Chem最新文献

N,N-Dimethylformamide (DMF) is a versatile chemical and universal solvent that is commonly synthesized from carbon monoxide and dimethylamine (DMA) under high temperature and pressure. However, this process leads to a large amount of carbon emissions. Herein, we propose an electrochemical strategy to directly convert carbon dioxide (CO₂) and DMA to DMF under ambient conditions. Loading palladium (Pd) onto copper (Cu) nanosheet catalysts with Cu vacancies (Pd/Cu-V_Cu) enabled the efficient synthesis of DMF, and the maximum yield and faradaic efficiency reached 385 mmol·h⁻¹·g_cat. ⁻¹ and 37.5%, respectively. In situ spectroscopy and density functional theory calculations indicated that Cu vacancies (Cu-V_Cu) promoted the adsorption of CO₂ on the catalyst surface, followed by its spontaneous coupling with DMA to form the C–N bond. Pd nanoparticles accelerated the electrochemical reduction of the intermediate ∗OCN(CH₃)₂OH to ∗OCHN(CH₃)₂OH, leading to highly efficient DMF electrosynthesis. This work paves the way for the synthesis of sustainable high-value organic nitrogen compounds from CO₂.

Potential bottlenecks in high-throughput determination of enantiomeric excess in chiral primary amines is being addressed, by Howard et al. in this issue of Chem, by developing a data-driven methodology that replaces extensive calibration measurements and the corresponding calibration curves through a combination of machine learning methods and computations that produces a theoretical model and predicted calibration curves.

Professor Heather J. Kulik is a professor in chemical engineering and chemistry at MIT. She received her BE in chemical engineering from the Cooper Union in 2004 and her PhD from the Department of Materials Science and Engineering at MIT in 2009. She completed postdocs at Lawrence Livermore and Stanford prior to joining MIT as a faculty member in 2013. Her research in computational inorganic chemistry has been recognized by an ONR YIP, a DARPA Director’s fellowship, an NSF CAREER Award, a Sloan Fellowship, an AIChE CoMSEF Impact Award, and a Hans Fischer Senior Fellowship from TU Munich, among others.

Inspired by the proposed biogenic skeletal diversification process, the divergent total syntheses of 10 structurally complex pallavicinia diterpenoids with three distinct carbon skeletons, pallavicinin, neopallavicinin, pallambins A–D, pallaviambins A/B, and pallavicinolides B/C, were accomplished. Among them, the total syntheses of pallaviambins A/B and pallavicinolides B/C were achieved for the first time, and the synthetic routes of pallavicinin, neopallavicinin, and pallambins A/B were the shortest. The total syntheses feature a stereoselective Ireland-Claisen rearrangement to construct the C10 quaternary carbon stereocenter, the 2-fluoroethyl vinyl ether used as a masked methyl ketone for the first time, a biomimetic C2–C8 aldol reaction to construct the pallavicinin skeleton, a biomimetic cascade reaction of C4–C8 aldol reaction/oxa-Michael addition/MeOH elimination for the synthesis of pallambins C/D, and the spontaneously intramolecular Diels-Alder reaction to generate the pallavicinolide skeleton.

Advanced carbon materials used for energy-related applications often contain nitrogen as a heteroatom, which can substantially influence their physical, chemical, and electronic properties. However, conventional analytical techniques for nitrogen environments provide limited compositional and structural information in high sensitivity, which significantly restricts rationalized materials design. Herein, we present the advanced temperature-programmed desorption (TPD) technique up to 2,100°C as a comprehensive analytical tool for chemical speciation in bulk nitrogen-doped carbon materials with record-high sensitivity. Employing complementary X-ray photoelectron spectroscopy, elemental analysis, and computational modeling, we discovered that the gas emission patterns can provide both compositional and structural information regarding nitrogen environments. Importantly, TPD enables the bulk quantification of nitrogen species at 10 ppm levels, which is two orders of magnitude more sensitive than conventional methods. Such an advanced characterization method provides a foundation for next-generation research, focusing on the structural design at the ppm level, and offers significant potential for industrial applications.

Contemporary lifestyle is interwoven with technological achievements that implement the use of permanent magnets. Polynuclear lanthanide single-molecule magnets (SMMs) lack strong magnetic communication, which renders the design of high-performing SMMs an ongoing challenge. To overcome this, incorporation of radical pyrazine (pyz^⋅−) linkers between lanthanides is a compelling approach. Careful tuning of the synthetic conditions led to dinuclear [(Cp∗₂Ln^III)₂(pyz^⋅−)(THF)₂][BPh₄] (Ln = Gd (1), Dy (2); Cp∗ = pentamethylcyclopentadienyl; THF = tetrahydrofuran) and tetranuclear [(Cp∗₂Ln^III)₄(pyz^⋅−)₄]‧10THF (Ln = Gd (3), Dy (4)) complexes. Magnetic and computational studies reveal one of the highest exchange couplings (J_Gd-pyz = −22.2 cm⁻¹) for a radical-bridged system, achieved by two 4f-SOMO interactions. This, combined with the significant anisotropy of the Dy^III, grants 2 and 4 with slow magnetic relaxation at zero field and open hysteresis loops. A giant coercive field of 65 kOe renders 4 as the hardest radical-bridged Dy-based SMM.

Plasma catalysis offers a flexible and decentralized solution for CO₂ hydrogenation to methanol under ambient conditions, avoiding the high temperatures and pressures required for thermal catalysis. However, the reaction mechanism, particularly plasma-assisted surface reactions, remains unclear, limiting the development of efficient catalysts for selective methanol synthesis. Here, we report a bimetallic Ni-Co catalyst effective in plasma-catalytic CO₂ hydrogenation to methanol at 35°C and 0.1 MPa, achieving 46% methanol selectivity and 24% CO₂ conversion. In situ plasma-coupled Fourier transform infrared characterization, along with density functional theory calculations, reveals that the engineered bimetallic sites act as primary active centers for methanol synthesis, promoting the rate-determining step in H-radical-induced reaction pathways by reducing steric hindrance effects. This work demonstrates the significant potential of bimetallic catalysts in plasma-catalytic CO₂ hydrogenation to methanol under ambient conditions, representing a major step toward sustainable CO₂ conversion and fuel production.

Synthesis of complex glycans is extremely challenging. In the current issue of Device, Seeberger and co-workers introduce a new oligosaccharide synthesizer. The introduced technology integrates innovative solutions to overcome difficulties associated with solid-phase oligosaccharide synthesis. The focus on an energy efficient, smaller, and user-friendly device forecasts exciting advances in glycochemistry.

The development of electric aviation is limited by the need for high-power and high-capacity Li batteries. Recently, in Joule, Helms and co-workers report an omics-enabled approach to the discovery of advanced electrolytes, particularly for batteries in electric aircraft applications.