Science China Chemistry最新文献

Alloying-type metal sulfides with high sodiation activity and theoretical capacity are promising anode materials for high energy density sodium ion batteries. However, the large volume change and the migratory and aggregation behavior of metal atoms will cause severe capacity decay during the charge/discharge process. Herein, a robust and conductive TiS₂ framework is integrated with a high-capacity SbS layer to construct a single phase (SbS)_1.15TiS₂ superlattice for both high-capacity and fast Na⁺ storage. The metallic TiS₂ sublayer with high electron activity acts as a robust and conductive skeleton to buffer the volume expansion caused by conversion and alloying reaction between Na⁺ and SbS sublayer. Hence, high capacity and high rate capability can be synergistically realized in a single phase (SbS)_1.15TiS₂ superlattice. The novel (SbS)_1.15TiS₂ anode has a high charge capacity of 618 mAh g⁻¹ at 0.2 C and superior rate performance and cycling stability (205 mAh g⁻¹ at 35 C after 2,000 cycles). Furthermore, in situ and ex situ characterizations are applied to get an insight into the multi-step reaction mechanism. The integrity of robust Na-Ti-S skeleton during (dis)charge process can be confirmed. This superlattice construction idea to integrate the Na⁺-active unit and electron-active unit would provide a new avenue for exploring high-performance anode materials for advanced sodium-ion batteries.

Bioorthogonal reactions involving transition metals have diversified applications in imaging, drug development, chemical catalysis and other fields. Transition metals used to catalyze the bioorthogonal reaction mainly include ruthenium, palladium, copper, and gold. However, the great potential for translational applications of bioorthogonal reaction needs to be further expanded and their reaction efficiency should be improved. Therefore, it is an urgent need for the development of this field to find more suitable catalysts to efficiently catalyze existing biological orthogonal reactions and expand the types of biological orthogonal reactions. Thus, this review not only summarizes those transition metal complexes-based catalysts participating in bioorthogonal reaction and some bioorthogonal reactions involving transition metals inside the cells, but also sheds light into the discovery of new transition metal complexes and their future development in applications.

A photocatalytic nonoxidative coupling of methane to multi-carbon compounds remains a huge challenge due to its high dissociation energy of C-H bonds and sluggish charge carrier dynamics. Au-modified carbon-doped ZnO (C-ZnO/Au) photocatalyst is constructed by an interfacial modification-assisted self-assembly approach for efficient photocatalytic nonoxidative coupling of methane to ethylene and hydrogen (2CH₄ = C₂H₄ + 2H₂). Benefitting from the presence of C-ZnO/Au interfaces, the catalyst not only weakens the excitonic confinement to improve the photogenerated charge carrier separation, but also enhances the stability of lattice oxygen to suppress C₂H₄ overoxidation. Moreover, this hybrid catalyst also accelerates the generation of Zn⁺-O⁻ pairs to activate C-H bonds, stabilizes the important reaction intermediate (*OCH₃) to achieve the C-C coupling, and promotes the generation of low-valence Zn to accelerate the dehydrogenation of the *OC₂H₅ into C₂H₄. Therefore, a stable photocatalytic methane conversion performance can be achieved over C-ZnO/Au heterojunctions with a stoichiometric generation of the oxidation product (C₂H₄, 45.85 µmol g⁻¹ h⁻¹) and reduction product (H₂, 88.07 µmol g⁻¹ h⁻¹). This work provides deep insights into the elemental doping and oxide/Au interfaces for the enhanced photocatalytic activity and product selectivity under mild conditions in the absence of extra oxidants.

Pentafluorosulfanylated (SF₅-) aromatics have shown great potential in drugs, and the bioisosteric replacement of aromatic ring with bicyclo[1.1.1]pentane (BCP) unit has attracted considerable attention recently. Consequently, pentafluorosulfanylated bicyclo[1.1.1]pentanes (SF₅-BCPs) should have application in the realm of drug discovery. In this study, a one-pot iodopentafluorosulfanylation of [1.1.1]propellane with SF₅Cl and CH₂I₂ for the practical synthesis of iodopentafluorosulfanylated bicyclo[1.1.1]pentane (SF₅-BCP-I) was developed. SF₅-BCP-I was the first example of SF₅-BCPs that could be transformed. The first general method to access SF₅-substituted bicyclo[1.1.1]pentane derivatives was demonstrated through photoredox-catalyzed radical addition of SF₅-BCP-I to alkenes and alkynes.

The performance of organic solar cells (OSCs) is mainly related to the bulk heterojunction (BHJ) microstructure of specific active layer systems, which is often in a metastable state. A promising strategy to address the abovementioned shortcomings of BHJs is to develop single-component active layer materials. Owing to the single-component small molecule materials with defined chemical structures generally exhibit poor absorption spectra, herein we first introduced narrow bandgap Y-series acceptors into the molecular skeleton of single-component materials, and designed two molecular dyads, SM-Et-1Y and SM-Et-2Y. The optical bandgaps ((E_{rm{g}}^{{rm{opt}}}{rm{s}})) of the two dyads are 1.364 and 1.361 eV, respectively, which are much smaller than those of previously reported single-component molecules. Consequently, the SM-Et-2Y-based single-component OSCs (SCOSCs) showed a power conversion efficiency (PCE) of 5.07%, superior to SM-Et-1Y (2.53%), which is one of the highest PCEs reported for SCOSCs to date. Moreover, both SM-Et-1Y- and SM-Et-2Y-based devices exhibited excellent photo-stability, retaining over 90% of their initial performance after 250 h of continuous illumination. Our results provide a deeper understanding of the molecular backbone and a guiding principle for the rational design or selection of non-fullerene single-component materials with suitable donor/acceptor ratios.

Simultaneously forming a carbon–carbon and a carbon–heteroatom bond in a single step through transition metal-catalyzed alkene difunctionalization strategy has emerged as a powerful tool for synthetic organic chemistry. Due to the uncontrollable reactivity, direct cross-coupling with bromoallenes as the building blocks for the selective allenation and borylation remains challenging. We herein report a new type of S- and P-stabilized bromoallenes for palladium-catalyzed modular allenation and borylation of alkenes to the divergent synthesis of multiply functionalized allenes in a highly regio- and diastereoselective manifold. The reaction features broad substrate scope and wide functional group compatibility, thus providing a straightforward method to install allenyl and boryl groups across alkenes. Control experiments highlight the crucial importance of S-, P-stabilization for the oxidative insertion of Pd-species into the allenyl–Br bond. The facile syntheses of bioactive allenic steroids and exocyclic allenes demonstrate the synthetic utility of this protocol.

Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides and β-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time. A wide range of enantioenriched pyrrolidines containing both heteroarenes and trifluoromethyl group with multiple stereogenic centers could be readily accessible by this method with good to high yields and excellent levels of both stereo- and regioselectivity (up to 99% yield, >20:1 rr, >20:1 dr, and up to 95% ee). Notably, substrate-controlled umpolung-type dipolar cycloaddition was also disclosed in this protocol to achieve regiodivergent synthesis with α-aryl substituted aldimine esters as the dipole precursors. Systematic DFT studies were conducted to explore the origin of the stereo- and regioselectivity of this 1,3-dipolar cycloaddition, and suggest that copper(II) salt utilized in this catalytic system could be reduced in-situ to the active copper(I) species and might be responsible for the observed high stereo- and regioselectivity.