Graphene oxide-Ag 2 CO 3 (GO-Ag 2 CO 3 ) composites have been prepared by a simple and effective precipitation method, and found to exhibit a higher photocatalytic activity toward degradation of organic dyes, including rhodamine B, methylene blue and methyl orange, in aqueous solution, than pure Ag 2 CO 3 crystal under visible light. The Ag 2 CO 3 crystal with 0.9 wt% GO content exhibited the highest photodegradation efficiency for organic dyes, which was 2 times that of pure Ag 2 CO 3 crystal. The improved photocatalytic activity of GO-Ag 2 CO 3 composites was attributed to the corporative effects of high-surfacearea of GO sheets, enhanced absorption of organic dyes, small band gap, more efficient separation of photogenerated electron-hole pairs, and good electron acceptor properties of GO. The photocorrosion of Ag 2 CO 3 crystal can be efficiently inhibited by GO, since the transfer of photogenerated electrons from the surface of Ag 2 CO 3 crystal to GO sheets can reduce the possibility of decomposing Ag + to Ag 0 , which resulted in an improved stability and recyclability of the GO-Ag 2 CO 3 composite in the photocatalytic reaction. This facile and straightforward method has promising applications in the fabrication of different graphene oxide-based heterostructure photocatalysts.
We report a simple and efficient visible-light-induced transitionmetal-free hydrogenation of aryl halides. The combined visible light and base system is used to initiate the desired radical-mediated hydrogenation. A variety of aryl fluorides, chlorides, bromides, and iodides could be reduced to the corresponding (hetero)arenes with excellent yields under mild conditions. Various functional groups and other heterocyclic compounds are tolerated.
A heterogeneous iridium-complex-catalyzed N-O-cleaving rearrangement/cyclization of 2,3-dihydroisoxazoles with alkenes has been developed. It provides divergent access to multiple substituted pyrrolidines, pyrroles, and carbazoles. The iridium catalyst remains highly catalytic active after seven cycles. The gram-scale synthesis afforded a carbazole with strong bluish-violet fluorescence.
Highly functionalized indoles and indolones were prepared via selectivity-switchable mono- or diolefinations. The Julia olefination of the products followed by a Brønsted acid-prompted cyclization afforded indolones, whereas the indoles were obtained by a sequential Wittig olefination and electrocyclization. This method opens divergent access to highly functionalized nitrogen-containing bicyclic or tricyclic heterocycles.
Az inc diiodide (ZnI 2 )-mediated direct synthesis of 2,3-dihydroisoxazoles via a[ 3 + +2] cycloaddition reaction of the nitrones and non-electrondeficient terminal alkynes has been developed. This method was applied in the formal synthesis of HPA-12 andaminoglucose.
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