Chem最新文献

Tim Cernak is an associate professor of Medicinal Chemistry at the University of Michigan. He holds appointments in the University of Michigan Department of Chemistry, Program in Chemical Biology, Center for Global Health Equity, and Michigan Institute for Data Science. Tim’s research interests include chemical synthesis, catalysis, total synthesis, cheminformatics, ecology, data science, automation, natural products, medicinal chemistry, agrichemistry, sustainability, cell imaging, mass spectrometry, conservation, robotics, extinction, and drug discovery. Tim has served on the advisory board of the University of Dundee’s Drug Discovery Unit, the Open Reaction Database, and Scorpion Therapeutics. He is a co-founder of Iambic Therapeutics.

Dr. Adam D. Moorhouse obtained his PhD at the University of Nottingham, UK. In the Moses group, he specializes in click chemistry to advance drug discovery processes. Dr. Joshua A. Homer completed his PhD at the University of Auckland, New Zealand. As a Research Investigator in the Moses group, he applies click chemistry to develop new antibiotics. Dr. John E. Moses is the founding professor of click chemistry at Cold Spring Harbor Laboratory, New York, focusing on innovating click reactions for drug discovery.

Nitrogen is the fundamental element for all living organisms to build proteins, nucleic acids, and various biomolecules. The industrial Haber-Bosch process, a cornerstone in converting atmospheric nitrogen (N₂) to metabolic ammonia (NH₃), is marked by its significant carbon footprint. With the widespread deployment of renewable energy systems, exploring sustainable approaches for ambient, low-carbon, and decentralized NH₃ production is promising yet challenging. This perspective summarizes our recent advancements in designing catalytic systems for NH₃ synthesis, which use innocuous N₂ or detrimental nitrate (NO₃⁻) as feedstocks, harnessing solar light and electricity as the source of green energy. We demonstrate some active sites’ engineering strategies to improve the activity and selectivity of catalytic NH₃ synthesis. A flow-through-coupled device is then highlighted for efficient NH₃ separation without any pH adjustment. We also discuss the challenges and perspectives of sustainable nitrogen loops powered by green energy in aspects of fundamental research and industrial application.

Electrochemical refinery, substituting the oxygen evolution reaction with thermodynamically favorable anode oxidation reactions coupled with cathode reduction reactions, is an emerging cost-effective strategy for the maximal utilization of electrical energy alongside the production of high-value chemicals for economic benefits and high efficiency. However, a summary and coherent perspective on the advances in electrochemical refinery have been long overdue. This review systematically sums up the recent advances and innovative strategies in electrochemical refinery aimed at enhancing economic benefits. Specifically, sacrificial-agent oxidation reaction coupling reduction reactions can achieve pollutant degradation and improve energy efficiency, while electrochemical synthesis reaction coupling reduction reactions can generate value-added products on both sides. Further, catalyst designs, specific reaction mechanisms, and cell configurations are discussed in detail. Finally, we showcase new insights on the current challenges and future perspectives on the development of coupled systems and hope to inspire further innovative work in this rapidly growing field.

Natural photosystems accomplish panchromatic light absorption by different chromophores that are non-covalently embedded in protein matrices and mostly lack close dye-dye interactions. In this article, we introduce a light-harvesting (LH) system established by four different merocyanine dyes that are co-facially stacked by dipole-dipole interactions and a peptide-like backbone in a folded heteromer architecture to afford a panchromatic absorption band consisting of several strongly coupled exciton states. This exciton manifold allows for ultrafast and efficient energy transport in the artificial antenna. Furthermore, due to the tight stacking of the dyes in their folded state, non-radiative processes are slowed down, thereby increasing the lifetime of the excited state and the fluorescence quantum yield from <3% for the individual dyes up to 38% for the folda-heteromer. Together with the panchromatic absorption, this leads to a substantial improvement of the fluorescence brightness upon broadband excitation in comparison with its constituent chromophores.

Transition metal-catalyzed cross-couplings represent the most dependable techniques for linking aryl electrophiles with nucleophiles to synthesize a diverse array of valuable aromatic compounds. Although aromatic ketones are crucial intermediates in the synthesis of aromatic compounds with numerous known methods for carbonyl transformations and aromatic ring modifications, few consider them as aryl electrophiles suitable for cross-coupling. This is primarily because forming new bonds with nucleophiles requires the cleavage of a strong C–C bond. Herein, we introduce a cross-coupling method that effectively utilizes aromatic ketones as versatile aryl electrophiles. The cornerstone of our strategy is the transformation of aromatic ketones into aromatic esters via sequential Claisen and regioselective retro-Claisen condensations. The resulting esters are then capable of undergoing reactions with various nucleophiles in a one-pot process.

Structure-defined N-glycans are essential tools to uncover the molecular basis of N-glycan functions. However, the difficulty in obtaining diverse collections of well-defined N-glycans has always been an obstacle that greatly hampers progress in glycoscience. Here, we developed a general platform for the concise total synthesis of N-glycans. Using the designed strategy, the general N-glycan precursors, including core pentasaccharide and core tetrasaccharide, were successfully assembled from common starting materials in only a few facile chemical and enzymatic steps. Starting from core pentasaccharide and core tetrasaccharide, a variety of biantennary N-glycans were prepared successfully in large quantities by taking advantage of enzymatic diversification. In particular, reverse galactosylation was employed as a selective protecting strategy, by which complex asymmetric N-glycans could be obtained easily and efficiently.

In this issue of Chem, Che et al. report a dinuclear copper(I) complex as an air-stable, efficient photocatalyst for C–C coupling reactions with unactivated aryl/alkyl halides. The photoinduced metal-metal-to-ligand charge transfer excited state is capable of cleaving C–X bonds via halogen-atom transfer, while Cu-arene interaction is revealed to play a key role in enabling this photocatalysis.

The principle of hard and soft acids and bases (HSAB) has given chemists a broad understanding of the observed selectivity in a variety of reaction classes. As we become increasingly aware of the principle's serious limitations, this study provides an alternative approach. The distinction between hard and soft electrons and holes (HSEH) adds to our understanding of reactivity. Because radicals are typically better stabilized at soft sites and lone pairs are better stabilized at hard sites, we can easily distinguish them. Simple electron density differences (from three single-point density functional theory [DFT] calculations) can be used to visualize this effect and condense the differences into a numerical descriptor. The usefulness of the concept is demonstrated by reproducing the experimentally observed reactivity of a wide range of molecules, including larger examples relevant to the material and pharmaceutical sciences.

In this issue of Chem, Chen, Zhang, and coworkers reported an unprecedented ground-state, kinetically trapped, photoinduced charge-transfer complex between an electron-deficient 1,8-naphthalimide acceptor and an electron-rich amine donor. This complex not only has fundamental physical implications in electron donor-acceptor interactions but may also address several challenges in redox-triggered polymerization, CO₂ reduction, and UV-light energy storage.