific oxygen species with the toluene oxidation activity indicates that high catalytic activity of MnO2 is originated from the rich oxygen vacancy and the strong mobility of oxygen species. This work illustrates the important role of crystal phase in determining the oxygen vacancies’ density and the mobility of oxygen species, thus influencing the catalytic activity of MnO2 catalysts, which sheds light on strategies of rational design and synthesis of multiphase MnO2 catalysts for volatile organic pollutants’ (VOCs) degradation.
Spiro-thiazolone–cyclopropane-oxindoles with three contiguous stereocenters, including two vicinal quaternary centers, were obtained via an organocatalytic asymmetric Michael/alkylation cascade reaction.
Asymmetric construction of tetrahydrothiophenes with four contiguouss tereocenters remains af ormidable challenge. Herein, the bottleneck was addressed by an unprecedented one-pot Michael-Henry-cascade-rearrangementr eaction that could simultaneously create four consecutive stereogenic centers including two tetrasubstituted carbon stereocenters. The highly functionalized chiral spirotetrahydrothiophenescaffolds were assembled in moderatet og ood yields ( % 54-79 %), excellent diastereo-(> 20:1 d.r.) ande nantio-selectivities (up to 93 % ee).Sulfur is au biquitous elementi nanumber of natural products and marketed drugs. Owing to its unique drug-like properties, sulfur-containing groups have been widely used in drug design and medicinal chemistry.[1] Therefore, highly stereoselective construction of chiralo rganosulfur scaffolds has attracted broad interests. [1a, 2] Among the various classes of organosulfur scaffolds, optically active polysubstituted tetrahydrothiophenesh ave attracted considerable attention in the past decades due to their broad prevalence in natural products and marketed drugs with al arge spectrum of biological activities. [3] In particular, chiral spiro-tetrahydrothiophene oxindole represents ap romising scaffold for drug discovery. [4] For the construction of chiral tetrahydrothiophenes [3,5] and spiro-tetrahydrothiophene oxindoles, [6] catalytic asymmetric sulfa-Michael/aldoland sulfa-Michael/Michaelcascade reactions between a,b-unsaturated compounds and mercaptoacetaldehyde analoguesh ave been reported. However,c urrent asymmetric synthetic methods only led to the assembly of functionalized tetrahydrothiophenes with three consecutive stereogenic centers. Simultaneously constructing tetrahydrothiophenes with four contiguous stereocenters remains af ormidable challenge.Owing to the synthetic challenge and therapeuticv alue, it is highly desirable to develop novel synthetica pproaches to assemble highly functionalized chiral spiro-tetrahydrothiophene oxindole scaffolds bearing four contiguous stereocenters.[7] Previously,T akahata et al. reported ap ractical synthesis of 4'-thioribonucleosides startingf rom 5-thioarabinose through the sulfonium-mediated ring-contraction reaction.[8] Inspired by this work, [8] and our previous findings on asymmetric synthesis of organosulfur scaffolds [9] ,h erein, novel Michael-Henry-cascaderearrangement reactions were designed to address the abovementioned bottleneck. We envisioned that the highly functionalized spiro-tetrahydrothiophene oxindole scaffold with four consecutive stereogenic centers couldb ee fficiently constructed via the sulfonium-mediated rearrangementr eaction [8,10] of the spiro-tetrahydrothiopyran oxindole scaffold (Scheme 1). This scaffold could be efficiently constructed using the organocatalytic asymmetricM ichael-Henry [11] cascade process. Thus, a new substrate 1,b earing the nucleophilic oxindole-C3 as the Michael donor and the carbonyl group forf urther tandem Henry reaction( Scheme1), was designed ands ynthesized. ...
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