Direct Evidences of Shallow Donor Level Enhanced Green Emission in ZnO Quantum Dots.

ZnO Quantum dots with particle sizes about 5 nm were prepared by sol-gel method, the research about the photo luminescence(PL)/photoluminescence excitation(PLE) spectrum and the fluorescence lifetime indicated that the green emissions can be divided into two parts which were attributed to different transit mechanisms. The higher energy green emission was due to the electrons transit from conduction band to oxygen vacancies while the lower energy green emission was assigned to the electrons transit from the shallow donor levels which enhanced the green emission to the oxygen vacancies and the shallow donor levels was also the reason why the green emission reach strongest intensity when the excitation energy was a little lower than the band gap energy. While the blue emission can be explained by the electrons transiting from Zinc intervals to the valence band. The two mechanisms of green emission are first highlighted and should be considered in the optical application.

Engaging sulfinate salts via Ni/photoredox dual catalysis enables facile Csp2 -SO2R coupling.

This report details the development and implementation of a strategy to construct aryl- and heteroaryl sulfones via Ni/photoredox dual catalysis. Using aryl sulfinate salts, the C-S bond can be forged at room temperature under base-free conditions. An array of aryl- and heteroaryl halides are compatible with this approach. The broad tolerance and mild nature of the described reaction could potentially be employed to prepare sulfones with biological relevance (e.g., in bioconjugation, drug substance synthesis, etc.) as demonstrated in the synthesis of drug-like compounds or their precursors. When paired with existing Ni/photoredox chemistry for Csp3 -Csp2 cross-coupling, an array of diverse sulfone scaffolds can be readily assembled from bifunctional electrophiles. A mechanistic manifold consistent with experimental and computational data is presented.

Coupling of C(sp3)-H bonds with C(sp2)-O electrophiles: mild, general and selective.

Herein is reported the mild and general coupling of amine/ether C(sp3)-H bonds with various kinds of C(sp2)-O electrophiles with high selectivity and efficiency. Valuable allylic/benzylic amines are generated in moderate to excellent yields. The utility of this transformation is demonstrated by a broad substrate scope (>50 examples), good functional group tolerance and facile product modification.