Chinese Journal of Chemistry最新文献

With the growing emphasis on green and sustainable development, the development of low-energy, environmentally friendly intelligent responsive materials has become an important direction. Among these, hydrochromic molecular switches have attracted considerable attention in recent years due to their mild stimulus (water), excellent reversibility, and ease of integration with other systems. These attributes make them particularly suitable for applications such as rewritable paper, smart labels, and environmental sensors. However, most existing molecular switches exhibit only a single visible absorption band, which inherently restricts their chromatic versatility and necessitates multi-dye blending to achieve multicolor outputs. To overcome this limitation, we present a rational molecular design strategy based on asymmetric amino modification of fluoran derivatives. By introducing distinct electron- donating and hydrophilic amino groups at the asymmetric 2- and 6-positions of the xanthene ring, we successfully constructed a series of high-performance hydrochromic molecular switches (M1–M3). Upon exposure to water, these molecules undergo a complete ring-opening isomerization, giving rise to intramolecular dual absorption in the visible region with peak separations exceeding 100 nm. Control experiments and theoretical calculations reveal that the two absorption bands originate from different localized π–π* transitions within the xanthene core, and critically depend on the 2-position amino substituent to activate the higher-energy transition channel. This unique electronic architecture enables precise color-switching behavior, yielding three distinct macroscopic colors: magenta, dark green, and purple-black. These hydrochromic molecular switches, when immobilized on solid substrates, demonstrate excellent reversibility over more than 50 write–erase cycles and maintain high optical contrast. Furthermore, they are fully compatible with water-jet printing, allowing for high-resolution, multicolor patterning on cellulose-based media for rewritable paper applications. This work not only provides a simple and efficient route to multicolor hydrochromism but also establishes asymmetric amino modification as a general principle for engineering intramolecular dual absorption, offering a new perspective for the molecular design and precise color regulation of next-generation stimuli-responsive dyes.

Herein, we report a visible-light-mediated chemo- and regio-selective installation of N and S groups onto alkynes to afford 1,2-disubstituted alkane derivatives through sequential thiol-yne click chemistry and hydroamidation of alkynes with arylthiophenols and sulfonyl azides. This transformation proceeds efficiently under mild conditions with broad substrate scope, accommodating both aromatic and aliphatic alkynes. Central to this approach is the selective activation of the aryl vinyl thioether intermediate with the excited photocatalyst via triplet-triplet energy transfer (EnT) strategy to reach its excited state, which subsequently undergoes hydrogen atom transfer (HAT) with C⁴−H bond of Hantzsch ester (HE) to result in a benzyl radical intermediate and the corresponding HE^• radical. Afterwards, these two radical species could react with sulfonyl azides, respectively, to individually yield the desired product of double hydrofunctionalization of alkynes. The afforded HE^• radical species could involve in the radical chain mechanism to furnish the product according to a combined experimental and computational study. The origins of selectivity for this reaction are also rationalized. This work establishes an alternative photocatalytic approach to tackling the challenges in selectively realizing the difunctionalization of alkynes to access 1,2-diheteroatom-substituted alkanes under mild conditions.

Organic materials have obtained unprecedented attention as emerging electrodes for sodium-ion batteries (SIBs), but they suffer from poor cycling stability and rate performance. Herein, we develop a simple strategy via locking the coplanarity to tune the electron and ion transport in linear polyimide for sodium-ion batteries. From unlocked and flexible molecular chain to spatially locked molecular chain, the polyimide cathodes possess better structural stability and higher electronic conductivity, exhibiting better cycling stability and higher reversible capacity. Moreover, the locked-in coplanar conformation endows the polyimide cathode with large surface area and rich porosity, leading to a rapid ion transport, which synergizes with the good electronic conductivity to improve the rate performance of the SIBs. As a result, the optimized polyimide electrode displays high capacity retentions of 99% after 100 cycles at 50 mA·g^–1 and 100% after 3000 cycles at 1000 mA·g^–1. This work expands the palette to design organic electrodes for high-performance SIBs.

A practical photoinitiated synthetic method for the site-selective γ - and α-chlorination of C(sp³)–H bonds of ketones, (E)-1,3-enones, and alkylbenzenes by chloramine-T (CAT) and N-chlorosuccinimide (NCS) under blue LED (λ_max = 456 nm) light irradiation is reported. Mechanistic studies suggest the reaction to proceed via a radical pathway where the chlorination reagent dichloramine-T (DCT) is generated in situ from the reaction of CAT with NCS. Its premised controlled formation along with that of the carbon-centered radical species derived from the substrate is thought to contribute to product site-selectivity. The developed protocol operates under mild reaction conditions at room temperature and demonstrates excellent functional group tolerance as exemplified by the site-selective γ-C(sp³)–H bond chlorination of carboxylic esters and amides, and late-stage functionalization of several bioactive natural products and drug molecules. The study also highlights the potential of CAT for the first time as a versatile and controllable chlorine radical atom source for site-selective halogenation reactions, expanding its synthetic utility beyond traditional applications.

The origin of a transformation's stereoselectivity is one of the core issues in asymmetric catalysis. Herein, we propose a general competitive induction model for predicting stereoselectivity in dual transition-metal-NHC asymmetric catalysis. This model is demonstrated to explore the origin of stereoselectivity for the asymmetric synthesis of spirooxindoles by Cu(I)/NHC-catalysed [3+3] annulation. Computational studies suggest a mechanism involving deprotonation, Brønsted-acid-assisted decarboxylation, nucleophilic addition, cyclic esterification, and protonation. Our studies suggest that nucleophilic addition is the reversible stereocenter-generating step, while subsequent irreversible cyclic esterification is the stereoselectivity-determining step. The metal-coordinated chiral NHC ligand and the NHC organocatalyst work together to induce chirality in the stereocenter-generating step. In the subsequent stereoselectivity-determining step, the NHC ligand is innocent due to its long distance from the reaction site. Thus, the stereoselectivity is fully determined by the NHC organocatalyst. This constitutes a significant difference from the widely proposed synergistic induction model. This competitive induction model elucidates how the two chiral sources govern stereoselectivity in the stereocenter-generating and stereoselectivity-determining steps, providing valuable insights for the rational design of cooperative asymmetric catalyst systems.

Direct C(sp³)−H alkylation of alkylpyridines provides an efficient route to C(sp³)-rich pyridine motifs, which are highly prevalent in pharmaceuticals and agrochemicals. While numerous ionic methods have been developed, they typically require strong bases, elevated temperatures, or pre-functionalized substrates. To circumvent these limitations, photocatalytic methods relying on radical reactions have emerged, however, pre-activation of the substrates is required or the olefin scope is limited. Here, we report a visible light photocatalytic strategy for pyridylic C(sp³)−H alkylation via in situ borane exchange between pyridine substrates and triphenylphosphine-borane. This method operates under mild conditions, avoids the need for strong bases or metal catalysts, and accommodates both styrenes and unactivated olefins as coupling partners. Mechanistic studies revealed that borane exchange enhances the acidity of the C(sp³)−H bonds, thereby enabling rapid deprotonation to form a pyridylic carbanion intermediate. Subsequent single-electron oxidation by the oxidized form of the photocatalyst (PC) then generates the key pyridylic radical intermediate, which adds to olefins to generate another carbon-centered radical. Final hydrogen atom transfer from an arylthiol affords the desired product in good yields.

Conventional lithium-ion batteries that utilize high melting point ethylene carbonate (EC) solvent and graphite anodes exhibit a narrow operating temperature range, which is insufficient to meet the wide-temperature requirements of electric vehicle power batteries. Herein, a novel electrolyte featuring an anion-enriched solvation structure is developed by incorporating ethyl difluoroacetate (DFAE), a fluorinated solvent with wide liquid range and weak solvation capability, which enables the stable operation of lithium metal batteries (LMBs) over a broad temperature range (–50 °C to 60 °C). The anion-enrich solvation structure facilitates rapid desolvation and enables the formation of inorganic-dominated interphases on both the cathode and anode surfaces. NMC811||DEF||Li cells exhibit a high specific capacity of 194.7 mAh·g^–1 at a 2 C rate and room temperature, retaining 77.16% capacity after 400 cycles. The pouch cell using DEF electrolyte successfully powered an LED panel at –50 °C, demonstrating practical viability. This innovative strategy provides a promising pathway for the development of next generation wide-temperature LMBs.

Two-dimensional conductive metal–organic frameworks (2D c-MOFs), constructed by coordination between metal ions and π-conjugated ligands, represent a unique class of materials that combine intrinsic porosity and electrical conductivity. However, the contribution of metal nodes to the overall electrical properties remains unclear. In this work, we systematically investigate the role of metal centers on a series of six highly crystalline hexahydroxytriphenylene (HHTP) based c-MOFs, M-HHTP, which incorporate alkaline earth including magnesium and calcium, as well as transition metals including cobalt, nickel, copper, and zinc. Comprehensive structural characterizations reveal that while all M-HHTP frameworks adopt a general honeycomb lattice, however, subtle variations in stacking patterns and coordination environments are induced by different metal ions. Electrical measurements show a pronounced dependence of conductivity on the nature of the metal nodes, in which the conductivity differs by four orders of magnitude due to the difference in metal centers. Furthermore, non-contact terahertz spectroscopy combined with theoretical calculations suggests that in alkaline earth metal-based MOFs, charge transport may proceed via a through-space hopping mechanism between organic ligands. This study elucidates the critical role of metal centers in governing charge transport in M-HHTP MOFs and offers valuable guidance for the rational design of high-performance 2D conductive frameworks.