Synthesis of 1,2-Diketones via a Metal-Free, Visible-Light-Induced Aerobic Photooxidation of Alkynes

1,2-Diketones were synthesized by the oxidation of corresponding alkynes using air as the oxidant under metal-free conditions upon irradiation of blue light. A cheap and readily available organic dye, eosin Y, was used as the photocatalyst. For various substituents on the aryl ring, the reaction proceeded smoothly to give the dicarbonylation products in moderate to good yields. Some oxidation-sensitive groups, such as formyl and the carbon–carbon double bond, were tolerated under the developed reaction conditions

HAT-Mediated Electrochemical C(sp²)–H Acylation of Quinolines with Alcohols

Herein, an electrochemical hydrogen atom transfer (HAT) strategy for C(sp2)–H formylation of electron-deficient quinolines and isoquinolines is described. The cheap methanol acts as a formyl source with a catalytic amount of N-hydroxyphthalimide (NHPI) as the hydrogen atom transfer (HAT) catalyst. The advantages of this reaction are transition-metal-catalyst- and chemical-oxidant-free conditions, and the protocol could also be applied to the direct C(sp2)–H acetylation or propionylation of quinolines

Improved performance of UV-LED by p-AlGaN with graded composition

AlGaN-based ultraviolet light emitting diodes(UV-LEDs) on AlN/sapphire template were grown by metal organic chemical vapour deposition. The AlN template was characterized by atomic force microscopy and high resolution X-ray diffraction. Atomic force microscopy image shows that the AlN surface is very flat, while high resolution X-ray diffraction results prove the good crystalline quality of the AlN template. A novel structure UV-LED which has several p-AlGaN layers with graded composition is compared with a common structure UV-LED which has a single p-Al0.5Ga0.5N layer. The forward bias voltage at20 mA driving current for the novel structure UV-LED is nearly3 V higher than that of the common structure UV-LED, however, the electroluminescence intensity of the former is over two times higher than that of the latter. The total quantum efficiency of the novel structure UV-LED is more than50% higher than that of the common structure UV-LED. The improvement is considered to be the result of better holes injection efficiency in the novel structure UV-LED.?2011 WILEY-VCH Verlag GmbH& Co. KGaA, Weinheim