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We describe here an approach for synthesizing quinolines either from

Semiconductor quantum dots (QDs) in conjunction with non-noble 3d-metal ions (e.g., Fe3+, Co2+, and Ni2+) have emerged as an extremely efficient, facile, and cost-effective means of solar-driven hydrogen (H2) evolution. However, the exact structural change of the active sites under realistic conditions remains elusive, and the mechanism of H2 evolution behind the remarkable activity is poorly understood. Here, we successfully track the structural variation of the catalytic sites in the typical H2 photogeneration system consisting of CdSe/CdS QDs and 3d-metal ions (i.e., Ni2+ used here). That is, the nickel precursor of Ni(OAc)2 changes to Ni(H2O)62+ in neutral H2O and eventually transforms to Ni(OH)2 nanosheets in alkaline media. Furthermore, the in operando spectroscopic techniques of electron paramagnetic resonance and X-ray absorption spectroscopy reveal the photoinduced transformation of Ni(OH)2 to a defective structure [Nix0/Ni1-x(OH)2], which acts as the real catalytic species of H2 photogeneration. Density functional theory (DFT) calculations further indicate that the surface Ni-vacancies (VNi) on the Ni(OH)2 nanosheets enhance the adsorption and dissociation of H2O molecules to enhance the local proton concentration, while the Ni0 clusters behave as H2-evolution sites, thereby synergistically promoting the activity of H2 photogeneration in alkaline media.

Transition-metal-catalyzed C-N bond-forming reactions have emerged as fundamental and powerful tools to construct arylamines, a common structure found in drug agents, natural products, and fine chemicals. Reported herein is an alternative access to heteroarylamine via radical-radical cross-coupling pathway, powered by visible light catalysis without any aid of external oxidant and reductant. Only by visible light irradiation of a photocatalyst, such as a metal-free photocatalyst, does the cascade single-electron transfer event for amines and heteroaryl nitriles occur, demonstrated by steady-state and transient spectroscopic studies, resulting in an amine radical cation and aryl radical anion in situ for C-N bond formation. The metal-free and redox economic nature, high efficiency, and site-selectivity of C-N cross-coupling of a range of available amines, hydroxylamines, and hydrazines with heteroaryl nitriles make this protocol promising in both academic and industrial settings.

[2+2] Photocycloaddition of two olefins is a general method to assemble the core scaffold, cyclobutane, found in numerous bioactive molecules. A new approach to synthesize cyclobutanes through multicomponent cascade reactions by merging aldol reaction and Witting reaction with visible-light-induced [2+2] cycloaddition is reported. An array of cyclobutanes with high selectivity has been achieved from commercially available aldehydes, ketones (or phosphorus ylide), and olefins with visible-light irradiation of a catalytic amount of (fac-tris(2-phenylpyridinato-C2 ,N)iridium) ([Ir(ppy)3 ]) at room temperature. Control experiments and spectroscopic studies revealed that the triplet-triplet energy transfer from the excited [Ir(ppy)3 ]* to enones, generated in situ from aldehyde and ketone or aldehyde and phosphorus ylide, is responsible for these simple and efficient muticomponent transformations.

Here is the first visible light catalytic intermolecular cross [2 + 2] cycloaddition of enynes with alkenes to alkynyl cyclobutanes established with good functional group tolerance and high reaction efficiency and selectivity. Detailed studies reveal that enynes, including nonaromatic ones, can be sensitized by fac-Ir(ppy)3 via an energy transfer pathway. Addition of the Lewis acid PPh3AuNTf2 enables the cross photo[2 + 2] cycloaddition reaction to take place under both direct visible light irradiation or sensitization by Ru(bpy)3(PF6)2.

Inspired by the cubic Mn4 CaO5 cluster of natural oxygen-evolving complex in Photosystem II, tetrametallic molecular water oxidation catalysts, especially M4 O4 cubane-like clusters (M=transition metals), have aroused great interest in developing highly active and robust catalysts for water oxidation. Among these M4 O4 clusters, however, copper-based molecular catalysts are poorly understood. Now, bio-inspired Cu4 O4 cubanes are presented as effective molecular catalysts for electrocatalytic water oxidation in aqueous solution (pH 12). The exceptional catalytic activity is manifested with a turnover frequency (TOF) of 267 s-1 for [(LGly -Cu)4 ] at 1.70 V and 105 s-1 for [(LGlu -Cu)4 ] at 1.56 V. Electrochemical and spectroscopic study revealed a successive two-electron transfer process in the Cu4 O4 cubanes to form high-valent CuIII and CuIII O. intermediates during the catalysis.

Inspired by the cubic Mn