Chinese Journal of Chemistry最新文献

Although rotaxane dendrimers have shown extensive applications in stimuli-responsive materials, photocatalysis, and chiral luminescent materials, the detailed elucidation of their stimuli-induced motion behaviors remains a major challenge primarily attributed to the dynamic and complicated three-dimensional architectures. Herein, we present the first successful preparation of a new family of selectively-deuterated rotaxane dendrimers, in which deuterated pillar[5]arene wheels were precisely distributed on different generations of the dendrimer skeleton. In particular, the third-generation fully-deuterated rotaxane dendrimer with 28 deuterated [2]rotaxane units was successfully synthesized, enabling the deuteration of 1,400 hydrogen atoms. More importantly, the introduction of acetate anions at varying ratios induced differential contraction motions across different generations of the rotaxane dendrimer, as systematically investigated using a combination of ¹H NMR and small-angle neutron scattering (SANS) techniques, providing fundamental insights into the operational mechanism of molecular machines and the cooperative behavior of dynamic systems for further development of novel smart nanodevices and materials.

Organofluorine compounds play a critical role in diverse fields such as medicinal chemistry, materials science, and agrochemicals. Due to their scarcity in nature, the construction of C–CF₃ bonds has emerged as one of the most actively pursued topics in synthetic chemistry. The direct deoxytrifluoromethylation of alcohols offers a highly attractive route to access valuable C(sp³)-CF₃ bonds, leveraging the ubiquity and ready availability of alcohols as feedstocks. Established strategies for such transformations typically require separate reagents for sequential deoxygenation of alcohol substrates and trifluoromethylation of activated intermediates. While dual-function reagents that combine activation and fluorination are well-established in deoxyfluorination chemistry, analogous reagents for deoxytrifluoromethylation have remained largely unexplored. In this study, we address this gap by introducing 2-trifluoromethyl-benzimidazolium salt as a novel dual-function reagent capable of promoting the deoxytrifluoromethylation of benzylic alcohols. This reagent uniquely integrates the ability to activate the alcohol substrate while simultaneously serving as a trifluoromethyl source in a single operational step. The transformation is facilitated by a synergistic system combining photoredox catalysis with a copper promotion. Under mild visible-light irradiation, the photoredox cycle initiates single-electron transfer processes, generating key benzylic radical intermediates from the activated alcohols. Concurrently, the copper species stabilizes the trifluoromethyl moiety and mediates the crucial C–CF₃ bond-forming cross-coupling step. This cooperative mechanism enables the efficient one-step conversion of benzylic alcohols into their trifluoromethylated analogues. The reaction demonstrates broad functional group tolerance, accommodating double bonds, aldehydes, ketones, nitro groups, halides, and other sensitive functionalities. Scalability was also confirmed through gram-scale synthesis. In summary, this work establishes the feasibility of a dual-function reagent for deoxytrifluoromethylation, expanding the toolbox for C–CF₃ bond formation. The developed methodology offers several advantages, including easy preparation and stability of the reagent, avoidance of substrate pre-functionalization, and excellent functional group compatibility. Furthermore, this study presents a less explored reagent system for copper-catalyzed or promoted trifluoromethylation of aliphatic substrates, opening avenues for further development in radical-mediated trifluoromethylation chemistry.

The selective radical hydroalkylation of 1,3-dienes, particularly using readily available alkyl radical sources, remains a challenging synthetic transformation, primarily due to the high reactivity of radical intermediates and the presence of multiple reactive sites within the 1,3-diene framework. Herein, we disclose a mild and efficient visible-light-driven 1,4-hydroalkylation of conjugated dienes with perfect atom economy. The key steps of this protocol involve catalytic generation of C-radicals from readily available 1,3-dicarbonyls, followed by a radical 1,4-addition to form the benzyl radicals, which then undergo a single-electron-reduction and final protonation. This method features broad substrate scope, operational simplicity and high efficiency. A variety of readily available malonates, β-ketoesters and diversely substituted ary-1,3-dienes were well accommodated, yielding the corresponding 1,4-hydroalkylated products in generally good yields (50%–82% yields). This approach also broadens the synthetic utility of 1,3-dicarbonyl compounds, facilitating gram-scale synthesis, late-stage modifications of drug-like molecules and further synthetic transformations. As a result, numerous high value-added molecules were obtained, showcasing the synthetic potential of this method. Control experiments revealed that visible-light-irradiation, the photocatalyst and the base are all indispensable for the success of this protocol. Preliminary mechanistic studies, encompassing radical-trapping experiment, deuteroxide quenching experiment, light on-off experiments and Stern-Volmer experiments, support the proposed mechanism.

Eneyne is one of the most prevalent building blocks in synthetic chemistry. Alkenyl C−H alkynylation affords an efficient synthesis of eneynes, however, the direct use of styrenes as the synthon has remained much unexplored so far. We present the first α-/β-C−H alkynylation of E- and Z aryl alkenes as well as α-substituted aryl alkenes, producing complex eneynes with excellent regio- and E/Z ratio selectivity, assisted by N,N-bidentate directing group under palladium catalysis. Notably, disubstituted E-aryl alkenes underwent α-C−H alkynylation and then β-C−H alkenylation to produce conjugated dieneynes. The robustness of the protocol was further demonstrated by the successful C−H conversion of substrates including 2-alkenyl benzyl amides and anilides, proceeding by five- to seven-membered endo-/exo-palladacycles.

A bis-carbene iridium catalyst with a unique structure, featuring a straightforward synthetic route and low-cost ligands was developed. This catalyst exhibits high catalytic activity in the Julia-type olefination reactions between sulfone compounds and benzyl alcohol derivatives, with catalyst loading reduced to as low as 0.5 mol%. Furthermore, by adjusting the reaction conditions, the resultant olefinic products can be further reduced in a single step to afford the corresponding alkane compounds. This study also explores the reaction mechanism, proposing a plausible catalytic cycle based on a series of control experiments.

The homolytic fragment of the adjacent C(sp³)–C(sp²) bonds in unstrained ketones has proven to be a formidable challenge. Traditional methods for C(sp³)–C(sp²) bond activation typically require harsh reaction conditions, transition-metal catalysts, or specifically designed strained substrates, which largely limit their practical application in organic synthesis. In this study, we develop a visible light photoinduced deacylative C−C and C−S couplings of ketones under mild conditions. This approach leverages the unique reactivity of dihydroquinazolinones, which are easily accessible from commercially available ketones. Upon visible light irradiation, these precursor compounds undergo controlled homolysis to generate open-shell radical species, thereby circumventing the high bond dissociation energy that typically hinders the cleavage of C(sp³)–C(sp²) bonds. The resulting carbon-centered radicals then engage in synthetically diverse cascade reactions with various sulfonyl coupling partners, including sulfonyl oximes, heteroaryl sulfones, and sodium arylsulfinates, enabling the efficient construction of C–C and C–S bonds. This strategy features mild reaction conditions, high efficiency, broad substrate scope and readily accessible starting materials. Mechanistic studies reveal that the process follows a non-chain radical mechanism, where dihydroquinazolinones undergo single-electron transfer (SET) with the excited-state photocatalyst, generating reactive alkyl radicals that engage in subsequent reactions. By transforming simple ketones into versatile radical precursors, our method provides a new platform for reaction design and late-stage functionalization, offering chemists a valuable tool for constructing complex molecular architectures from unstrained ketones.

Quantum dots (QDs) have attracted significant attention in devices such as solar cells and photodetectors. Although polymer-based hole transport layers (HTLs) have been employed in QD devices, their mechanical flexibility remains underexplored and insufficient for wearable applications. Here, we present a novel interlayer design for PbS QD solar cells and photodetectors by incorporating a low-cost thermoplastic elastomer, SEBS (styrene-ethylene-butylene-styrene), into the polymer HTL. The addition of 10 wt% SEBS promotes a more ordered molecular packing of PM6. As a result, PbS QD solar cells achieved a power conversion efficiency of 11.43%, while the corresponding photodetectors exhibited a high specific detectivity of 2.12 × 10¹³ Jones—among the highest reported values. Beyond performance improvements, SEBS significantly enhances the mechanical flexibility of the HTLs. This work presents a new and effective strategy for simultaneously optimizing the optoelectronic performance and mechanical robustness of QD-based devices.

Developing high-performance, durable, and cost-effective oxygen reduction reaction (ORR) catalysts is essential for advancing next-generation energy devices like zinc-air batteries (ZABs). Herein, we engineer a hybrid Fe-N-C catalyst (FeSA-Fe_NP/CeO₂@NC) integrating atomically dispersed Fe-N_x sites, Fe nanoparticles, and oxygen vacancy-rich CeO₂ nanoparticles within a nitrogen-doped carbon matrix. Interfacial charge transfer and oxygen vacancy-mediated electron redistribution, synergistically enhanced by strong metal-support interactions (SMSI), optimize the electronic configuration of Fe-N_x sites and reduce their electron density. The resulting catalyst exhibits exceptional ORR activity and stability, featuring a half-wave potential of 0.925 V (vs. RHE) in alkaline media and minimal degradation (1% and 2.8% negative shifts after 10,000/20,000 cycles). In ZABs, it achieves a peak power density of 310.29 mW·cm^–2 while sustaining stable operation for over 600 h. This work demonstrates dual role of CeO₂ in enhancing activity and stability, establishing a design principle for high-performance electrocatalysts in energy conversion systems.

Despite the widespread use of allyl bromides in organic synthesis, the asymmetric transformation of allyl bromides has been less developed. To date, the asymmetric transformation of allyl bromides has been limited to single-site functionalization, and the development of dual-site asymmetric functionalization remains unexplored. In this work, the unprecedented asymmetric dual-site functionalization of allyl bromides has been realized through an efficient organocatalytic system, overcoming the persistent limitation of single-site transformations. Employing dinucleophiles including 3-aminobenzofurans, 2-aminoindoles, and cyclohexane-1,3-diones, this methodology affords benzofuro[3,2-b]pyridines and α-carbolines in good yields with excellent stereoselectivity. The transformation proceeds via a chemoselective S_N2′ pathway mediated by a chiral pyrrolidinyl sulfonamide catalyst, which generates ammonium salts in situ to achieve stereocontrol. The protocol was successfully extended to enantioenriched privileged pyran frameworks, and was applied to diverse downstream transformations. Gram-scale synthesis maintained high enantioselectivity, confirming practical utility. This approach effectively addresses key challenges in efficient construction of complex fused-ring heterocycles, substantially expanding the synthetic applications of allyl bromides.