Rhodium(II)-Catalyzed Denitrogenative Annulation for the Synthesis of Substituted Tetrahydroisoquinolines.

Tetrahydroisoquinoline (THIQ) derivatives stand out as a promising class of compounds due to their diverse range of biological activities, making them particularly valuable in drug discovery. To enhance their structural diversity, an Rh-catalyzed denitrogenative annulation method has been introduced for synthesizing these derivatives. An intriguing aspect of this method is the ability of the Brønsted acid to prevent further annulation while facilitating the production of the desired THIQ derivatives, achieving impressive yields of up to 86%. This synthetic approach was subsequently leveraged to create an analogue of cyclocelabenzine, a compound showing potential as an anti-inflammatory agent.

Progress in electrocatalytic hydrogen evolution of transition metal alloys: synthesis, structure, and mechanism analysis.

At present, the problems of high energy consumption and low efficiency in electrocatalytic hydrogen production have limited the large-scale industrial application of this technology. Constructing effective catalysts has become the way to solve these problems. Transition metal alloys have been proved to be very promising materials in hydrogen evaluation reaction (HER). In this study, the related theories and characterization methods of electrocatalysis are summarized, and the latest progress in the application of binary, ternary, and high entropy alloys to HER in recent years is analyzed and studied. The synthesis methods and optimization strategies of transition metal alloys, including composition regulation, hybrid engineering, phase engineering, and morphological engineering were emphatically discussed, and the principles and performance mechanism analysis of these strategies were discussed in detail. Although great progress has been made in alloy catalysts, there is still considerable room for applications. Finally, the challenges, prospects, and research directions of transition metal alloys in the future were predicted.

Heterogeneous cobalt polysulfide leaf-like array/carbon nanofiber composites derived from zeolite imidazole framework for advanced asymmetric supercapacitors.

Developing new electrode materials is one of the keys to improving the energy density of supercapacitors. In this article, a novel cobalt polysulfide/carbon nanofibers (C,N-CoxSy/CNF) film derived from zeolitic imidazolate framework is first prepared by a facile strategy. The composite material with two-dimensional leaf-shaped nanoarray neatly grown on the surface of carbon nanofibers is composed of CoS, CoS2, Co9S8, N-doped carbon nanosheets, and carbon nanofibers. It is found that the composite can not only increase the contact area with the electrolyte but also provide abundant redox-active sites and a Faraday capacitance for the entire electrode. The C,N-CoxSy/CNF composite exhibits excellent electrochemical properties, including a high capacity of up to 1080F g -1 at 1 A g -1 and a good rate capability (80.4 % from 1 A g -1 to 10 A g -1). A C,N-CoxSy/CNF//AC asymmetric supercapacitor device is assembled using C,N-CoxSy/CNF as the positive electrode and activated carbon as the negative electrode, showing high energy density (37.29 Wh kg -1@813.6 W kg -1) and good cycle stability (90.5% of initial specific capacitance at 10 g-1 after 5000 cycles). This C,N-CoxSy/CNF composite material may also be used as a potential electrode for future lithium-ion batteries, zinc-ion batteries, lithium-sulfur batteries, etc.

Synthesis and Photophysical Characterization of 2,3-Dihydroquinolin-4-imines: New Fluorophores with Color-Tailored Emission.

In this study, a series of variously substituted 2,3-dihydroquinolin-4-imines (DQIs) were synthesized from N-substituted propargylanilines by copper(I)-catalyzed annulation. The approach adopted in this study under mild, effective conditions exhibited broad substrate tolerance, particularly for functional groups substituted on anilines. Most of the DQI derivatives synthesized under optimal conditions were obtained in good isolated yields of 63-88 %. 2,3-Dihydroquinolinimine thus obtained was easily converted to important structures like 2,3-dihydroquinolone and tetrahydrobenzodiazepin-5-one, confirming the importance of this strategy in constructing various heterocycles. Surprisingly, 2,3-dihydroquinolinimines thus obtained exhibited bright fluorescence with quantum yields up to 66 %. The density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed for understanding the excited-state nature of DQI system. Accordingly, a tailored DQI derivative bearing methoxy group at C-6 position and acetoxy group at C-7 position was designed and synthesized to give emission at 559 nm with redshift compared to the 7-methoxy substituted DQI. A detailed study of DQI structures with their photophysical properties was performed with five control molecules and consequently demonstrated the uniqueness of the chemical structures of DQIs.