China is undergoing unprecedented rapid urbanization, which is accompanied by the formation of more than 2000 black and odorous urban rivers. Dissolved organic matter (DOM) is an essential component in aquatic ecosystems and regulates the carbon and nutrient cycle, but its characteristics in highly polluted urban rivers are still not well understood. Here, water samples from the mainstream, tributaries, ponds, and reservoirs within the highly urbanized Maozhou River watershed (Shenzhen, China) were analyzed using absorption and fluorescence spectroscopy, stable carbon isotope analysis, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to explore the impact of urbanization on DOM characteristics. The results showed elevated dissolved organic carbon concentrations in the disturbed waters (mainstream, tributary, and pond) compared to those in the reservoir water. Results of the spectroscopic, isotopic, and FT-ICR MS analyses suggest that disturbed water DOM had lower aromaticity, average molecular weight, and plant-and soil-derived terrestrial (e.g., lignin-like) contributions but greater contributions from microbial-derived protein-like and anthropogenic sulfur-containing compounds (e.g., synthetic surfactants) than those of reservoir DOM. These characteristics were strengthened from the upper to the lower mainstream, which implies greater anthropogenic impact on downstream waters. Point-source wastewater effluent input caused increases in DOM level in the mainstream water and abrupt changes in DOM characteristics with very strong anthropogenic characteristics. The distinct chemistry of urban DOM from natural organic matter highlights a potentially strong impact of rapid urbanization on carbon and nutrient cycle in aquatic ecosystems.

A highly enantioselective NiH‐catalyzed hydrocyclization of alkynones with unparalleled anti‐ and endocyclic selectivities is described. The choice of the precatalysts has significant influence in tuning the regio‐ and enantioselectivity. Using Ni(OTs)2/Phox as a precatalyst and (EtO)2MeSiH as a hydride source, an array of enantioenriched O‐, N‐, and S‐containing heterocyclic tertiary allylic alcohols are obtained in 24–81 % yields with 80:20–99:1 er. Mechanistic investigations and synthetic application are also carried out. This study represents an efficient access to a set of allylic alcohols that are unable to access by the state‐of‐the‐art coupling reactions.

The potential threats of ethidium bromide to laboratory staff have drawn more and more attention. Considering that commercial available substitutes still cannot replace ethidium bromide due to some drawbacks, it can be a better solution by functionalizing directly on ethidium bromide moiety. In this work, ethidium bromide is ameliorated via changing the bromide anion into moieties with more twist structures to prevent the aggregation caused quenching in aggregations, and increase more hydrophobic ability to form nanoparticles in aqueous. The nanoparticles of these probes show negative zeta potential, low toxicity, good photostability, and high sensitivity, both in solution tests and gel electrophoresis experiments. Meanwhile, the weak penetration ability through skin constitutes a dual protection for users. Furthermore, the one step synthesis from commercial available ethidium bromide and the convenient purification also do help to these probes in applications.

An enantioselective nickel-catalyzed syn-hydrocyclization of alkyne-tethered ketoamides for the synthesis of α-hydroxy γ-lactams is reported. Using Ni(OTs)2•6H2O/(S,S)-Me-Duphos as a precatalyst and (EtO)2MeSiH as a hydride source, a broad range of...

An enantioselective NiH-catalyzed syn-hydrocyclization of alkyne-tethered ketoamides for the synthesis of α-hydroxy γ-lactams is reported. Using Ni(OTs)2•6H2O/(S,S)-Me-Duphos as a precatalyst and (EtO)2MeSiH as a hydride source, a broad range of enantioenriched γ-lactams with a fully substituted stereogenic center are obtained in 32–84% yields with 89.5:10.5–96.5:3.5 er. Synthetic utilities, including scale-up reaction and product derivatization, are also demonstrated. This research represents a ligand-enabled regioselective functionalization of alkynes and provides an efficient strategy to access functional group-enriched chiral heterocycles.