CCS Chemistry最新文献

3d-Metal-catalyzed tertiary C(sp³)–H bond activation has been a formidable challenge. Herein, a tertiary C(sp³)–H bond is smoothly activated by Ni–Al bimetallic catalysts for dual C–H annulation of formamides with alkynes, delivering a series of δ-lactams with a quaternary carbon up to 98% yield. Various tertiary C(sp³)–H bonds such as noncyclic, monocyclic and bridged-ring tertiary C(sp³)–H bonds are all compatible with the reaction.

Three-dimensional (3D) interlocking frameworks are attracting increasing research attention owing to their intriguing mechanical properties, large surface areas, and rich open sites. The study in this paper entailed the first use of tuning solvents to realize the synthesis of metal–organic frameworks (MOFs) and metallosalen-based covalent–organic frameworks (COFs) with similar 3D interlocked structures from the same precursors. These interlocking crystalline frameworks are efficient catalysts for CO₂ photoreduction. Our study is the first to investigate the impact of differences in the metal coordination environment within structurally similar COFs and MOFs in CO₂ photoreduction activity. Among the materials tested, the photocatalytic performance of the M-N₂O₄-MOFs (M = Zn, Co, and Ni) was found to be superior to that of their M-N₂O₂-COF counterparts. Notably, the Ni-N₂O₄-MOF achieved a CO production rate of 3.96 mmol g⁻¹ h⁻¹ and a CO selectivity of 93.7%. In contrast, the Ni-N₂O₂-COF exhibited a production rate of only 0.64 mmol g⁻¹ h⁻¹ with a 61.1% CO selectivity. Furthermore, a descriptor for the CO evolution rate was derived from the conduction band minimum and the reaction energy of the rate-determining step, which are two key factors influencing photocatalytic activity. This study opens up new avenues for employing interlocking crystalline frameworks in the efficient photoreduction of CO₂.

We present here an unexpected active and robust catalyst Pt/SiC-Ni, affording a high-performance direct methanol fuel cell (DMFC) with proton exchange membrane. The unique Ni-doped SiC support is obtained by an unusual method through the reaction deposition of CH₄ with NiSi₂ nanoalloys at low temperatures, in open spherical-shell morphology composed of SiC-Ni nanosheets, possessing high specific surface area (410 m² g⁻¹) and high conductivity. The membrane electrode assembly achieves a power of ∼1.12 kW g_Pt⁻¹ in DMFC with the Pt/SiC-Ni as the anodic catalyst. There are various coordination effects between the high surface area SiC with internally doped Ni and the externally loaded Pt NPs including surface reaction and mass transfer, which endows the DMFC with high power and stability. Additionally, differential electrochemical mass spectrometry and TGA-MS demonstrate the challenge of support corrosion has been significantly solved, another key factor for improving durability. The abovementioned findings are the first to demonstrate that metal-doping modified SiC materials loaded with Pt will be a highly promising catalyst for DMFC applications.

The asymmetric radical carboamination of 1,1-disubstituted alkenes from readily available alkyl halides and arylamines provides expedient access to value-added chiral α-tertiary N-arylamines but has been less recognized. A challenge arises mainly from the difficult reaction initiation inherent in alkyl halides and the construction of fully substituted chiral C–N bonds from sterically congested tertiary alkyl radicals. Herein, we report a copper-catalyzed asymmetric three-component radical carboamination of acrylamides utilizing an anionic chiral N,N,N-ligand under mild conditions. This ligand was essential for the reaction initiation by enhancing the reducing capability of copper and enabling the enantiocontrol over tertiary alkyl radicals. The substrate scope was broad, covering an array of acrylamides, aryl- and heteroaryl-amines, as well as alkyl halides and sulfonyl chlorides, enabling good functional group tolerance. When combined with the follow-up transformation, this strategy provides a versatile platform for accessing structurally diverse chiral α-tertiary N-arylamine building blocks of interest in organic synthesis.